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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Astrovirology: Expanding the search for life Viruses are the most numerically abundant biological entity on Earth, are central to life, yet very little is known about viruses in the space environment and their place in Astrobiology. Everything we know about the virosphere is on Earth. It is time to contextualize the potential roles of viruses and virus-like entities in both astrobiology and space biology. There are multiple critical knowledge gaps in our understanding of viruses in the space environment and potential role in other hypothetical biospheres in our Solar System and beyond. Gareth Trubl, Ken Stedman, Kathy Bywaters, & Penny Boston ... Gary Trubl (
DeepTrek: Exploring the Martian Underground This community contribution outlines 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. There are two Papers: DeepTrek Science DeepTrek Mission Concepts The papers can be found here: The Endorsement Page can be found here: Vlada Stamenkovic, Jesse Tarnas, Kennda Lynch, and Penelope Boston, (lead team) and many more.... Kennda Lynch (
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 Models for Planetary Sciences Habitability has been generally defined as the capability of an environment to support life. Ecologists have been using Habitat Suitability Models (HSMs) for more than four decades to study the habitability of Earth at local to global scales. Astrobiologists have been proposing different habitability models for some time, with little integration and consistency between them and different in function to those used by ecologists. In this white paper, we suggest a mass-energy habitability model as an example of how to adapt and expand the models used by ecologists to the astrobiology field. We propose to implement these models into a NASA Habitability Standard (NHS) to standardize the habitability objectives of planetary missions. These standards will help to compare and characterize potentially habitable environments, prioritize target selections, and study correlations between habitability and biosignatures. Habitability models are the foundation of planetary habitability science. The synergy between the methods used by ecologists and astrobiologists will help to integrate and expand our understanding of the habitability of Earth, the Solar System, and exoplanets. Abel Mendez, Edgard G. Rivera-Valentín, Dirk Schulze-Makuch, Justin Filiberto, Ramses Ramírez, etc. Abel Mendez (
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 (
Importance of Applying Abiotic / Prebiotic Chemistry to the Search for Life on Other Planets. The purpose of this white paper is to summarize how prebiotic and origin of life chemistry is an essential part of searching for life elsewhere, and that as we move into the next decade of planetary missions, we should increasingly invest in understanding the boundaries between abiotic and biotic systems. The boundary between abiotic and biotic chemistry could significantly vary, depending on the geological environment. It is possible that the same chemical signature observed on two different worlds could be biological in one and have an abiotic origin in another, depending on the geobiological state of those worlds. While samples from Earth represent an excellent “end-member” for what biological systems might be capable of, Earth field samples cannot represent the “abiotic end-member” of this spectrum, because biology has suppressed prebiotic / abiotic chemistry on this planet. To more accurately interpret whether an organic signature from another world is a biosignature, we need to gain a more complete understanding of abiotic chemical possibilities and create a good library of analog samples for mission instruments to assess. Due to prevalence of Earth life, these will need to be laboratory-generated samples, rather than samples from the field. Laurie Barge, Laura Rodriguez, Jessica Weber, Bethany Theiling, Pin Chen, Scott Perl, Bryana Henderson Laurie Barge (
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 (
Ocean Worlds Exploration and the Search for Life We recommend the establishment of a dedicated Ocean Worlds Exploration Program within NASA, providing sustained funding to support the science, engineering, research, development, and mission planning needed to implement a multi-decadal, multi-mission program to explore Ocean Worlds for life and understand the conditions for habitability. The two new critical flagship missions within this program would 1) land on Europa or Enceladus in the decade 2023-2032 to investigate geophysical and geochemical environments while searching for biosignatures, and 2) access a planetary ocean to directly search for life in the decade 2033-2042. The technological solutions for a landed mission are already in-hand, evidenced by the successful delta-Mission Concept Review of the Europa Lander pre-flight project in the fall of 2018. Following an initial landed mission, an ocean access mission will require substantial research, development, and analog testing this decade enable the initiation of a pre-flight project at the start of the following decade. Network for Ocean Worlds Samuel M. Howell (
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 (
Sampling Ocean Materials, Traces of Life or Biosignatures in Plume Deposits on Enceladus’ Surface This white paper provides a scientific justification for exploring plume deposit materials on the surface of Enceladus and proposes a sampling system implementation Choukroun M., Backes P., Cable M.L., Hodyss R., Badescu M., Marteau E., Molaro J.L., Moreland S., Nordheim T., Okamoto T., Riccobono D., Zacny K. Mathieu Choukroun (
The Need for Increased Astromedicine Research and Missions The future may demand human habitability on extracelestial bodies and as such, there is an ongoing need for deeper understandings about how the human body adapts to life in orbit and on various planets and celestial bodies. Peter Anto Johnson Peter Anto Johnson (
The Present and Future of Observational Studies of Ocean Worlds Do the icy moons, Europa and Enceladus, host habitable conditions at submerged hydrothermal vents? Are there other ocean worlds in our Solar System with similar potential astrobiological significance? Thanks to the plentitude of recent discoveries of extremophile organisms, the limits for habitable conditions have greatly expanded, and the hypothesized sub-surface oceans on these moons represent one of the most habitable niches in our Solar System. The true composition of these habitats and that of the encompassing torus produced by their internal activity and plumes (add ref) are still poorly known. In this respect, observational and remote-sensing studies can provide unique insights into the processes sustaining the activity on these bodies and the potential habitability of their sub-surface. Measuring the composition of the plumes will test for chemical diversity of internal “oceans”, while by performing high-resolution mapping, we will be able to identify the regions of active release, and the processes responsible for the activity. As we discuss in this paper, remote sensing with space and ground-based observatories, in coordination with in-situ remote sensing of these objects will reveal unique information regarding the processes acting on these astrobiologically relevant worlds, and the potential for habitability of their sub-surface oceans. Villanueva, Gerónimo L. (NASA-GSFC,, Nixon (NASA-GSFC), Paganini (NASA-HQ), Cordiner (NASA-GSFC/CUA), Milam (NASA-GSFC), Chin (NASA-GSFC) Geronimo Villanueva (
The Search for Past and Extant Life on Mars Universal models for the molecular biology to support Darwinism and contraints from prebiotic chemistry combine to focus mission design to identify past and extant life on Mars Steven Benner, Jan Špaček Steven Benner (
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 (
