Lunar and Planetary Institute

Planetary Science and Astrobiology
Decadal Survey
White Paper Proposals

The purpose of this site is to allow members of the planetary science community to inform one another of their intent to submit a white paper as part of the planetary decadal survey. This site is for information only. Listing a white paper proposal here does not commit the author to submitting a white paper to the Decadal Survey, and you are not required to list your white paper here in order to submit it for the Decadal Survey.

Click here to submit a white paper proposal.

Link to white papers from previous (2011) Planetary Decadal survey

Link to mission concept studies for upcoming Decadal

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Detecting signs of ancient life on Mars The aim of this white paper is to document the need to continue our search for ancient life on Mars. It will discuss the work done so far on this topic, possible ancient biosignatures that could exist on the surface of Mars, potential environments that could preserve ancient biosignatures, current methods of detection, and instrument development that would aid in the search. It would also discuss how this knowledge could be used to inform future Mars sample return missions, in situ robotic missions, and human missions. With the upcoming Mars 2020 (Perseverance) and ExoMars missions, there is a need to continue the momentum and broaden our search to as many paleoenvironments as possible. Andrew Czaja Andrew D. Czaja (
Habitability of Small Bodies This white paper aims to (a) synthesize the understanding of habitability in dwarf planets and large transneptunian objects and (b) build the case warranting future exploration of these objects with space missions; research and analysis needed to better understand their internal environments; and Earth-bound observations that may help assess their astrobiological significance and enable their future exploration. This paper is chartered by SBAG in response to one of five key questions encompassing the science sought at small bodies in the next decade: “Do sustainable habitable environments exist on any of the small bodies?” Cross-referencing with white papers from the outer planet community and astrobiology white papers will be coordinated with the relevant points of contact. White paper chartered by SBAG - All co-authors welcome! Julie Castillo-Rogez (
Mars and other Habitable Worlds as Prebiotic Environments This contribution will consider Mars and other habitable worlds as potential environments in which prebiotic chemistry is ongoing. Chemical analyses of the Martian surface have led to an enhanced understanding of the geochemical environment afforded by this planet. As a relatively accessible environment that is potentially hospitable for life, Mars represents an accessible environment with potential implications for other celestial bodies, such as Titan, Enceladus, and other exoplanets. This white paper will consider lessons learned from Mars exploration and their impacts on exploration of Mars, as well as the implications of the data obtained regarding exploration of other celestial bodies as potential prebiotic environments. Aaron Engelhart, Kennda Lynch, Penelope Boston, Jennifer Blank, Alberto Fairen, Mary Beth Wilhelm, and other interested parties, contact us! Kennda Lynch (
Mars Underground: Searching for Signs of Subsurface Life (Shallow and Deep) on Mars and Elsewhere This community contribution will outline the rational, key science objectives, and mission strategies for the research and exploration of subsurface environments with a focus on the search for life in the subsurface. Kennda Lynch, Vlada Stamenkovic, Penelope Boston, Jesse Tarnas, Hermes Hernan Bolívar-Torres, Rachel L. Harris, Jorge A. Torres and others, please contact us! Kennda Lynch (
Pale Blue Dot Explorer: A Case for Adding Earth to the Planetary Sciences List of Targets Obtaining observational data to inform the science of future missions focused on Earth-like exoplanets is of prime importance for NASA Planetary Science and Astrobiology. However, Earth observations as a proxy for an exoplanet is an area of interdivisional research not well captured by existing NASA programs. Here, spectroscopic observations in reflected light yield critical information about the atmospheric and surface environment of a planet at any stage in its evolution, including its propensity for life. Only an Earth-observing mission (currently only allowed within Earth Sciences) designed to understand characterization strategies for Earth as a guide to our search for life (a primary objective of Planetary Sciences) on Earth-like exoplanets (a primary focus of Astrophysics) can meaningfully respond to these important observational needs. To accommodate this, we propose adding Earth to the list of planets allowable by the Planetary Science Division’s objectives. A specific research investigation would be a spacecraft whose goal would be to characterize Earth as an exoplanet proxy — a Pale Blue Dot Explorer. Such a mission’s objective would be to monitor the habitability and biological signatures of Earth in reflected light over broad wavelengths and phase angles. Sanjoy Som, Tyler Robinson, and any interested parties Sanjoy Som (
Returning Samples from Enceladus for Life Detection This white paper complements the Planetary Mission Concept Study (PMCS) report “Flagship Concepts for Astrobiology at Enceladus”, which does not address sample return. Sample return allows adaptation of analyses to prior findings, access to the full diversity of existing and future interrogation techniques, and time to assess the validity of results. Previous experience has shown that all three aspects are crucial to life detection. Sample return may require substantially less plume sample (milligrams = a few flybys) than in situ investigations (grams) to perform life detection. A Saturn orbiter flying about ten times through Enceladus’ plume minimizes the mission duration to ≈ 15 years, but the effect of collection at ≥ 1 km/s must (and can) be minimized. Technology developments are needed for sample collection and preservation, as well as for the implementation of Restricted Earth Return planetary protection policy for cold samples. The ease of access of ocean material through the plume allows one to bypass the sequence of missions to “fly by, orbit, land, rove, and return samples”. The considerations discussed here could apply to other worlds showing hints of erupted material that could sample a subsurface ocean. M. Neveu, A. Anbar, A. Davila, D. Glavin, S. MacKenzie, C. Phillips-Lander, B. Sherwood, Y. Takano, P. Williams, H. Yano Marc Neveu (
Salty Environments: The importance of current and ancient brine environments as habitats, and preservers of biosignatures Beyond Earth the most likely habitable liquids are salty aqueous solutions, indeed, brines are potentially stable on present day Mars. Further, there is evidence of past salty aqueous environments on Mars (e.g. evaporite deposits in Columbus Crater, intercrater depressions in Terra Sirenum, Jezero Crater, and Gale Crater). Brines can also play an important role in preserving biosignatures and enabling prebiotic chemistry through wet dry cycles. The goal of this contribution is to highlight the value and importance of further research to understand briny environments. This white paper will provide a summary recommendation of the priority research objectives, technology development, and mission strategies that should be focused on in the next decade of planetary exploration. Scott Perl, Kennda Lynch, Edgard Rivera-Valentin, Aaron Engelhart, Bonnie Baxter, Brian Wade, Penelope Boston, Alberto Fairen, and more (contact us)! Scott Perl (
Towards a more universal life detection strategy This white paper argues for a more universal approach to life detection. We recommend that life detection missions focus on looking for signatures of life deemed to be shared by all possible types of life, independent of their specific biochemistries, rather than looking for signatures of life that could arguably be specific to Terran-life. We outline recommendations for generalizing our search criteria, as well as steps to implement in order to grow our knowledge of universal biosignatures while increasing our detection capabilities. Furthermore, we present specific guidelines for using the proposed universal biosignatures to inform instrument selection and science measurements criteria for future missions aimed at life detection. These guidelines include building a standard reference inventory that should be shared across disciplines focused on life detection, building a synergistic framework between multiple instruments and measurements that allows for a more robust interpretation of a biosignature signal, as well as enhancing contamination knowledge to ensure adequate pre-flight protocols for planetary missions that will take place in the next decade. Luoth Chou, Natalie Grefestette, Sarah S. Johnson, Heather Graham, and more. Luoth Chou (
Venus, an astrobiology target This paper summarizes the case for considering Venus as a target for astrobiology exploration to search for biosignatures in the atmosphere/clouds. Limaye et al. Sanjay S. Limaye (
Vital Signs: The Seismology of Icy Ocean Worlds Seismic investigations offer the most comprehensive view into the deep interiors of planetary bodies. The InSight mission and concepts for a Europa Lander and a Lunar Geophysical Network present unique opportunies for seismology to play a critical role in constraining interior structure and thermal state. In oceanic icy worlds, measuring the radial depths of compositional interfaces using seismology in a broad frequency range can sharpen inferences of interior structures deduced from gravity and magnetometry studies, such as those planned for NASA’s proposed Europa Mission and ESA’s JUICE mission. Seismology may also offer information about fluid motions within or beneath ice—which complements magnetic studies—and can record the dynamics of ice layers, which would reveal mechanisms and spatiotemporal occurrence of crack formation and propagation. S. D. Vance, S. W. B. Banerdt, S. Kedar, M. P. Panning, T. W. Pike, S. C. Stähler Steven Vance (
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Experimentally Exploring Exoplanets (E^3): Investigating the distribution of life-necessary elements via the exoplanets in our backyard New observational data of exoplanets will become available in the near future, providing an opportunity to search for habitable worlds beyond Earth. However, our ability to interpret these data are limited without an understanding of geochemical relationships that pertain to planets with compositions that differ from Earth. Geochemical experiments—those that examine the nature and rates of chemical reactions—allow us to investigate these relationships remotely. Specifically, the partitioning of elements driven by planetary differentiation, mantle melting, and crustal processes such as weathering or plate tectonics are all key unknowns that can be investigated with experimental petrology and weathering experiments. This white paper will discuss the benefit of petrologic experiments that utilize the exoplanets in our backyard (e.g., rocky planets, meteorites, exotic chemical systems on Earth) as well as novel compositions derived from stellar abundances within our galactic neighborhood. Additionally, we discuss the benefits of performing weathering experiments under simulated exoplanetary surface conditions and studying ancient Earth as a potential analogue for habitable exoplanets. Such experiments are necessary to produce the baseline data needed to create models for exoplanetary mantle melting, predicted crust composition, and ultimately the availability of elements necessary to foster and maintain life as we know it. K. Brugman, A. Johnson, S. Jacob, M. Karageozian, E. Kohler, J. O’Rourke, C. Till, C. Unterborn Kara Brugman (
On the Use of Planetary Science Data for Studying Extrasolar Planets There is an opportunity to advance both solar system and extrasolar planetary studies that does not require the construction of new telescopes or new missions but better use and access to inter-disciplinary data sets. This approach leverages significant investment from NASA and international space agencies in exploring this solar system and using those discoveries as “ground truth” for the study of extrasolar planets. This white paper illustrates the potential, using phase curves and atmospheric modeling as specific examples. A key advance required to realize this potential is to enable seamless discovery and access within and between planetary science and astronomical data sets. Further, seamless data discovery and access also expands the availability of science, allowing researchers and students at a variety of institutions, equipped only with Internet access and a decent computer to conduct cutting-edge research. D. J. Crichton, J. S. Hughes, R. West, J. Jewell, T. J. W. Lazio Joseph Lazio (
