Wednesday, April 28, 1993 8:30 - 10:25 AM Appleby J.* Welcome and Introduction No abstract available. Huntress W. T. Jr.* Objectives of the Workshop No abstract available. Venneri S. L.* Advanced Instrument Concepts No Abstract Available Duston D.* Strategic Defense Initiative Science and Technology Program No Abstract Available Pilcher C. B.* Solar System Exploration During the Next Five to Ten Years No Abstract Available Brinton H. C.* Selection and Development of SSED Science Instruments No Abstract Available Wednesday, April 28, 1993 PLUTO FAST FLYBY MISSION 10:40 - 12:00 PM Chair(s): H. Reitsema Stern A.* Pluto Fast Flyby Mission and Science Overview Planning for the Pluto Fast Flyby (PFF) mission centers on the launch of two small (110-160 kg) spacecraft late in the 1990s on fast, 6-8-year trajectories which do not require Jupiter flybys. The cost target of the two-spaceraft PFF mission is $400 million. Scientific payload definition by NASA's Outer Planets Science Working Group (OPSWG) and JPL design studies for the Pluto flyby spacecraft are now being completed, and the program is in Phase A development. Selection of a set of lightweight, low-power instrument demonstrations is planned for May 1993. According to plan, the completion of Phase A and then detailed Phase B spacecraft and payload design work will occur in FY94. The release of an instrument payload AO, followed by the selection of the flight payload, is also scheduled for FY94. I will describe the scientific rationale for this mission, its scientific objectives, and give an overview of the spacecraft and strawman payload. Malin M. C.* Visible Imaging on the Pluto Fast Flyby Mission Objectives for visible imaging of the Pluto-Charon system, as prescribed by the Outer Planets Science Working Group, are to acquire: (1) global observations (FOV of ~5000 IFOVs) at 1 km/line-pair for the purpose of characterizing surface morphology and geology; (2) global observations in 3-5 broadband colors at 5-10 km/line-pair for studies of surface properties and composition as it relates to morphology; and (3) selected observations at higher spatial resolution for study of surface processes. Several factors of the Pluto Fast Flyby mission make these difficult objectives to achieve: at Plutos distance from the Sun, there is nearly 1/1000 the amount of light as at the Earth, the flyby velocity is high (~15 km/sec), and the science requirements dictate a large data volume (1 km/line-pair implies between 20 and 50 MBytes for the panchromatic global image, and a comparable amount for the multispectral dataset). The low light levels can be addressed through a large aperture, image intensification, long exposures with precision pointing and image motion compensation (scan mirror or spacecraft movement), or time-delay integration. The high flyby velocities require short exposures, image motion compensation, or observations from considerable distance (e.g., longer focal lengths and larger apertures). Large data volume requires a large spacecraft data buffer, an internal instrument data buffer, or real-time data compression. The difficulty facing the successful Pluto Fast Flyby imaging investigation will be overcoming these technical challenges within the extremely limited mass (~2 kg) and power (~2 W) available. Smith W. H.* Hammer P. Reitsma H. Albert H. Nelson R. McKinnon W. Baines K. Infrared Mapping Spectrometer The Pluto Fast Flyby Mission is among the most challenging missions NASA has yet conceived. The challenge lies in achieving the high level of science return sought within the extremely limited resources available. The motivation is the distillation of the resources into instruments that attain the Pluto Fast Flyby science measurement goals. Success in this effort implies a utilization of novel methods and instruments, but to reduce cost must use components and mechanisms that are readily available. Novel implementations must extend the capabilities of the optical instruments beyond those of historically utilized designs in order to achieve the science measurements within mass and power limitations. The concepts, designs, and breadboard fabrication of fully integrated sensors must therefore achieve the ground rule: PFF sensors shall meet or exceed PFF stated science measurement requirements within the mass and power limitations. PRIMIS, the Pluto Reflectance Imaging-Mapping Interferometric Sensor, centers around an unobscured telescope integrated with a four-color simultaneous imager constructed with polarization beam splitters and digital array scanned interferometers (DASIs) for the infrared and the vacuum ultraviolet. This configuration reduces the instrument's mass but increases the throughput to achieve very high S/N observations. Very careful attention is given to the integration and sharing of electronics, optics, and support structures for mass reduction while constraining power requirements; e.g., PRIMIS uses no moving parts to increase reliability while reducing mass, power usage, and complexity, eliminating many potential failure modes. The telescope is both the light collector and the passive radiator for cooling the focal plane and instruments, eliminating the need for a separate passive cooler. The appropriate data acquisition timeline and subsequent onboard data analysis that is consistent with anticipated computational and memory resources is outlined. Suggested data acquisition modes (along with examples) that can save substantial data space with acceptable compromises on information content are shown from our measurements with DASIs. McClintock W.* Ultraviolet Spectrometer Ultraviolet spectroscopy can answer fundamental questions about Pluto's atmosphere, including its composition, pressure and temperature profile, and aerosol characteristics. Ultraviolet results will contribute to comparative studies of Triton and Pluto, two distant bodies known to have CH4 and N2 in their atmospheres. Potential atmospheric constituents have strong emission and absorption signatures in the wavelength range 55-200 nm. These species are best observed using a variety of techniques, including disk maps, limb scans, and solar and stellar occultations. The Voyager UVS observations of Triton provide a template to which Pluto observations should be designed. The mission design dictates that the UVS have a mass and power approaching 1 kg and 1 W respectively. The science objectives dictate the following functional requirements for a UVS: (1) an airglow mode with imaging spectroscopy; (2) a well-baffled telescope for limb scans; (3) a solar/stellar occultation mode; (4) wavelength coverage of 55-200 nm with a spectral resolution of 0.5 nm; and (5) sensitivity comparable to or better than the Voyager UVS. One instrument that meets the mission and science requirements is a dual- channel airglow/solar occultation design. The airglow channel is based on a single channel of the Cassini UltraViolet Imaging Spectrometer (UVIS), which is modified to cover the range 55-200 nm. The solar occultation channel, which consists of a concave grating in a Wadsworth mount feeding a vacuum photodiode array, looks transverse to the airglow channel through the spacecraft antenna. We estimate that such an instrument can be constructed using current technology that will weigh less than 1.3 kg and consume less than 1 W of power. The concept of combining the UVS with a visible imager and an infrared mapper in a single remote sensing instrument package is attractive from a programmatic standpoint. It should be recognized that planetary observations at extreme ultraviolet (EUV) wavelengths require special technologies and may be compromised by this approach. Wednesday, April 28, 1993 MARS ENVIRONMENTAL SURVEY (MESUR) MISSION 1:00 - 3:00 PM Chair(s): M. Tomasko Squyres S.* The MESUR Mission The MESUR mission is the most ambitious mission to Mars planned by NASA for the coming decade. It will place a network of small, robust landers on the martian surface, making a coordinated set of observations for at least one full martian year. The mission addresses two main classes of scientific objectives. The first require a large number of simultaneous observations from widely distributed sites. These include establishing networks of seismic and meteorological stations that will yield information on the internal structure of the planet and the global circulation of the atmosphere, respectively. The second are objectives that require sampling as much as possible the full diversity of the planet. These include a variety of geochemical measurements, imaging of surface morphology, and measurement of upper atmospheric properties at a range of latitudes, seasons, and times of day. MESUR presents some major challenges for development of instruments, instrument deployment systems, and onboard data processing techniques. The instrument payload has not yet been selected, but the strawman payload is (1) three-axis seismometer, (2) meteorology package that senses pressure, temperature, wind speed and direction, humidity, and sky brightness, (3) alpha-proton-X-ray spectrometer (APXS), (4) thermal analysis/evolved gas analysis (TA/EGA) instrument, (5) descent imager, (6) panoramic surface imager, (7) atmospheric structure instrument (ASI) that senses pressure, temperature, and acceleration during descent to the surface, and (8) radio science. Because of the large number of landers to be sent (about 16), all of these instruments must be very lightweight. All but the descent imager and the ASI must survive landing loads that may approach 100 g. The meteorology package, seismometer, and surface imager must be able to survive on the surface for at least one martian year. The seismometer requires deployment off the lander body. The panoramic imager and some components of the meteorology package require deployment above the lander body. The APXS must be placed directly against one or more rocks near the lander, prompting consideration of a microrover for deployment of this instrument. The TA/EGA requires a system to acquire, contain, and heat a soil sample. Both the imagers and, especially, the seismometer will be capable of producing large volumes of data, and will require use of sophisticated data compression techniques. Danielson E.* Visible Imager No Abstract Available Kaiser W.* Crisp D. Micrometeorological Package Recent trends in planetary and Earth science include the development of compact spacecraft and planetary landers. This leads to opportunities for advanced science return by the use of multiple vehicles and lander networks. The wide deployment of instruments is an important part of new programs for understanding planetary atmospheres, for monitoring seismicity and probing planetary structure, and for space science. An important part of this initiative is the development of compact, low-mass, low-power sensors and instruments that enable science return by small spacecraft. Challenges arise for sensor and instrument development because user requirements call for advances in performance with simultaneous large reduction in device mass, volume, and cost. Many important, conventional instruments operate at or near theoretical limits. Furthermore, for fundamental reasons, reducing the scale (volume and mass) of typical conventional instruments leads to a sharp reduction in performance. Clearly, new methods are required for sensor and instrument technology. The JPL microsensor and microinstrument program is directed toward developing a class of devices based on new measurement principles for emerging science applications. Recent developments at JPL include accurate, miniaturized instruments for measuring pressure, temperature, and humidity in the martian planetary boundary layer and in Earths upper troposphere and lower stratosphere. These instruments incorporate state-of-the-art electronics and silicon micromachined structures along with more conventional measurement technologies to reduce their size, cost, and power consumption. Our sensors are based on measurement technologies that are inherently accurate, durable, and offer simple calibration. In addition, these devices take advantage of silicon micromachining batch fabrication and calibration to enable low-cost production. Their small size, mass, and inherent raggedness make them ideal for deployment on a variety of measurement platforms, including the Mars MESUR landers, radiosondes, and dropsondes. First, in this presentation the requirements for meteorological measurements on Mars and Earth will be reviewed, and the Micro Weather Station instrument concept for Mars and Earth will be described. Components of the Micro Weather Station have been demonstrated. Highlighted in this presentation will be a new microhygrometer operating on accurate dewpoint principles. This device combines a millimeter-scale surface acoustic wave oscillator element with a compact temperature control element. This compact structure, packaged on a conventional power transistor header, has a volume of approximately 1 cm^3. Precision testing of this instrument demonstrates 0.1K dewpoint accuracy. In addition, new pressure-sensor devices have been developed for the Micro Weather Station. These devices employ silicon micromachined structures, including thin, free-standing membrane elements. The pressure sensors measure absolute pressure using thermal conductance techniques. Their sensitivity exceeds the requirements for Mars and upper atmosphere applications. The development of temperature, wind, and atmospheric aerosol sensors will also be described. The program described here provides new instrument capabilities for a wide range of applications and many new opportunities for Earth and planetary science. The Team Leader for this investigation is Dr. David Crisp; team members include Drs. W. Kaiser, M. Hoenk, and T. VanZandt, all at JPL. Economou T.* The APX Spectrometer for Martian Missions Obtaining the chemical composition of any planetary body should be a prime science objective of each planetary mission. The APX spectrometer has been designed to provide a detailed and complete chemical composition of all major (except H) and minor elements with high accuracy, in situ and remotely. From such complete analyses a first-order mineralogy of analyzed samples can be deduced. Laboratory studies in the past have shown that rock types (e.g., dunites, basalts, Philippinate 300 sample) were identified uniquely in blind test analyses. Such identification is more accurate than can be obtained from any other remote spectroscopic technique. The APX technique is based on three modes of nuclear and atomic interactions of alpha particles with matter resulting in three different energy spectra containing the compositional information. The instrument uses 50 to 100 mCi of Cm242 or Cm244 transuranium radioisotopes to provide a monoenergetic beam of alpha particles (6.01 MeV and 5.80 MeV respectively), and solid-state detectors for acquiring the energy spectra. The technique has been used for the first time on the Surveyor missions in 1967-1968 to obtain the first chemical composition of the Moon. Since then the instrument has been miniaturized and refined to improve its performance. The alpha and proton detectors were combined into a single telescope with a very thin Si front detector that acts like an alpha detector and at the same time as an absorber of alpha particles for the proton detector in the back. An X- ray mode was incorporated into the instrument that is by itself equivalent to an X-ray fluorescence instrument. A rather complicated logic determines if the particle is an alpha, proton, or an unwanted background event. This arrangement has improved the energy resolution of proton lines, eliminated the need for an additional guard detector system and substantially reduced the size of the sensor head. However, the big saving in size and power in the APX instrument comes from replacing the cryogenicaly cooled Si or HP Ge X-ray detectors in the X-ray mode with HgI2 ambient-temperature X-ray detectors that do not require cryogenic cooling to operate and still achieve high energy resolution. These detectors are being provided by Xsirius, Inc. in Marina del Ray. The spectrometer as it is implemented for Mars-94 and Mars-96 Russian missions (the Mars-94 and Mars-96 APX experiment are a collaboration of IKI of Moscow, The University of Chicago, and Max Planck Institut fur Chemie in Mainz) and for NASA's Pathfinder mission (the APX experiment for Pathfinder will be a collaboration of MPI Mainz and The University of Chicago) to Mars in 1996 has a combined weight of about 600 g and operates on 250 mW of power. It still can benefit from better quality alpha sources that are available from the Russians and more hybridized electronics. Banerdt W.* Kaiser W. Van Zandt T. A Microseismometer for Terrestrial and Extraterrestrial Applications The scientific and technical requirements of extraterrestrial seismology place severe demands on instrumentation. Performance in terms of sensitivity, stability, and frequency band must match that of the best terrestrial instruments, at a fraction of the size, mass, and power. In addition, this performance must be realized without operator intervention in harsh temperature, shock, and radiation environments. These constraints have forced us to examine some fundamental limits of accelerometer design in order to produce a small, rugged, sensitive seismometer. Silicon micromachined sensor technology offers techniques for the fabrication of monolithic, robust, compact, low-power and -mass accelerometers [1]. However, currently available sensors offer inadequate sensitivity and bandwidth. Our implementation of an advanced silicon micromachined seismometer is based on principles developed at JPL for high-sensitivity position sensor technology. The use of silicon micromachining technology with these new principles should enable the fabrication of a 10^-11 g sensitivity seismometer with a bandwidth of at least 0.01 to 20 Hz. The low Q properties of pure single-crystal silicon are essential in order to minimize the Brownian thermal noise limitations generally characteristic of seismometers with small proof masses [2]. A seismometer consists of a spring-supported proof mass (with damping) and a transducer for measuring its motion. For long-period motion a position sensor is generally used, for which the displacement is proportional to the ground acceleration. The mechanical sensitivity can be increased either by increasing the proof mass or decreasing the spring stiffness, neither of which is desirable for planetary applications. Our approach has been to use an ultrasensitive capacitive position sensor with a sensitivity of better than 10^-13 m/Hz^1/2. This allows the use of a stiffer suspension (leading to a wider operating bandwidth and insensitivity to physical shock) and a smaller proof mass (allowing lower instrument mass). We have built several prototypes using these principles, and tests show that these devices can exhibit performance comparable to state-of-the-art instruments. The total volume of the final seismometer sensor is expected to be a few tens of cubic centimeters, with a total mass and power consumption of approximately 100 g and 100 mW. References: [1] Petersen K. E. (1982) Proc. IEEE, 70, 420. [2] Melton B. S. (1976) Rev. Geophys. Space Phys., 14, 93. Boynton W.* Thermal Analyzer/Evolved Gas Analyzer (TA/EGA) The MESUR mission will place several landers (currently 16) on the surface of Mars in a variety of locations selected to sample the diversity of martian environments. The landers will be small and will have limited resources of mass, power, volume, and data rate. Among the instruments in the strawman payload, the thermal and evolved gas analyzer is probably the least mature. This instrument is actually a combination of two instruments: a calorimeter that heats a sample and carefully determines the heat required and a gas analyzer that determines the molecular composition of gases evolved from the sample during the heating process. The calorimeter is sensitive to phase changes, e.g., the melting of ice, and can thus be used to characterize at least some of the phases present. By correlating the evolution of gases with a phase change, one can better determine the nature of the phase change. For example, a high-temperature endothermic phase change occurring with evolution of CO2 suggests decomposition of carbonate. More subtle information can be determined by looking at details of the phase change. For example, ice will "premelt" at temperatures below 0 degrees C in a fashion that depends on the nature of the silicate surface with which it is in contact. Several concepts exist for the calorimeter. The two most common are the differential scanning calorimeter (DSC) or the differential thermal analyzer (DTA). The former generally denotes a device where sample and reference cells are actively controlled to heat at the same rate and the difference in power is recorded. The latter generally refers to a device in which sample and reference cells are heated with the same power input and the temperature difference is monitored. The DSC is more accurate but the DTA is simpler. The evolved gas analyzer can be either a collection of a few specific sensors, e.g., one for water and one for CO2, or it can be a general nonspecific analyzer such as a gas chromatograph. Normally a general-purpose instrument is preferred since it can detect surprises, but with the limited resources of MESUR and our knowledge of the two Viking lander sites, it may make sense in this case to use the simpler approach. Such an approach may preclude an exciting discovery in the polar regions where our knowledge of the martian volatiles is limited. This talk describes a candidate DSC and EGA as a basis for discussion of issues associated with using a combined thermal and evolved gas analyzer on MESUR. Wednesday, April 28, 1993 MISSIONS TO SMALL BODIES (ASTEROIDS AND COMETS) 3:20 - 5:00 PM Chair(s): P. Feldman Neugebauer M.