We Should Search for Extant Life on Mars in this Decade This white paper makes the case that a search for extant life on Mars should be conducted in this decade. Four possible habitable environments on Mars are described along with technologies for exploring them. Cosigners are sought. A complete draft can be found at C.R. Stoker, J.G. Blank, P.J. Boston, et al. Carol Stoker (
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Exobodies in Our Back Yard: Science from Missions to Nearby Interstellar Objects The recent discovery of the first confirmed Interstellar Objects (ISOs) opens the potential for near term ISO missions, either to the two known objects, or to similar objects found in the future. Such ISOs are the only exobodies we have a chance of accessing directly in the near future. This White Paper focuses on the science possible from in situ spacecraft exploration of nearby ISOs. Eubanks, T.M. Thomas Marshall Eubanks (
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 (
ynergy between Ice Giant and Exoplanet Exploration: The Solar System’s Planets “As Exoplanets” Given the uniqueness of the Ice Giants as solar system targets, and the longevity of the cruise phase and orbital tour, an Ice Giant mission has the potential to make major impacts to exoplanetary science. In particular there is significant novel science in viewing our solar system’s planets “as exoplanets.” This complements detailed characterization of the Ice Giant planets themselves. Jonathan Fortney, University of California, Santa Cruz, Mark Marley, NASA Ames Research Center, Laura Mayorga, Johns Hopkins Applied Physics Laboratory, Abigail Rymer, Johns Hopkins Applied Physics Laboratory Jonathan Fortney (
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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 (
Ice Giants - The Return of the Rings Here we highlight recent advances in our knowledge about Saturn’s ring system and bring forward the outstanding science issues that could be addressed by studying the ring systems of the ice giants. We focus on the interactions between planetary rings and other elements in the system, including the moons, the host planet, and its magnetosphere and conclude that the ring science, in accordance with magnetospheric and atmospheric science disciplines, are essential in advancing our knowledge of the solar system evolution, the origin and evolution of the moons and Ocean Worlds, as well as contemporary phenomena observed in the ice giant systems. We suggest the study of the ice giant ring systems to be considered a top priority for the future ice giant explorations. Hsiang-Wen Hsu Sean Hsu (
Keys of a Mission to Uranus or Neptune, the Closest Ice Giants Uranus and Neptune are the archetypes of "ice giants", a class of planets that may be among the most common in the Galaxy. They hold the keys to understand the atmospheric dynamics and structure of planets with hydrogen atmospheres inside and outside the solar system; however, they are also the last unexplored planets of the Solar System. Their atmospheres are active and storms are believed to be fueled by methane condensation which is both extremely abundant and occurs at low optical depth. This means that mapping temperature and methane abundance as a function of position and depth will inform us on how convection organizes in an atmosphere with no surface and condensates that are heavier than the surrounding air, a general feature of giant planets. Owing to the spatial and temporal variability of these atmospheres, an orbiter is required. A probe would provide a reference atmospheric profile to lift ambiguities inherent to remote observations. It would also measure the abundances of noble gases which can be used to reconstruct the history of planet formation in the Solar System. Finally, mapping the planets' gravity and magnetic fields will be essential to constrain their global composition, atmospheric dynamics, structure and evolution. An exploration of Uranus or Neptune will be essential to understand these planets and will also be key to constrain and analyze data obtained at Jupiter, Saturn, and for numerous exoplanets with hydrogen atmospheres. Tristan Guillot, Jonathan Fortney, Emily Rauscher, Mark Marley, Vivien Parmentier, Mike Line, Hannah Wakeford, Yohai Kaspi, Ravit Helled, Masahiro Ikoma, Heather Knutson, Kristen Menou, Diana Valencia, Daniele Durante, Shigeru Ida, Sc Tristan Guillot (
Keys of a Mission to Uranus or Neptune, the Closest Ice Giants Uranus and Neptune are the archetypes of "ice giants", a class of planets that may be among the most common in the Galaxy. They hold the keys to understand the atmospheric dynamics and structure of planets with hydrogen atmospheres inside and outside the solar system; however, they are also the last unexplored planets of the Solar System. Their atmospheres are active and storms are believed to be fueled by methane condensation which is both extremely abundant and occurs at low optical depth. This means that mapping temperature and methane abundance as a function of position and depth will inform us on how convection organizes in an atmosphere with no surface and condensates that are heavier than the surrounding air, a general feature of giant planets. Owing to the spatial and temporal variability of these atmospheres, an orbiter is required. A probe would provide a reference atmospheric profile to lift ambiguities inherent to remote observations. It would also measure the abundances of noble gases which can be used to reconstruct the history of planet formation in the Solar System. Finally, mapping the planets' gravity and magnetic fields will be essential to constrain their global composition, atmospheric dynamics, structure and evolution. An exploration of Uranus or Neptune will be essential to understand these planets and will also be key to constrain and analyze data obtained at Jupiter, Saturn, and for numerous exoplanets with hydrogen atmospheres. Tristan Guillot, Jonathan Fortney, Emily Rauscher, Mark Marley, Vivien Parmentier, Mike Line, Hannah Wakeford, Yohai Kaspi, Ravit Helled, Masahiro Ikoma, Heather Knutson, Kristen Menou, Diana Valencia, Daniele Durante, Shigeru Ida, Scott Bolton, Cheng Li Tristan Guillot (
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 (
Unique Science Return from Direct Probes of the Atmospheres of the Ice Giants We describe the main scientific goals that can be addressed uniquely by direct probes into the atmospheres of Uranus and Neptune. The Galileo Probe of the atmosphere of Jupiter illustrated the potential for unexpected science return, where key measurements such as the abundances of noble gases and the precise measurement of the helium mixing ratio were only made available through in situ measurements. We advocate for measurements that will put the results of the Galileo Probe into a broader context. Atmospheric entry probes targeting the 10-bar level would yield unique insight into (i) the formation history of the outer planets and that of the Solar System, and (ii) the various processes at play in planetary atmospheres. Direct probes would focus on key measurements of composition, structure, and dynamics. Glenn Orton, David Atkinson, Olivier Mousis, Kunio Sayanagi, Tom Spikler Glenn Orton (
Uranian System Science on a New Frontiers Budget A New Frontiers mission concept that focuses on the Uranian moons, magnetosphere, and rings. Erin Leonard, Catherine Elder, Tom Nordheim, Richard Cartwright, Alex Patthoff, and any interested parties Erin Leonard (
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Advanced Curation of Astromaterials for Planetary Science The next decade will provide many new opportunities to study astromaterials from sample return missions and from Earth-based collection campaigns. In order to maximize the science returns of these samples, the techniques and practices of sample curation and processing must also evolve. The field of advanced curation is focused on making the technological and scientific advances needed to maximize the science returns on NASA's astromaterials. Francis M. McCubbin Francis M. McCubbin (