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Dwarf planets

Comparative Planetology Beyond Neptune Enabled by a Near-Term Interstellar Probe A properly instrumented Interstellar Probe could enable flyby geoscience investigations of a Kuiper belt dwarf planet, advancing comparative planetology in the trans-Neptunian region. Please email Kirby Runyon to co-sign or to help co-author. K. D. Runyon, K. E. Mandt, P. Brandt, M. Paul, C. Lisse, R. McNutt, Jr., C.B. Beddingfield, S.A. Stern Kirby Runyon (
Science Case for the Future Exploration of Dwarf Planet Ceres Dwarf planet Ceres is the largest object in the main belt and the most water-rich object in the inner solar system after Earth. Ceres had sufficient water and silicates (i.e., radioisotopes) to host a deep ocean in its history, leading to a layered interior structure with a high degree of aqueous alteration. The Dawn mission revealed evidence for recent and possibly ongoing geologic activity on Ceres, the potential presence of liquid below an ice-rich crust, and high concentrations of organic matter (locally) and carbon (globally) in the shallow subsurface. Recent expressions of brine-driven exposure of material onto Ceres’ surface can be found at Occator Crater and the ~4-km tall, geologically recent mountain Ahuna Mons. The hints of deep liquid and long-lived energy sources led to Ceres’ being categorized as a “candidate ocean world” in the Roadmap for Ocean Worlds. This white paper reviews the science case for future exploration of Ceres in the context of better understanding the evolution of icy worlds, the fate of ocean worlds, and the origin of volatiles and organics in the inner solar system. White paper chartered by SBAG - All co-authors welcome! Julie Castillo-Rogez (
Understanding the formation and evolution of the Kuiper Belt by exploring the Haumea system Since its discovery in 2003, the dwarf planet Haumea has revealed itself to be one of the most intriguing bodies of the Solar System. It has an elongated shape and is spinning at an unusually fast rate of 4h. In addition, it is surrounded by a system of two satellites and a ring, and it is believed to be the parent body of the only collisional family in the Kuiper Belt known to date. The characteristics of the Haumea system and family have led to speculations on possible formation scenarios, including single and multiple collisions or rotational fission. It is also speculated that this dwarf planet could be the remnant core of a larger, differentiated KBO, the mantle of which was disrupted by a giant impact. All these elements indicate that the Haumea system holds key information for several formation and evolution processes of bodies in the Kuiper Belt and the dwarf planet is now one of the most observed objects in that region of the Solar System. The in-situ observation and data collection on Haumea and its system would provide for invaluable insight into the history of the Kuiper Belt and the Solar System ̧ as well as the on-going processes that lead to high spin rates, rings, and satellite systems. Haumea is therefore an ideal mission target. The tremendous success of the New Horizons mission to the Pluto system and 2014 MU69 has demonstrated the feasibility of missions to the trans-Neptunian region. In this white paper, we will make a case for an exploration mission to the dwarf planet Haumea. Julie Brisset, Estela Fernandez-Valenzuela, Amanda Sickafoose, Flaviane Venditti, Akbar Whizin, Esther Beltran, Julie Castillo, Will Grundy, David Minton, Jose Ortiz, Noemi Pinilla-Alonso, Darin Ragozzine, John Stansberry Julie Brisset (
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Giant planets

Exploration of the Ice Giant Systems This white paper discuss the need for spacecraft exploration of the Ice Giants Uranus and Neptune. Exploration of the Ice Giant systems is critical to understand the last class of unexplored planets in our Solar System and to gain important insight into how our Solar System formed and evolved. Investigation of Uranus or Neptune would allow us to gain fundamental understanding on: 1) How these worlds formed and migrated through the Solar System. 2) The processes that control the current conditions of this class of planet. 3) How the rings and satellites formed and evolved and how Triton was captured from the Kuiper Belt. 4) Whether the large satellites of the Ice Giants are Ocean Worlds that may have harbored life now or in the past. 5) The role of the Ice Giants in the delivery of volatiles and impactors to Earth. Additionally, investigating these Ice Giants would provide important insights into the characteristics of many exoplanets, which have been found to fall into a similar size range. Chloe Beddingfield, Cheng Li, Sushil Atreya, Patricia Beauchamp, Ian Cohen, Jonathan Fortney, Heidi Hammel, Matthew Hedman, Mark Hofstadter, Abigail Rymer, Paul Schenk, Mark Showalter, Amy Simon, et al. Chloe Beddingfield (
Magnetospheric Studies: A requirement for addressing interdisciplinary mysteries in the Ice Giant systems A future mission to Uranus or Neptune will address scientific mysteries based on insights gained through the Voyager 2 flyby and Earth based observations. As proven by prior missions, magnetospheric measurements will advance space physics and are key to resolve mysteries across many other disciplines, including planetary interiors, atmospheres, rings, and moons, as we will discuss. everybody who is interested Peter Kollmann (
New Frontiers-class Uranus Orbiter: Exploring the feasibility of achieving multidisciplinary science with a mid-scale mission Uranus presents a compelling scientific target for many reasons, providing a unique opportunity to explore Ice Giant system science. For many reasons, the imperative and timely exploration of Uranus will not only enhance our understanding of the Ice Giant planets but also extends to planetary dynamics throughout our solar system and beyond. The timeliness of a mission to Uranus is thus a primary motivation for evaluating what science can be done with a lower-cost, potentially faster-turnaround mission, such as a New Frontiers (NF)-class orbiter to Uranus. Just as our understanding of those planets was transformed beyond expectations by dedicated orbiter missions (e.g., Galileo, Juno, Cassini), so too will our knowledge of Uranus expand from the necessary multiyear measurements and investigation. Ian Cohen, C. Beddingfield, S. Brooks, S. Brueshaber, R. Cartwright, A. Coustenis, R. Chancia, G. Clark, G. DiBraccio, S. Dutta, L. Fletcher, M. Hedman, R. Helled, R. Holme, Y. Kasaba, P. Kollmann, S. Luszcz-Cook, and others (please join us!) Ian Cohen (
The Saturn Ring Skimmer The innovative Saturn Ring Skimmer mission concept will observe individual ring particles for the first time, will directly measure the magnetosphere in the region where it is shaped by the rings, and will directly measure the atmosphere of a disk. By taking a broad look at how the rings, the magnetosphere, the upper atmosphere, and the planetary interior compose a coherent interconnected system, the Saturn Ring Skimmer will address new science questions that we didn’t know to ask until the end of Cassini. By studying disk dynamics at the individual particle level, the Saturn Ring Skimmer will use this natural laboratory to help us understand exo-disks and planetary formation. By determining the role played by Saturn’s rings in driving the Saturn system to be very different from Jupiter, the Saturn Ring Skimmer will help us to understand a whole class of exoplanets. We advocate for the New Frontiers list to include an entry that addresses these science objectives. Matthew S. Tiscareno, Matthew M. Hedman, Mar Vaquero, and the Saturn Ring Skimmer Team Matt Tiscareno (
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In-space computing infastructure will revolutionize science missions In-space computational resources such as high-volume storage and fast processing will enable instruments to gather and store much more data than would normally be possible, even if it cannot be downlinked to earth in any reasonable time. The data can be kept on-site for selective retrieval or on-site batch processing guided by downlinked summaries. Under this paradigm, science analysis benefits from on-site summarization, archival for future downlink, access to 3-6 orders of magnitude more data, and multi-sensor fusion without data loss. A secondary benefit is support for increasingly-autonomous systems, including mapping, planning, and multi-robot collaboration. Key to both of these concepts is treating the spacecraft not as an autonomous agent, but as an interactive batch processor, which reduces need for "quantum leaps" in machine intelligence to realize the benefits, and enables regime where analysis techniques are well understood, verifiable, and trusted by the science community. JPL, Ames, APL, Caltech, USGS, Lockheed Martin Joshua Vander Hook (
The Next-Generation Planetary Radar Planetary radar observations have a laudable history of “firsts” including the determination of the astronomical unit at the precision sufficient for interplanetary navigation, the distribution of water at the south pole of the Moon, indications of water ice in the permanently shadowed regions at the poles of Mercury, polar ice and anomalous surface features on Mars, indications that the asteroid 16 Psyche is an exposed (metallic) core of a planetoid, establishing the icy nature of the Jovian satellites, and the initial characterizations of Titan's surface. In many cases, these discoveries by planetary radar systems have motivated missions or radar instruments on missions. This white paper summarizes the current state of the Nation's planetary radar infrastructure and future prospects. T. J. W. Lazio et al. Joseph Lazio (
The Planetary Data System The PDS aspires to provide an integrated world-wide data services platform that enables the efficient discovery, dissemination, use and analysis of internationally sponsored planetary science archives. This paper will describe our vision for the PDS over the next decade and beyond. Louise Prockter, Matt Tiscereno, the PDS node leads and staff, PLANETARY DATA USERS LIKE YOU! PLEASE SIGN ON TO THIS PAPER, THANK YOU!. Louise M Prockter (
Use of Autonomy to Increase Science Return and Enable Novel Science A close partnership between people and semi-autonomous machines has enabled decades of space exploration, but to continue to expand our horizons, our systems must become more capable. Increasing the nature and degree of autonomy - allowing our systems to make and act on internal decisions - enables new science capabilities. Fundamentally, this opens up the exploration of regions that were previously inaccessible, enabling new science observations that are currently beyond our reach. Increased autonomy also improves the quality and yield of our science data, by allowing better and more reliable utilization of observing time, capturing unpredictable exogenous events of interest, and classifying and prioritizing on-board data, resulting in better use of limited downlink resources. All of the missions being considered for inclusion in the Planetary Decadal can benefit from application of autonomy to increase science return and enable novel science observations. PSD-wide set of scientists, engineers and technologists. John Day (
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A case for Mars Polar Science The scope is to show all of the important science that we can do related to ice and climate in the next decade, at mid-latitudes and the poles. With all of the knowledge gained since the arrival of MRO, the time is right for new missions in orbit and on the ground to study the fundamental aspects of Mars in the Amazonian that have received less attention than older terrains. Open to anyone Isaac Smith (
Emerging Capabilities for Mars Exploration This white paper will provide an overview of emerging capabilities and key technologies relevant to future Mars exploration, surveying developments in a number of areas, including: • Entry, Descent, and Landing • Surface & Aerial Mobility • Subsurface Access • Autonomy • Avionics • Communications & Navigation • Power • Propulsion • Small Satellite Technologies The white paper will provide an assessment of the current state-of-the-art and trends in key capability/technology areas relevant to Mars exploration, forecasting current technology developments that can influence next-decade Mars mission plans while also identifying key capability gaps that motivate targeted future technology investments. Chad Edwards, Scott Hubbard, et al. Chad Edwards (