* Current Mission Concepts, Scientific and Measurement Objectives Studies of comets and asteroids address most of the major goals of solar system exploration because (1) they are the best-preserved samples of the material from which the solar system formed, (2) they record the radial properties of and the degree of mixing in the protoplanetary nebula, (3) they contain complex organic material that may have been responsible for the origin of life on Earth, and (4) the coma of an active comet displays a wealth of astrophysical processes involving interactions between gas, dust, plasma, and sunlight. The scientific and measurement objectives of space missions to comets and asteroids developed in detail in the early 1980s by groups such as the Space Science Board and NASA's Comet Rendezvous Science Working Group remain relevant despite the intervening observations by the flybys of three comets and one asteroid. The sophistication of the measurements that can be made increases as one scales up from flybys to fly-throughs to rendezvous missions, which may carry either penetrators or soft landers, to sample-return missions of various types, such as fast collection of gas and dust from the coma of a comet or surface or subsurface samples of an asteroid or the nucleus of a comet. Veverka J.* Remote Sensing Science There are a large number of widely diverse small bodies in the solar system grouped as asteroids, comets, and small satellites. The members of each of these groups are also very diverse, and studies have begun to reveal interrelationships among the groups, e.g., 2060 Chiron, an "asteroid" that became a comet, and 4015 (1979 VA), a comet that became an "asteroid." Improving our understanding of the links between these groups will involve two major types of remote sensing scenarios: flyby missions and rendezvous or orbit missions. Some missions may involve both types, e.g., a flyby of one body on the way to a rendezvous with another. A vigorous program to study small bodies should include both flybys and rendezvous missions to provide complementary information. Multiple flybys will allow us to explore the diversity of small bodies, while rendezvous missions will allow us to gather detailed measurements of a specific type of body. Galileo's encounter with the asteroid Gaspra in October 1991, at a flyby speed of 8 km/s and a miss distance of 1600 km, highlighted some of the challenges of this type of mission. They include the extremely short (~30 min) time interval for acquiring the best data and difficulties in keeping instruments pointed accurately at closest approach. Dust surrounding comets poses an additional hazard for comet close encounters. Instrumentation for asteroid studies encompasses a wide range of imaging devices, medium- and high-resolution spectrometers, radiometers, and LIDAR. For example, general considerations for IR reflectance spectroscopy include a signal to noise ratio of 100:1 or better for integration of times of 1 s or less, spatial resolution of the surface of 10-100 m, and pixel size of 50-500 micrometers. An array detector is preferred for accurate registration with imaging. Surface mineralogy reflectance spectroscopy should include three important spectral windows: 0.3-1.1 micrometers for spectral imaging, 0.7-2.8 micrometers for the primary IR range, and 2.8-4.0 micrometers for the secondary IR range. The relative importance of each window depends on the type of asteroid to be studied. Thermal emission spectroscopy provides direct information on composition and crystal structure. Instrument requirements include a wavelength range of 6-25 micrometers at a minimum, 6-50 desirable; spectral resolution of 10 cm^-1; signal-to-noise ratio of 500:1; and spatial resolution ~5-10 mrad minimum, <1 mrad desirable. An IR radiometer, the best instrument to determine the thermal inertia of the surface, should have a wavelength range of at least 10-30 micrometers, with 5-100 micrometers desirable, and should include a VIS channel for albedo measurements. Low spatial resolution, ~1 mrad, is adequate, and sensitivity should be delta T ~ +/- 1 K over temperatures of 90-300 K. Instrumentation for comet studies is equally challenging and is very complex. For example, coma spectroscopy should include measurements at UV-VIS and mid- IR wavelengths. In the UV-VIS, a wavelength range of 1100-9000 angstroms is desirable; within this range it is essential to measure Lyman-alpha (1216 angstroms) and OH (3085 angstroms). The spectrograph should have an array detector and spectral resolution of ~1 angstrom, and ideally should have no moving parts that could be fouled with dust. Several detectors are needed to cover a broad spectral range. In the mid-IR (5-10 micrometers) the spectral region beyond about 5 micrometers is useful for measurement of polar molecules such as H2O, CH4, CO, and NH3 as well as minor organic species that may include prebiotic molecules. A very-high-spectral resolution (>10^5) is required. Innovative designs will be needed to meet these requirements while also achieving minimum mass and size. Boynton W.* In Situ Measurements We are now completing the reconnaissance phase of planetary exploration and are entering the detailed discovery phase, which generally calls for in situ measurements to address the next level of scientific questions. We have flown by all the planets except Pluto, for which a flyby is now being planned, and we have flown by asteroids and comets. We have made in situ measurements of some planetary atmospheres and on the surface of Mars. NASA has yet to launch a mission with a small body as a primary objective, but such missions may soon take place. The scientific questions that can be formulated for the small bodies of the solar system are far more detailed than might be expected based on our limited astronomical data. This is because NASA has been funding the study of meteorites and cosmic dust in the laboratory for many years. These studies have brought the full complement of laboratory instrumentation to bear on understanding the information these objects contain on how they formed and evolved. Because meteorites come from the asteroid belt and possibly from comets, we know to a large extent what types of measurements provide the most insight in understanding different aspects of these bodies. Generally, the types of measurements encompass elemental abundances, mineralogy and texture, and isotopic studies, including age dating. The state of the art is such that not all these measurements can be made in situ, but many can. Elemental abundances can be determined with a variety of instruments. Gamma ray spectroscopy can determine all major elements, some minor elements, and a few trace elements based on the emission of gamma rays from nuclei that either have interacted with cosmic-ray-produced neutrons or are radioactive. A combined alpha, proton, and X-ray spectrometer can determine most major and some minor elements, but is not sensitive to trace elements (limit about 100 ppm). It has the advantage over gamma ray spectrometry of being smaller and needing less calibration, but it requires a sample to be brought to it, whereas the gamma ray spectrometer analyzes a large volume near the instrument. Mineralogy can be determined via X-ray diffraction, Mossbauer spectroscopy, or combined thermal and evolved gas analysis. Each technique has its merits for specialized applications; they are listed in decreasing order of specificity. Isotopic studies are not so easy to carry out on a planetary body. Analysis of noble gases and light elements are probably the only isotopic measurements that have the precision necessary to address science issues. Age determinations by K/Ar dating may be possible in some situations. The Comet Penetrator/Lander of the CRAF mission will be discussed as an example of a combined approach for in situ studies. Taylor G. J.* Lunar Science: Using the Moon as a Testbed The Moon is an excellent testbed for innovative instruments and spacecraft. Excellent science can be done, the Moon has a convenient location, and previous measurements have calibrated many parts of it. I summarize these attributes and give some suggestions for the types of future measurements. Lunar Science: The Lunar Scout missions planned by NASA's Office of Exploration will not make all the measurements needed. Thus, test missions to the Moon can also return significant scientific results, making them more than technology demonstrations. Location: The Moon is close to Earth, so cruise time is insignificant, tracking is precise, and some operations can be controlled from Earth, but it is in the deep space environment, allowing full tests of instruments and spacecraft components. Calibrations: The existing database on the Moon allows tests of new instruments against known information. The most precise data come from lunar samples, where detailed analyses of samples from a few places on the Moon provide data on chemical and mineralogical composition and physical properties. Apollo field excursions provided in situ measurement of surface geotechnical properties and local magnetic field strength. Orbital data obtained by Apollo missions also supply a useful set of standards, although not global in extent; data include chemical composition by gamma and X-ray spectrometry, imaging, and magnetic field strength. Observations at high spectral resolution have been obtained from terrestrial telescopes, providing spectral calibration points for numerous 1-5-km spots on the lunar surface. Finally, additional multispectral imaging has been obtained by the Galileo spacecraft and a global multispectral dataset will be acquired by the Clementine mission. Thus, the Moon is a large, Earth-orbiting standard on which to test new instruments. Potential Instruments: The following list shows examples of the types of instruments that could take advantage of the Moon's virtues as a testbed. Lunar Scout I and II do not include items 1-4. Items 5-7 are thus essential if Scout does not fly; but even if Scout is successful, new generations of these instruments (smaller, better resolution, etc.) can still use the global data base obtained by Scout as calibrations. (1) Atmospheric sensors, such as UV spectrometers and mass spectrometers. (2) Magnetic field detectors, such as magnetometers and electron reflectometers. (3) Altimeters for topography measurements. (4) Microwave radiometers, especially for heat flow determination. (5) Imaging spectrometers to obtain mineralogical information about the Moon. (6) Imaging systems for geologic mapping. (7) Devices to make chemical analyses from orbit-present instruments, such as gamma ray spectrometers, are large and heavy, so new, smaller devices are essential for future planetary missions. In Situ Analyses: Excellent lunar science could be done using rovers carrying experimental payloads. Possible instruments include devices to do chemical and mineralogical analyses, high-resolution stereo imaging systems, gas analyzers, seismometers, heat flow probes, and atmospheric sensors. Lane A.* Mars '94 Occident Experiment No Abstract Available Hubbard S.* Planetary Instrumentation: Closing Comments No abstract available. Thursday, April 29, 1993 SDIO-DEVELOPED INSTRUMENT TECHNOLOGY WITH POTENTIAL APPLICATION TO PLANETARY EXPLORATION 8:30 AM Duston D.* Introduction and Overview No abstract available. Thursday, April 29, 1993 TECHNOLOGY SCHEDULED TO BE FLIGHT TESTED 8:45 - 12:00 PM Chair(s): D. Duston Rustan P.* Small Satellite Sensors and Image Processing I The Clementine mission will demonstrate and flight qualify several lightweight spacecraft components developed by the Ballistic Missile Defense Organization. The sensors and processors to be tested in the spacecraft were developed to detect ballistic missiles. In the Clementine mission, these technologies will be tested in a dual-use role for a civil scientific sector application, such as looking at cold objects, the Moon, and a near-Earth asteroid against a space background. Specifically, the mission will test two lightweight star tracker camers, a UV/VIS camera, a near-infrared camera, a long-wave infrared camera, a lidar, and a 32-bit computer. The star tracker cameras, 370 g each, will provide three-axis attitude determination using only a single starfield image, with a field of view of 20 degrees X 43 degrees. Each camera consumes 7 W and is accurate to 150 microradians. The UV/VIS imaging system is a CCD camera with a bandpass from 250 nm to 1000 nm; it will carry a filter wheel with six positions at 415 nm, 750 nm, 900 nm, 950 nm, 1000 nm, and broadband from 400 to 950 nm. The UV/VIS camera weighs 500 g, uses 6 W of power, and has a field of view of 4.2 degrees X 5.6 degrees. The near-infrared camera will have a mechanically cooled 256 X 256-pixel Indium Antimonide Focal Plane Array (InSb FPA) with a bandpass from below 1100 nm up to 2800 nm and a filter wheel with positions at 1100 nm, 1250 nm, 1500 nm, 2000 nm, 2600 nm, and 2780 nm. The camera weighs about 1600 g, uses 30 W of power including the cryocooler, and has a field of view of 5.6 degrees X 5.6 degrees. The long-wave infrared camera will have a mechanically cooled 128 X 128 HgCd telluride FPA. The array will be mechanically cooled and will have a broadband response from 8000 to 9500 nm. The camera weighs about 1550 g, uses 30 W of power, and has a field of view of 1 degree X 1 degree. The lidar consists of a laser transmitter and a high-resolution camera. The laser transmitter is a diode-pumped Nd-YAG laser with a mass of 1 kg, a pulse energy of 180 mJ at a pulse length of 10 ns, and a repetition rate of 8 Hz. The high-resolution camera is a Si CCD, weighs 1250 g, uses 12 W of power, and has a field of view of 0.3 degrees X 0.4 degrees. Finally, the 32-bit processor is a reduced instruction set computing (RISC) processor that operates at about 20 Mips and 3.5 MFlops. It has a mass of ~500 g and is expected to be radiation immune to about 15 krads (Si). Additionally, the mission uses advanced lightweight technologies in the electrical, mechanical, structure and materials, and attitude control systems. The mission is expected to be launched in January 1994 in a Titan IIG launch vehicle, spend two months mapping the lunar orbit from a 400-km orbit, and flyby the near-Earth asteroid Geographos in August 1994. Ledebuhr A.* Small Satellite Sensors and Image Processing II No Abstract Available Pleasance L.* Small Satellite Sensors and Image Processing III No Abstract Available Mill J.* Phenomenology Sensors and Processors No Abstract Available Holtkamp D.* Lightweight LIDAR No Abstract Available Thursday, April 29, 1993 TECHNOLOGY STILL IN THE LABORATORY 1:00 - 4:00 PM Dyer W. R.* Interceptor Seeker Technology BMDO interceptor sensor technologies that can support NASA planetary missions include lightweight, nuclear hard LWIR seekers; nuclear hard LWIR HgCdTe FPA producibility, multiple quantum array detectors; multianode microchannel array UV seekers; high-speed, lightweight, nuclear hard signal processors; and miniature solid-state and CO2 ladar. The nuclear hard LWIR (8-14 micrometers) Advanced Technology Seeker (LATS) has cooled optics, microscan mirrors, and microlenses for long acquisition range and nuclear hardness. Its mass is 4.5 kg and its volume is 14,000 cc. The LATS consumes 2 W of power and uses a 128 x 128 HgCdTe FPA 25-micrometer pitch. Readout noise is 190 electrons, and D* at the 40K FPA operating temperature is 10^13 cm-Hz**0.5/W. The BMDO Pilotline Experiment Technology (PET) program is developing producible nuclear hard HgCdTe FPAs for both low-background (10^9-10^13 photons/cm^2/s) and high-background (10^13-10^15 photons/cm^2/s) applications. Both 128 x 128 and 256 x 256 FPAs will be addressed. A total of 80-100 FPAs will be constructed to demonstrate producibility. The detectors have 30- micrometer pitch, 14-micrometer cutoff, 70% quantum efficiency, 10^14 W/cm^2 NEFD, and a dynamic range of 94 db. GaAs and AlGaAs LWIR multiple quantum well arrays (128 x 128) are under development. These arrays have 8.5-10.5 spectral bands, 60-micrometer pitch, and D* = 10^10 cm-Hz**0.5/W. The program goal is 2-4% conversion efficiency with a responsivity of 0.1-0.2 amps/W). A 224 x 224 multianode microchannel array solar blind (0.25-0.238 micrometers) UV seeker was under development in the BMDO Ultraseek program. A brassboard weighing 7.7 kg was built. The seeker had 10-20% quantum efficiency, 10-100-Hz variable frame rate, 10-degree FOV, and 100-microradian IFOV with an off-axis telescope and 10-cm aperture. A six-position filter wheel with 0.5-s response time was used. The signal processor used in the Ultraseek brassboard was from the Signal Processor Packaging Design (SPPD) program. It has a throughput of 396 MOPS. The SPPD uses hybrid wafer-scale integration, weighs 75 g, and consumes 10 W of power. A hardened signal processor called the Advanced Hardened Avionics Technology (AHAT) processor is also under development. AHAT was to have a 3 GOP throughput and weighed 1 kg. Miniature solid-state and CO2 laser radars are under development. They will have 200-400-km acquisition range against -23 db targets, with 20-cm range and cross-range resolution. Mass of the laser radars will be 3-5 kg. Optical phased array beam steering is also under development for use with both BMDO laser radars. Lau C.* Advanced Processor Technology No Abstract Available Frederick W. G. D.* Advanced Sensors I In order to meet the surveillance, acquisition, tracking, and kill assessment requirements for SDIO sensor and interceptor platforms, research and development has been underway for the last 10 years on focal plane arrays, cryocoolers, optics and coatings, digital and memory circuit components, and spacebased signal and data processors. Focal plan array efforts have concentrated on radiation-hardened SWIR, MWIR, and LWIR Hg Cd telluride; MWIR In antimonide; visible silicon CCDs; and VLWIR As-doped silicon. Cryocooler research and development included the development of long-life (>7 years) coolers operating at 10, 40, and 65K to provide cooling of focal plane arrays and optics. The radiation-hardened optics work comprised the preparation and figuring of Be in sizes up to 1 m in diameter, as well as research and development on the preparation and characterization of Si carbide. In addition, techniques were developed to deposit antireflection coatings on Be and Si carbide optics. Radiation-hardened digital and memory components (such as A/D converters, SRAMs, ferroelectronic memories, etc.) were developed through extension and hardening of DARPA VHSIC technology.Finally, radiation- hardened time-dependent and object-dependent signal processors and data processors have been developed for spacebased applications, including Brilliant Pebbles and Brilliant Eyes satellites. Kukkonen C.* Advanced Sensors II No Abstract Available Duston D.* Advanced Sensors III No Abstract Available Nisenoff M.* Superconducting Sensors/Processors One requirement of an SDIO surveillance mission is the capability of acquiring and tracking cold bodies against the cold background of space, a requirement paralleling the NASA mission to planets such as Pluto. A technology that enables very high speed at very-low-power on-focal-plane array signal processing for large (10,000-1,000,000 pixels) VLWIR sensors required to operate at 10 K is low-temperature superconductivity (LTS). Significant progress has recently been made in LTS digital signal processing. Superconducting transimpedance amplifiers (TIA), 12-bit analog-to-digital converters (ADC), high-speed shift registers (SR), digital multiplexers (MUX), and wide-band superconducting detectors have been demonstrated and operated at 10 K in Nb nitride technology. A proof of concept for the conversion of photons to bits for detection by a LTS single pixel through the ADC was demonstrated in 1992. An operational focal plane with interface electronics and an LTS analog signal processor all operating at 10 K will be demonstrated using a scene generator in the 4QFY94. A LTS foundry exists that is capable of providing custom circuits with appropriate interface electronics. Todays superconductor technology will enable the achievement of low-power, low- weight, high-fidelity goals for future NASA planetary missions. Heighwey E.