Enabling Robotic and Human Exploration at Mars via Relay Networks Will describe the current Mars Relay Network and describe why a dedicated relay infrastructure is needed to advance human interests at Mars. Roy Gladden, others Roy Gladden (
Enabling Synergy: Improving the Information Infrastructure for Planetary Science In this whitepaper we advocate that the Planetary Science (PS) community build a discipline-specific digital library, in collaboration with the existing astronomy digital library, ADS. We suggest that the PS data archives increase their level of curation to allow for direct linking between the archival data and the derived journal articles. And we suggest that a new component of the PS information infrastructure be created to collate and curate information on features and objects in our solar system, beginning with the USGS/IAU Gazetteer of Planetary Nomenclature. Co-sign the draft document available at: Michael J. Kurtz, Alberto Accomazzi, Edwin A. Henneken Alberto Accomazzi (
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 (
Maximizing the Value of Solar System Data through Planetary Spatial Data Infrastructures Planetary spatial data returned by spacecraft are of critical importance to NASA and other space agencies. Many planetary spatial data remain inaccessible to the general science user because particular skills are necessary to process and interpret them from the raw initial state. There is a critical need for planetary data to be more accessible and usable to the science user and stakeholders. Planetary Spatial Data Infrastructures (PSDIs) bring together data products with effective plans for data acquisition, widely available data processing tools that can be used to create usable products, plans for funding, creating and making available higher order products, a means for disseminating data and products, and the science users. We recommend that Planetary Spatial Data Infrastructures should be created for all bodies and key regions in the Solar System. Jani Radebaugh, The Mapping and Planetary Spatial Data Infrastructure Team Jani Radebaugh (
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 (
A Comparative View of Glacial and Periglacial Landforms on Earth and Mars The identification of landforms related to the current or past presence of ice on Mars relies largely on morphology. This white paper focuses on the importance of comparative planetary geology and glaciology to (1) identify and characterize sites with potential for human in-situ resource utilization; (2) characterize the climate and geological history of Mars through glacial and periglacial deposits and landforms; and (3) list techniques of use in terrestrial (peri)glacial environments, as well as analogue sites of interest, to help define future robotic explorations of Martian icy environments. A. Grau Galofre, C. Andres, P. Becerra, A. Bhardwaj, F. Butcher, P. Christensen, S. Conway, A. Coronato, E. Hauber, S. Hibbard, P. Knightly, T. Meng, G. Osinski, E. Petersen, J. Plaut, J. Rabassa, L. Sam, J. Serla, K. Whipple Anna Grau Galofre (
A Critical Zone Network Approach to the Study of Mars The last few decades of research have led to significant discoveries about the Martian atmosphere and surface, and we are just beginning to explore the subsurface. The shallow subsurface of Earth plays host to a variety of interconnected physical, chemical, and biological processes affecting landscape evolution over time. Similar processes were putatively important on early Mars (at least in limited extent) and may continue to interact in the modern subsurface. As we continue to reveal more of the Martian subsurface, it is proposed that the application of concepts from Critical Zone science can be used in a similar system-wide manner. Included in this proposal is a definition of the Mars Critical Zone, with reference to hydrologic, nutrient, and mineralogic focus areas as examples that apply Critical Zone science concepts on Mars. Laura E. Fackrell (; Rachel R. Rotz (,2; Huseyin Demir (; Paul A. Schroeder ( of Geology, University of Georgia 2Department of Marine and Earth Sciences, Florida G Laura Fackrell (
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 (
GANGOTRI mission concept on the glacial key to the Amazonian climate of Mars Besides Earth, Mars is the only terrestrial planet with evidence of extensive glaciations. Terrestrially, the glacial record is key to recent climate evolution. However, geologically recent martian midlatitudinal glaciers are yet to be examined in situ. Accordingly, our mission concept will explore a ~Ma old H2O ice sheet in situ towards (1) understanding climate-driven processes of midlatitudinal glaciers as a key H2O reservoir within Mars’s critical zone; and (2) determining the habitability and biomarker preservation potential of young martian glaciations. The human exploration goal is to understand the utility of glacial ice as an in situ resource. Our mission will deploy a mobile thermo-mechanical 10 - 30 meter deep drilling platform on Mars. A quadrupole mass spectrometer (QMS) and tunable laser spectrometer (TLS) will help resolve the fundamental discrepancy between observed and modeled variability of atmospheric D/H ratios across Mars. Meanwhile, global atmospheric events will be examined with drill-mounted laser scattering sensitive to eolian dust and volcanogenic ash. Drill-mounted UV fluorescence spectrometry will provide the first continuous chronological sequence of organics and potential biomarkers of Amazonian Mars. Locating thick metastable ice with the shallowest regolith cover is essential for effective thermo-mechanical drilling. Consequently, we will map depth to ground ice with a gamma and neutron spectrometer, calibrated against wheel-mounted shallow acoustic seismic sensors. Supporting field reconnoitering instruments will consist of a mast mounted infrared or raman spectrometer, and a rotorcraft with imaging capability. Suniti Karunatillake, Ali Bramson, Kris Zacny, Luju Ojha et al. Co-authors and endorsers are welcome! Suniti Karunatillake (
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, 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 Methane Monitoring duplicate K. Winslow Farrell, Jr. K. Winslow Farrell, Jr. (
Mars Methane Monitoring System The focus of this white paper is to build a record of the presence of methane and other trace gases in the Martian atmosphere for multiple Martian years through a series of low-cost, low-risk missions. The paper describes the development, over multiple launches, of a network of trace gas monitoring stations on the Martian surface. The development of this long duration monitoring system would take place in multiple phases, beginning with a single pathfinder mission designed for launch availability by 2024. This pathfinder mission would land a single SIMPLEx-class Mars lander in the Gale crater to monitor the release of methane for a Martian year. A later mission concept would land four landers on multiple locations on the Martian surface as a network to monitor the release of trace gases on Mars, including methane, for a nominal mission of two Martian years. The pathfinder mission would extend the temporal record of the level of methane concentrations in the Martian atmosphere begun with detections of methane from the Curiosity rover. The more comprehensive mission – a long duration monitoring network based on four landers -- would establish a spatiotemporal record of seasonal and diurnal variations of methane and other trace gas concentrations in locations on Mars across multiple summer and winter seasons. The pathfinder mission would record observations of methane in Gale crater, as an extension of ephemeral methane detection ‘spikes’ and rate of decay of those concentrations that began with the Curiosity rover. The design and development of a single pathfinder lander is expected to fit within the cost profile of a SIMPLEx mission. The reference architecture for the pathfinder includes a hard landing system, such as the SHIELD system from JPL, and ruggedized scientific instrumentation now in development. The mission profile of the