High Science Value Return of Small Spacecraft at Mars In the coming decade, small spacecraft missions, both orbiters and landers, can provide decadal-class science capability, augment flagship missions, establish dedicated Mars infrastructure, and gather key reconnaissance in preparation for human exploration of Mars, at mission costs of a fraction of current Discovery Program cost caps. The paradigm shift in capability cost is enabled by many factors, including order-of-magnitude reduction in cost to emerging launch enabled by rideshare and small launch vehicles, new advances in propulsive and aero-braking technologies, existence and development of small spacecraft compatible science instruments capable of high precision measurement required for decadal-class science, the proliferation of commercial development and use of small spacecraft technology, and new policies and programmatic frameworks to enable a future small spacecraft program. The small spacecraft community has matured and has developed high-TRL components that are a fraction of the mass and cost of larger conventional flight systems. The opportunity for low-cost, frequent access to Mars is optimal and will only become greater over the next decade. This white paper will focus on five key areas: science, implementation, technology, applications, and policy; with the primary focus on science. Small spacecraft can play an integral role in being pathfinders for future large-scale missions and campaigns, and encourage collaboration from partners in academia and other institutions around the world. They provide a mechanism for entry of new participants to learn and eventually lead in their own missions for interplanetary exploration. Small spacecraft present a unique opportunity to take continuous and simultaneous measurements of high-temporal planetary processes when used as a multi-element network. These networks could consist of orbiters from different viewing perspectives and/or small landers as single elements or networks of landers working in concert to provide multi-dimensional science return. Small spacecraft provide tremendous science value because of their low-cost basis and high-value measurement capability. N. Barba, C. Edwards, V. Stamenkovic, R. Woolley, D. Banfield, A. Chmielewski, R. Davis, S. Diniega, R. Lillis, S. Matousek, M. Mischna, Luca Montabone, P. Niles, M. Shihabi, C. Swann, L. Tamparri, F. Tan, J. Tarnas, S. Vijendran et al. Nathan Barba (
Interplanetary Dust Detection at Mars - A Significant Knowledge Gap and a Straightforward Remedy Interplanetary dust and meteoritic infall on Mars affects a broad swath of important scientific questions. First, since Mars lacks standing water, crustal recycling, and eruptive volcanism, infall is the dominant source of modern carbon input onto the martian surface. Secondly, the hypothesis has been proposed that Phobos and Deimos derive their dark albedo and carbon-rich reflectance spectrum from interplanetary dust, for which the flux is relatively high because the moons lie in Mars' gravitational well. Third, meteoritic infall has been proposed as an explanation for both the "background" levels of atmospheric methane, and the periodic methane outbursts as a product of meteor shower activity. Also, since meteor activity has never been directly measured on Mars, actual measured data are unavailable for hazard avoidance for future crewed missions. Dust and meteoritic infall are scientifically important to our understanding of Mars and its moons, but data on dust flux and annual variations remain a near-complete knowledge gap. To date, only one NASA mission carried an instrument dedicated to dust detection at Mars - the Mariner IV flyby. That spacecraft was physically damaged by an intense meteor storm while still near Mars' orbit, highlighting the need for such measurements. This paper will advocate for a dedicated dust detection instrument for a future Mars orbiter as a straightforward solution for the current knowledge gap. Dust detection instruments are high-heritage instruments with a long history of successful employment across the Solar System. Marc Fries Marc Fries (
MACIE: Mars Astrobiological Caves and Internal habitability Explorer MACIE is an astrobiology-focused mission concept to explore the subsurface of Mars. We recommend exploring the martian subsurface by accessing naturally formed subsurface entry points including lava tube caves and pit craters. Our 3 primary science objectives are: (1) determine whether evidence of life is present in the subsurface, (2) determine the habitability of the subsurface, and (3) determine the geologic history. We examine current robotic platforms that may be utilized to access the subsurface and the types of instrumentation and landing considerations required to undertake this type of mission. Note: MACIE was named for Macie Roberts, one of NASA's first human computers. C. M. Phillips-Lander, J. J. Wynne, N. Chanover, C. Demirel-Floyd, K. Uckert, A. Parness, T. Titus, K. Williams, A. Stockton, S. Johnson, D. Wyrick, E. Eshelman, P. Boston, J. Blank, A. Fairen, A. Kereszturi, L. Montabone, J. Martin-Torres Charity M. Phillips-Lander (
Mars' Ancient Dynamo and Crustal Remanent Magnetism This paper discusses the importance of further investigating Mars' crustal magnetic field. High resolution magnetic field data are vital in order to extent our understanding regarding the crustal magnetic fields and the ancient martian dynamo. Those are ultimately linked to the deep interior of the planet and thermal evolution, as well as surfaces process throughout time. Anna Mittelholz et al. Anna Mittelholz (
Mars lower levels of the atmospheric boundary layer This contribution will outline the necessity of precise definition of the last meters of the atmosphere above the ground for the landing phase and the landed items and the necessary correlations of the measurements done with the existing modelization tools. It will try to establish a link between the atmosphere scientists proposals and realizations in terms of models, and the reality of the measurements on ground as performed by engineers. There is still a gap to fill between the ideal of the models and the reality of what the hardware can produce in terms of results. MC Desjean, F Cirpiani, F Forget (TBC) DESJEAN Marie-Christine (
Mars Science Helicopter: Compelling Science Enabled by an Aerial Platform Controlled aerial flight vehicles equipped with a capable scientific payload can revolutionize our understanding of Mars, providing wide-ranging access to locations not reachable by rovers and landers. The Mars 2020 helicopter technology demonstration (MHTD) will show that an Unmanned Aerial System (UAS) can fly in the Martian environment, enabling exploration and mission architectures that were previously impossible. This paper will describe the logical next step to the Mars 2020 MHTD: a Mars Science Helicopter (MSH). In addition to describing vehicle specifications, flight characteristics, and potential science payloads for a reference helicopter design, we will also introduce three high-level mission concepts that showcase the breadth of science investigations made possible by MSH. J. Bapst, T. J. Parker, J. Balaram, T. Tzanetos, L. H. Matthies, C. D. Edwards Jonathan Bapst (
Measuring Mars Atmospheric Winds from Orbit Goal is to emphasize the importance of global measurements of vector-resolved (2D) atmospheric winds from orbit. White paper will list the scientific value of the measurements (winds are key to atmospheric transport of dust, water, trace gases; winds are the predominant force scuplting the surface for the last 1-2 Gy+) and emphasize that there are instruments that are ready for flight (JPL Sub-mm instrument, MARLI lidar at GSFC, others?) that could perform these measurements. Scott Guzewich, co-authors welcome Scott Guzewich (
Mid-Latitude Ice on Mars: A Science Target for Planetary Climate Histories and a Resource for Exploration This white paper focuses on the outstanding questions surrounding the distribution and properties of mid-latitude ice on Mars, especially as relevant to Mars being a testbed for planetary climate history studies and the ice being a resource to enable future exploration to the planet. The major outstanding questions to be addressed in the next decade surrounding the nature of mid-latitude ice on Mars are: - What climate record is preserved in these mid-latitude deposits? - How accessible is the ice as a resource for future exploration? We are happy to add additional co-authors (contact Ali if you are interested in being a co-author), and are now starting to solicit endorsers/co-signers! To add yourself as a cosignatory of this White Paper, please fill out the following form: Ali M. Bramson, Patricio Becerra, Samuel W. Courville, Colin M. Dundas, Shannon M. Hibbard, Gareth A. Morgan, Matthew R. Perry, Eric I. Petersen, Nathaniel E. Putzig, Hanna G. Sizemore, Isaac B. Smith, David E. Stillman Ali Bramson (
The evolution of habitable environments on terrestrial planets: Insights and knowledge gaps from studying the geologic record of Mars We have evidence for an astounding array of habitable environments on ancient Mars, but we don’t yet have good constraints on: (1) The evolution of these environments over time (timing, persistence, distribution); (2) The conditions they occurred under (hydroclimate, water sources/chemistry); (3) Effect of later processes on the geologic record and biosignatures (diagenesis). This white paper will provide a brief overview of the state of knowledge in these areas and discuss the significance of knowledge gaps relative to big picture questions. We will then explore the types of data needed to resolve these knowledge gaps and suggest possible approaches for acquiring these datasets from orbit and in situ. Briony Horgan, Janice Bishop, Wendy Calvin, Lauren Edgar, Chris Edwards, Abby Fraeman, Tim Goudge, Kennda Lynch, Liz Rampe, Melissa Rice, Katie Stack, Christina Viviano Briony Horgan (
The geometry and distribution of Valles Marineris This paper addresses the observable double curve of the Valles Marineris system and proposes it came about as a result of a Coriolis deflection of a debris train from a Paleo moon. Further evidence in support of this hypothesis is the observed distribution of Valles Marineris, which follows an inverse square law distribution, the type of distribution that is predicted of a partial debris ring in orbit following tidal disruption Dan James Dan James (
The importance and feasibility of in-situ planetary aeolian and meteorological investigations This white paper will outline (1) the Mars, planetary, and fundamental science questions that could be aided through in-situ, concurrent investigation of meteorology, surface-atmosphere exchange of sediment and volatiles, and near-surface sediment flux rates. (2) the types of studies/measurements needed to address these questions (e.g., to do field studies analogous to terrestrial aeolian and meteorological studies, coupled with models). (3) why it's feasible to engage in such investigations on Mars in the coming decade. Serina Diniega Serina Diniega (
The science case for a modern multi-channel polarization sensitive LIDAR for investigation of planetary ices and atmospheres The white paper will cover mostly the science case for investigating Martian ice and volatiles using a multichannel polarization sensitive LIDAR as covered in this paper: The white paper would mostly discuss applications to Martian climate, ices and volatiles, but would highlight the interplanetary usefulness of such an instrument. If you would like to be a co-author or co-signer, please contact me or leave your name at this Google doc: Adrian J. Brown, Shane Byrne, Anthony Colaprete, Gorden Videen, Ken Herkenhoff, Michael Mishchenko, Nicholas Heavens, Patricio Becerra, Isaac Smith, Scott Guzewich, Timothy N. Titus, Michael Mischna, Rachel W. Obbard, Michael J. Wolff, Paul Hayne Adrian J. Brown (
Toward predicting Martian dust storms and climate This will emphasize (i) the importance of understanding dust lifting mechanisms for modeling the Martian dust cycle and hence climate, (ii) the importance of making in situ meteorological (especially wind) and aeolian measurements and mapping global surface dust/sand availability, (iii) the fact that until we can model realistic present day dust cycles - vs prescribing them based on observations - we cannot hope to model realistic past dust cycles, and (iv) the possibilities for predicting dust storms and their impact on climate, and why this may be vital for manned mission EDL/Ascent Vehicle/surface operations. Open to anyone Claire Newman (
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Mercury's Low Reflectance Material - Evidence for graphite flotation in a Magma Ocean? This white paper will identify the unique scientific opportunity to understand planetary evolution by investigating Mercury's low reflectance material. R. Klima, C. Ernst, N. Chabot, K. Vander Kaaden, S. Besse, M. Fries Rachel Klima (