* Neutral Particle Beam Sensing: Proposed Experiment No Abstract Available Thursday, April 29, 1993 INFORMAL WORKING GROUP MEETINGS 3:20 - 5:30 PM No abstract available. Friday, April 30, 1993 WORKING GROUP REPORTS AND PANEL DISCUSSION 8:30 - 12:00 PM Chair(s): S. Hubbard No abstract available. Wednesday, April 28, 1993 CONTRIBUTED POSTERS 5:00 - 6:30 PM Basedow R. Silverglate P. Rappoport W. Rockwell R. Rosenberg D. Shu K. Whittlesey R. Zalewski E. The HYDICE Instrument Design and Its Application to Planetary Instruments The Hyperspectral Digital Imagery Collection Experiment (HYDICE) instrument represents a significant advance in the state of the art in hyperspectral sensors. It combines a higher signal-to-noise ratio (SNR) and significantly better spatial and spectral resolution and radiometric accuracy than systems flying on aircraft today. The need for "clean" data, i.e., data free of sampling artifacts and excessive spatial or spectral noise, is a key driver behind the difficult combination of performance requirements laid out for HYDICE. Most of these involve the sensor optics and detector. This paper presents an optimized approach to those requirements, one that comprises pushbroom scanning, a single, mechanically cooled focal plane, a double-pass prism spectrometer, and an easily fabricated yet wide-field telescope. Central to the approach is a detector array that covers the entire spectrum from 0.4 to 2.5 micrometers. Among the major benefits conferred by such a design are optical and mechanical simplicity, low polarization sensitivity, and coverage of the entire spectrum without suffering the spectral gaps caused by beamsplitters. The overall system minimizes interfaces to the C141 aircraft on which it will be flown, can be calibrated on the ground and in flight to accuracies better than those required, and is designed for simple, push-button operation. Only unprocessed data are recorded during flight. A ground data processing station provides quick-look, calibration correction and archiving capabilities, with a throughput better than the requirements. Overall performance of the system is expected to provide the solid database required to evaluate the potential of hyperspectral imagery in a wide variety of applications. HYDICE can be regarded as a testbed for future planetary instruments. The ability to spectrally image a wide field of view over multiple spectral octaves offers obvious advantages, and is expected to maximize science return for the required cost and weight. Bedard A. J. Jr. Nishiyama R. T. Rugged, No-Moving-Parts Windspeed and Static Pressure Probe Designs for Measurements in Planetary Atmospheres Instruments developed for making meteorological observations under adverse conditions on Earth can be applied to systems designed for other planetary atmospheres. Specifically, a wind sensor developed for making measurements within tornados [1] has no moving parts, detecting induced pressure differences proportional to wind speed. Addition of strain gauges to the sensor would provide wind direction. The device can be constructed in a rugged form for measuring high wind speeds in the presence of blowing dust that would clog bearings and plug passages of conventional wind speed sensors. Sensing static pressure in the lower boundary layer required development of an omnidirectional, tilt-insensitive static pressure probe [2]. The probe provides pressure inputs to a sensor with minimum error and is inherently weather-protected. Both the wind sensor and static pressure probes have been applied in a variety of field programs and can be adapted for use in different planetary atmospheres. References: [1] Bedard A. J. Jr. and Ramsey C. (1988) J. Appl. Meteor., 22, 911-918. [2] Nishiyama R. T. and Bedard A. J. Jr. (1991) Rev. Sci. Inst., 62, 2143-2204. Berwald D. H. Nordin P. Design of a Particle Beam Satellite System for Lunar Prospecting No abstract available. Blacic J. Pettit D. Cremers D. Roessler N. Laser-induced Breakdown Spectroscopy Instrument for Elemental Analysis of Planetary Surfaces We have performed laboratory calibrations in air and in vacuum on standard rock powders to quantify the LIBS analysis. We have performed preliminary field tests using commercially available components to demonstrate remote LIBS analysis of terrestrial rock surfaces at ranges of over 25 m, and we have demonstrated compatibility with a six-wheeled Russian robotic rover vehicle. Based on these results, we believe that all major and most minor elements expected on planetary surfaces can be measured with absolute accuracy of 10- 15% and much higher relative accuracy. We have performed preliminary systems analysis of a LIBS instrument to evaluate probable mass and power requirements; results of this analysis are summarized in Table 1, which in the hard copy appears here. Boain R. J. Clementine II: A Double Asteroid Flyby and Impactor Mission Recently JPL was asked by SDIO to analyze and develop a preliminary design for a deep-space mission to fly by two near-Earth asteroids, Eros and Toutatis. As a part of this mission, JPL was also asked to assess the feasibility of deploying a probe on approach to impact Toutatis. This mission is a candidate for SDIO's Clementine II. SDIO's motivations were to provide further demonstrations of precision, autonomous navigation for controlling the flight paths of both a spacecraft and a probe. NASA's interest in this mission is driven by the opportunity to obtain the first close-up images and other scientific measurements from a spacecraft of two important near-Earth objects. For Toutatis this is especially important since it was observed and imaged extensively just last December using Earth-based radar; Clementine II will provide the opportunity to corroborate the radar data and validate the ultimate potential of the radar technique. Scientifically, the probe impact at Toutatis will allow the acquisition of data pertaining to the dynamic strength of surface material, data on the properties of the regolith and on stratification below the surface, and will potentially allow the measurement of thermal diffusivity between the interior and the surface. These determinations will be accomplished by means of high- resolution imagery of the impact crater and its surroundings invisible, ultraviolet, and infrared wavebands from the spacecraft flying by some 30 min after the probe strike. In addition, if the spacecraft can be equipped with a lightweight mass spectrometer and dust analyzer, the potential also exists to measure the particle sizes and distribution and the composition of the ejecta cloud. This mission is planned to be launched in July of 1995, with the Eros encounter on March 13, 1996, and the Toutatis flyby on October 4, 1996, some 440 days after launch. The Eros encounter is characterized by a flyby speed of 8.4 km/sec and a Sun-target-spacecraft phase angle of 120 degrees. Thus, the principal visible light images of Eros will be obtained after closest approach. The Eros miss distance is nominally set at 30 km. For Toutatis, the encounter is characterized by an approach speed of 17.8 km/sec and a phase angle of 20 degrees. With this approach geometry, Toutatis presents a sunlit face to the spacecraft and probe. The probe will hit the asteroid at approximately 18 km/sec. To facilitate imagery of the impact crater and to assure continuous line-of-sight tracking through encounter, the closest approach distance at Toutatis is selected to be 50.0 km. Burke B. E. Mountain R. W. Gregory J. A. Huang J. C. M. Cooper M. J. Savoye E. D. Kosicki B. B. High-Performance Visible/UV CCD Focal Plane Technology for Spacebased Applications We describe recent technology developments aimed at large CCD imagers for spacebased applications in the visible and UV. Some of the principal areas of effort include work on reducing device degradation in the natural space- radiation environment, improvements in quantum efficiency in the visible and UV, and larger device formats. One of the most serious hazards for space-based CCDs operating at low signal levels is the displacement damage resulting from bombardment by energetic protons. Such damage degrades charge-transfer efficiency and increases dark current. We have achieved improved hardness to proton-induced displacement damage by selective ion implants into the CCD channel and by reduced temperature of operatlon. To attain high quantum efficiency across the visible and UV we have developed a technology for back- illuminated CCDs. With suitable antireflection (AR) coatings such devices have quantum efficiencies near 90% in the 500-700 nm band. In the UV band from 200 to 400 nm, where it is difficult to find coatings that are sufficiently transparent and can provide good matching to the high refractive index of silicon, we have been able to substantially increase the quantum efficiency using a thin film of HfO2 as an AR coating. These technology efforts have been applied to a 420 x 420-pixel frame-transfer imager, and future work will be extended to a 10^24 x 10^24-pixel device now under development. This work was sponsored by the Department of the Air Force. Chen Y. C. Lee K. K. Every Good Virtue You Ever Wanted in a Q-switched Solid-State Laser and More--Monolithic, Diode-pumped, Self-Q-switched, Highly Reproducible, Diffraction-limited Nd:YAG Laser The applications of Q-switched lasers are well-known, for example, laser radar, laser remote sensing, satellite orbit determination, moon orbit and "moonquake" determination, satellite laser communication, and many nonlinear optics experiments. Most of the applications require additional properties of the Q-switched lasers, such as single-axial and/or single-transverse mode, high repetition rate, stable pulse shape and pulse width, or ultracompact and rugged oscillators with some or all of the above properties. Furthermore, space-based and air-borne lasers for lidar and laser communication applications require efficient, compact, lightweight, long-lived, stable- pulsed laser sources. Diode-pumped solid-state lasers (DPSSL) have recently shown the potential of satisfying all these requirements. We will report the operating characteristics of a diode-pumped monolithic self-Q-switched Cr,Nd:YAG laser where the chromium ions act as a saturable absorber for the laser emission at 1064 nm [1]. The pulse duration is 3.5 ns and the output is highly polarized with an extinction ratio of 700:1 [1]. It is further shown that the output is single-longitudinal-mode with transform- limited spectral linewidth without pulse-to-pulse mode competition [2]. Consequently, the pulse-to-pulse intensity fluctuation is less than the instrument resolution of 0.25% [2]. This self-stablilization mechanism is because the lasing mode bleaches the distributed absorber and establishes a gain-loss grating [3,4] similar to that used in the distributed feedback semiconductor lasers. Repetition rate above 5 KHz has also been demonstrated [3]. Figure 1, which appears in the hard copy, shows how compact, simple, and rugged this laser oscillator is. For higher power, this laser can be used for injection seeding an amplifier (or amplifier chain) or injection locking of a power oscillator pumped by diode lasers. We will discuss some research directions on the master oscillator for higher output energy per pulse as well as how to scale the output power of the diode-pumped amplifier(s) to multikilowatt average power. References: [1] Li S.-Q. et al. (1993) Opt. Lett., 18, 203. [2] Li S.-Q. et al. (1993) Opt. Lett., 18, April 1 issue. [3] Chen Y. C. et al. (1993) Opt. Lett., 18, in press. [4] Li S.-Q., Appl. Phys. Lett., submitted. Chenette D. L. Wolcott R. W. Selesnick R. S. Planetary and Satellite X-Ray Spectroscopy: A New Window on Solid-body Composition by Remote Sensing The rings and most of the satellites of the outer planets orbit within the radiation belts of their parent bodies, an environment with intense fluxes of energetic electrons. As a result these objects are strong emitters of X-rays. The characteristic X-ray lines from these bodies depend on atomic composition, but they are not sensitive to how the material is arranged in compounds or mixtures. X-ray fluorescence spectral analysis has demonstrated its unique value in the laboratory as a qualitative and quantitative analysis tool. This technique has yet to be fully exploited in a planetary instrument for remote sensing. The characteristic X-ray emissions provide atomic relative abundances. These results are complementary to the molecular composition information obtained from IR, visible, and UV emission spectra. The atomic relative abundances are crucial to understanding the formation and evolution of these bodies. They are also crucial to the proper interpretation of the molecular composition results from the other sensors. The intensities of the characteristic X-ray emissions are sufficiently strong to be measured with an instrument of modest size. Recent developments in X-ray detector technologies and electronic miniaturization have made possible space-flight X-ray imaging and nonimaging spectrometers of high sensitivity and excellent energy resolution that are rugged enough to survive long-duration space missions. Depending on the application, such instruments are capable of resolving elemental abundances of elements from carbon through iron. At the same time, by measuring the bremsstrahlung intensity and energy spectrum, the characteristics of the source electron flux can be determined. We will discuss these concepts, including estimated source strengths, and will describe a small instrument capable of providing this unique channel of information for future planetary missions. We propose to build this instrument using innovative electronics packaging methods to minimize size and weight. Cheng L.-J. Chao T.-H. Dowdy M. Mahoney C. Reyes G. Polarimetric Multispectral Imaging Technology The Jet Propulsion Laboratory is developing a remote sensing technology on which a new generation of compact, lightweight, high-resolution, low-power, reliable, versatile, programmable scientific polarimetric multispectral imaging instruments can be built to meet the challenge of future planetary exploration missions. The instrument is based on the fast programmable acousto-optic tunable filter (AOTF) of tellurium dioxide (TeO2) that operates in the wavelength range of 0.4-5 micrometers. Basically, the AOTF multispectral imaging instrument measures incoming light intensity as a function of spatial coordinates, wavelength, and polarization. Its operation can be in either sequential, random access, or multiwavelength mode as required. This provides observational flexibility, allowing real-time alternation among desired observations, collecting needed data only, minimizing data transmission, and permitting implementation of new experiments. These will result in optimization of the mission performance with minimal resources. This instrument can be used for two types of applications for future planetary exploration missions. First, the instrument is placed on a flight platform for mapping the interesting features on the surface and in the atmosphere of a planet or a moon. For example, this instrument is an excellent candidate as a visible-infrared imaging spectrometer for the Lunar Observer and a polarimetric imaging spectrometer for the Pluto Fast Flyby. The same instrument can be used to investigate atmospheric physics and chemistry of Jupiter and Saturn. In the other application, the instrument is used on a rover or a surface package on Mars and the Moon as an intelligent vision instrument for searching, identifying, mapping, and monitoring geological features, characterizing atmospheric contents and their time variability, as well as collecting valuable samples. For example, these instrument applications will support major scientific objectives of the Mars Environmental Survey (MESUR) program and the Evolutionary Mars Sample Return Program. In the past we built two AOTF imaging spectrometer breadboard systems covering visible to short-wavelength infrared ranges and successfully demonstrated capabilities for identifying minerals and mapping content distributions; characterizing botanical objects; and measuring polarization signatures. In addition, we demonstrated the use of an optical fiber bundle as an image transfer vehicle in the AOTF system with the objective of developing an AOTF system with a flexible observation head for rover applications. Recently we completed a polarimetric multispectral imaging prototype instrument and performed outdoor field experiments for evaluating application potentials of the technology. We also investigated potential improvements on AOTF performance to strengthen technology readiness for applications. This paper will give a status report on the technology and a prospect toward future planetary exploration. De Young R. J. Situ W. A Remote Laser-mass Spectrometer for Determination of Elemental Composition Determination of the elemental composition of lunar, asteroid, and planetary surfaces is a major concern for science and resource utilization of space. The science associated with the development of a satellite or lunar rover laser- mass spectrometer instrument is presented here. The instrument would include a pulsed laser with sufficient energy to create a plasma on a remote surface. Ions are ejected from this plasma, which travel back to the spacecraft or rover where they are analyzed by a time-of-flight mass spectrometer, giving the elemental and isotope composition. This concept is based on the LIMA-D instrument onboard the former Soviet Union Phobos-88 spacecraft sent to Mars. A laser-mass spectrometer placed on a rover or satellite would substantially improve the data return over alternative techniques. The spatial resolution would be centimeters, and a complete mass spectrum could be achieved in one laser shot. An experiment is described that demonstrates these features (Fig. 1, which in the hard copy appears here). A 400-mj Nd:YAG laser is focused, to an intensity of 10^11 W/cm^2, onto an Al, Ag, Cu, Ge, or lunar simulant target. A plasma forms from which ions are ejected. Some of these ions travel down an 18-m evacuated flight tube to a microchannel plate detector. Alternatively, the ions are captured by an ion trap where they are stored until pulsed into a 1-m time-of-flight mass spectrometer, giving the elemental composition of the remote surface. A television camera monitors the plasma plume shape, and a photo diode monitors the temporal plasma emission. With this system, ions of Al, Ag, Cu, Ge, and lunar simulant have been detected at 18 m. The mass spectrum from the ion trap and 1-m time-of-flight tube will be presented. Figure 2, which in the hard copy appears here, shows ions of Al (1803 eV), Cu (1483 eV), Ag (1524 eV), and lunar simulant detected at 18 m (bulk chemistry and mineralogy similar to Apollo 11 lunar mare basalts). Experimental results will be presented that demonstrate the characteristics and ability of detecting laser-produced ions over very long distances. Edwards C. D. Jr. Folkner W. M. Kahn R. D. Preston R. A. Investigation of Mars Rotational Dynamics Using Earth-based Radio Tracking of Mars Landers The development of space geodetic techniques over the past two decades has made it possible to measure the rotational dynamics of the Earth at the milliarcsecond level, improving our geophysical models of the Earth's interior and the interactions between the solid Earth and its atmosphere. We have found that the rotational dynamics of Mars can be determined to nearly the same level of accuracy by acquiring Earth-based two-way radio tracking observations of three or more landers globally distributed on the surface of Mars (Fig. 1, which in the hard copy appears here). Our results indicate that the precession and long-term obliquity changes of the Mars pole direction can be determined to an angular accuracy corresponding to about 15 cm/yr at the planet surface. In addition, periodic nutations of the pole and seasonal variations in the spin rate of the planet can be determined to 10 cm or less. Measuring the rotation of Mars at this accuracy would greatly improve the determination of the planet's moment of inertia and would resolve the size of a planetary fluid core, providing a valuable constraint on Mars interior models. Detecting seasonal variations in the spin rate of Mars would provide global constraints on atmospheric angular momentum changes due to sublimation of the Mars CO2 polar ice caps. Finally, observation of quasisecular changes in Mars obliquity would have significant implications for understanding long-term climatic change. The key to achieving these accuracies is a globally distributed network of Mars landers with stable, phase-coherent radio transponders. By simultaneously acquiring coherent two-way carrier phase observations between a single Earth tracking station and multiple Mars landers, Earth media errors are essentially eliminated, providing an extremely sensitive measure of changes in the differential path lengths