single lander pathfinder mission aims to provide an observation outpost for in-situ measurements of methane releases in the Martian atmosphere in Gale crater. The more complex network mission includes the hard landing of four instrument packages capable of detecting methane and trace gases such as oxygen from the atmosphere above the Martian surface and reporting those observations when detected levels rise above a threshold level. Once on Mars, each lander would transmit reports of trace gas observations to other landers in the network to independently command instruments to generate detailed, coordinated confirming measurements of the presence and amount of trace gases in other locations. Landing site choices for the initial pathfinder mission and for the monitoring network mission derive from locations where variations in Martian trace gas concentrations have been observed and could be expected to recur. Martian landing sites could include areas that have exhibited periodic methane releases peaking in the Martian summer; landing site selections include mid-latitude locations such as Gale crater, Nili Fossae, and Thaumasia where ephemeral releases of methane have been identified. Farrell, K. Winslow Karr Winslow Farrell, Jr. (
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 (
Maximizing the Science and Resource Mapping Potential of Orbital VSWIR Spectral Measurements of Mar The last 16 years have witnessed rapid expansion in the understanding of the composition and aqueous alteration of Mars’ surface from orbital data from the Observatoire pour la Mineralogie, l’Eau, les Glaces et l’Activité (OMEGA) (Bibring et al., 2004) and the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) (Murchie et al., 2007). Both are sensitive to water-, hydroxyl-, sulfate-, and carbonate-bearing phases and ferric phases that record past persistent liquid water, as well as geotechnical properties of surface materials. As the spatial resolution of such data has improved, the diversity of mineral phases that are recognized have likewise expanded. The same phases typically contain bound water, a resource for future human exploration, and the only near-surface reservoir in the >50% of Mars over which ice likely does not occur in the shallowest subsurface. Knowledge of the distribution and abundance of these water-bearing phases, and their geologic implications, is limited by spatial resolution of the available data. A more complete inventory and stratigraphy of these materials can be obtained from Mars orbit, using complementary approaches: hyperspectral imaging at several meters per pixels at 0.7–4 µm, and meter-per-pixel imaging at selected VSWIR wavelengths. Scott L. Murchie, et al. Scott L. Murchie (
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 an Exploration Target for In Situ Resources 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. We pose that the major outstanding questions to be addressed in the next decade surrounding the nature of mid-latitude ice on Mars are: 1. What climate record is preserved in these mid-latitude deposits? 2. How accessible is the ice as a resource for future exploration? We are currently finalizing the white paper and looking for co-signatories! You can download the most recent draft here: To add yourself as a cosignatory of this White Paper, please fill out the following form: A. M. Bramson, J. Bapst, P. Becerra, S. W. Courville, C. M. Dundas, S. M. Hibbard, S. Karunatillake, M. T. Mellon, G. A. Morgan, M. R. Perry, E. I. Petersen, N. E. Putzig, H. G. Sizemore, I. B. Smith, D. Stillman, P. Wooster Ali M. 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 Importance of the Climate Record in the Martian Polar Caps The goal of this white paper is to highlight the importance of continued study of the stratigraphic record of climate in the Martian polar ice caps. Our current knowledge of this record has enabled us to interpret the existence of astronomically forced climatic variations on Mars, analogous to Earth’s Milankovich cycles. This link has allowed us to place constraints on what the climate may have looked like in the recent past and to pose hypotheses about the transport of ice between regions of the Martian surface. Fully deciphering this record will require knowing the thickness of annual layers, and ages of specific strata, in order to develop climate scenarios associated with specific accumulation or ablation periods. Achieving this goal will have profound implications for our understanding of astronomically forced planetary climate. Furthermore, it can potentially help us to infer whether Mars could have had habitable environments in the recent past. Patricio Becerra, Adrian J. Brown, Shane Byrne, Kenneth E. Herkenhoff, Margaret E. Landis, Briony Horgan, Alyssa Pascuzzo, Jeffrey J. Plaut, Ganna Portyankina, Nathaniel E. Putzig, Isaac B. Smith, Nicolas Thomas, Timothy N. Titus, Jennifer Whitten Patricio Becerra (
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 (
The Water Cycle on a Salty Mars: Science and Exploration Strategies for Understanding Present-day Atmosphere-Regolith Interactions Characterizing the dynamics of the present-day Martian water cycle is important to understanding climatic processes, water ice stability, habitability, the potential for in-situ resource utilization (ISRU), as well as the evolutionary history of Mars. The wealth of data now available from orbiters (e.g., Jakosky and Farmer, 1982; Boynton et al., 2002; Melchiorri et al., 2009), as well as in-situ measurements by the Phoenix Lander (Zent et al., 2010; Fischer et al., 2019) and Mars Science Laboratory (Harri et al., 2014), suggest the regolith is an important component of the water cycle. The detection of hygroscopic salts (e.g., Osterloo et al., 2008; Hecht et al., 2009; Navarro-Gonzalez et al., 2010; Leshin et al., 2013) further increases the role of the regolith in the water cycle. Hygroscopic salts lead to temperature-dependent water vapor sinks and sources in the shallow subsurface that compete for water on diurnal and seasonal timescales (e.g., Chevrier et al., 2008; Rivera-Valentín & Chevrier, 2015; Gough et al., 2020; Savijärvi et al., 2020a; Savijärvi et al., 2020b), including liquid formation (e.g., Gough et al., 2011; 2014; Hanley et al., 2012; Nuding et al., 2014; Fischer et al., 2016; Rivera-Valentín et al., 2018; Rivera-Valentín et al., 2020). In order to further Mars exploration, planetary science, and astrobiology strategies for the coming decade, we identify key knowledge gaps in the present understanding of the Martian water cycle, in particular salt-based atmosphere-regolith exchange processes. Additionally, we recommend strategies enabled through synergies between experimental and field research, as well as mission science that will help resolve open questions in our understanding of Mars’ present-day climate. Edgard G. Rivera-Valentín, Germán Martínez, Kennda Lynch, Vincent F. Chevrier, Raina V. Gough, Margaret Tolbert, Jennifer Hanley, Alejandro Soto, David Stillman, Katherine M. Primm Edgard G. Rivera-Valentín (
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 (
Artificial Intelligence for the Advancement of Lunar and Planetary Science and Exploration Over the past decades of NASA’s inner solar system exploration, data obtained from the Moon alone accounts for ~76%. Most of the lunar orbital spacecraft of the past and present carried imaging cameras and spectrometers (including multispectral and hyperspectral payloads), as well as a large variety of other passive and active instruments. For example, NASA’s Lunar Reconnaissance Orbiter (LRO) has been operating for more than 10 years, providing us with ~1206 TB of lunar data which amounts to ~99.5% of the total data contributed by NASA built instruments. Given recent advances in instrument and communication capabilities, the amount of data returned from spacecraft is expected to keep rising quickly. The white paper focus on potential components of AI and ML that could help to accelerate the future exploration of the Moon and other planetary bodies. The white paper highlights on selected AI/ML-based approaches for lunar and planetary surface science and exploration, the need for open-source availability of training, validation, and testing datasets for AI-ML based approaches, and need for opportunities to further bridge the gap between industry and academia for advancing AI-ML based research in lunar and planetary science and exploration. Indhu Varatharajan, Valentin Bickel, Daniel Angerhausen, Eleni Antoniadou, Shashwat Shukla, Abhisek Maiti, Ross Potter, Nishan Srishankar, Frank Soboczenski, Carl Shneider, Michelle Faragalli, Mario D’Amore Indhu Varatharajan (