Sample Return from Mercury This paper will discuss the importance of future exploration of Mercury with the ultimate goal being the return of a sample to Earth for laboratory based analyses. K. Vander Kaaden, F. M. McCubbin, P.K. Byrne, N.L. Chabot, C.M. Ernst, C.I. Johnson, M.S. Thompson Kathleen E. Vander Kaaden (
Science Opportunities from Mercury's Ice-bearing Polar Deposits Mercury's polar deposits offer a unique opportunity to study organics and water ice in the inner Solar System. In this paper, we will discuss the compelling science related to polar ice on Mercury, and outline key next steps in addressing important outstanding science questions. Ariel N. Deutsch, Nancy L. Chabot, Indhu Varatharajan, Carolyn Ernst, and any other interested parties (please let us know!) Ariel Deutsch (
The Case for Landed Mercury Science In this white paper, we detail outstanding questions related to several aspects of Mercury’s character and evolution that can be addressed either more fully, or uniquely, by a landed mission. We discuss major outstanding questions of Mercury science that encompass five categories, and suggest how they might be addressed. Paul K. Byrne, David T. Blewett, Nancy L. Chabot, Steven A. Hauck, Erwan Mazarico, and Kathleen E. Vander Kaaden Paul Byrne (
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The Moon

A Next Generation Lunar Orbiter A next generation lunar orbiter would support multiple goals of the lunar science community, as defined by the Lunar Exploration Roadmap, the Next Steps on the Moon Specific Action Team (Next-SAT), and the Advancing Science of the Moon Specific Action Team (ASM-SAT). Science goals addressed by the orbiter would include, but not be limited to (1) understanding the bombardment history of the inner solar system through detailed study of crater populations (including present-day impact rates), (2) furthering our understanding of the diversity of lunar crustal rocks, including lithologies that are rare in or absent from the Apollo sample collection (e.g., highly silicic lithologies and potential mantle material), (3) investigation of the lunar poles and the volatile resources they hold, (4) refining our knowledge of lunar volcanism to better understand the thermal and compositional evolution of the Moon, and (5) investigation of space weathering and regolith development processes to understand how airless body surfaces evolve over time. Tim Glotch et al. Timothy Glotch (
ASSESSING THE RECENT IMPACT FLUX IN THE INNER SOLAR SYSTEM We review the current state of knowledge of the recent impact flux, and possible changes in that flux, in the inner solar system. We rely heavily on the preserved bombardment history of the Moon, for which we have physical samples that allow us to tie remote observations to the absolute time scale. We discuss observations of impact craters and their products, including returned samples, coincident events on the Moon and other bodies, and identify key gaps, both in time and in the nature of available information. Finally, we propose future actions that would enable us to fill these critical gaps. R. R. Ghent, N. E. B. Zellner, I. Daubar, J.-P. Williams, S. Marchi, N. C. Schmerr Rebecca Ghent (
Exploring end-member lunar volcanism at the Aristarchus Plateau The Aristarchus Plateau contains the Moon's largest explosive volcanic deposit, the widest and deepest sinuous rille, and evidence for silicic volcanic materials. Exploring the diverse volcanic units in this region would help to determine the timing and nature of peak volcanism, constrain the compositional variability and volatile content of the lunar interior, and close strategic knowledge gaps about extracting in situ utilizable resources such as water trapped in the volcanic glass. The Plateau also hosts Aristarchus crater, a well-preserved impact feature that has excavated a diverse array of mineralogies, which could also be accessed to investigate impact processes. Erica Jawin et al. Erica Jawin (
Extending Science from the Lunar Laser Ranging Experiment Lunar Laser Ranging (LLR) is an on-going scientific experiment since 1969. LLR-capable stations on Earth continue to perform high-accuracy range measurements to the five optical passive retroreflector arrays on the near-side of the Moon’s surface. The analysis of LLR data has contributed to a variety of scientific disciplines such as lunar geophysics, Earth rotation and orientation, planetary ephemerides and precision tests of fundamental physics. This decadal white paper will address the potential science impact from the growing LLR-participating stations, improvements in the dynamical model of the Earth-Moon system, benefit from the next-generation of retro-reflectors and laser technology, as well as unique opportunities from upcoming lunar missions. Viswanathan et al. Vishnu Viswanathan (
Lunar Volatiles and Solar System Science This white paper will review advances in our understanding of the distribution, origin and behavior of lunar volatiles over the past decade, outline outstanding science questions old and new, and identify key measurements/technologies needed to address these questions. We explore the case that understanding the past, present and future of the lunar volatile system is not only lunar science, but solar system science. Parvathy Prem, et al. Parvathy Prem (
Microwave radiometry of planetary surfaces Describing current results and future design of microwave instruments. Most likely targeted for lunar orbit, but could be applied to other bodies and landed instruments. Matt Siegler, David Blewitt, Jianqing Feng, Paul Hayne... Matthew Siegler (
Science case for lander or rover missions to a lunar magnetic anomaly/swirl -Lunar magnetic anomalies are unique natural laboratories for investigating a wide range of planetary processes, including impact effects, planetary magnetism, space weathering, mini-magnetospheres, levitated dust activity, and the volatile cycle on airless bodies. -A robotic mission to a magnetic anomaly is listed in NASA's Strategic Plan for Lunar Exploration. -The paper will list the key planetary science questions that can be addressed by surface exploration of a lunar magnetic anomaly, including traceability to the Decadal Survey, SCEM, and other community documents that describe science priorities, as well as SKGs for human exploration. -The paper will describe how the science questions can be answered by robotic rover or static lander missions, and the instrument payloads needed to collect the relevant data. -Notional landing sites, rover traverse paths, and mission durations will be proposed. David T. Blewett, et al. David T. Blewett (
Understanding and Mitigating Plume Effects during Powered Descents on the Lunar Surface Understanding the effects rocket exhaust has on the lunar surface is critical to safely landing spacecraft and to planning sampling strategies. This document will outline gaps in knowledge regarding plume effects, and what measurements are necessary to fill these gaps. Ryan Watkins and Phil Metzger Ryan Watkins (
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Outer planet satellites

EXPLORATION STRATEGY FOR THE OUTER PLANETS 2023-2032: Goals and Priorities The outer solar system is home to a diverse range of objects, holding important clues about the formation and evolution of our solar system, the emergence and current distribution of life, and the physical processes controlling both our own and exoplanetary systems. This White Paper summarizes the Outer Planets Analysis Group's (OPAG's) priorities as they relate to the Decadal Survey. Taking into account the science to be achieved, the timing of solar system events, technological readiness, and programmatic factors, our mission recommendations are as follows. OPAG strongly endorses the completion and launch of the Europa Clipper mission, maintaining the science capabilities identified upon its selection, and a Juno extended mission at Jupiter. For the decade 2023-2032, OPAG endorses a new start for two directed missions: first, a mission to Neptune or Uranus (the ice giants) with atmospheric probe(s), and second, a life detection Ocean World mission. A Neptune mission is preferred because, while the Neptune and Uranus systems provide equally compelling opportunities to address the Origins and Processes Questions, Triton is a higher priority ocean world target than the Uranian satellites. The mission to Neptune or Uranus should fly first because a delay threatens key science objectives, and additional technological development is required for a directed life detection mission. Along with missions, we emphasize the necessity of maintaining a healthy Research and Analysis (R&A) program as well as a robust Earth-based observing program. OPAG's top two technology priorities are rapid development of a next-generation radioisotope power source for a mission to Neptune or Uranus, and development of key life detection technologies in support of an Ocean World mission. Outer Planets Assessment Group Jeffrey M. Moore (
Geophysical exploration of Enceladus Enceladus is one of the most geophysically compelling objects in the Solar System. This white paper will discuss what and how geophysical measurements can be used to study Enceladus' internal structure, where the tidal energy is being deposited and how is it being transported, and whether or not Enceladus is currently in a steady-state or its orbit and internal structure keep evolving. The paper will also discuss methods of mapping science requirements to measurement requirements as well as required technological advances that would enable resolving the knowledge gaps. The paper will provide guidelines for developing missions to Enceladus with a focus on the geophysical investigation. Anton Ermakov, Julie Castillo-Rogez, Joseph Lazio, Ryan Park, Christophe Sotin Anton Ermakov (
Io Exploration Io is the best place in the solar system to study tidal heating and extreme volcanism, and is a key destination for future exploration. Keane, Bagenal, Barr Mlinar, Beyer, Bland, de Kleer, Elder, Grava, Gregg, Hendrix, Jessup, Jozwiak, Kerber, Kite, Klima, Lopes, Mandt, McEwen, Neumann, Nimmo, Quick, Radebaugh, Rathbun, Retherford, Roberts, Schenk, Sood, Tsang, Vertesi, Williams, et al. James Tuttle Keane (
The Case for Titan Science in the Next Decade This white paper will highlight the current status of Titan science and make the case for how future exploration (agnostic to architecture) would help answer big-picture questions of importance both to exploration of other ocean worlds and general planetary science. S.M. MacKenzie, S. P. Birch, C. Sotin, S. Horst, E. Barth et al. Shannon MacKenzie (
The science case for spacecraft exploration of the Uranian satellites The 27 Uranian moons remain enigmatic, with incomplete spatial coverage and moderate to low spatial resolution collected during the Voyager 2 flyby. The best information we have about the surface compositions of these moons comes from ground- and space-based telescopes, which lack the spatial resolution to determine linkages between composition and geologic terrains and features. Furthermore, previously collected datasets hint at the possibility that the classical Uranian moons could be ocean worlds, but a spacecraft orbiting Uranus, making multiple close flybys of these moons, is needed to fully determine whether they have subsurface oceans. Richard J. Cartwright, Chloe B. Beddingfield, Catherine M. Elder, Tom A. Nordheim, Dale P. Cruikshank, William M. Grundy, Ali M. Bramson, Michael M. Sori, Devon M. Burr, Marc Neveu, Robert E. Jacobsen, Michael P. Lucas, Bryan J. Holler, et al. Richard J. Cartwright (
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Particles and Fields

The in-situ exploration of Jupiter's radiation belts Very energetic electrons and ions are trapped by the gigantic magnetic field of Jupiter, forming dangerous and therefore not sufficiently explored "radiation belts". This White Paper explains why a multi-spacecraft mission dedicated to the radiation belts of Jupiter should be given a high priority in the Planetary Decadal Survey and what scientific and technological challenges should be adressed to enable it. It will highlight how unique the Jupiter's radiation belts groundtruth laboratory is for advancing our understanding of space plasma physics in the Solar System and beyond. The impact of a mission dedicated to the radiation belts of Jupiter on other research fields such as moons surface processing or astrobiology will be highlighted. and what are the key in-situ observations that are missing and needed in order to advance our understanding of not only energetic space plasma physics in the Solar System and beyond, but also Everybody who is interested Quentin Nénon (