between the Earth tracking station and the Mars landers due to Mars rotation. Time variability of the instrumental phase delay through the radio transponder may represent the limiting error source for this technique. Calibration of the transponder stability to about 0.1 nsec or less, over a single tracking arc of up to 12 hr, is sufficient to provide the decimeter-level determination of Mars orientation parameters quoted above. We will provide a detailed description of the multilander tracking technique and the requirements it imposes on both the lander radio system and the Earth- based ground tracking system. This concept is currently part of the strawman science plan for the Mars Environmental Survey (MESUR) mission and complements many of the other MESUR science goals. Fink U. Low F. Hubbard B. Rieke M. Rieke G. Mumma M. Nozette S. Neukum G. Hamel H. DiSanti M. Buie M. Hoffman A. Design Concept for an IR Mapping Spectrometer for the Pluto Fast Flyby Mission The design of an IR mapping spectrometer that exceeds all the criteria of the Pluto Fast Flyby Mission will be presented. The instrument has a mass of ~1700 g and uses less than 4 W of power. The design concept is based on an f/3 spectrograph using an aberration-corrected concave holographic grating. Up to four spectral regions can be covered simultaneously by dividing the grating into two to four sections, each imaging the entrance slit on a different area of the array. The spectrography will be fed by a lightweight 5" f/3 telescope based on SDIO precepts. In order to provide spectroscopic access to the fundamental molecule frequencies, an extended-range NICMOS array to ~3.5 micrometers and an InSb array going to 5.8 micrometers will be considered. Garvin J. B. Bufton J. L. Harding D. J. Multibeam Laser Altimeter for Planetary Topographic Mapping Laser altimetry provides an active, high-resolution, high-accuracy method for measurement of planetary and asteroid surface topography. The basis of the measurement is the timing of the round-trip propagation of short-duration pulses of laser radiation between a spacecraft and the surface. Vertical, or elevation, resolution of the altimetry measurement is determined primarily by laser pulsewidth, surface-induced spreading in time of the reflected pulse, and the timing precision of the altimeter electronics. With conventional gain- switched pulses from solid-state lasers and nanosecond-resolution timing electronics, submeter vertical range resolution is possible anywhere from orbital altitudes of ~1 km to altitudes of several hundred kilometers. Horizontal resolution is a function of laser beam footprint size at the surface and the spacing between successive laser pulses. Laser divergence angle and altimeter platform height above the surface determine the laser footprint size at the surface; while laser pulse repetition rate, laser transmitter beam configuration, and altimeter platform velocity determine the spacing between successive laser pulses. Multiple laser transmitters in a single laser altimeter instrument that is orbiting above a planetary or asteroid surface, could provide across-track as well as along-track coverage that can be used to construct a range image (i.e., topographic map) of the surface. We are developing a pushbroom laser altimeter instrument concept that utilizes a linear array of laser transmitters to provide contiguous across- track and along-track data. The laser technology is based on the emerging monolithic combination of individual, 1-square-centimeter diode-pumped Nd:YAG laser pulse emitters. The laser pulse output at 1 micrometer that results from each element is approximately 1 nsec in duration and is powerful enough to measure distance to the surface from short range (1-10 km). Laser pulse reception is accomplished in this concept by a single telescope that is staring at nadir and is equipped with a single detector element in its focal plane. This arrangement permits a fixed alignment of each transmitter output into a separate, dedicated sensor footprint, yet minimizes instrument complexity. For example, a linear array of 20 laser transmitters oriented perpendicular to the orbit motion could map an asteroid surface at a spatial resolution of 50 m in a 1-km swath. The two-dimensional topographic image might be most appropriate for missions in which multispectral imaging data are also acquired. The instrument is also capable of laser pulse energy measurement for each sensor footprint, yielding a measure of surface reflectance at the monochromatic 1-micrometer laser wavelength. It should also be possible to produce a device that is capable of simultaneous operation on all elements for long-range operation at the mJoule-per-pulse performance level or time-division-multiplexed operation of single laser emitter elements to produce the desired pushbroom laser altimeter sensor pattern on the planetary or asteroid surface. Thus the same device could support operational ranging to an asteroid from long range and scientific observations at high-resolution simply by simultaneously or sequentially addressing the multiple laser transmitter elements. Details of the multi- emitter laser transmitter technology, the instrument configuration, and performance calculations for a realistic Discovery-class mission will be presented. Glenar D. A. Hillman J. J. Acousto-Optic Infrared Spectral Imager for Pluto Fast Flyby Acousto-Optic tunable filters (AOTFs) enable compact, two-dimensional imaging spectrometers with high spectral and spatial resolution, and with no moving parts. Tellurium dioxide AOTFs operate from about 400 nm to nearly 5 micrometers, and a single device will tune continuously over one octave by changing the RF acoustic frequency applied to the device. An infrared (1.2-2.5 micrometers) Acousto-Optic Imaging Spectrometer (AImS) has been designed, which closely conforms to the surface composition mapping objectives of Pluto Fast Flyby. It features a 75-cm focal length telescope, infrared AOTF and 256 x 256 NICMOS-3 focal plane array for acquiring narrowband images with a spectral resolving power (lambda/delta lambda) exceeding 250. We summarize the instrument design features and its expected performance at Pluto-Charon encounter. Gooding J. L. Ming D. W. Gruener J. E. Gibbons F. L. Allton J. H. Thermal Analyzer for Planetary Soils (TAPS): An In Situ Instrument for Mineral and Volatile-Element Measurements TAPS offers a specific implementation for the generic thermal analyzer/evolved-gas analyzer (TA/EGA) function included in the Mars Environmental Survey (MESUR) strawman payload; applications to asteroids and comets are also possible [1]. The baseline TAPS is a single-sample differential scanning calorimeter (DSC), backed by a capacitive-polymer humidity sensor, with integrated sampling mechanism [2]. After placement on a planetary surface, TAPS acquires 10-50 mg of soil or sediment and heats the sample from ambient temperature to 1000-1300 K (Fig. 1). During heating, DSC data are taken for the solid and evolved gases are swept past the water sensor. Through groundbased data analysis, multicomponent DSC data are deconvolved [3] and correlated with the water-release profile to quantitatively determine the types and relative proportions of volatile- bearing minerals such as clays and other hydrates, carbonates, and nitrates (Fig. 2). The rapid-response humidity sensors also achieve quantitative analysis of total water [4]. After conclusion of soil-analysis operations, the humidity sensors become available for meteorology. The baseline design fits within a circular-cylindrical volume <1000 cm3, occupies 1.2 kg mass, and consumes about 2 Whr of power per analysis. Enhanced designs would acquire and analyze multiple samples and employ additional microchemical sensors for analysis of CO2, SO2, NOx and other gaseous species. Atmospheric pumps are also being considered as alternatives to pressurized purge gas. References: [1] Gooding J. L. (1989) in Proc. 18th North Amer. Thermal Anal. Soc. Conf., Vol. 1 (I. R. Harrison, ed.), 222-228. [2] Gooding J. L. (1991) LPSC XXII, 457-458. [3] Gooding J. L. (1991) in Proc. 20th North Amer. Thermal Anal. Soc. Conf. (M. Y. Keating, ed.), 329-334. [4] Gooding J. L. et al. (1992) in Proc. 21st North Amer. Thermal Anal. Soc. Conf. (W. Sichina, ed.), 477-481. Figure 1, which appears in the hard copy, shows the TAPS Mark-1B packaging concept. Figure 2, which appears in the hard copy, shows the simultaneous DSC [(P(Sx- Rx) spline] and evolved-water [WSy spline] data from analysis of gypsum by the TAPS Mark-1 sensor testbed. Gradie J. Wang S. Imaging Spectrometers Using Concave Holographic Gratings Imaging spectroscopy combines the spatial attributes of imaging with the compositionally diagnostic attributes of spectroscopy. Imaging spectroscopy is useful wherever the spatial variation of spectral properties is important, such as mapping spectrally distinct compositional units on surfaces (planetary, terrestrial, medical, industrial), spectral emission and absorption of gases and surfaces (planetary, etc.), or regional spectral changes over time. Imaging spectrometers produce a series of spatial images at many wavelengths in a number of ways: (1) a single-spot field of view that is step-wise scanned over the spatial field while the wavelengths (or wavenumbers) are scanned sequentially (single-detector element); (2) a single-spot field of view that continuously scans the field of view while sampling all wavelengths simultaneously (a linear-array detector); (3) a slit that continuously scans the field of view while sampling all wavelengths simultaneously (a two- dimensional array detector); or (4) frames of the full field of view taken at sequential wavelengths. For space-based remote sensing applications, mass, size, power, data rate, and application constrain the scanning approach. For the first three approaches, substantial savings in mass and size of the spectrometer can be achieved in some cases with a concave holographic grating and careful placement of an order-sorting filter. A hologram etched on the single concave surface contains the equivalent of the collimating, dispersing, and camera optics of a conventional grating spectrometer and provides substantial wavelength- dependent corrections for spherical aberrations and a flat focal field. These gratings can be blazed to improve efficiency when used over a small wavelength range or left unblazed for broadband uniform efficiency when used over a wavelength range of up to 2 orders. More than 1 order can be imaged along the dispersion axis by placing in front of the one- or two-dimensional detector an appropriately designed step order-sorting filter. This filter can be shaped for additional aberration corrections. The VIRIS (trademark) imaging spectrometer based on the broadband design provides simultaneous imaging of the entrance slit from lambda = 0.9 to 2.6 micrometers (1.5 orders) onto a 128 x 128 HgCdTe detector (at 77 K). The VIRIS (trademark) spectrometer has been used for lunar mapping with the UH 24-in telescope at Mauna Kea Observatory. The design is adaptable for small, low mass, space-based imaging spectrometers. Huffman R. E. Zdyb J. Link R. Strickland D. J. The Atmospheric Ultraviolet Radiance Integrated Code (AURIC) Validation of Version 1.0 Abstract withdrawn by author Johnson E. A. Microtextured Metals for Stray-Light Suppression in the Clementine Startracker Anodized blacks for suppressing stray light in optical systems can now be replaced by microscopically textured metal surfaces. This presentation will detail an application of these black surfaces to the Clementine star-tracker navigational system, which will be launched in early 1994 to examine the Moon, en route to intercept an asteroid. Rugged black surfaces with Lambertian BRDF <10^-2 srad^-1 are critical for suppressing stray light in the star-tracker optical train. Previously available materials spall under launch vibrations to contaminate mirrors and lenses. Microtextured aluminum is nearly as dark, but much less fragile. It is made by differential ion beam sputtering, which generates light-trapping pores and cones slightly smaller than the wavelength to be absorbed. This leaves a sturdy but light-absorbing surface that can survive challenging conditions without generating debris or contaminants. Both seeded ion beams and plasma immersion (from ECR plasmas) extraction can produce these microscopic textures without fragile interfaces. Process parameters control feature size, spacing, and optical effects (THR, BRDF). Both broad and narrow absorption bands can be engineered with tuning for specific wavelengths and applications. Examples will be presented characterized by FTIR in reflection mode. Textured metal blacks are also ideal for blackbody calibrators (0.95 normal emissivity), heat rejection, and enhanced nucleate boiling. Joseph C. L. New Technologies for UV Detectors Several technologies are currently being developed, leading to substantial improvements in the performance of UV detectors or leading to significant reductions in power or weight. Four technologies discussed in this poster are (1) thin-film coatings to enhance the UV sensitivity of CCDs, (2) highly innovative magnet assemblies that dramatically reduce weight and that result in virtually no external flux, (3) new techniques for curving microchannel plates (MCPs) so that single plates can be used to prevent ion feedback and to present highly localized charge clouds to an anode structure, and (4) high- performance alternatives to glass-based MCPs. In item (2) just listed, for example, very robust magnets are made out of rare earth materials such as samarium cobalt, and cladding magnets are employed to prevent flux from escaping from the detector into the external environment. These new ultralight magnet assemblies are able to create strong, exceptionally uniform magnetic fields for image intensification and focusing of photoelectrons. The principle advantage of such detectors is the quantum efficiencies of 70-80% obtained throughout ultraviolet wavelengths (900-2000 Angstroms), the highest of any device. Despite the improvements achieved under item (3) above, high-performance alternatives to conventional glass-based MCPs potentially offer three distinct new advantages that include (1) a 30-100-fold improvement in dynamic range resulting in correspondingly higher signal-to-noise ratios, (2) the use of pure dielectric and semiconductor materials that will not outgas contaminants that eventually destroy photocathodes, and (3) channels that have constant spacing providing long-ranged order since the plates are made using photolithography techniques from the semiconductor industry. The manufacturers of these advanced-technology MCPs, however, are a couple of years away from actually producing a functioning image intensifier. In contrast to the use of CCDs for optical, ground-based observations, there is no single detector technology in the ultraviolet that dominates or is as universally suitable for all applications. Thus, this poster addresses several technological problems, recent advances, and the impact that these new enabling technologies represent for UV applications. Joshi P. B. Lightweight Modular Instrumentation for Planetary Applications PSI is currently developing under SDIO sponsorship an instrumentation suite for monitoring the spacecraft environment and for accurately measuring the degradation of space materials in LEO. The instrumentation, called SAMMES (Space Active Modular Materials ExperimentS), features compact (~6-in cube), light-weight (~2.5 kg) modules incorporating a variety of sensors and low- power (~5 W) processing electronics. The LEO Environment Monitor Module (EMM) sensor complement consists of two passively called Quartz Crystal Microbalances and three calorimeters for contaminant detection and characterization, three actinometers for measuring AO flux, two RADFETs for total dose radiation measurement, a Sun position sensor, and a solar irradiance sensor. The EMM is designed as a remote terminal for MIL-STD-1553B communication with an experiment bus controller and for independent operation of its sensors. The present design can be modified to be fully autonomous, with module-based mass memory, onboard data processing, and software upload capability. The SAMMES architecture concept can be extended to instrumentation for planetary exploration, both on spacecraft and in situ. The operating environment for planetary application will be substantially different, with temperature extremes and harsh solar wind and cosmic ray flux on lunar surfaces, temperature extremes and high winds on venusian and martian surfaces. Moreover, instruments for surface deployment, which will be packaged in a small lander/rover (as in MESUR, for example), must be extremely compact with ultralow power and weight. With these requirements in mind, we have extended the SAMMES concept to a sensor/instrumentation scheme for the lunar and martian surface environment, as illustrated in Fig. 1. Figure 1, which appears in the hard copy, show the sensor/instrumentation concept for lunar/martian application. Keski-Kuha R. A. M. Osantowski J. F. Leviton D. B. Saha T. T. Content D. A. Boucarut R. A. Gum J. S. Wright G. A. Fleetwood C. M. Madison T. J. Optical Technologies for UV Remote Sensing Instruments Over the last decade significant advances in technology have made possible development of instruments with substantially improved efficiency in the UV spectral region. In the area of optical coatings and materials, we discuss the importance of recent developments in chemical vapor deposited (CVD) silicon carbide (SiC) mirrors, SiC films, and multilayer coatings in the context of ultraviolet instrumentation design. For example, the development of chemically vapor deposited (CVD) silicon carbide (SiC) mirrors, with high ultraviolet (UV) reflectance and low scatter surfaces provides the opportunity to extend higher spectral/spatial resolution capability into the 50-nm region. Optical coatings for normal incidence diffraction gratings are particularly important for the evolution of efficient extreme ultraviolet (EUV) spectrographs. SiC films are important for optimizing the spectrograph performance in the 90-nm spectral region. Diffraction grating technology has always played a pivotal role in the development of spectroscopic instrumentation for ultraviolet space flight instrumentation. An essential element in the successful diffraction grating development program is the ability to quantitatively evaluate the performance of test diffraction gratings in the early stages of the instrument development program. The Diffraction Grating Evaluation Facility (DGEF) at Goddard Space Flight Center was established to evaluate the performance of new technology diffraction gratings and other optical components for future space-flight instrumentation especially in the vacuum ultraviolet. DGEF is a unique, world-class, extremely versatile facility with enormous evacuable optical set- up volume allowing mirrors and gratings to be evaluated in their design configurations with respect to design specifications, manufacturer's data, and optical analytical results. We will discuss the performance evaluation of the flight optical components for the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) instrument, a spectroscopic instrument to fly aboard the Solar and Heliospheric Observatory (SOHO) mission, designed to study dynamic processes, temperatures, and densities in the plasma of the upper atmosphere of the Sun in the wavelength range from 50 nm to 160 nm. The optical components were evaluated for imaging and scatter in the UV. We will also review the performance evaluation of SOHO/CDS (Coronal Diagnostic Spectrometer) flight gratings tested for spectral resolution and scatter in the DGEF and present preliminary results on resolution and scatter testing of Space Telescope Imaging Spectrograph (STIS) technology development diffraction gratings. Kher A. Mitra S. Multiscale Morphological Filtering for Analysis of Noisy and Complex Images Images acquired with passive sensing techniques suffer from illumination variations and poor local contrasts that create major difficulties in interpretation and identification tasks. On the other hand, images acquired with active sensing techniques based on monochromatic illumination are degraded with speckle noise. Mathematical morphology offers elegant techniques to handle a wide range of image degradation problems. Unlike linear filters, morphological filters do not blur the edges and hence maintain higher image resolution. Their rich mathematical framework facilitates the design and analysis of these filters as well as their hardware implementation. Morphological filters are easier to implement, more cost effective and efficient than several conventional linear filters. Morphological filters to remove speckle noise while maintaining high resolution and preserving thin image regions that are particularly vulnerable to speckle noise [1] have been developed and applied to SAR imagery. These filters used combination of