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 (
Electrostatic Dust Transport Effects on Shaping the Surface Properties of the Moon and Airless Bodies across the Solar System Electrostatic dust charging and subsequent transport on the lunar surface due to direct exposure to the solar wind plasma and solar radiation is a more than five-decade-old problem. Dust activity has been suggested as an explanation for several lunar surface observations from the beginning in the Apollo era. Beyond the Moon, related observations indicate that this electrostatic process may be a universal phenomenon on airless bodies across the solar system. Recent studies have made important breakthroughs in understanding the fundamentals of dust charging, mobilization and lofting mechanisms, offering strong support for its occurrence on the surfaces of airless bodies. This white paper reviews historical and recent observational evidence, reports recent findings, examines knowledge gaps and outstanding science questions, and provides recommendations for future studies. Special attention is given to in situ measurements over the next decade in order to ultimately solve the outstanding questions and, more importantly, understand the primary implications for the evolution of the surfaces of the Moon and other airless bodies across the solar system. Furthermore, potential risks posed by electrostatic dust transport to future surface exploration of these bodies, especially any long-term human presence on the lunar surface, needs to be well characterized in order to define and implement appropriate risk mitigation strategies and methods through proper systems design and testing. Xu Wang et al. Xu Wang (
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 (
MoonShake: a future Lunar Seismic Network Delivered by Penetrators The proposed mission would bury seismometers on the Moon using penetrators deployed directly from a small spacecraft or from a descending lander. This paper identifies the most compelling questions in lunar science: 1) To constrain the thickness of the lunar core to within 50 km and determine whether it is liquid; 2) Determine crustal thickness (at the target sites to within 5 km), and constrain the average thickness in conjunction with data from the GRAIL gravity mission; 3) Determine the depth of deep moonquakes to within 50 km, and determine whether they occur at a range of depths; 4) Determine the number of meteoroids that hit the Moon every year; 5) Analyze lunar asymmetry in crust, mantle and core; 6) Determine regional variations (for example, differences between high and low heat-flow regions); 7) Determine properties of the lunar regolith from the deceleration of the penetrator (at each site). Nunn et al. Ceri Nunn (
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 (
Understanding the Lunar-hour in your timezone We’ll describe the Moon’s role in the temporal shaping of the international Standard measure of Time, utilizing solar system science, spacetime, and NCBI methods of molecular understanding, shaping, and coordinating. M.A. Norton. —PARTNERS WELCOME! M.A. Norton (
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Outer planet satellites

Agnostic Biosignature Exploration at Europa through Plume Sampling Water-rock interactions, potentially enhanced by tidal heating, could supply the Europan ocean with chemical energy sources and material resources required by active life. An Astrobiology Biosignature Explorer at Europa (ABEE) New Frontier mission would be designed to search for biomolecules contained in plume material. Paul Mahaffy, NASA Goddard Space Flight Center Greenbelt, MD 20771 Paul Mahaffy (
An Exploration Strategy for Europa We will be submitting a white paper entitled “An Exploration Strategy for Europa” to the upcoming Planetary Science & Astrobiology Decadal Survey on Wednesday July 15th. We invite community members to join this white paper as co-signers. Please visit this link to download a copy of the white paper draft, and to submit your info to be added as a co-signer. Cynthia Phillips and many others Cynthia Phillips (
A Proposed Sample Return from Titan Titan is scientifically fascinating in many ways, not the least of which is as a representative of the icy moons of the outer solar system, and a representative of the "water worlds" with liquid oceans under an ice shell. It is also the only body other than the Earth with a hydrological cycle (albeit with rains of methane taking the place of water in the phase-change cycle). Titan is also a high priority target for astrobiology. The surface and atmosphere are rich in the complex organic compounds known as tholins, which are ubiquitous in the outer solar system and Kuiper belt, yet not well understood. These are likely to be the building blocks of the early solar system from which life arose. Samples of Titan’s surface and atmospheric tholins, as well as the many other components of Titan’s surface, would be invaluable. While some analysis of such compounds may be possible using lightweight instruments on board a probe, a detailed investigation of these complex compounds will require an analysis using a full laboratory on Earth. Sample return from Triton would thus have a high science value. We wish to suggest here that it is possible to do this with credible technology. In Situ Resource Utilization (ISRU) propellant production has been proposed for missions to Mars, the moon, and asteroids, and an initial demonstration of ISRU, production of oxygen from carbon dioxide, will fly to Mars with the Perseverance rover. Titan, however, is nearly an optimal target for ISRU propellant production, with free hydrocarbons available on the surface, and water available in the form of surface rocks. By using the available resources of Titan to produce propellant, a sample return mission would be feasible. Geoffrey A. Landis and Steven R. Oleson Geoffrey A. Landis (
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 (
High-resolution mapping of satellite surfaces and atmospheres with radio interferometry The next decade will see significant investment in exploration of outer Solar System satellites by spacecraft. Ground-based radio interferometers have been enabling discoveries at these worlds for decades, with significant advancements in recent years resulting from the Atacama Large Millimeter Array (ALMA). Extending the ground-based high-resolution radio interferometer facilities to lower frequencies will open new scientific realms, sensing different atmospheric lines and deeper into satellite surfaces, and will augment thermal and atmospheric observations by planned and proposed spacecraft. The next-generation VLA (ngVLA) would enable high spatial resolution mapping of outer Solar System satellites at lower frequencies than ALMA, leading directly to new discoveries at these worlds as well as enhancing the science return of spacecraft programs. Katherine de Kleer, Mark Gurwell, Imke de Pater, Bryan Butler, Arielle Moullet, Sam Trumbo, Robert Sault, Chris Moeckel, Joshua Tollefson, Stefanie Milam Katherine de Kleer (