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Small bodies

Asteroids Inside Out: Radar Tomography The interior structures of small bodies provide crucial constraints on their formation mechanisms. It is also of vital importance for planning mitigation tactics for near-Earth asteroids (NEAs), should they be needed. To date, there are no direct measurements of the interiors of asteroids. Radar tomography can deliver 3-D characterizations of small bodies’ interiors, with the potential to provide information not only on interior structure, but also interior compositions. This technique involves monostatic or bistatic radar, which sample the scattering from different orientations relative to a target body. If used with ground-based assets, the potential for applying this technique to multiple targets at relatively low costs could improve our understanding of small bodies in the next decades. This white paper summarizes the opportunities over the next decades, current state of the art, outstanding knowledge gaps, with a particular note for the upcoming Apophis encounter. Mark Haynes, Anne Virkki, Flaviane Venditti, Dylan Hickson, Lance Benner, Carol Raymond, Joseph Lazio, Tony Freeman, Erik Asphaug, Patrick Taylor, Alain Herique, Wlodek Kofman Mark Haynes (
Captured Small Solar System Bodies in the Ice Giant Region This whitepaper advocates for the inclusion of small, captured Outer Solar system objects, found in the Ice Giant region in the next Decadal Survey. These objects include the Trojans and irregular satellite populations of Uranus and Neptune. The captured small bodies provide vital clues as to the formation of our Solar system. They have unique dynamical situations, which any model of Solar system formation needs to explain. The major issue is that so few of these objects have been discovered, with very little information known about them. The purpose of this document is to prioritize further discovery and characterization of these objects.  The working document for this whitepaper can be found at: This Whitepaper supports diversity in the Community. Any and all co-authors are welcome. Holt, TR., Castillo, J., Denk, T. Nesvorny, D., Porter, S., Rhoden, A., Rappolee, S., Schindhelm, R., Verbiscer, A and other welcome Co-Authors Timothy R Holt (
Cryogenic Cometary Sample Return Refractory cometary materials are complex on a nanometer scale and can only be studied in the laboratory, using instruments with spatial resolution well-suited to the samples. There is every reason to expect that the icy components of comets are similarly complex on small spatial scales. The recent development of space-based cryocooler technology with high heritage enables practical cryogenic cometary sample return, which would enable analyses of cometary volatiles using the same kind of coordinated, high-spatial resolution laboratory-based techniques that has been so productive for the study of refractory cometary materials. Andrew J. Westphal Andrew Westphal (
Developing a Modeling Pipeline for Planetary Defense Developing a pipeline of models for integrated planetary defense; model Integration and Interoperability; different models and model domains to share data and link with each other to streamline communication and facilitate research Angela Stickle, Lorien Wheeler... all co-authors and contributions welcome! Angela Stickle (
Enabling Reactive Missions for Fast, High-Value Targets Oort Cloud comets (including Manx comets) and interstellar objects are high science value targets whose exploration can bring fundamental constraints on the origin of our solar system and its place in the Universe. These are challenging targets in terms of their orbital properties, fast velocities, and detection when these objects are near their perihelia. Their exploration is limited by NASA’s current paradigm for competed mission calls that is not compatible with rapid response to new target discoveries and require targets to be identified at the time of proposal submission. Two approaches have been suggested to explore these targets: spacecraft in storage, ready to launch following target discovery and spacecraft in standby orbit, as is being done by ESA’s recently selected Comet Interceptor mission. Both mission scenarios have pros and cons. Launch following discovery offers greater flexibility in terms of target access but requires the fast turnaround of a launch vehicle. On the other hand, a spacecraft in a standby orbit is more responsive but has more limited target accessibility. In both cases, developing spacecraft for unknown targets bears a number of implications regarding the definition of basic spacecraft capability (e.g., delta-V) and payload. This white paper will provide suggestions and recommendations for broadening NASA’s competed mission calls so that they can encompass reactive missions. J. Castillo-Rogez, K. Meech, K. Moore, S. Courville, K. Mitchell Julie Castillo-Rogez (
Exploration Leading to Low-Latency Telepresence on Mars from Deimos The strategy of using robotic precursor spacecraft to prepare for human space exploration at a common venue has its roots in the Lunar Orbiter and Surveyor missions preparatory to initial Apollo Program human landings on the Moon in 1969. In the context of Mars human exploration, this strategy can be applied to Deimos with compelling prospects for compounded scientific returns on investment. Rationale is developed for humans in a radiation-shielded subsurface Deimos habitat from which low-latency telepresence (LLT) through robotic proxies on Mars is conducted to perform exploration on this planet at productivity levels far beyond those achieved on the Moon by Apollo astronauts. The critical path to this end starts with robotic missions to Deimos focused on determining this strategic moon's physical properties. With appropriate priority placed on Deimos observations and sampling for Earth return, JAXA's Martian Moons eXploration (MMX) mission can take the first steps on this path. Daniel R. Adamo (et al) Daniel R. Adamo (
Interplanetary and interstellar dust as windows into solar system origins and evolution The zodiacal cloud is comprised of dust particles, each a tiny time capsule from a comets, asteroids, or of interstellar origin, that are the closest samples of the primitive building blocks of our planets. Measuring the composition of these grains enables us to: (1) Discover whether today's local interstellar dust matches the composition of the feedstock from which the solar system formed. (2) Determine whether comets' fine-grained component preserves unprocessed pre-solar dust or shows signs of processing in the early solar system. (3) Learn whether comets' and asteroids' organic material share a common source or formed from distinct reservoirs. Making compositional measurements of the zodiacal dust cloud would sample a large number of bodies, complementary to traditional missions with single or few targets, which have shown unexpectedly large compositional diversity. M. Horanyi, N. Turner, T. Balint, S. Kempf, Z. Sternovsky, J. Szalay, A. Poppe Mihaly Horanyi (
Interstellar Objects The recent discovery of the first interstellar object 1I/`Oumuamua passing through the solar system in 2017 has provoked intense, sustained interest by the scientific community. `Oumuamua was accessible to ground based telescopes for less than a month, and a little longer from space. After this brief period of observation, `Oumuamua’s characteristics were quite different from what was expected from the first interstellar object (ISO), namely the first ISO was expected to have obvious cometary activity. Over 120 papers have been written about this object (and this number continues to grow). Incorporating a diverse range of scientific disciplines including galactic, stellar, and planetary dynamics, planetesimal formation, tidal disruption, shape modeling, and the nature and evolution of comets, this one discovery has really energized a new interdisciplinary awareness in the study of planet formation because ISOs enable the close up study of material from other planetary systems, allowing us to assess similarities and differences in the chemistry and physical processes driving planetary growth in other planetary systems. The second ISO, 2I/Borisov, was discovered less than 2 years after the first, much sooner than expected, and has characteristics which are very different from ‘Oumuamua. When LSST comes on line, it will greatly increase the discovery rate. This white paper will discuss the strategies for followup and coordination of observations of these objects in the era of the 2020’s with the availability of 30-m class telescopes and new space-infrared facilities. K.J. Meech, O.R. Hainaut, S. Raymond, A. Fitzsimmons, M. Micheli, D. Farnocchia, R. Jedicke, C. Bailer-Jones, B. Yang, R. Weryk Karen Meech (
Main Belt Comets as clues to the Distribution of Water in the Early Solar System No one knows how water arrived at our planet or if our solar system, with a planet possessing the necessary ingredients for life within the habitable zone, is a cosmic rarity. We do not know the role that the gas giants played in delivering essential materials to the habitable zone. The answers to these questions are contained in volatiles unaltered since the formation of the giant planets. To access this record, we need: (1) a population of icy bodies that faithfully records the history of volatile migration in the early solar system; (2) a source of volatiles that we can access affordably; (3) knowledge that the volatiles were not altered by aqueous interaction with their parent body; and (4) measurements from multiple chemical markers with sufficient precision to distinguish between original volatile reservoirs. Main belt comets (MBCs) are the perfect targets for this investigation because they satisfy the criteria outlined above. MBCs are part of a large population of icy asteroids residing in the outer asteroid belt that have emerged as significant reservoirs of primordial water and potentially other volatiles. These icy asteroids may have formed in-situ or been dynamically implanted as the giant planets grew. Unlike short period or long period comets, they have remained on stable orbits within the asteroid belt since the era of planet formation or migration and preserve a record of their accretional environment. K. J. Meech, C. Raymond, M. Choukroun, J. Castillo-Rogez, O. Hainaut, H. Hsieh, G. Huss, D. Jewitt, A. Krot, A. Morbidelli, D. Prialnik Karen Meech (
Near-Earth Object Characterization Using Ground-Based Radar Systems Ground-based planetary radar plays a vital role in the physical and dynamical characterization of near-Earth objects for both science and planetary defense by providing constraints on their heliocentric orbit, size, rotation state, morphology, satellites, and material properties. These characteristics are invaluable information for understanding the formation and evolution of asteroids and comets, which are the building blocks of the Solar System, for developing impact mitigation technologies, and for ensuring safe spacecraft encounters. Ground-based planetary radar systems are a crucial tool for obtaining high-precision astrometry and characterization of near-Earth asteroids and comets with astrometric precision and imaging capabilities exceeding those of any other ground-based instruments. They can also be used for characterizing the nuclei of comets, which are typically indistinguishable from the dust coma at optical wavelengths, and probe the decimeter-scale come particle abundance, which is relevant especially for the study of disintegrating comets. These capabilities make radar a low-cost complement to spacecrafts destined for specific targets. We recommend that NASA gives its full support for continued funding to facilities with ground-based radar systems to ensure their availability to the planetary science community and as a resource for planetary defense initiatives through the next decade. A. Virkki, P. Taylor, F. Venditti, S. Marshall, E. Rivera-Valentin, D. Hickson et al. Anne Virkki (