linear (one-dimensional) structuring elements in different (typically four) orientations (the median operators by Maragos [2]). Although this approach preserves more details than the simple morphological filters using two- dimensional structuring elements, the limited orientations of one-dimensional elements approximate the fine details of the region boundaries. A more robust filter designed recently overcomes the limitation of the fixed orientations. This filter uses a combination of concave and convex structuring elements. Morphological operators are also useful in extracting features from visible and infrared imagery. A multiresolution image pyramid obtained with successive filtering and a subsampling process aids in the removal of the illumination variations and enhances local contrasts. A morphology-based interpolation scheme has also been introduced to reduce intensity discontinuities created in any morphological filtering task. The generality of morphological filtering techniques in extracting information from a wide variety of images obtained with active and passive sensing techniques will be discussed. Such techniques are particularly useful in obtaining more information from fusion of complex images acquired by different sensors such as SAR, visible and infrared [3]. References: [1] Kher A. and Mitra S. (1992) Proc. SPIE. [2] Maragos P. (1989) IEEE Trans. Pattern Anal. Mach. Intellig., 11. [3] Mitra S. and Kher A. (1992) Paper presented at the International Space Year Conference at JPL, Pasadena, California, 10-13 February, 1992. Klein E. J. A Unique Photon Bombardment System for Space Applications The innovative (patents pending) Electromagnetic Radiation Collection and Concentration System (EMRCCS) described here is the foundation for the development of a multiplicity of space and terrestrial system formats. The system capability allows its use in the visual, infrared, and ultraviolet ranges of the spectrum for EM collection, concentration, source/receptor tracking, and targeting. The nonimaging modular optical system uses a physically static position aperture for EM radiation collection. Folded optics provide the concentration of the radiation and source autotracking. The collected and concentrated electromagnetic radiation is utilized in many applications, e.g., solar spectrum in thermal and associative photon bombardment applications for hazardous waste management, water purification, metal hardening, hydrogen generation, photovoltaics, etc. in both space and terrestrial segment utilization. Additionally, at the high end of the concentration capability range, i.e., 60,000+, a solar-pulsed laser system is possible. The system outputs the concentrated flux, orthogonal (normally incident) to the input plane of an output port. The orthogonality remains constant regardless of the radiation input angle to the collection aperture, allowing simplification of radiation receptor design and highly efficient utilization of the concentrated radiation. The system configuration is arrayed for extremely high levels of flux concentration in windowing and targeting applications. Other system design formats provide power generation and thermal processes for heating and absorption cooling. Fixed portable and mobile (space and terrestrial) applications include designs that incorporate a phased RF and/or the system array for purposes of radiation source acquisition/tracking and data derivation. The data is utilized in source acquisition (array capture angle of +/-75 degrees in the orthogonal E and H planes), source autotracking in the same angular intervals, and, subsequent to source and receptor acquisition, control of direction and magnitude of the output concentrated radiation at a given target range. In addition, the phased array can provide EM channel voice or data capability. Koch D. Borucki W. Reitsema H. Detection of Other Planetary Systems Using Photometry Detection of extrasolar short-period planets, particularly if they are in the liquid-water zone, would be one of the most exciting discoveries of our lifetime. A well-planned space mission has the capability of making this discovery using the photometric method. An Earth-sized planet transiting a Sun-like star will cause a decrease in the apparent luminosity of the star by one part in 10,000 with a duration of about 12 hours and a period of about one year. Given a random orientation of orbital plane alignments with the line-of- sight to a star, and assuming our solar system to be typical, one would expect 1% of the stars monitored to exhibit planetary transits. A null result would also be significant and indicate that Earth-sized planets are rare. For the mission to be successful one needs a sensor system that can simultaneously monitor many thousands of stars (F, G, and K dwarfs) with a photometric precision of one part in 30,000 per hour of integration. The stellar magnitude, integration time, and desired photometric precision determine the aperture size. The field of view and limiting stellar magnitude determine the number of stars that can be monitored. A 1.5-m telescope is required to attain the photometric precision for 12.5 mag stars. An 8-degree field of view will yield many thousands of stars and several transit detections per month. Confirmation of a detection will involve detection of a second transit that will yield a period and predict the time for a third and subsequent transits. The technology issues that need to be addressed are twofold: One is for an appropriate optical design; the other is for a detector system with the necessary photometric precision. Two candidates for the detector system are silicon diodes and CCDs. It has been demonstrated that discrete silicon diodes have the required precision. However, the technology for building them into arrays with readouts needs development. The other approach is to use silicon CCDs. These already exist as arrays. However, the required photometric precision technology has yet to be demonstrated. Data processing complexity can be reduced by using the local-area-readout technique to obtain the flux for a few hundred stars per CCD. Koppel L. N. Franco E. D. Kerner J. A. Fonda M. L. Schwartz D. E. Marshall J. R. An Integrated XRF/XRD Instrument for Mars Exobiology and Geology Experiments By employing an integrated X-ray instrument on a future Mars mission, data obtained will greatly augment those returned by Viking; details characterizing the past and present environment on Mars and those relevant to the possibility of the origin and evolution of life will be acquired. A combined XRF/XRD instrument has been breadboarded and demonstrated to accommodate important exobiology and geology experiment objectives outlined for MESUR and future Mars missions. Among others, primary objectives for the exploration of Mars include the intense study of local areas on Mars to "establish the chemical, mineralogical, and petrological character of different components of the surface material; to determine the distribution, abundance, and sources and sinks of volatile materials, including an assessment of the biologic potential, now and during past epoches; and to establish the global chemical and physical characteristics of the martian surface" [1]. The XRF/XRD breadboard instrument identifies and quantifies soil surface elemental, mineralogical, and petrological characteristics and acquires data necessary to address questions on volatile abundance and distribution. Additionally, the breadboard is able to characterize the biogenic element constituents of soil samples providing information on the biologic potential of the Mars environment. For example, experimental results employing the breadboard indicate that accurate and precise data including the detection, identification, and quantification of elements to trace levels (ppm) from carbon to zirconium (6 < Z < 40), and relative abundance of amorphous vs. crystalline minerals in Mars soil surface samples can be obtained. The breadboard has been designed and built with regard to expected Mars environmental operating conditions, mission constraints, and technical requirements that include general instrument design considerations. Preliminary XRF/XRD breadboard experiments have confirmed the fundamental instrument design approach and measurement performance. Experimental accomplishments and results include the following: XRD observation of the principal diffraction lines of montmorillonite; XRF measurement of aluminum, silicon, calcium, titanium, and iron abundances in palagonite powder samples commensurate with expectations; calibration of a carbon-detecting XRF channel with detectability limits in the order of 0.01 wt%. The breadboard experiments provided valuable confirmation of models used to simulate and optimize the instrument's performance, and indicated practical improvements in its design. References: [1] COMPLEX (1978) National Academy of Sciences, Washington, DC, 97 pp. Kumar C. K. Klein L. Giraud M. Remote Measurement of Planetary Magnetic Fields by the Hanle Effect No abstract available. Kumer J. B. Aubrun J. N. Rosenberg W. J. Roche A. E. Resolution-enhanced Mapping Spectrometer A familiar mapping spectrometer implementation utilizes two-dimensional detector arrays with spectral dispersion along one direction and spatial along the other. Spectral images are formed by spatially scanning across the scene (i.e., push-broom scanning). For imaging grating and prism spectrometers the slit is perpendicular to the spatial scan direction. For spectrometers utilizing linearly variable focal-plane-mounted filters the spatial scan direction is perpendicular to the direction of spectral variation. These spectrometers share the common limitation that the number of spectral resolution elements is given by the number of pixels along the spectral (or dispersive) direction. In this presentation we discuss resolution enhancement by first passing the light input to the spectrometer through a scanned etalon or Michelson. Thus, while a detector element is scanned through a spatial resolution element of the scene, it is also temporally sampled. For example, to enhance resolution by a factor of 4 in a given spectral element, one would design the etalon to have finesse 4 in that spectral region, scan the etalon through a free spectral range as the detector is spatially scanned through spatial resolution element, and take eight samples in the process. To plug numbers in a specific example, suppose the mapping spectrometer pixel at 1 micrometer had unenhanced resolution 60 cm^-1, but 15 cm^-1 resolution is desired. Further assume that 2 s is required to scan across a spatial element. An etalon with gap 83.33 micrometers would give it the required free spectral range of 60 cm^-1, reflectivity 46.5% would give it the required finesse ~4, and a sample rate of 8 per second while scanning the gap through 1/2 wavelength (i.e., 0.5 micrometers in this example, in order to scan through the 60 cm^-1 free spectral range) in eight steps of 0.5 micrometers/8 would provide a spectrum of resolution of 15 cm^-1 resolution within the order sorting 60 cm^-1 provided by the unenhanced spectrometer. Our presentation will address the analysis for all the pixels in the dispersive direction. We will discuss several specific examples. We will also discuss the alternate use of a Michelson for the same enhancement purpose. Suitable for weight constrained deep space missions, we have developed hardware systems including actuators, sensors, and electronics such that low-resolution etalons with performance required for implementation (performance requirement typified by the example above) would weigh less than 1 lb. Lesho J. C. Cain R. P. Uy O. M. Proposal for a Universal Particle Detector Experiment The Universal Particle Detector Experiment (UPDE), which consists of parallel planes of two diode laser beams of different wavelengths and a large surface metal oxide semiconductor (MOS) impact detector is proposed. It will be used to perform real-time monitoring of contamination particles and meteoroids impacting the spacecraft surface with high resolution of time, position, direction, and velocity. The UPDE will discriminate between contaminants and meteoroids, and will determine their velocity and size distributions around the spacecraft environment. With two different color diode lasers, the contaminant and meteoroid composition will also be determined based on laboratory calibration with different materials. Secondary particles dislodged from the top aluminum surface of the MOS detector will also be measured to determine the kinetic energy losses during energetic meteoroid impacts. The velocity range of this instrument is 0.1 m/sec to more than 14 km/sec, while its size sensitivity is from 0.2 micrometers to millimeter-sized particles. The particulate measurements in space of the kind proposed here will be the first simultaneous multipurpose particulate experiment that includes velocities from very slow to hypervelocities, sizes from submicrometer to pellet-sized diameters, chemical analysis of the particulate composition, and measurements of the kinetic energy losses after energetic impacts of meteoroids. This experiment will provide contamination particles and orbital debris data that are critically needed for our present understanding of the space environment. The data will also be used to validate contamination and orbital debris models for predicting optimal configurations of future space sensors and for understanding their effects on sensitive surfaces such as mirrors, lenses, paints and thermal blankets. Figure 1, which appears in the hard copy, shows the UPDE sensor. Lognonne P. Karczewski J. F. DT/INSU-CRG Garchy Team OPTIMISM Experiment and Development of Space-Qualified Seismometers in France The OPTIMISM experiment will put two magnetometers and two seismometers on the martian floor in 1995, within the framework of the Mars '94 mission. The seismometers are put within the two small surface stations. The seismometer sensitivity will be better than 10^-9 g at 1 Hz, 2 orders of magnitude higher than the Viking seismometer sensitivity. A priori waveform modeling for seismic signals on Mars [1] shows that it will be sufficient to detect quakes with a seismic moment greater than 10^15 Nm everywhere on Mars. Such events, according to the hypothesis of a thermoelastic cooling of the martian lithosphere, are expected to occur at a rate close to one per week [2] and may therefore be observed within the 1-year lifetime of the experiment. Due to severe constraints on the available power, mass budget, g load, and size of the small stations, it was necessary to completely redesign the seismometer sensors and electronic. The sensor has been developed in order to support a high g load of 200g/10 ms without reducing its sensitivity. It consists of a new leaf-spring vertical seismometer, with a free period close to 0.5 s and an inertial mass of 50 g. The seismometer has two modes, working either with a velocity transducer, for high-frequency seismic measurements, or with a displacement transducer, for long-period seismic measurements. The seismometer's mass is 340 g, and its size is 9 cm3. Along the same lines, a low-power, hybrid technology has been used for the electronic. The velocity transducer and displacement transducer need a power of a few milliwatts, with a sensitivity of 10^-10 for the displacement transducer. This seismometer will be the first space-qualified or automatic very broad band seismometer, to be developed in France. The next generation will consist of a tri-axial seismometer, with performances at least 1 order of magnitude better than the OPTIMISM seismometer. References: [1] Lognonné and Mosser, 1992. [2] Solomon et al., 1991. Lucke R. L. Stocker A. D. Filtering Interpolators for Image Comparison Algorithms Comparing two or more images, either by differencing or ratioing, is important to many remote sensing problems. Because the pixel sample points for the images are (almost) always separated by some nonzero shift, a resampling, or interpolation, process must be performed if one image is to be accurately compared to another. Considered in Fourier space, an interpolator acts as a filter that attenuates some frequencies (usually high) of the image. Thus, when the shifted and unshifted images are compared, the former has been filtered, while the latter has not; the effect of this difference is called interpolation error. The key idea of this paper is to apply a filter to the unshifted image that matches the filtering effect of applying the interpolator to the shifted image, thereby drastically reducing interpolation error. The resulting interpolators, called filtering interpolators, are derived and discussed in detail elsewhere [1]. Basic results will be given in this presentation. The cost of reducing interpolation error is some loss of high-frequency information. This paper presents parameterized families of local convolutional interpolators (polynomial and trigonometric) that can be adjusted to the desired trade-off between interpolation error reduction and high-frequency information retention. These interpolators allow as many images as desired, all with different shifts, to be compared on an equal footing. The method is derived for images with the same pixel spacing and purely translational shifts. Performance suffers if these conditions are not met, but is still better than ordinary interpolation. Four-point interpolators are probably the most useful because they give good interpolation performance with reasonable computational efficiency. One-dimensional formulas are given; for two dimensions, the interpolators are applied to each dimension separately. In tests on simulated imagery, the filtering interpolators reduced interpolation error to below the level of sensor noise for 13-bit data (LSB = rms noise) on highly structured scenes. References: [1] Lucke R. L. and Stocker A. D. (1993) IEEE Trans. Signal Processing, in press. Mahaffy P. Mauersberger K. Mass Spectrometric Measurement of Martian Krypton and Xenon Isotopic Abundance The Viking gas chromatograph mass spectrometer experiment provided significant data on the atmospheric composition at the surface of Mars, including measurements of several isotope ratios. However, the limited dynamic range of this mass spectrometer resulted in marginal measurements for the important Kr and Xe isotopic abundance. The 129Xe to 132Xe ratio was measured with an uncertainty of 70%, but none of the other isotope ratios for these species were obtained. Accurate measurement of the Xe and Kr isotopic abundance in this atmosphere provides a important data point in testing theories of planetary formation and atmospheric evolution. The measurement is also essential for a stringent test for the martian origin of the SNC meteorites, since the Kr and Xe fractionation pattern seen in gas trapped in glassy nodules of an SNC (EETA 79001) is unlike any other known solar system resevoir. Current flight mass spectrometer designs combined with the new technology of a high performance vacuum pumping system show promise for a substantial increase in gas throughput and the dynamic range required to accurately measure these trace species. The wide dynamic range of present space flight mass spectrometer analyzer/detector systems allows ionization pressures to be pushed toward the point where the gas mean free path in the ion source is limiting. However, the fixed capacity of miniaturized high-vacuum pumping systems has put significant constraints on several previous mass spectrometer experiments, including the Viking mass spectrometer. The noble gases are not pumped by chemical pumps and with a very limited capacity by miniaturized ion pumps. In addition, ion pumped system can release previously pumped material with a corresponding loss of accuracy. A recent commercial development in high-vacuum pumping technology is that of wide-range turbomolecular/molecular drag pump hybrids where both stages are attached to the same rotating shaft. The natural exhaust pressure of the molecular drag stage is approximately 10 mbar. Compression ratios of 10^7 or higher for N are achieved with very small pumping systems. It is expected that with continued development toward a ruggidized flight pump a mass of less than 1 kg for a system with a pumping speed of 10 to 30 liters/sec can readily be achieved. The pump capacity is only limited by power constraints and eventual failure of the bearings after several thousand hours of operation. With reference to the payload described by the MESUR Science Definition Team, a mass spectrometer experiment incorporating such a pump together with a recently developed thermal analyzer [1] could provide information on the volatile composition of martian near-surface solid-phase material in addition to carrying out the isotope measurements described. References: Mauersberger K. et al. (1992) LPI Tech. Rpt. 92-07. Mancinelli R. L. White M. R. Orenberg J. B. A DTA/GC for the In Situ Identification of the Martian Surface Material The composition and mineralogy of the martian surface material remain largely