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 a Titan Flagship-class Orbiter with Probes The Cassini-Huygens mission greatly advanced our knowledge of the Saturn system, and in particular its giant moon, Titan. Many questions remain open about Titan, including its origin, evolution, internal geology and structure, meteorology, atmospheric composition and chemistry, interaction with Saturn, and more. The forthcoming Dragonfly aerorover mission will give unique insights into some of these questions, but many questions about the global landscape and atmosphere, and the northern seas and lakes, will not be fully addressed. This points to a clear need for a Titan orbiter mission, to provide global-scale information, combined with probes to investigate the seas in situ. This white paper will discuss the science drivers for such a mission and the need for a mission concept study to investigate plausible architectures for implementation. Conor A. Nixon, NASA Goddard Space Flight Center, USA James Abshire, University of Maryland, College Park, USA Jason Barnes, University of Idaho, USA Nathalie Carrasco, Université Paris-Saclay, France, Mathieu Choukroun, Jet Propulsion Laboratory, Caltec Conor Nixon (
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 (
Triton: Fascinating moon, likely ocean world, compelling destination! Neptune’s moon Triton has been explored by just one spacecraft, Voyager 2, in 1989. Images revealed a unique geologically young surface with cryovolcanic landforms found nowhere else in the solar system. Geysers erupt from a surface with a temperature of just 38K. Triton is noteworthy for its retrograde, highly inclined orbit, making it almost certainly a captured Kuiper Belt dwarf planet. Is Triton an ocean world? Crater counts suggest that Triton’s surface age is <100 Ma, possibly <10 Ma old. Although Triton’s orbit has long since circularized and eccentricity tides are negligible today, obliquity tides could be particularly strong on Triton because of its high inclination orbit. These tides could supply the necessary energy for surface processes that would erase craters, and possibly maintain a liquid layer below the surface. Do the oceans of moons of outer planets provide habitable environments and host life? A mission to Triton answers the call to explore ocean worlds. Will Grundy, Jason Hofgartner, Emily Martin, Karl Mitchell, Francis Nimmo, Carol Paty, James Roberts, Kirby Runyon, Lynnae C. Quick, Paul Schenk, Alan Stern, Orkan Umurhan Candy Hansen (
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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 (
Combined Emerging Capabilities for Near-Earth Objects (NEOs) This paper assess the joint capabilities of emerging telescopes for near-Earth objects (NEOs) survey and characterization, and what they will add to the current capabilities or replace. Facilities considered in this assessment include: * The Transiting Exoplanet Survey Satellite (TESS) * The James Webb Space Telescope (JWST) * The Nancy Grace Roman Space Telescope (formerly WFIRST) * The Near-Earth Object Camera (NEOCam) * The Vera C. Rubin Observatory (formerly LSST) * The Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer (SPHEREx) S.N. Milam, H.B. Hammel, J. Bauer, M. Brozovic, T. Grav, B.J. Holler, C. Lisse, A. Mainzer, V. Reddy, M. E. Schwamb, T. Spahr, C.A. Thomas, D. Woods Stefanie Milam (
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 (
Planetary Defense Preparedness: Identifying the Potential for Post-asteroid Impact Time Delayed and Geographically Displaced Hazards A considerable amount of effort has been done to quantify the effects of an asteroid impact on Earth, including processes such as air blast with overpressure shock and thermal radiation, crater formation and ejecta deposition, seismic shaking, and tsunamis These first-order effects are typically localized in time and diminish with increased distance from the impact (or air burst) location. However, delayed downstream and downwind effects will propagate, and disturb areas not immediately affected by the initial impact. This white paper highlights the need to consider these effects in future modeling efforts. T. N. Titus , D. Robertson, J.B. Sankey, A.J. Oliphant,, I.P. Aneece Timothy N Titus (
Planetary Radar Astronomy with Ground-Based Astrophysical Assets [This was previously submitted to the Astro2020 decadal survey with plans to update it for the planetary science decadal.] Planetary radar is a unique method for studying solid bodies in the solar system and arguably the most powerful method for post-discovery physical and dynamical characterization of near-Earth objects. Motivated by the George E. Brown, Jr. Near-Earth Object Survey Act and the National Near-Earth Object Preparedness Strategy and Action Plan, we argue planetary radar plays a critical and unique role in the tracking and characterization of near-Earth objects, where all facilities used for planetary radar are astrophysical or deep-space communication assets. With the construction of a dedicated planetary radar facility (or facilities) unlikely, it is imperative that the single-dish radio telescopes with radar transmitters currently in use: Arecibo Observatory and the Goldstone Solar System Radar (part of the Deep Space Network), along with the Green Bank Telescope, often used in conjunction with the transmitting telescopes, remain viable. Access to these facilities for planetary radar must be sustained, if not expanded considerably, to keep pace with the expected near-Earth object discovery rates of future surveys like the Large Synoptic Survey Telescope and a space-based infrared observatory like NEOCam. Satisfying federal mandates requires continued and expanded support of planetary radar programs, upgrades to the facilities that host the planetary radar systems, and adequate communication between Congress and all relevant agencies that manage the facilities and the planetary radar programs. Continued research into improved radar transmitter technology and the use of phased array radars on interplanetary distance scales is warranted. Any breakdown of the planetary radar programs using single-dish astrophysical assets would be detrimental to planetary defense and small-body exploration on the timescale of the decadal survey. Patrick Taylor, Edgard Rivera-Valentin, Amber Bonsall, et al. Patrick Taylor (
Rapid Response and Robotic Telescopes For Small Body Transient Science This whitepaper is to discuss the need for rapid response and robotic telescopes in order to investigate transient phenomena such as outbursts on small bodies of all types. We are also emphasizing the need for facilities, instruments, data processing and archives to allow and enbale rapid response solar system science and the need for equity of access to data and resources for all. If you would like to be a co-author or co-signer, please contact me or join the Google doc: Tim Lister - all coauthors welcome ! Tim Lister (
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 Crucial Role of Ground- and Space-Based Remote Sensing Studies of Cometary Volatiles in the Next Decade (2023-2032) Abstract: The study of comets affords a unique window into the birth, infancy, and subsequent history of the solar system. There is strong evidence that comets incorporated pristine interstellar material as well as processed nebular matter into their nuclei, providing insights into the composition and prevailing conditions over wide swaths of the solar nebula at the time of planet formation. Their populations bear a record spanning the life of the solar system. Dynamically new Oort cloud comets harbor primitive ices that have been stored thousands of astronomical units from the Sun and have suffered minimal thermal or radiative processing since their emplacement ~4.5 Gyr ago. Periodic, more dynamically evolved comets such as the Halley-type and Jupiter-family comets reveal the effects of lives spent over a range of heliocentric distances, including perihelion passages into the very inner solar system. Systematically characterizing the information imprinted in the native ice compositions of these objects is critical to understanding the formation and evolution of the solar system, the presence of organic matter and water on the terrestrial planets, the chemistry present in protoplanetary disks around other stars, and the nature of interstellar interlopers such as 2I/Borisov. Although comet rendezvous and sample return missions can provide remarkable insights into the properties of a few short-period comets, the on-sky capacity necessary to perform population-level comet studies while simultaneously remaining sensitive to the paradigm-challenging science that individual comets can reveal can only be provided by remote sensing observations. Here we report the state-of-the-art in ground- and space-based remote sensing of cometary volatiles, review the remarkable progress of the previous decade, articulate the pressing questions that ground- and space-based work will address over the next ten years, and advocate for the technology and resources necessary to realize these aspirations. Nathan X. Roth, Dennis Bodewits, Boncho Bonev, Anita Cochran, Martin Cordiner, Neil Dello Russo, Michael DiSanti, Sara Faggi, Adam McKay, Stefanie Milam, John W. Noonan, Anthony Remijan, Geronimo Villanueva Nathan X. Roth (