Nearly Isotropic Comets and Manxes Small primitive bodies were witness to the solar system’s formative processes. When gas was present in our solar system’s protoplanetary disk, during the first 5 million years of solar system formation, a local chemical signature was imprinted on the planetesimals. The connection to today’s solar system relies on how this material was dynamically redistributed during the planet-forming process. To connect early planet formation to the modern era, we must measure the compositions of a range of primitive bodies from different locations in the solar system and compare them with the predictions from models of early solar sys- tem formation, some of which predict significant reshuffling of material throughout the solar system. Long period comets (LPCs) are among the most difficult minor bodies to characterize due to their brief “once-in-a-human-lifetime” passages through the inner solar system. On the one hand, LPCs are typically brighter than short period comets because they likely have volatiles that turn on at larger distances. However, their activity also makes it very difficult to characterize their nuclei, and LPCs are rarely discovered before they are active. Large all sky surveys such as PanSTARRS and the Catalina sky survey are changing this. Many LPCs are discovered at very large distances, some even before the activity begins. Recently a new class of objects on long period comet orbits has been discovered that are nearly or completely inactive. Informally termed “Manxes” for their nearly tailless appearance, some have surface mineralogy that suggests similarity to inner solar system rocky material—i.e. they may have formed near the water-ice line. These objects may provide data that will help us distinguish between dynamical solar system formation models. This white paper will provide the context for what we can learn in the era of the LSST about the early solar system from studies of a large sample of these, and provide suggestions on what type of follow up data are needed for new discoveries. Karen Meech, Olivier Hainaut, Bin Yang, Marco Micheli, Erica Bufanda, Jacqueline Keane, Jan Kleyna Karen Meech (
Small body sample return and their laboratory analysis A summary of the scientific goals, state-of-knowledge, and future needs for small body sample return and their laboratory analysis. Seth Jacobson, Maitrayee Bose Seth Jacobson (
The case for Themis asteroid family science in the next decade We summarize the case for Themis asteroid family science in the next decade. The Themis family likely formed from the impact disruption of a primordial icy object. By studying (24) Themis and family members further, we are using Nature's rock-hammer to explore the origin and interior processes of icy small bodies in the inner solar system. Co-authors and co-signers welcome. M.E. Landis, J. Castillo-Rogez, P.O. Hayne, K. Hughson, T.H. Prettyman, A.S. Rivkin, B.E. Schmidt, J.E.C. Scully, N. Yamashita, and M. Villarreal Margaret Landis (
The Future of Planetary Defense in the Era of Advanced Surveys This white paper is curated by the SBAG and discusses Planetary Defense goals of discovery, tracking, characterization and mitigation in the era of advanced survey that will be upon us in the next decade. Mainzer et al. - White paper curated by SBAG - All co-authors welcome! Amy Mainzer (
The Importance of Plasma and Magnetic Investigations in Small Body Missions In this white paper we highlights the valuable information about a body's internal structure and atmosphere that can be gained by more widely incorporating magnetometers, space plasma, and energetic particle instrument suites into small body mission payloads. In addition, we also call attention to the synergy between small body and heliospheric science that would occur. M. N. Villarrreal, R. Lillis, J. G. Luhmann, C. O. Lee, J. G. O'Rourke, R. Oran, and K. M. Moore Michaela Villarreal (
Understanding Solar System formation through small body exploration This white paper is curated by SBAG and concerns one of five overarching questions to be addressed through the exploration of small Solar System bodies in the next decade: “What do small bodies tell us about the formation of the Solar System and the conditions in the early solar nebula?” Prior to the formation of macroscopic solid bodies the solar nebula experienced extensive physical and chemical evolution, like any protostellar disk. The first generation of planetesimals inherited such processed interstellar material, and were shaped by the physical processes responsible for their formation. Various types of secondary processing, acting over the age of the Solar System, have evolved the primordial planetesimals into the populations of small Solar System bodies observable today. It is an intriguing but challenging problem to understand to what extent the currently measurable physical properties and chemical compositions of small bodies inform about the earliest days of the Solar System. This white paper aims to summarize our current understanding of this issue, and to propose how knowledge gaps best can be addressed in the next decade. Cross-referencing with other relevant white papers is a priority, and collaboration among point of contacts is encouraged. Davidsson et al. White paper curated by SBAG. All co-authors are welcome! Björn J. R. Davidsson (
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Closing the Gap Between Theory and Observations of Venus Atmospheric Dynamics with New Measurements The purpose of this white paper is to advocate for state-of-the-art atmospheric measurements from new missions to Venus. Venus is a captivating planet of great international scientific and public interest due to the lessons offered toward understanding other planets, including our own. The Venus community is now in a position where current technologies and numerical tools applied to the exploration of Venus’ atmosphere, are defining a new set of questions to be answered in order to advance the physical understanding of the Venusian atmosphere. The time dependent 3D numerical tools are capable of simulating a multitude of atmospheric properties. These numerical tools/simulations are highlighting regions where the current understanding of nonlinear interactions are failing and need to be guided and constrained with new modern observations. Modern observations include simultaneous measurements of key parameters such as temperature, density, composition, motion, and solar input in vertical, horizontal, and temporal dimensions. New missions to Venus that include the necessary state-of-the-art instrumentation need to address the gaps in knowledge illuminated by current numerical simulations. Addressing these gaps in knowledge will help guide the scientific questions in order to provide a better understanding of Venus’ global atmospheric dynamics. Full texts of Venus-releated white papers are given at Amanda Brecht, Stephen Brecht, Sebastian Lebonnois, Janet Luhmann, Josette Bellan, Stephen Bougher, Yingjuan Ma, Helen Parish Amanda Brecht (
EMPIRE Strikes Back: Venus Exploration in the New Human Spaceflight Age The case for including unique Venus science opportunities during a Venus flyby component for future human spaceflight missions on the pathway to Mars. COSIGNERS: Jennifer Whitten, Constantine Tsang, Jonathan Sauder, Stephen Kane (UC Riverside), Dmitry Gorinov, Shannon Curry, Darby Dyar (PSI), Ye Lu (Kent State University), Joe O'Rourke, Chuanfei Dong (Princeton), Ryan McCabe (Hampton Univ.), Pat Beauchamp, Jeremy Brossier (Wesleyan University) Working document: Noam R. Izenberg, R. L. McNutt, K. Runyon, Paul Byrne (NCSU) Noam R. Izenberg (
Importance of airglow and auroral emissions as tracers of Venus’ upper atmosphere dynamics and evolution The goal of this white paper is to advocate for a thorough monitoring of Venus’ upper atmosphere, through future space missions. Venus is a natural laboratory, which enables the study of solar wind interactions with planetary bodies without intrinsic magnetic field. Beyond the basic knowledge of the composition, structure, and dynamics of an atmosphere, aeronomic emissions provide further elements toward answering fundamental questions related to dynamics, energy transport, escape processes, solar wind/magnetospheric interactions with the upper atmospheres and the history of water at Venus. This paper includes an overview of the current state of knowledge on the upper atmosphere circulation regimes, identifies knowledge gaps that need to be addressed, and emphasizes strong arguments on why we need to go back to Venus. Additionally, we highlight which upper atmosphere observations are necessary to improve Global Climate Models (GCM) and our understanding of atmospheric physical processes at play. Emilie Royer, Candace Gray, Amanda Brecht, Dmitry Gorinov Emilie M Royer (
Revision of New Frontiers Goals for a Venus Mission we propose two new goals to replace the six in the current “VISE” priority investigation; these new goals fully encompass the measurements we list above, and are of equivalent scientific importance. They are: 1. Examine the physics and chemistry of Venus to understand its current state and evolution, including past habitability. 2. Characterize the Venus surface–atmosphere interface and how it is shaped by physical and chemical processes. Achieving either of these goals would produce transformative science and justify an entire New Frontiers mission. Therefore, we propose that this New Frontiers recommendation be renamed simply “Venus Explorer” in recognition of the wide variety of modern mission types that can address important Venus science questions. The complete text of this white paper can be found at M. Darby Dyar, Noam Izenberg, Giada Arney, Jeff Balcerski, Paul Byrne, Lynn Carter, Candace Gray, Gary Hunter, Kevin McGouldrick, Patrick McGovern, Joseph O'Rourke, Emilie Royer, Allan Treiman, Jennifer Whitten, and Colin Wilson Darby Dyar (
The Venus Life Equation Assessing the chance of current life on Venus starting with terrestrial ecosystem principles. Working document: Noam Izenberg, David J. Smith, Dianna Gentry, Martha Gilmore, David Grinspoon, Mark Bullock, Penny Boston Noam Izenberg (
The Venus Strategic Plan A summary of 2019 update to the Venus Goals, Objectives, Investigations document, the Venus Roadmap, and the Venus Technology plan. Venus White Paper organizing google doc: Noam R. Izenberg, M. Darby Dyar, Allan Treiman, Joseph O’Rourke, James Cutts, Gary Hunter, Michael Amato, Giada Arney, Jeffery Balcerski, Paul Byrne, Lynn Carter, Samuel Clegg, James Head III, Candace Gray, Scott Hensley, Natasha Johnson, Stephen Kane++ Noam Izenberg (
Venus Exploration Targets: Update of 2014 VETW Tables and findings from the 2019 Venera-D Landing Site Workshop Updating Venus Exploration Targets Workshop to the 2019 edition of the Venus GOI, and updating Venus lander target studies from Venera-D JSDT and 2019 Landing Site workshop. Noam Izenberg, Larry Esposito, Tracy Gregg, Paul Byrne Noam Izenberg (
Venus Tesserae: Current state of knowledge and remaining open questions on the importance of Venus Tesserae and open questions regarding this geologic unit This paper argues for the exploration of the tessera, an enigmatic unit that likely records the most ancient geologic record on Venus. The composition and formation of tessera are not well-agreed upon, but these two observations have implications for the geologic history of Venus and the importance of the role of water. Working document available here: Jennifer L. Whitten, Martha S. Gilmore, Jeremy Brossier, Paul K. Byrne, Joshua J. Knicely, Sue E. Smrekar Jenny Whitten (
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State of the Profession

Options for a Sustainable Planetary Science Initiated by the DPS Environmental Affairs Subcommittee Cuk, M., Kohout, T., Lellouch, E., Lissauer, J.J., Virkki, A.K. Matija Cuk (
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Advancing Space Science Requires NASA Support for Coordination Between the Science Mission Directorate Communities This is a white paper that was submitted to Astro2020 and will be submitted to the Planetary and Heliophysics decadal surveys ( Abstract: There is a growing awareness within the space science community that cross-disciplinary studies will make the greatest advances toward many major scientific objectives. This requires greater coordination and collaboration between the four communities represented by the Divisions of the NASA Science Mission Directorate. As an example, the Exoplanet Science Strategy (NAS, 2018) specifically points out that such collaboration is needed to advance exoplanet science and calls for a coordinated effort throughout the entire space science community. However, this need for coordination is not limited to the exoplanet community. The impact of space weather on the Earth and the planets in our solar system requires coordination between the Earth Science, Planetary and Heliophysics communities. Efforts to understand our habitable heliosphere in the context of astrospheres observed outside of our solar system requires coordination between the Heliophysics, Astrophysics and Planetary communities. Many professional societies and organizations now recognize this need and are beginning to bring scientists together, primarily in the form of topical workshops and Town Halls. We outline here specific steps that can be taken by NASA and by the space science community to further cross-disciplinary research. However, it is important to note that the only way that this effort can be successful is if it is initiated within NASA and is supported through directed resources provided by NASA to the community. Kathleen Mandt and 70+ coauthors from 20+ institutions Kathleen Mandt (