unknown. To determine its composition and mineralogy several techniques are being considered for in situ analyses of the martian surface material during missions to Mars. These techniques include X-ray fluorescence, X-ray diffraction, alpha-proton backscattering, gamma ray spectrometry, mass spectrometry, differential thermal analysis (DTA), differential scanning calorimetry (DSC), and pyrolysis gas chromatography. Results of a comparative study of several of these techniques applicable to remote analysis during MESUR-class missions indicate that DTA/GC would provide the most revealing and comprehensive information regarding the mineralogy and composition of the martian surface material [1]. We have successfully developed, constructed, and tested a laboratory DTA/GC. The DTA is a Dupont model 1600 high-temperature DTA coupled with a GC equipped with a MID detector. The system is operated by a Sun Sparc II workstation. When gas evolves during a thermal chemical event, it is shunted into the GC and the temperature is recorded in association with the specific thermal event. We have used this laboratory instrument to define experimental criteria necessary for determining the composition and mineralogy of the martian surface in situ (e.g., heating of sample to 1100 degrees C to distinguish clays). Our studies indicate that DTA/GC will provide a broad spectrum of mineralogical and evolved gas data pertinent to exobiology, geochemistry, and geology. Some of the important molecules we have detected include organics (hydrocarbons, amides, amines, etc.), CO(sub)3^2-, NO3-, NO2-, NH4+, SO(sub)4^2-, H2O, CO2. The technique can also discern the mineral character of the sample (i.e., clay vs. silicates vs. glasses; degrees of hydration, etc.) [2]. It is thought that the surface of Mars consists primarily of an amorphous juvenile silicate material similar to palagonite with not more than 15 wt% clay [3]. This type of mixture is easily determined by DTA/GC using the high- temperature (1100 degrees C) capability of the DTA [1,2]. This is important to the definition of mission analytical techniques, which must be able to analyze samples ranging from those containing no clay or evaporites to samples composed of significant amounts of highly structured clay and evaporites within a predominately amorphous matrix. References: [1] Schwartz D. E. et al. (1993) Adv. Space Res., 13, in press. [2] Mancinelli R. L. et al. (1992) LPSC XXIII, 831-832. [3] Orenberg J. B. and Handy J. (1992) Icarus, 96, 219-225. Marouf E. A. Onboard Signal Processing: Wave of the Future for Planetary Radio Science? Future spacecraft-based radio observations of planetary surfaces, rings, and atmospheres could significantly benefit from recent technological advances in real-time digital signal processing (DSP) hardware. Traditionally, the radio observations have been carried out in a "downlink" configuration in which about 20-W spacecraft-transmitted RF power illuminates the target of interest and the perturbed signal is collected at an Earth receiving station. The downlink configuration was dictated by the large throughput of received data, corresponding to a relatively large recording band width (about 50 kHz) needed to capture the coherent and scattered signal components in the presence of trajectory, ephemeris, and measurement uncertainties. An alternative "uplink" configuration in which powerful Earth-based radio transmitters (20-200 kW) are used to illuminate the target and data are recorded on board a spacecraft could enhance the measurements signal-to-noise ratio by a factor of about 1000, allowing a quantum leap in scientific capabilities. The recorded data must be preprocessed to reduce its volume while preserving its salient information content. The latter include time-history of estimates of the amplitude and phase of the coherent signal and dynamic power spectra of the scattered signal, computed at adaptable resolutions. The "compressed" data is later relayed to the Earth for further detailed processing and analysis. Onboard data compression can readily be accomplished either by a DSP processor that is a part of an Uplink Radio Science Instrument, or by a configurable spacecraft "DSP subsystem" that serves as a preprocessing engine for multiple spacecraft instruments. In either case, the hardware architecture must be sufficiently flexible to allow implementation of a broad class of preprocessing algorithms, adaptable to a given observation geometry and corresponding signal dynamics. Specific signal compression needs and expected scientific gain are illustrated for potential future uplink observation of planetary ring systems. Similar argument can be made for radio observations of the tenuous atmosphere of Pluto and for radio imaging of the martian surface, two potential targets for the Pluto FFM and the Mars MESUR missions. Mathias S. Spaceborne Passive Radiative Cooler Radiative coolers are passive refrigeration devices for satellites and space probes that provide refrigeration for an infrared or other type of detector that operates at cryogenic temperatures. Typically a cooler can supply 20 milliwatts of cooling at about 85 Kelvin, and over 500 milliwatts of cooling at about 165 Kelvin. The exact cooler temperatures and heat loads are dependent upon the clear field of view of the cooler to space. Some features of the Arthur D. Little passive radiative cooler are (1) The cooler has no moving parts leading to very long life and high reliability; (2) The cooler weight is approximately 3 lb; (3) The detector may be easily replaced without disassembling the cooler; (4) The alignment of the detector is insensitive to induced launch vibration and thermal cycling; (5) A movable field lens provides a simple method of adjusting the system focus during testing at operating temperatures; (6) The optical axis is referenced to the room-temperature mounting flange interface, eliminating the need for iterative optical adjustments in thermal vacuum chambers at the system level; (7) Heater and temperature sensors provide precise detector temperature control; (8) The design offers protection against overheating of the sensitive detector element during nonoperational spacecraft attitude acquisition; (9) A modular "bolt-on" concept provides simple integration and interface definition of the cooler with an optical system; and (10) There is maximum protection of the low temperature optical elements from contamination. McEwen A. S. Systematic Processing of Clementine Data for Scientific Analyses If fully successful, the Clementine mission will return about three million lunar images and more than 5000 images of Geographos. Effective scientific analyses of such large datasets require systematic processing efforts. Described below are concepts for two such efforts. Global Multispectral Imaging of the Moon. The lunar orbit has been designed to enable global coverage with the UV/VIS and near-IR cameras. Global coverage will require 120 frames per orbit times 300 orbits times 16 frames (6 near-IR filters and double coverage in 5 UV/VIS filters to improve S:N), for a total of 576,000 image frames. Lunar scientists cannot analyze half a million small images. We will need a single global 11-wavelength image cube with full geometric and radiometric calibrations and photometric normalizations. Processing steps could include (1) decompressing the data, (2) radiometric calibration, (3) removal of camera distortions, (4) co-registration of each set of 16 images to 0.2 pixel, (5) replacing bad or missing data, (6) merging UV/VIS double coverage, (7) identifying three control points per orbit, (8) along-track frame matching (geometry and brightness), (9) reprojecting images, (10) photometric function normalization, (11) mosaicking into single-orbit strips, (12) brightness matching of orbit strips, and (13) mosaicking orbit strips into map quadrangles. The final global dataset at a scale of 100 m/pixel will require a set of 70 CD-ROMS (650 Mbytes/CD) for archiving and distribution. Once systematic processing is completed, a series of global maps can be derived that show the distribution and abundances of pyroxenes, olivine, anorthosite, shocked anorthosite, norite, troctolite, glassy materials, and titanium. Videos of Geographos. Clementine is expected to acquire continuous imaging throughout the closest approach sequence at Geographos with frame rates of 4.5 or 9 frames/s. (For comparison, the highest frame rate on Galileo is 0.4 frame/s, and there was no imaging near closest approach to Gaspra.) The high frame rates and continuous imaging are ideal for production of computer "movies" of the flyby, which can be recorded onto video tapes. These movies will consist of actual observations, rather than simulated sequences generated from a shape model. They will enable the viewer to see all the details of the topography, morphology, and distribution of compositional units as the viewing and illumination geometries change. Several different video sequences of Geographos are anticipated, including separate sequences for each imaging system and merged datasets. The LIDAR will provide the highest spatial resolutions (in four colors), the thermal-IR detector will provide nightside imaging, the UV/VIS camera will provide the highest resolution of the entire visible and illuminated surface during the 75 s before and after closest approach, and the UV/VIS plus near-IR detectors will map the mineralogy. Meyer C. Sources Sought for Innovative Scientific Instrumentation for Scientific Lunar Rovers Lunar rovers should be designed as integrated scientific measurement systems that address scientific goals as their main objective. Scientific goals for lunar rovers are (1) to develop a more complete understanding of the stratigraphy, structure, composition, and evolution of the lunar crust by close examination of the geology and geochemistry of multiple, wide-spaced landing sites on the Moon; (2) to improve the understanding of the lunar regolith and history of solar system events that have affected the lunar surface; (3) to improve the understanding of the lunar interior and set constraints on planetary evolution using geophysical techniques; and (4) to identify and characterize potential lunar "resources" that could be utilized by future human missions. Teleoperated robotic field geologists will allow the science team to make discoveries using a wide range of sensory data collected by electronic "eyes" and sophisticated scientific instrumentation. Rovers need to operate in geologically interesting terrain (rock outcrops) and to identify and closely examine interesting rock samples. Analytical instrumentation should measure the maturity of soils and the chemical composition (major, minor, and trace) and mineralogy of soils and fresh surfaces of rock samples. Some ingenious method is needed to obtain fresh rock surfaces. Manipulator arms are needed to deploy small close-up cameras and lightweight instruments, such as alpha backscatter spectrometers, as "stethoscopes" to the clasts in boulders. Geoscience missions should also deploy geophysical packages. Enough flight-ready instruments are available to fly on the first mission, but additional instrument development based on emerging technology is desirable. There are many interesting places to explore on the Moon (i.e., the lunar poles) and it is highly desirable to fly multiple missions with continuously improved instrument sets. For example, there are needs for (1) in situ reflectance spectroscopy measurements (with high spectral resolution TBD) to determine the spectra (~0.3-2.5 micrometers) and mineral contents of rocks and soils in a manner analogous to what is done from a distance by Earth-based telescopes or from lunar orbit; (2) Mossbauer spectroscopy to determine soil maturity and mineralogy and relative abundance of iron-bearing phases; (3) close-up images by a "field-lens" electronic camera with artificial lighting and good depth focus (autofocus?) allowing scientists in the control room to have the ability to make discoveries and document what has been analyzed by the analytical instruments; (4) precise and accurate analytical measurements of the chemical composition of soils and rocks--especially the critical determination of the Fe/Mg ratio and one or more of the large ion lithophile elements; (5) cryogenic systems to cool solid-state detectors such as infrared sensitive CCD arrays, Si(Li) X-ray or Ge gamma-ray detectors; (6) multispectral imagery by CCD cameras including telephoto, metric, or panoramic; (7) bore-sited laser range-finding equipment with gimbals that read out angles for precise site survey; and (8) thermally evolved gas analysis. Paige D. A. Wood S. E. Vasavada A. R. Drill/Borescope System for the Mars Polar Pathfinder The primary goals of the Mars Polar Pathfinder Discovery mission are to characterize the composition and structure of Mars' north polar ice cap, and to determine whether a climate record may be preserved in layers of ice and dust. The Mars Polar Pathfinder would land as close as possible to the geographic north pole of Mars and use a set of instruments similar to those used by glaciologists to study polar ice caps on Earth: a radar sounder, a drill/borescope system, and a thermal probe. The drill/borescope system will drill ~50 cm into the surface and image the sides of the hole at 10-micrometer resolution for compositional and stratigraphic analysis. Several uncertainties have guided the development of this instrument. It is presently not known whether the surface at the north pole consists of solid ice or packed snow, or how difficult it will be to drill. In order to more quantitatively investigate design and power requirements, we built a thermal chamber for testing the drill/borescope instruments under Mars-like conditions with complete remote control. To minimize the number of mechanisms and moving parts, an integrated drill/borescope system would be desirable for Mars Polar Pathfinder (MPP). However, for these initial tests we used separate off-the- shelf components; a Hilti model TE-10A rotary percussion drill, and an ITI 26- in rigid borescope attached to a Sony XC-999 cigar-type color CCD camera. The drill rotates at about 500 rpm while hammering at about 50 Hz, using about 150 W. Using a 1-in continuous-flute drill bit, it is able to drill through 12 in of -80 degrees C solid ice in about two minutes, with no down-force applied except for its own weight. A talus pile of the low-density shavings forms around the surface, but the hole is left clear after the drill is retracted. The borescope is a hard-optics right-angled device with fiber-optic illumination at its tip. It is able to focus from near contact to infinity. The borescope has a 13-degree vertical field of view, which amounts to about 3 mm of vertical distance at the viewing distance in our 1-in diameter holes. This equipment, and high-resolution vertical scans of two boreholes, are part of a videotape6. We prepared three types of samples: pure ice, ice with dust layers, and snow with dust layers. To make the ice/dust sample we successively poured and froze a suspension of 2-micrometer cinder particles in water. The dust settles as the water freezes, and forms layers between clear ice. The first close-up images of the inside of a hole were taken in the solid ice/dust sample with the borescope as it is lowered slowly to the bottom. The ice in these images appears almost black, and the dust layers are reddish horizontal bands. Of course, we do not yet know what the subsurface of Mars' north polar cap will look like up close, but this experiment helps demonstrate the wealth of information that could be obtained. The first scan covers just 10 in of stratigraphy, which could represent many thousands of years of Mars climate history. The actual MPP borescope could be programmed to automatically search for layers, or the science team back on Earth could control its motion interactively. The other type of sample we looked at was composed of "snow" and dust layers. We formed small "snow" grains by spraying water mist into liquid nitrogen, then sprinkled layers of this "snow" into a bucket followed by fine layers of dust. Each dust layer was cemented with a small spray of liquid water. The sample was then allowed to anneal for several hours at -3 degrees C before cooling to -80 degrees C for drilling. The second sequence of close-up borescope images in the video shows parts of a scan of a hole drilled in a snow/dust sample. The snow grains are bright spheroids 50-100 micrometers in diameter and some dark dust particles can be seen scattered among them, especially near the dust layers. Pledger D. Billing-Ross J. Honeywell's Compact, Wide-Angle UV-Visible Imaging Sensor Honeywell is currently developing the Earth Reference Attitude Determination System (ERADS). ERADS determines attitude by imaging the entire Earth's limb and a ring of the adjacent star field in the 2800 degrees-3000 angstrom band of the ultraviolet. This is achieved through the use of a highly nonconventional optical system, an intensifier tube, and a mega-element CCD array. The optics image a 30-degree region in the center of the field, and an outer region typically from 128 degrees to 148 degrees, which can be adjusted up to 180 degrees. Because of the design employed, the illumination at the outer edge of the field is only some 15% below that at the center, in contrast to the drastic roll-offs encountered in conventional wide-angle sensors. The outer diameter of the sensor is only 3 in; the volume and weight of the entire system, including processor, are 1000 cm3 and 6 kg, respectively. The basic ERADS configuration has many unusual features that could also be utilized for purposes other than attitude reference. The ability to image over a 360-degree azimuth with a small, strapdown sensor could find application wherever surveillance of the entire surrounding field is desired. Because field-of-view is brought into the optical system in seven isolated segments, it is possible to use different wavebands for different parts of the view field. In order to utilize a fiber-optic field flattener, the incoming ultraviolet is downconverted with high quantum efficiency to visible radiation. The same sensor, therefore, can be used for visible wavelengths with only a change in the input filter. The segmentation of the field also makes it possible to isolate the effects of bright sources, such as the Sun, and continue operation in other areas. The phototube provides the necessary gating and eliminates the requirement for a mechanical chopper. In conjunction with the antiblooming CCD, it provides a very wide dynamic range. The ERADS processor is designed to provide a complete image readout at 2 Hz, and this frequency is dynamically variable. ERADS is a very smart sensor, and a high degree of processing capability is built into it to provide object recognition and analysis. CCDs of 4 and 16 megapixels are becoming available that will allow expansion of ERAD'S resolution capabilities in the future. Reedy R. C. Auchampaugh G. F. Barraclough B. L. Burt W. W. Byrd R. C. Drake D. M. Edwards B. C. Feldman W. C. Martin R. A. Moss C. E. Nakano G. H. Gamma Ray/Neutron Spectrometers for Planetary Elemental Mapping Los Alamos has designed gamma ray and neutron spectrometers for Lunar Scout, two robotic missions to map the Moon from 100-km polar orbits. Knowledge of the elemental composition is desirable in identifying resources and for geochemical studies and can be obtained using gamma ray and neutron spectrometers. Measurements with gamma ray and neutron spectrometers complement each other in determining elemental abundances in a planet's surface. Gamma rays with energies of ~0.2-10 MeV escaping from a planetary surface can map most elements using characteristic gamma rays [1]. NaI(Tl) gamma ray spectrometers on Apollo determined Th, Fe, Ti, K, and Mg over 20% of the Moon's surface [1], and a high-purity germanium gamma ray spectrometer (GRS) cooled by a passive radiator is on the Mars Observer, which will map Mars starting late 1993 [2]. Our GRS is a high-purity n-type germanium (Ge) crystal surrounded by an CsI(Na) anticoincidence shield (ACS) and cooled by a split Stirling cycle cryocooler [3]. The ACS eliminates events in the Ge due to cosmic-ray particles, serves as a back-up gamma ray detector, and allows the GRS to be mounted close to the spacecraft. The cryocooler is the British Aerospace design marketed by TRW, and a pair of compressors and expanders are used to minimize vibration effects. The fluxes of neutrons escaping from the Moon are very sensitive to hydrogen in the top meter of the surface and provide information on the abundance of elements that strongly absorb thermal neutrons [4]. The Mars Observer GRS will be the first instrument to measure neutrons from another planet using a special ACS designed to measure thermal and epithermal neutrons [2]. Our neutron spectrometer will measure fast and slow (epithermal and thermal) neutrons in the ranges of 0.5 MeV to 25 MeV and ~0.01-1000 eV, respectively [5]. The fast neutron sensor consists of four