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 (
Why we should study the Themis asteroid family in the 2023-2032 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-signers welcome until 7/8, mature draft available here: M.E. Landis, J. Castillo-Rogez, P.O. Hayne, K. Hughson, K.E. Miller, D. Kubitschek, T.H. Prettyman, A.S. Rivkin, B.E. Schmidt, J.E.C. Scully, N. Yamashita, and M. Villarreal Margaret E. Landis (
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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 (
Habitability, Geodynamics, and the Case for Venus Geodynamics, like Earth’s plate tectonics (PT), governs long-term planetary evolution and habitability. Beyond Earth, only Venus may have key elements of PT: subduction (the 1st step in PT) and continents. Revealing Venus’ geodynamics is key to understanding how PT began on Earth, and how to predict the geodynamic evolution of other rocky bodies. S. Smrekar, see paper for additional authors Suzanne Smrekar (
Habitability, Geodynamics, and the Case for Venus Geodynamics, like Earth’s plate tectonics (PT), governs long-term planetary evolution and habitability. Beyond Earth, only Venus may have key elements of PT: subduction (the 1st step in PT) and continents. Revealing Venus’ geodynamics is key to understanding how PT began on Earth, and how to predict the geodynamic evolution of other rocky bodies. S. Smrekar, see paper for additional authors Suzanne Smrekar (
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 (
Laboratory Studies in Support of Venus Exploration: Surface and Near-Surface Reminder of the importance of laboratory studies in support of mission science, emphasizing many of the unknowns about Venus' lower atmosphere, surface, and near-subsurface. Allan Treiman, Justin Filiberto, Molly McCanta Allan Treiman (
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

Nonbinary Systems: Looking Towards the Future of Gender Equity in Planetary Science Gender equity remains one of the biggest issues facing the field of planetary science, and there is broad interest in addressing gender disparities within space science and related disciplines. Many studies of these topics have been performed by professional planetary scientists who are relatively unfamiliar with research in fields such as gender studies and sociology. As a result, they adopt a normative view of gender as a binary choice of ‘male’ or ‘female’, leaving planetary scientists whose genders do not fit within that model out of such research entirely. Reductive frameworks of gender and an overemphasis on quantification as an indicator of gendered phenomena are harmful to people of marginalized genders, especially those who live at the intersections of multiple axes of marginalization such as race, disability, and socioeconomic status. In order for the planetary science community to best serve its marginalized members as we move into the next decade, a new paradigm must be established. This paper aims to address the future of gender equity in planetary science by recommending better survey practices and institutional policies based on a more profound approach to gender. Strauss et al. Beck Strauss (
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 (
Scientific Consensus is Dead, Long Live Scientific Consensus NASA makes many thousands of zero-sum decisions every year regarding funding and mission planning. A primary stated goal for the outcomes of these decisions is that scientific merit be recognized and rewarded. How does one evaluate merit in a time of unprecedented publication volume? In the lack of reproducible consensus for metrics of scientific value it is human nature to fall back on heuristics that amplify bias. This same difficulty in assimilating information deforms all researchers’ ability to sharpen experimental narratives through collaborative review and engagement. This whitepaper uses summary results from the 981 most-cited articles from the journal Astrobiology and 807 of their authors’ complete publication histories to illustrate the accelerating problem of forging consensus in the information age, and argues that current metrics-based structures are guaranteed to result in biased outcomes. Three solutions are proposed that NASA should consider to mitigate bias, speed democratization in science, and better inform exploration in the lab and beyond. Aaron Pital Aaron C Pital (
The importance of Code of Conduct policies for conferences, mission teams, and research endeavors This white paper aims to Define what a Code of Conduct is – as in what it should contain and what it aims to do; Explain why a Code of Conduct is valuable for conferences, mission teams, and research groups; Discuss existing examples and “evaluate” their contents; and Make solid recommendations for what NASA should do going forward to encourage and enable this practice. S. Diniega, C.T. Udovicic, C. Elder, J. Scully, J. Rathbun, A. Rutledge, J. Castillo-Rogez, I. Daubar, R. Pappalardo, C. Richey, M. Villarreal, M. Milazzo, T. Goudge, J. Filiberto, K. Bennett, J. Roberts Serina Diniega (
The Value of Participating Scientist Programs to NASA’s Planetary Science Division We recommend that Participating Scientist programs are included on every mission, regardless of whether it is competed or directed. This paper summarizes the results of our 2017 study on this topic, which found tremendous value in participating scientist programs to the intellectual and demographic diversity of missions. We also found that Participating Scientist programs provide great training opportunities. Louise Prockter and many others Louise Prockter (
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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 (
Armada: A Flagship Multi-Mission Architecture Armada is a fleet of 20 small spacecraft capable of reaching outer planet destinations, proposed as an alternative to traditional single destination Flagship Missions. Stephen Bailey, David Paige Stephen Bailey (
Critical Laboratory Studies to Support and Advance Planetary Science and Planetary Missions: Overview, Challenges, and Recommendations Laboratory work (experiments and theory) is crucial to interpret Solar System observations and mission data, and is a key incubator for new mission concepts and instrument development & calibration. We present here an overview of the specific planetary science areas where laboratory studies are critically needed. These areas include planetary/satellites atmosphere/exosphere, planetary/satellites surfaces and rings, planetary/satellites interiors, asteroids &meteorites, comets, Kuiper belt objects, and astrobiology. Generating targeted experimental and theoretical laboratory data that are relevant for a better understanding of the physical and chemical processes occurring in these environments is crucial. For each part, we give i) a brief overview of the state-of-the-art laboratory work, ii) challenges and needs to support upcoming missions and future concepts, and analyze and interpret past/current missions/datasets including ground-based observations, and iii) recommendations for high priority laboratory studies. Higher order remarks on specific challenges encountered by planetary scientists performing laboratory work are also presented. Edith Fayolle, Murthy Gudipati, Stefanie Milam, Ella Sciamma-O'Brien, Silvia Protopapa, Farid Salama, Brain Drouin, Aaron Noell, Sarah Waller, and more to be added/contacted soon – feel free to reach out and we will send you the first draft when ready Edith Fayolle (