COORDINATION AND RECOMMENDATIONS FOR PLANETARY BODIES CARTOGRAPHIC COORDINATES AND ROTATIONAL ELEMENTS This paper considers the issue of how rotational elements and other coordinate system definitions for planetary bodies for mapping and other purposes should be made and updated. Since 1979, the IAU Working Group on Cartographic Coordinates and Rotational Elements (WGCCRE, referred to hereafter as the WG) has issued a report approximately every 3 years that makes such recommendations. The report includes recommendations on coordinate systems and related parameters (body orientation and shape) that can be used for making cartographic products to support research and mission planning purposes of planetary bodies. These recommendations, which are open to further modification when indicated by community consensus, are intended to facilitate the use and comparison of multiple datasets by promoting the use of a standardized set of mapping parameters for all planetary bodies. After over 40 years since the first such report, the WG is looking to assess its future activities and interactions with related organizations that produce or use recommendations and standards for planetary mapping. The Planetary Science and Astrobiology Decadal Survey committee and panels can advance this process by considering the general issue of how mapping standards should be generated and used. This paper will discuss issues such as the best way to collect community input, whether the foundational principles being used are adequate or whether changes are needed, the best methods for reporting parameters, the best procedures for updating coordinate systems, how conflicting published information on planetary coordinate systems could be addressed in a timely way, who would do the necessary research in these areas, and how this work could be funded. Other issues considered include whether organizations are needed to consider issues specific to individual types of bodies (e.g. the Moon, Mars, outer planets, exoplanets) or even missions, and how mapping standards should be addressed. Possible approaches to addressing these many issues will be presented. Flora Paganelli, Brent Archinal, Charles.H. Acton, Albert Conrad, Randolph L. Kirk, Daniel Hestroffer, Jean-Luc Margot, Paul K. Seidelmann, Iwan P. Williams, others WGCCRE Flora Paganelli (SETI Institute/HU) (
Enabling and Enhancing Science Exploration Across the Solar System: Aerocapture Technology for SmallSat to Flagship Missions This white paper seeks to inform the NRC Planetary Sciences Decadal Committee on how aerocapture technology development will benefit a wide range of planetary science missions across the solar system. Aerocapture has long been considered a compelling technology that could significantly enhance science return, reduce costs, and/or shorten transit times for orbital missions to Mars, Venus, Titan, Uranus, and Neptune. Aerocapture uses the drag from a single atmospheric pass to provide the delta-V needed for orbit insertion, rather than a large burn of a rocket engine. This results in a drastic reduction in the propellant required onboard the spacecraft, which can give more room for other useful payload, such as science instrumentation. This paper will highlight the benefits that aerocapture can bring to missions at destinations across the Solar System, with mission classes from SmallSat to large flagship. The paper will discuss aerocapture implementation options and discuss how a cost-effective small satellite technology demonstration opportunity in the near-term will act as a springboard for opening aerocapture technology to many missions in the next decade. Alex Austin, JPL; Adam Nelessen, JPL; Marcus Lobbia, JPL; Jim Cutts, JPL; George Chen, JPL; Erik Bailey, JPL; Christophe Sotin, JPL; Ethiraj Venkatapathy, ARC; Paul Wercinski, ARC; Alan Cassell, ARC; other coauthors welcome! Alex Austin (
Enabling a New Generation of Outer Solar System Missions: Engineering Design Studies for Nuclear Electric Propulsion We discuss a nuclear electric propulsion (NEP) capability that would (1) enable a class of outer solar system missions that cannot be done with radioisotope power systems and (2) significantly enhance a range of other deep-space mission concepts. NASA plans to develop Kilopower technology for lunar surface power. Kilopower can also serve as a power source for a 10-kWe NEP system; therefore, we highlight 10-kWe NEP benefits to encourage the NASA Science Mission Directorate (SMD) to advocate (as a potential beneficiary) for NASA’s plan to develop Kilopower and to motivate further 10-kWe NEP–related concept studies. Available online at John R. Casani, JPL; Marc A. Gibson, GRC; David I. Poston, LANL; Nathan J. Strange, JPL; John O. Elliott, JPL; Ralph L. McNutt, Jr., APL; Steven L. McCarty, GRC; Patrick R. McClure, LANL; Steven R. Oleson, GRC; Christophe J. Sotin, JPL John R. Casani (
Enabling the Next Frontiers in Astrobiology – Ocean and Ice Worlds Explorations with a Radioisotope Power System Inside a Pressure Vessel A new exploration paradigm requires novel technological solutions. Exploring Ocean and Ice Worlds below the surface can help us to understand the origin and evolution of life in the universe. In our solar system, NASA has identified six Ocean Worlds, namely: Earth, Europa, Ganymede, Calisto, Enceladus, and Titan. Other potential targets include Dione, Triton, and Pluto. Their oceans are situated below tens of kilometers thick ice shells. These planetary destinations contain known building blocks of life, which are: water molecules, carbon, and energy. In some regions, water-ice may periodically reach the surface and eject to space from hydrothermal vents. Extreme radiation at Europa, and space weathering on the surface at all target destinations necessitate subsurface access to resolve questions about their astrobiology potential. On such science missions, while searching for signs of extinct or extant life, we would address – among others – questions related to habitability, chemical composition, salinity, local hydrology, D/H ratio in the ice shell and the sub-ice ocean, morphology, water properties, seismology in the ice shell, porosity, elemental abundances, tidal functions of the ocean, and imaging for context. To address these science questions, we need a suitable payload that can survive the environment. Furthermore, to overcome these environmental constraints, we need to develop enabling technologies for melting through the ice shell and to swim in the ocean below the ice. Key technological challenges revolve around the power source, and mitigation of extreme pressures and the cold. Far away from the sun, and melted into the ice, we can only rely on long-lived internal power generation. Radioisotope Power Systems (RPS), utilizing the heat of decaying Plutonium-238, could be good candidates to address power needs. The RPS could support the science payload and the subsystems, as well as provide a heat source for melting the ice and keeping the components at operating temperatures. Mitigating the pressure while inside the ice shell, and in the ocean below it, requires a RPS that operates inside a pressure vessel. In this white paper, we discuss mission architecture trades and the sizing of a RPS housed inside a pressure vessel. Through an enabling technology focused approach, we address all relevant and interconnected aspects of the concept of operations through all mission phases (e.g., ATLO, launch, cruise, descent/landing, surface operations, subsurface operations in the ice shell, swimming in the ocean, and the end of mission), subsurface mobility; and planetary protection. In this framework, we also address how the concept of operations could influence mission design considerations, mission architectures, and drive RPS requirements in response to environmental constraints, g-load tolerance, as well as the sizing of the power and thermal systems for science measurements. (Two Ocean Worlds are not addressed, namely Earth and Titan, as the discussed power system is not applicable to them.) The findings inform the science community on instrument accommodation possibilities and the use of RPS inside a pressure vessel. Primary focus will be given to Europa and Enceladus, as they provide bounding cases for ice-shell and ocean explorations. Once developed, the RPS inside a pressure vessel configuration could be used at subsequent planetary destinations with less demanding requirements. T. Balint, Y. Lee, S. Howell, S. Perl, M. Cable, K. Craft, S. MacKenzie, B. Bairstow, S. Johnson, E. Clark, B. Donitz, P. Schmitz, T. Hurford – All co-authors are welcome! Tibor Balint (
Global Geodynamics of Solid Bodies The global geodynamics of solid bodies – their rotational variations, tidal response and normal mode excitation together with their global magnetic and gravitational fields, can provide unique and critical information about the surfaces and interiors of solid objects of almost any size, from the Earth down to sub-kilometer scale asterods. Measurement of global scale planetary dynamics have been used to constrain the internal bulk characteristics of the Earth, Moon, Mars, Titan and some asteroids, and are a major goal of the Insight mission, the Europa clipper mission, and undoubtedly other missions in the future. This white paper will review the existing work and potential future advances in the study solid body dynamics in the solar system, including rotational dynamics (polar motion, length of day changes, and librational resonances) and geodetic, gravity and magnetic data acquisition. T. Marshall Eubanks, Bruce Bills Thomas Marshall Eubanks (
Integrating Machine Learning for Planetary Science: Perspectives for the Next Decade In past decades planetary science datasets have been constrained in size and number by limited opportunities for measurements. Since the last decadal survey, data collection for planetary science has expanded by orders of magnitude. Data science techniques can help address new challenges and requirements imposed by future mission designs and growing data volumes. Within this white-paper we discuss how data science and machine learning techniques can be integrated into the full mission lifecycle from formulation to operations to archival analysis. We discuss required infrastructure needs and identify barriers and solutions toward realizing the benefits of data science in the field of planetary science. We are actively seeking early-career scientists to contribute as authors (including PhD candidates, postdoctoral researchers, and researchers and faculty). We are also seeking co-signers, participants, and supporters of this effort at all career levels. A. R. Azari, H. Kerner, K. Skinner, G. Doran, A. Smith, R. Dewey, C. Harris, K. Yeakel, additional authors and co-signers welcome at all levels of career! Abigail Azari (
Making Planets on Earth: How Experimental Petrology Is Essential to Planetary Exploration This white paper will outline the breadth of capabilities of the field of experimental petrology that are crucial to planetary exploration across the solar system and beyond. Experimental petrology serves as the main way in which scientists build petrological databases and establish fundamental relationships between petrological reservoirs (e.g., petrologic hygrometers, barometers, and thermometers). Data from planetary missions is limited, and constraints from experimental work allow us to unlock the most information possible from returned data (e.g., spectral data) and physical samples. This includes determining asteroidal parent bodies; quantifying volatile concentrations in planetary bodies; determining the pressure (and, thus depth) and temperature of the formation of a rock body; constraining the chemical environment of the core, mantle, crust, surface, and atmosphere of rocky bodies. Kayla Iacovino, Kathleen Vander Kaaden, Nicole G. Lunning, et al. Kayla Iacovino (
Non-Robotic Science Autonomy Development The past few years have seen a rise in localized efforts toward developing autonomy for mission science data output and interpretation. As more missions are directed toward the outer planets and moons (e.g., Juno, Dragonfly, Europa Clipper), it will become necessary to develop science mission autonomy. Science mission autonomy encompasses more than robotics and on-board operational decisions, but also decisions regarding instrument use, data downlink, and ultimately data interpretation. Developing science autonomy is critical to NASA’s Strategic Goal 1 (2018): Expand human knowledge through new scientific discoveries, and specifically Objective 1.1: Understand the Sun, Earth, solar system, and universe. Strategies for data economy are very important for enabling science discovery, and employing the wrong strategy can limit the science potential of a mission. This white paper describes the current needs for science autonomy and the summarizes the benefits of promoting science autonomy development. Bethany Theiling, Brian Powell, Heather Graham, Lu Chou, Eric Lyness, Jamie Cook, Jennifer Stern, Alex Pavlov, Will Brinckerhoff, Jennifer Eigenbrode, Andrej Grubisic, James McKinnon, Barbara Thompson Bethany Theiling (