boron-loaded plastic scintillator rods optically coupled to photomultiplier tubes. Thermal and epithermal neutrons will be measured with 3He gas proportional counters. The epithermal counter will be wrapped with cadmium to remove thermal neutrons, and the "bare" counter measures both thermal and epithermal neutrons. This work was done under the auspices of the US DOE. References: [1] Evans L. G. et al. (1993) in Remote Geochemical Analysis, Cambridge, in press. [2] Boynton W. V. et al. (1992) JGR, 97, 7681. [3] Moss C. E. et al. (1993) LPSC XXIV, in press. [4] Feldman W. C. et al. (1991) GRL, 18, 2157. [5] Auchampaugh G. et al. (1993) LPSC XXIV, in press. Rona M. Infrared Rugates by Molecular Beam Epitaxy Rugates are optical structures that have a sinusoidal index of refraction (harmonic gradient-index field). As their discrete high/low index filter counterparts, they can be used as narrow rejection band filters. However, since rugates do not have abrupt interfaces, they tend to have a smaller absorption, hence deliver a higher in-band reflectivity. The absence of sharp interfaces makes rugates even more desirable for high-energy narrowband reflectors. In this application, the lack of a sharp interface at the maximum internal standing wave electric field results in higher breakdown strengths. Our method involves fabricating rugates, with molecular beam epitaxy [1], on GaAs wafers as an A1(x)Ga(1-x)As single-crystal film in which x, the alloying ratio, changes in a periodic fashion between 0 < x < 0.5 [2]. The single- crystal material improves the rugate performance even further by eliminating the enhanced optical absorption associated with the grain boundaries. Salient features of our single crystal rugate fabrication program, including the process control system and methodology and some representative results, are shown [3]. References: [1] Rona M. and Sullivan P. W. (1982) Laser Induced Damage in Optical Materials: 1982 Proceedings of the Symposium (NBS-SP-69), (H. E. Bennett et al., eds.), pp. 234-242. [2] Rona M. Proceedings of the Topical Meeting in High Power Laser Optical Components, 30-31 October 1989, Unclassified Papers, Naval Weapons Center NWC-TP 7080, part 1 (J. L. Stanford, ed.), pp. 431-436. [3] Rona M. Report to the Materials Director Wright Laboratory, Air Force Systems Command, Wright Patterson Air Force Base, Ohio 45433-6533, Report No. WL-TR-91-4144. Russell C. T. Luhmann J. G. Plasma, Magnetic, and Electromagnetic Measurements at Nonmagnetic Bodies The need to explore the magnetospheres of the Earth and of the giant planets is widely recognized and is an integral part of our planetary exploration program. The equal need to explore the plasma, magnetic, and electromagnetic environments of the nonmagnetic bodies is not so widely appreciated. The previous, albeit incomplete, magnetic and electric field measurements at Venus, Mars, and comets have proven critical to our understanding of their atmospheres and ionospheres in areas ranging from planetary lightning to solar wind scavenging and accretion. In the cases of Venus and Mars, the ionospheres can provide communication paths over the horizon for low-altitude probes and landers, but we know little about their lower boundaries. The expected varying magnetic fields below these planetary ionospheres penetrates the planetary crusts and can be used to sound the electrical conductivity and hence the thermal profiles of the interiors. However, we have no knowledge of the levels of such fields, let alone their morphology. Finally, we note that the absence of an atmosphere and an ionosphere does not make an object any less interesting for the purposes of electromagnetic exploration. Even weak remanent magnetism such as that found on the Moon during the Apollo program provides insight into the present and past states of planetary interiors. We have very intriguing data from our space probes during times of both close and distant passages of asteroids that suggest they may have coherent magnetization. If true, this observation will put important constraints on how the asteroids formed and have evolved. Our planetary exploration program must exploit its full range of exploration tools if it is to characterize the bodies of the solar system thoroughly. We should especially take advantage of those techniques that are proven and require low mass, low power, and low telemetry rates to undertake. Rust D. M. Kumar A. Thompson K. E. A Compact Imaging Detector of Polarization and Spectral Content A new type of image detector will simultaneously analyze the polarization of light at all picture elements in a scene. The Integrated Dual Imaging Detector (IDID) consists of a polarizing beam splitter bonded to a charge-coupled device (CCD), with signal-analysis circuitry and analog-to-digital converters, all integrated on a silicon chip. The polarizing beam splitter can be either a Ronchi ruling, or an array of cylindrical lenslets, bonded to a birefringent wafer. The wafer, in turn, is bonded to the CCD so that light in the two orthogonal planes of polarization falls on adjacent pairs of pixels. The use of a high-index birefringent material, e.g., rutile, allows the IDID to operate at f-numbers as high as f/3.5. Without an auxiliary processor, the IDID will output the polarization map of a scene with about 1% precision. With an auxiliary processor, it should be capable of 1:10^4 polarization discrimination. The IDID is intended to simplify the design and operation of imaging polarimeters and spectroscopic imagers used, for example, in planetary, atmospheric and solar research. Innovations in the IDID include (1) two interleaved 512 x 1024-pixel imaging arrays (one for each polarization plane); (2) large dynamic range (well depth of 10^6 electrons per pixel); (3) simultaneous read-out of both images at 10 million pixels per second each; (4) on-chip analog signal processing to produce polarization maps in real time; and (5) on-chip 10-bit A/D conversion. When used with a lithium-niobate Fabry-Perot etalon or other color filter that can encode spectral information as polarization, the IDID can collect and analyze simultaneous images at two wavelengths. Precise photometric analysis of molecular or atomic concentrations in the atmosphere is one suggested application. Serra-Ricart M. Garrido Ll. Gaitan V. Aloy A. Digital Image Compression Using Artificial Neural Networks The problem of storing, transmitting, and manipulating digital images is considered. Because of the file sizes involved, large amounts of digitized image information are becoming common in modern projects. Transmitting images will always consume large amounts of bandwidth, and storing images will always require special devices. Our goal is to describe an image compression transform coder based on artificial neural networks techniques (hereafter Neural Network Compression Transform Coder or NNCTC). Like all generic image compression transform coders, the NNCTC embodies a three-step algorithm: invertible transformation to the image (transform), lossy quantization (quantize), and entropy coding (remove redundancy). Efficient algorithms have already been developed to achieve the two last steps, quantize and remove redundancy [4]. The NNCTC offers an alternative invertible transformation based on neural network analysis [3]. A comparison of the compression results obtained from digital astronomical images by the NNCTC and the method used in the compression of the digitized sky survey from the Space Telescope Science Institute based on the H-transform [3] is performed in order to assess the reliability of the NNCTC. Artificial neural network techniques are based on the dot-product calculation, which is very simple to perform in hardware [4]. It is in this sense that the NNCTC can be useful when high compression and/or decompression rates are required (e.g., space applications, remote observing, remote database access). References: [1] Wickerhauser M. V. (1992) Digital Signal Processing, 2, 204. [2] Serra-Ricart M. et al. (1993) Astron. J., in press. [3] Fritze K. et al. (1977) Astr. Nachr., 298, 189. [4] Morgan M. et al., eds. (1990) Artificial Neural Networks Electronic Implementations, IEEE Computer Society, Los Alamitos. Shelfer T. D. Morris R. V. Agresti D. G. Nguyen T. Wills E. L. Shen M. H. Prototype Backscatter Mossbauer Spectrometer for MESURment of Martian Surface Mineralogy We have designed and successfully tested a prototype of a backscatter Mossbauer spectrometer (BaMS) targeted for use on the martian surface to (1) determine oxidation states of iron and (2) identify and determine relative abundances of iron-bearing mineralogies. No sample preparation is required to perform measurements; it is only necessary to bring sample and instrument into physical contact. The prototype meets our projected specifications for a flight instrument in terms of mass (<500 g), power (<2 W), and volume (<300 cm3). A Mossbauer spectrometer on the martian surface would provide a wide variety of information about the current state of the martian surface: 1. Oxidation State: Iron Mossbauer spectroscopy (FeMS) can determine the distribution of iron among its oxidation states. Is soil oxidized relative to rocks? 2. Mineralogy: FeMS can identify iron-bearing mineralogies (e.g., olivine, pyroxene, magnetite, hematite, ilmenite, clay, and amorphous phases) and their relative abundances. FeMS is not blind to opaque phases (e.g., ilmenite and magnetite), as are visible and near-IR spectroscopy. 3. Magnetic Properties: FeMS can distinguish between magnetite and maghemite, which are putative mineralogies to explain the magnetic nature of martian soil. 4. Water: FeMS can distinguish between anhydrous phases such as hematite, olivine, pyroxene, and hydrous phases such as clay, ferrihydrite, goethite, and lepidocrocite. What are the relative proportions of hydrous and anhydrous iron-bearing mineralogies? In summary, a BaMS instrument on MESUR would provide a very high return of scientific information about the martian surface (with no sample preparation) and would place a very low resource demand (weight, power, mass, data rate) on spacecraft and lander. Our BaMS instrument can be flight-qualified within two years and is also suitable for lander missions to the Moon, comets, and asteroids. References: [1] Agresti D. G. et al. (1992) Hyperfine Interactions, 72, 285. [2] Bell J. F. III et al. (1990) JGR, 95, 14447. [3] Klingelhofer G. et al. (1992) Hyperfine Interactions, 71, 1449. [4] Morris R. V. et al. (1989) JGR, 94, 2760. [5] Morris R. V. and Lauer H. V. Jr. (1990) JGR, 95, 10257. Shirley D. J. Spacecraft Computer Technology at Southwest Research Institute Southwest Research Institute (SwRI) has developed and delivered spacecraft computers for a number of different near-earth orbit spacecraft including shuttle experiments and SDIO free-flyer experiments. Here we describe the evolution of the basic SwRI spacecraft computer design from those weighing in at 20 to 25 lb and using 20 to 30 W to newer models weighing less than 5 lb and using only about 5 W, yet delivering twice the processing throughput. These newer designs, because of their reduced size, weight, and power are especially applicable to planetary instrument requirements. The basis of our design evolution has been the availability of more powerful processor chip sets and the development of higher-density packaging technology, coupled with more aggressive design strategies in incorporating high-density FPGA technology and use of high-density memory chips. In addition to reductions in size, weight, and power, the newer designs also address the necessity of survival in the harsh radiation environment of space. Spurred by participation in such programs as MSTI, LACE, RME, Delta 181, Delta Star, and RADARSAT, our designs have evolved in response to program demands to be small, low-powered units, radiation tolerant enough to be suitable for both Earth-orbit microsats and for planetary instruments. Present designs already include MIL-STD-1750 and Multi-Chip Module (MCM) technology with near-term plans to include RISC processors and higher-density MCMs. Long-term plans include development of whole-core processors on one or two MCMs. Snyder W. A. Gursky H. Heckathorn H. M. Lucke R. L. Berg S. L. Dombrowski E. G. Kessel R. A. The Backgrounds Data Center The Strategic Defense Initiative Organization (SDIO) has created data centers for midcourse, plumes, and backgrounds phenomenologies. The Backgrounds Data Center (BDC), located at the Naval Research Laboratory (NRL), has been designated by the SDIO as the prime archive for data collected by SDIO programs for which substantial backgrounds measurements are planned. The BDC will be the prime archive for MSX data, which will total about 15 TB over three years. Current BDC holdings include data from the VUE, UVPI, UVLIM, FUVCAM, TCE, and CLOUDS programs. Data from IBSS, CIRRIS 1A, and MSTI, among others, will be available at the BDC in the near future. The BDC will also archive data from the Clementine mission. The BDC maintains a Summary Catalog that contains "metadata," that is, information about data, such as when the data were obtained, what the spectral range of the data is, and what region of the Earth or sky was observed. Queries to this catalog result in a listing of all datasets (from all experiments in the Summary Catalog) that satisfy the specified criteria. Thus, the user can identify different experiments that made similar observations and order them from the BDC for analysis. On-site users can use the Science Analysis Facility (SAF) for this purpose. For some programs, the BDC maintains a Program Catalog, which can classify data in as many ways as desired (rather than just by position, time, and spectral range as in the Summary Catalog). For example, datasets could be tagged with such diverse parameters as solar illumination angle, signal level, or the value of a particular spectral ratio, as long as these quantities can be read from the digital record or calculated from it by the ingest program. All unclassified catalogs and unclassified data will be remotely accessible. The activities and functionality of the BDC will be described. Information is presented about the BDC facilities, user support capabilities, and hardware and software systems. Soreide D. C. McGann R. L. Erwin L. L. Morris D. J. The Enhanced-Mode Ladar Wind Sensor and Its Application in Planetary Wind Velocity Measurements For several years we have been developing an optical air-speed sensor that has a clear application as a meteorological wind-speed sensor for the Mars landers. This sensor has been developed for airplane use to replace the familiar, pressure-based Pitot probe. Our approach utilizes a new concept in the laser-based optical measurement of air velocity (the Enhanced-Mode Ladar), which allows us to make velocity measurements with significantly lower laser power than conventional methods. The application of the Enhanced-Mode Ladar to measuring wind speeds in the martian atmosphere has a number of advantages over previously fielded systems. The point at which the measurement is made is approximately 1 m from the lander. This eliminates the problem of flow distortion caused by the lander. Because the ladar uses a small, flush-mounted window in the lander instead of being mounted out in the wind, dust damage and erosion will be dramatically reduced. The calibration of the ladar system is dependent only on the laser wavelength, which is inherently fixed. Our approach does require the presence of aerosol particles, but the presence of dust in the martian atmosphere is well established. Preliminary calculations indicate that the Enhanced-Mode Ladar will only consume .001 Wsec per velocity update, not including the power for signal processing. We have developed a brassboard version of the Enhanced- Mode Ladar for airplane applications that we will flight test in early April. This brassboard has been used to measure wind speeds (in Earth's atmosphere) with a backscatter coefficient similar to that on Mars. Results of a single set of measurements (wind speed vs. time backscatter coefficient = 4.5E-6) are shown in Fig. 1, which appears in the hard copy. Srivastava S. K. A Low Cost, Lightweight, and Miniaturized Time-of-Flight Mass Spectrometer (TOFMS) Time-of-flight mass spectrometers (TOFMS) are commonly used for mass analysis and for the measurement of energy distributions of charged particles. For achieving high mass and energy resolution these instruments generally comprise of long flight tubes, often as long as a few meters. This necessitates high voltages and a very clean environment. These requirements make them bulky and heavy. We have developed [1] an instrument and calibration techniques [2] that are based on the design principles of TOFMS. However, instead of one long flight tube it consists of a series of cylindrical electrostatic lenses that confine ions under study along the axis of the flight tube. This results in a short flight tube (i.e., low mass), high mass resolution, and high energy resolution. A laboratory version of this instrument is in routine operation. A schematic diagram of this instrument is shown in Fig. 1, which appears in the hard copy. References: [1] Krishnakumar E. and Srivastava S. K. (1992) Int. Jour. Mass Spetrom. and Ion Proc., 113, 1-12. [2] Srivastava S. K. (1990) U.S. Patent #4,973,840. Stofan E. R. Saunders R. S. Senske D. Nock K. Tralli D. Lundgren P. Smrekar S. Banerdt B. Kaiser W. Dudenhoefer J. Goldwater B. Schock A. Neuman J. Venus Interior Structure Mission (VISM): Establishing a Seismic Network on Venus Introduction: Magellan radar data show the surface of Venus to contain a wide range of geologic features (large volcanos, extensive rift valleys, etc.) [1,2]. Although networks of interconnecting zones of deformation are identified, a system of spreading ridges and subduction zones like those that dominate the tectonic style of the Earth do not appear to be present. In addition, the absence of a mantle low-viscosity zone suggests a strong link between mantle dynamics and the surface [3,4]. As a natural follow-on to the Magellan mission, establishing a network of seismometers on Venus will provide detailed quantitative information on the large-scale interior structure of the planet. When analyzed in conjunction with image, gravity, and topography information, these data will aid in constraining mechanisms that drive surface deformation. Scientific Objectives: The main objective for establishing a network of seismometers on Venus is to obtain information on both shallow and deep structure of the planet. Problems that will be specifically addressed are (1) identifying the location of the crust/mantle boundary; (2) determining the presence or absence of a mantle low-viscosity zone; (3) establishing the state of the core (is there a liquid outer core ?); (4) measuring the spatial and temporal distribution of Venus quakes; and (5) determining source mechanisms for Venus quakes. Mission Structure: The Venus Interior Structure Mission (VISM) consists of three seismometers deployed from landers on the surface in a triangular pattern (two located approximately 250 km from each other and the third at the apex of the triangle at a distance of 1000 km). The landers will be delivered by a carrier bus that will be placed into Venus orbit so it can act as relay to transmit data from the surface to the Earth (data rate of 100Mb/day/lander). By necessity, the surface stations must be relatively long- lived, on the order of six months to one year. In order to achieve this goal, each lander will employ a General Purpose Heat Source (GPHS)-powered Stirling engine to provide cooling (refrigeration to 25 degrees C) and electric power. Upon reaching the surface, a seismometer is deployed a small distance from each lander and is directly coupled to the surface. Seismic data are recorded at a rate of 1100 b/s (including lander engineering telemetry). The seismometer will be enshrouded by a shield so as to isolate it from wind noise. The instrument is an accelerometer patterned after that proposed for MESUR, having a sensitivity in the range of 0.05 Hz to 40 Hz. On the basis of theoretical analyses, it should be possible to observe over 600 events of magnitude 4.0 or better over the lifetime of the network, which will provide sufficient data to characterize the large-scale interior structure of Venus. References: [1] Head J. W. et al. (1992) JGR, 97, 13153-13197. [2] Solomon S. C. et al. (1992) JGR, 97, 13199-13255. [3] Kiefer W. S. et al. (1986) GRL, 13, 14-17. [4] Smerkar S. E. and Phillips R. J. (1991) EPSL, 107, 582-597. Swenson C. M. Baker K. D. Pound E. Jensen M. D. Plasma Diagnostics by Antenna Impedance Measurements The impedance of an electrically short antenna immersed in a plasma provides an excellent in situ diagnostic tool for electron density and other plasma parameters. By electrically short we mean that the wavelength of the free-space electromagnetic wave that would be excited at the driving frequency is much longer than the physical size of the antenna. Probes using this