Space Launch System (SLS) Utilization for Planetary Missions This contribution will outline the benefits of NASA’s Space Launch System (SLS) heavy-lift launch vehicle for planetary missions, particularly high C3 missions to the outer planets and beyond. While past literature has outlined the mass, volume and departure energy capabilities offered by the baseline configurations of SLS, this white paper will also discuss the performance enabled by additional payload stages flown on the Block 2 SLS. Initial analysis using contemporary cryogenic stages and solid motors shows that the vehicle stack could deliver approximately 15 metric tons (t) to a Trans-Jovian Injection C3 of 83 km2/s2 , and could launch a half-metric-ton spacecraft to a C3 greater than 300 km2/s2, more than double the record-setting departure energy of the New Horizons spacecraft. This approach presents an enabling architecture leveraging proven technologies that would be available within the period of the next Planetary Decadal and would open tradespace for larger scientific spacecraft and/or reduced transit times. Robert W. Stough, Erika Alvarez, Chad E. Brown, David Hitt David Hitt (
Sustaining Mature Thermal Protection Systems Crucial for Future In-Situ Planetary Missions This white paper seeks to inform the NRC Planetary Sciences Decadal Committee with insights into the need for, and approaches to, sustaining critical thermal protection systems (TPS) for in-situ planetary missions in the coming decade. Phenolic Impregnated Carbon Ablator (PICA) and Heatshield for Extreme Entry Environment Technology (HEEET) are NASA-invented technologies essential for in-situ planetary missions for which no alternatives exist. These two technologies are mission critical for landers, probes, aerial platforms, and for skimmer missions across many of the solar system destination including Venus, Saturn, Uranus, Neptune and sample return missions. PICA and HEEET are both at high technology readiness levels and are ready for mission infusion now. However, unless NASA makes a commitment to maintain these technologies for the future, missions in the next decade will be negatively impacted. The challenges for each specially capable TPS described herein are multifaceted: the technology is only needed for NASA in-situ missions, which occur at a low cadence; some of the raw materials or production processes or system integration for the technology are unique; and the knowledge and expertise in manufacturing, design and/or system integration lies with a small group of people within NASA and industry whose vital skills and the relevant capability will be needed in the future. A periodic readiness assessment by NASA, followed by mitigation if needed, is recommended. Ethiraj Venkatapathy, Jay Feldman, Matt Gasch, Mairead Stackpoole, Don Ellerby, David Hash, Alan Cassell, Helen Hwang, Ethiraj Venkatapathy (
Terrestrial collection of extraterrestrial materials: Providing continued, long-term sample analysis opportunities for research and mission support This white paper summarizes the scientific importance of terrestrial collection of extraterrestrial materials. These collections provide samples of a wide range of planetary bodies, including those not accessible by sample return, new samples of the Moon and Mars, and the only new cometary samples until the return of the next cometary sample return mission. Extraterrestrial samples collected on Earth have proven critical to informing preparation for, analyses during, and context after small body and planetary missions, making their ongoing collection timely for many missions envisioned in the coming decade, particularly those involving sample return. As a result of their serendipitous arrival at Earth, these samples can be recovered at relatively low cost, curated, and analyzed in multiple laboratories with state-of-the-art instrumentation that is not subject to flight constraints. Hope Ishii, Cari Corrigan, and other welcome Co-Authors Hope Ishii (
Terrestrial Planets Comparative Climatology A single mission concept to study the atmospheres of both Venus and Mars to increase our knowledge of terrestrial planet formation history and climate evolution. Leslie Tamppari, Amada Brecht, Larry Esposito, Scott Guzewich, Kandis Lea Jessup, Armin Kleinböhl, Kevin Bains, Brian Drouin. Open to all others Leslie K Tamppari (
The Importance of Ground-Based Radar Observations for Planetary Exploration Ground-based planetary radar observations have enabled and continue to facilitate the exploration of our Solar System through characterization of planets and their moons, including spacecraft landing-site characterization, e.g., for Viking (Tyler et al., 1976; Simpson et al., 1978) and most recently InSight (Putzig et al., 2017) at Mars, and improved target astrometry, such as for Europa (Brozovic et al., 2020). The power of radar for planetary geology is its ability to sense subsurface features buried beneath regolith, such as cryptomare on the Moon (Campbell and Hawke, 2005), and surface features obscured by a dense atmosphere, e.g., Venus (Campbell et al., 1980) and Titan (Campbell et al., 2003). Regolith properties can also be constrained via polarimetric radar studies, which characterize regolith grain size and shape distribution, bulk density, composition, and roughness (Campbell et al., 1990; Carter et al., 2004; Carter et al., 2009; Neish et al., 2013; Virkki and Bhiravarasu, 2019; Rivera-Valentín et al., 2020), including the presence of buried ice, such as at Mercury (Harmon and Slade, 1992) and the Moon (Patterson et al., 2017). Furthermore, high-precision spin-state analysis has been used to monitor the rotation of Venus (Campbell et al., 2019), while radar speckle studies have revealed the interior structure of Mercury (Margot et al., 2007; 2012). New analytical and modeling techniques as well as laboratory-based insights for radar analysis, along with improvements to existing radar facilities, motivate a renewed interest in radar studies of planetary surfaces in the upcoming decade. With a broad fleet of spacecraft exploring the Solar System, synergies with ground-based radar studies allow for higher-order analysis of both datasets and thus an improved understanding of planetary processes. In the next decade, increased collaboration between ground-based radar and space-based observations, along with multi-wavelength ground-based observations, are encouraged to further Solar System studies. Interested signers and co-authors are invited to email Ed at Edgard G. Rivera-Valentín, Patrick A. Taylor, Anne K. Virkki, Michael C. Nolan, Marina Brozović, Bruce Campbell, Dylan Hickson, Ellen Howell, Heather Meyer, Catherine Neish, Noemí Pinilla-Alonso, Carolina Rodriguez Sanchez-Vahamonde, et al. Edgard G. Rivera-Valentín (
The value of isotopic measurements as probes of origin, evolution, and biotic processes We will describe the utility of isotopic measurements for understanding planetary bodies, including constraining the origins of their building blocks, evolutionary processes on planetary bodies, and as a discriminator for detection of biosignatures. We will provide examples of successful application of isotopic measurements, and highlight potential applications in the coming decade. Kelly Miller, Bethany Theiling, Chris Glein, Amy Hofmann, Marc Neveu, Chris House Kelly Miller (
User-focused Data Catalogs to Enhance the Long-term Results of Planetary Missions Mission teams should incorporate procedures that enable others to analyze their data. Navigating the Planetary Data System (PDS) to find the data one wants to work with is nontrivial, as are evaluating (e.g., where on a geologic target were spectra acquired, what are the signal-to-noise ratios, etc.) and analyzing the data without the guidance of the mission team’s corporate knowledge. A survey conducted by the MER Data Catalog Project ( indicates that everyone from homeschooling parents to PhD planetary scientists would like to access spacecraft data, but they cannot find the data products they want, do not have time to look through the full mission dataset to find data on their target(s) of interest, and lack the context or background to use the data they can find. A catalog designed with the end-user in mind, supplemented with documentation aimed at introducing non-team researchers to the nuances of analyzing the spacecraft’s data, can enable professional scientists and students who were not selected as team members to contribute to the mission’s long-term results. This can expand the range of researchers to include people who typically do not work on spacecraft missions, such as faculty and students at teaching-focused institutions including but not limited to tribal colleges, Historically Black Colleges and Universities (HBCUs), and community colleges. Additionally, easily accessible and usable data catalogs will enable future astronauts exploring extraterrestrial sites in situ to groundtruth the interpretations of robotically acquired data. Shoshanna Cole, Jayne Aubele Shoshanna Cole (
Venus as a Nearby Exoplanetary Laboratory Models of remotely detectable habitable environments relies upon in-situ data from Earth and Venus, including a deeper understanding of how the two planets diverged in surface conditions. We advocate a continued comprehensive study of Venus, including models of early atmospheres, compositional abundances, and Venus-analog frequency analysis from current and future exoplanet data. Stephen Kane, Giada Arney, David Crisp, Shawn Domagal-Goldman, Colin Goldblatt, David Grinspoon, James W. Head, Adrian Lenardic, Victoria Meadows, Cayman Unterborn, Michael J. Way, Kevin Zahnle Stephen Kane (
Volatile Sample Return in the Solar System We advocate here a focused effort towards the realization of volatile sample return from various environments including: comet nucleus, asteroid/NEO, lunar, Mars, ocean world/satellites, plumes. As part of recent mission studies (e.g. CAESAR and Mars sample return), new concepts, technologies, and protocols have been considered for specific environments and cost. Here we provide a cohesive and comprehensive plan for volatile sample collection and the environmental challenges, transit/storage considerations, Earth re-entry, and curation. Laboratory and theoretical simulations are considered and proposed to verify sample integrity during each mission phase. Sample collection mechanisms are evaluated for a given object/environment with consideration for technology and efficient techniques. Transport and curation are essential for sample return to maximize the science investment and ensure pristine samples for terrestrial analysis upon return and after years of preservation. All aspects of a volatile sample return mission are driven by the science motivation which will be considered – for example, isotope fractionation, noble gases, organics and prebiotic species, as well as planetary protection considerations for collection environments and Earth. The analyses of returned samples are not a focus of this white paper since the expectation of sample return is to promote new investigations with state- of- the- art capabilities not necessarily known/employed to date. Key points: • The value of sample return missions has been clearly demonstrated by previous sample return programs and missions. • No previous mission has returned substantial volatile material key to understanding (exo)planet formation, evolution, and habitability. • Returning volatiles from planetary bodies poses unique and potentially severe technical challenges. These include preventing changes to samples between (and including) collection and analyses, and meeting planetary protection requirements. S. Milam, J. Dworkin, J. Elsila, D. Glavin, P. Gerakines, J. L. Mitchell, K. Nakamura-Messenger, M. Neveu, L. Nittler, J. Parker, E. Quintana, S. Sandford, J. Schlieder, R. Stroud, M. Trainer, M. Wadhwa, A. Westphal, M. Zolensky Stefanie Milam (
Volcanism Across the Solar System Volcanism is a fundamental process in the Solar System, providing information about planetary internal structure, composition, differentiation history, atmospheric accumulation, and crustal formation. This white paper summarizes why this topic is important, major mysteries that remain, and measurements that could be made to resolve them. Laura Kerber, Lisa Gaddis, James Tuttle Keane, Devanshu Jha, etc. Laura Kerber (
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