impedance technique have had a long history with sounding rockets and satellites, stretching back to the early sixties [1]. This active technique could provide information on composition and temperature of plasmas for comet or planetary missions. There are several advantages to the impedance probe technique when compared with other methods. The measurement of electron density is, to first order, independent of electron temperature, vehicle potential, probe surface contamination, and orientation to the geomagnetic field. Surface heating and variations of the antenna surface physics do not effect the VLF and RF characteristics of the antenna and hence do not effect the accuracy of the measurements. As such, the technique is ideal for probes plunging into planetary atmospheres where surface contamination is a concern. Currently two classes of instruments are built and flown by SDL-USU for determining electron density, the so-called capacitance and plasma frequency probes. The plasma frequency probe [7] operates in nearly collisionless plasmas and can provide absolute electron density measurements with 1% accuracy at sampling rates as high as 20 kHz, and the capacitance probe can provide electron density measurements with about 5% accuracy in strongly collisional plasmas. The instrumentation weighs less than 0.5 kg, consumes less than 1 W (continuous operation), and only requires a simple 0.1-m antenna [4]. Recently, from l9S7 to 1991, the plasma frequency probe has successfully flown on 11 sounding rockets launched into the Earth's ionosphere at low, mid, and high latitudes and 5 more are being readied for missions in the immediate future. The impedance of such short antennas has been extensively studied theoretically [2,3,5] and laboratory experiments have shown excellent agreement with theory [6]. When the current distribution on the antenna matches a natural mode of the plasma, energy is carried away by a plasma wave resulting in a large contribution to the antenna impedance. A measurement of the antenna impedance provides information on the normal modes of a plasma from which electron density, temperature, or ion composition could be deduced. The versatility and simplicity of an impedance probe would be ideal for the limited resources of planetary missions. References: [1] Baker K. D. et al. (1969) Small Rocket Inst. Tech., 49-57. [2] Balmain K. D. (1964) IEEE Trans. Antennas Propagat., 12, 605-617. [3] Bishop R. H. (1970) Ph.D. thesis, Univ. of Utah. [4] Jensen K. D. and Baker H. D. (1992) J. Spacecraft Rockets, 29, 91-95. [5] Nakatani D. T. and Kuehl H. H. (1976) Radio Sci., 11, 433-444. [6] Nakatani D. T. and Kuehl H. H. (1976) Radio Sci., 11, 517-529. [7] Swenson C. M. (1989) M.S. thesis, Utah State Univ. Toepfer A. J. Eppler D. Friedlander A. Weitz R. Use of Particle Beams for Lunar Prospecting A key issue in choosing the appropriate site for a manned lunar base is the availability of resources, particularly oxygen and hydrogen for the production of water, and ores for the production of fuels and building materials. NASA has proposed two Lunar Scout missions that would orbit the Moon and use, among other instruments, a hard X-ray spectrometer, a neutron spectrometer, and a Ge-gamma ray spectrometer to map the lunar surface. This passive instrumentation will have low resolution (tens of kilometers) due to the low signal levels produced by natural radioactivity and the interaction of cosmic rays and the solar wind with the lunar surface. This paper presents the results of a concept definition effort for a neutral particle beam lunar mapper probe. The idea of using particle beam probes to survey asteroids was first proposed by Sagdeev et. al. [1], and an ion beam device was fielded on the 1988 Soviet probe to the Mars moon Phobos. During the past five years, significant advances in the technology of neutral particle beams (NPB) have led to a suborbital flight of a neutral hydrogen beam device in the SDIO- sponsored BEAR experiment. An orbital experiment, the Neutral Particle Beam Far Field Optics Experiment (NPB-FOX) is presently in the preliminary design phase. The development of NPB accelerators that are space-operable leads one to consider the utility of these devices for probing the surface of the Moon using gamma ray, X-ray and optical/UV spectroscopy to locate various elements and compounds [2]. We consider the utility of the NPB-FOX satellite containing a 5-MeV particle beam accelerator as a probe in lunar orbit. Irradiation of the lunar surface by the particle beam will induce secondary and backscattered radiation from the lunar surface to be detected by a sensor that may be co- orbital with or on the particle beam satellite platform, or may be in a separate orbit. The secondary radiation is characteristic of the make-up of the lunar surface. The size of the spot irradiated by the beam is less than 1- km wide along the groundtrack of the satellite, resulting in the potential for high resolution. The fact that the probe could be placed in polar orbit would result in global coverage of the lunar surface. The orbital particle beam probe could provide the basis for selection of sites for more detailed prospecting by surface rovers. This work was partially supported by the U.S. Army Strategic Defense Command under Contract No. DASG60-90-C-0103, Grumman Corporation Subcontract # 52- 87979. References: [1] Sagdeev R. Z. et. al. (1984) Proc. Cospar Conference. [2] Meinel C. et al. (1990) in Proc. Space 90, Engineering, Construction, and Operations in Space II (S. W. Johnson and J. P. Wetzel eds.). Treuhaft R. N. Subnanoradian, Groundbased Tracking of Spaceborne Lasers Over the next few decades ground-based tracking of lasers on planetary spacecraft will supplement or replace tracking of radio transponders. This paper describes research on two candidate technologies for ground-based, angular, laser tracking: The infrared interferometer and the optical filled- aperture telescope. The motivation for infrared and optical tracking will be followed by a description of the current (10-50 nanoradian) and future (subnanoradian) stellar tracking demonstrations with the University of California-Berkeley Infrared Spatial Interferometer (ISI) on Mt. Wilson [1], and the University of California-San Diego Optical Ronchi Telescope on Table Mountain [2]. In the long term, lasers will replace radio transponders to increase telemetry data rates, rougly tenfold, by communication over optical channels [3]. In the short term (next 10 years), few-nanoradian tracking of a low-power laser may outperform single-frequency radio tracking. For example, radio tracking at 3 cm wavelengths is afflicted by charged particle fluctuations at the 5-10 nanoradian level; charged particle effects are negligible for infrared and optical frequencies. Tracking of low-power lasers at planetary distances seems feasible with the above-mentioned instruments. For example, a 0.5-W, laser through a 10-cm aperture at Mars could be tracked by both of the above instruments, with modest upgrades to be implemented before this spring-summer observing season. Angular tracking interferometric phase-time series from ISI will be discussed. It will be shown that new hardware, which will improve detector efficiency, will enable reliable cycle ambiguity resolution in moderate seeing. High correlations between measurements of path lengths within ISI, and those along the paths through the atmosphere to the target star, suggest that most of the atmospheric turbulence contributing to poor seeing is occurring within about 10 m of the ground. For the Table Mountain Ronchi telescope, signal-to-noise improvements will enable tracking of a visual magnitude 11 star. Demonstrations of this capability will occur this summer after hardware upgrades in the spring. The above demonstrations will yield 10-50 nanoradian performance, but it has been shown that subnanoradian performance enables many mission enhancements. For example, subnanoradian angular tracking enables detection of Jupiter's spacecraft-relative position about 100 days before encounter. Subnanoradian tracking is largely prevented by atmospheric refractivity fluctuations for both the above mentioned devices. Methods of minimizing atmospheric effects using optimal stochastic estimation and direct calibration will be described. References: [1] Bester M. et al. (1992) Ap. J., 392, 357. [2] Lanyi G. et al. (1992) Telecommunications and Data Acquisition Progress Report 42-110, (E. Posner, ed.), 104-111, Jet Propulsion Laboratory, Pasadena, California. [3] Lesh J. R. et al. (1990) Telecommunications and Data Acquisition Progress Report 42-103, 97-109, July-September 1990, Jet Propulsion Laboratory, Pasadena, California. Trombka J. I. Floyd S. Ruitberg A. Evans L. Starr R. Metzger A. Reedy R. Drake D. Moss C. Edwards B. Franks L. Devore T. Quam W. Clark P. Boynton W. Rester A. Albats P. Groves J. Schweitzer J. Mahdavi M. A Team Approach to the Development of Gamma Ray and X-Ray Remote Sensing and In Situ Spectroscopy for Planetary Exploration Missions An important part of the investigation of planetary origin and evolution is the determination of the surface composition of planets, comets, and asteroids. Measurements of discrete line X-ray and gamma ray emissions from condensed bodies in space can be used to obtain both qualitative and quantitative elemental composition information. Remote sensing X-ray and gamma ray spectrometers aboard either orbital or flyby spacecraft can be used to measure line emissions in the energy region ~0.2 keV to ~10 MeV. These elemental characteristic excitations can be attributed to a number of processes such as natural radioactivity, solar X-ray fluorescence, and cosmic ray primary- and secondary-induced activity. Determination of composition for the following elements can be expected: O, Si, Fe, Mg, Ti, Ca, H, Cl, K, Th, and U. Global elemental composition maps can be obtained using such spectrometer systems. More complete elemental composition can be obtained by landing packages that include X-ray and gamma ray spectrometer systems along with X-ray, charged particle, and neutron excitation sources on planetary surface. These in situ systems can be used on stationary, roving, and penetrator missions. Both the remote sensing and in situ spectrometer systems have been included aboard a number of U.S. and Russian planetary missions [1,2]. The Planetary Instrument Definition and Development Program (PIDDP) X- Ray/Gamma Ray Team has been established to develop X-ray and gamma ray remote sensing and in situ technologies for future planetary exploration missions. This team represents groups having active programs with NASA, the Department of Energy (DOE), the Department of Defense (DOD), and a number of universities and private companies. A number of working groups have been established as part of this research program. These include groups to study X-ray and gamma ray detectors, cryogenic cooling systems, X-ray and particle excitation sources, mission geochemical research requirements, detector space radiation damage problems, field simulation studies, theoretical calculations and X-ray and nuclear cross sections requirements, and preliminary design of flight systems. Major efforts in this program will be devoted to the development of X-ray/gamma ray remote sensing systems for the NEAR (Near Earth Asteroid Rendezvous) mission and for in situ X-ray and gamma ray/neutron systems for penetrators, soft landers, and rovers for MESUR missions. References: [1] Fichtel C. and Trombka J. I. (1982) Gamma Ray Astrophysics New Insight and into the Universe, NASA SP-453, 19-65. [2] Boynton W. V. et al. (1992) JGR, 97, 7681-7698. Tward E. Miniature Long-Life Space Cryocoolers Cryogenic coolers for use in space on small satellites require low power and minimum weight. The need for exceptional reliability in a space cooler is made even more critical on small satellites since cooler redundancy is often not an option due to weight constraints. In this paper we report on two reliable, small, efficient low-power, vibrationally balanced coolers designed specifically for use on small satellites. TRW has designed, built, and tested a miniature integral Stirling cooler and a miniature pulse tube cooler intended for long-life space application. Both efficient, low-vibration coolers were developed for cooling IR sensors to temperatures as low as 50 K on lightsats. The vibrationally balanced nonwearing design Stirling cooler incorporates clearance seals maintained by flexure springs for both the compressor and the drive displacer. The design achieved its performance goal of 0.25 W at 65 K for an input power to the compressor of 12 W. The cooler recently passed launch vibration tests prior to its entry into an extended life test and its first scheduled flight in 1995. The vibrationally balanced, miniature pulse tube cooler intended for a 10-year long-life space application incorporates a nonwearing flexure bearing compressor vibrationally balanced by a motor-controlled balancer and a completely passive pulse tube cold head. The maximum cooling power measured at 80 K is 800 mW for an input power to the compressor of 30 W. The cooler is suitable for cooling sensors and optics between 60 K and 200 K, with cooling powers up to 3.5 W at 200 K. Self-induced vibration measurements indicate that the cooler can be balanced to reduce vibration forces below 0.02 newtons from 0 to 500 Hz. Uy O. M. Environmental Monitors in the Midcourse Space Experiments (MSX) The Midcourse Space Experiment(MSX) is an SDIO-sponsored space-based sensor experiment with a full complement of optical sensors. Because of the possible deleterious effect of both molecular and particulate contamination on these sensors, a suite of environmental monitoring instruments are also being flown with the spacecraft. These instruments are the Total Pressure Sensor based on the cold-cathode gauge, a quadrupole mass spectrometer, a Bennett-type ion mass spectrometer, a cryogenic quartz crystal microbalance (QCM), four temperature-controlled QCMs, and a Xenon and Krypton Flash Lamp Experiment. These instruments have been fully space-qualified, are compact and low cost, and are possible candidate sensors for near-term planetary and atmospheric monitoring. The philosophy of adopted during design and fabrication, calibration and ground testing, and modeling will be discussed. Wdowiak T. J. Utlraviolet Imaging Spectrometer Wide-field imaging systems equipped with objective prisms or gratings have had a long history of utility in ground-based observations of meteors [1] and comets [2]. Deployment of similar instruments from low Earth orbit would allow the first UV observations of meteors. This instrument can be used for comets and Lyman alpha coronae of Earth-orbit-crossing asteroids. A CaF2 prism imaging spectrograph designed for stellar observations was used aboard Skylab to observe Comet Kohoutek (1973f), but its 1300-Angstrom cut-off precluded Lyman alpha images and it was not used for observation of meteors [3]. Because the observation of the UV spectrum of a meteor has never been attempted, researchers are denied the opportunity to obtain composition information from spectra at those wavelengths. We propose construction of a flight instrument functioning in the 1100-3200-Angstrom spectral range that is suitable for a dedicated satellite ("QuickStar") or as a space-station-attached payload. It can also be an autonomous package in the space shuttle cargo bay. The instrument structure is of graphite fiber epoxy composite, and has an objective diffraction grating, low expansion optics, multichannel plate electro-optics, and event discrimination capability through processing of video data. It would either have a field-of-view (fov) of 12 degrees and f number of 0.75 or a wider fov of 20-25 degrees and f number of 1. The instrument has a heritage from the UV auroral imager of the Swedish Viking spacecraft [4]. References: [1] Harvey G. A. (1977) NASA TN D-8505. [2] Richter N. B. (1963) Nature of Comets, p. 75, Methuen. [3] Henize K. G. et al. (1975) in NASA SP- 355, 129-133. [4] Anger C. D. et al. (1987) GRL, 14, 387-390. Young D. T. Development of Miniaturized Optimized Smart Sensors (MOSS) for Space Plasmas The cost of space plasma sensors is high for several reasons: (1) most are one-of-a-kind and state-of-the-art, (2) the cost of launch to orbit is high, (3) ruggedness and reliability requirements lead to costly development and test programs, and (4) overhead is added by overly elaborate or generalized spacecraft interface requirements. Possible approaches to reducing costs include development of small "sensors" (defined as including all necessary optics, detectors, and related electronics) that will ultimately lead to cheaper missions by reducing (2), improving (3), and, through work with spacecraft designers, reducing (4). Despite this logical approach, there is no guarantee that smaller sensors are necessarily either better or cheaper. We have previously [1] advocated applying analytical "quality factors" to plasma sensors (and spacecraft) and have begun to develop miniaturized particle optical systems by applying quantitative optimization criteria. We are currently designing a Miniaturized Optimized Smart Sensor (MOSS) in which miniaturized electronics (e.g., employing new power supply topology and extensive use of gate arrays and hybrid circuits) are fully integrated with newly developed particle optics to give significant savings in volume and mass. The goal of the SwRI MOSS program is development of a fully self- contained and functional plasma sensor weighing ~1 lb. and requiring ~1 W. MOSS will require only a typical spacecraft DC power source (e.g., 30 V) and command/data interfaces in order to be fully functional, and will provide measurement capabilities comparable in most ways to current sensors. References: [1] Young D. T. (1989) AGU Monograph, 54, 143-157. Zukic M. Torr D. G. X-Ray, Far, and Extreme Ultraviolet Coatings for Space Applications The improved FUV filters that we have designed and fabricated were made as combinations of three reflection and one transmission filter. Narrowband filtering with a bandwidths of 5 nm and a throughput at the central wavelength of more than 20% is achieved, for example, at 130.4 nm and 135.6 nm with the average blocking of out-of-band wavelengths of better than 4 x 10^-4%. In the case of broadband filters a multiple reflector centered at 150 and 170 nm combined with corresponding transmission filters had a bandwidth of more than 11 nm and transmittance greater than 60%. The average blocking of out-of-band wavelengths is better than 4 x 10^-4% with less than 10-5% transmittance at 121.6 nm [1-5]. The idea of utilizing the multiple reflections from pi multilayer reflectors constitutes the basis of the design approach used for the narrowband and broadband filters. The multiple reflector combinations provide spectral performance for narrow- and broadband filters superior to what was previously available [6-9]. The idea of utilizing imaging mirrors as narrowband filters constitutes the basis of the design of extreme ultraviolet imagers operating at 58.4 nm and 83.4 nm. The net throughput of both imaging-filtering systems is better than 20%. The superiority of the EUV self-filtering camera/telescope becomes apparent when compared to previously theoretically designed 83.4-nm filtering- imaging systems, which yielded transmissions of less than a few percent [10] and therefore less than 0.1% throughput when combined with at least two imaging mirrors. Utilizing the self-filtering approach, instruments with similar performances are possible for imaging at other EUV wavelengths, such as 30.4 nm [11-12]. The self-filtering concept is extended to the X-ray region where its application can result in the new generation of X-ray telescopes, which could replace current designs based on large and heavy collimators. The calculated reflectance for an 80-degree angle of incidence shows a reflectance peak value of 35.8% at 0.73 nm (2.621 KeV) with the bandwidth of the reflector less than 0.01 nm. The in-band to out-band ratio is more than 3000, with an instrument monochromatic sensitivity factor T[%] delta lambda [nm] > 3600. At an 85- degree angle of incidence the peak reflectance is more than 65% at 0.44 nm with a bandwidth of less than 0.006 nm providing the ratio T[%] delta lambda [nm] > 10,000. References: [1] Zukic M. and Torr D. G. (1992) Appl. Opt., 31, 1588. [2] Zukic M. and Torr D. G. (1993) in Topics in Applied Physics (K. H. Guenther, ed.) Chapter VII, Springer-Verlag series on Thin Films, in press. [3] Zukic M. et al. (1990) Appl. Opt., 29, 4284. [4] Zukic M. et al. (1990) Appl. Opt., 29, 4293. [5] Zukic M. et al. (1992) Proc. SPIE, 1745, 99. [6] Flint B. K. (1979) Opt. Eng., 18, 92. [7] Flint B. K. (1978) Proc. SPIE, 140, 131. [8] Fairchild E. T. (1973) Appl. Opt., 12, 2240. [9] Elias L. R. et al. (1973) Appl. Opt., 12, 138. [10] Seely J. F. and Hunter W. R. (1991) Appl. Opt., 30, 2788. [11] Zukic M. et al. (1991) Proc. SPIE, 1546, 234. [12] Zukic M. et al. (1992) Proc. SPIE, 1744, 178.