Developing Active Source Seismology for Planetary Science Increasingly, the planetary science community has turned toward lander and rover based subsurface investigations to answer science questions about subsurface habitability, geologic history, and the availability of resources like water ice. Yet, as we have advanced many subsurface sounding instruments toward spaceflight readiness, the development of active source seismology has failed to launch. Despite the success and scientific value of the active source seismology experiments conducted by Apollo astronauts on the Moon, no new planetary active seismology experiments to investigate subsurface properties have been conducted. The absence of active source seismology from the planetary explorer’s toolbox limits potential future science gains. We recommend that the Decadal Survey place the development and maturation of active source seismology instrumentation as a high priority for the coming decade. Samuel Courville Samuel Courville (
Distributed Instruments for Planetary Surface Science A distributed instrument is an instrument designed to collect spatially and temporally correlated data from many networked, geographically distributed point sensors. In this paper, we present the case for distributed instruments by listing some critical science questions that can be answered by deploying distributed instruments on planetary surfaces. We also discuss the technological challenges associated with such distributed instruments and present some of the recent developments in sensor distribution mechanisms, computing, communication, power, and thermal management technologies. We provide concrete recommendations for NASA to develop these technologies and concepts further, thereby enabling the deployment of distributed instruments for planetary surface science in the near future. Ashish Goel, Robert Anderson, Saptarshi Bandyopadhyay, Erik Brandon, Joshua Vander Hook, Michael Mischna, Federico Rossi Ashish Goel (
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 (
Ethical Exploration and the Role of Planetary Protection in Disrupting Colonial Practices The purpose of this white paper is to call on the planetary science and space science community, especially in the field of planetary protection, to grapple with the legacy of colonial violence that has been tied to exploration on Earth and revise planetary protection policy accordingly. Current planetary protection policy does not take into account the ethical questions of space exploration or acknowledge the moral stakes in missions to the Moon and Mars. We propose that robust discussion on ethical questions pertinent to planetary protection, grounded in historical context, must lead to enforceable planetary protection policies. With crewed missions to the Moon and Mars planned for the coming decade, these conversations must be engaged with now. Frank Tavares, Mary Beth Wilhelm Frank Tavares (
GEOCHRONOLOGY AS A FRAMEWORK FOR INNER SOLAR SYSTEM HISTORY Major advances in planetary science will be driven by determining absolute ages of geologic units on multiple bodies in the inner Solar System in the next decade. Absolute ages calibrate body-specific chronologies and create a framework for understanding Solar System formation, the effects of impact bombardment on life, and the evolution of planets and their interiors. We recommend that the Decadal Survey: · Support Mars Sample Return to ensure the return to Earth of a set of carefully-chosen, well-documented samples for geochronology and other critical studies of Mars’ evolution and past habitability. · Provide sustained funding to continue to raise the technology readiness levels of in situ dating instruments for future exploration of planetary surfaces. · Include a Solar System chronology mission as one of the priorities on the New Frontiers mission list, setting the science goals of such a mission but allowing flexibility in how those goals are accomplished. · Invest in analytical instrumentation and curation sufficient to provide for both replacement of existing capacity and development of new capabilities. · Leverage NASA’s investments in infrastructure and funding supporting planetary geochronology by partnering with NSF on their Decadal geochronology initiative. Barbara Cohen and others Barbara Cohen (
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 n 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. Contact us if interested in contributing or co-signing (including PhD candidates, postdoctoral researchers, and researchers and faculty). A. R. Azari, B. Biersteker, R. M. Dewey, G. Doran, E. J. Forsberg, C. D. K. Harris, H. R. Kerner, K. A. Skinner, & A. W. Smith (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 (
Measuring the Radiant Energy Budgets and Internal Heat of Planets and Moons With Future Missions The studies of the radiant energy budgets and internal heat of planets and moons are of wide interest in the science community. Some progress has been achieved with recent studies, but there are still significant limitations in current observations and studies. We recommend future missions to better measure the radiant energy budgets and internal heat of planets and moons in our solar system. L.Li, R.A.West, M.E.Kenyon,C.A.Nixon, P.M.Fry, D.Wenkert, M.D.Hofstadter, A.Sanchez-Lavega, K.H.Baines, A.Mallama, R.Hu, R.K.Achterberg, D.Banfield, U.Dyudina, J.J.Fortney, T.Guillot, A.P.Ingersoll, L.Fletcher, S.Limaye, M.Marley, M.D.Smith, K.Soderlund Liming Li (
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 (
Opportunities and Challenges for Structural Geology and Tectonics in the Planetary Sciences Structural geology is a core discipline of the geological sciences, and provides the fundamental tools to study tectonics across the Solar System. Yet, the discipline in underrepresented in the planetary science community. This white paper addresses why this field is important, what the state of the field is, before it: (1) outlines opportunities for expansion and addition to the field of planetary tectonics; (2) discusses challenges for advancement of planetary structural geology and tectonics; and (3) offers suggestions for enabling future discovery, engagement, and impact with structural geology analyses of Solar System worlds. Christian Klimczak, Paul K. Byrne, Chloe Beddingfield, Hiu Ching Jupiter Cheng, others Christian Klimczak (
Planetary Science with Astrophysical Assets: Defining the Core Capabilities of Platforms A compiled, uniform set of basic capabilities and needs to maximize the yield of Solar System science with future Astrophysics assets while allowing those assets to achieve their Astrophysics priorities. Within considerations of cost and complexity, inclusion of capabilities that make a particular platform useable to planetary science provide a critical advantage over platforms lacking such capabilities. J. Bauer, S. Milam, G. Bjoraker, S. Carey, D. Daou, L. Fletcher, W. Harris, P. Hartogh, C. Hartzell, A. Hendrix, C. Nugent, A. Rivkin, T. Swindle, C. Thomas, G. Villanueva, S. Wolk James Gerbs Bauer (
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 (
Synergies between ground-based and space-based observations in the solar system and beyond The goal of this white paper is to provide examples where ground-based and space-based observations are combined, and used to obtain understanding or constrain parameters beyond what the separate measurements could yield. V. Kofman, G. Orton, S. Faggi, G. Liuzzi, M. Cordiner, F. Venditti, M. Lippi, E. Villard, G. L. Villanueva, S. Milam Vincent Kofman (
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 (TPCC) mission concept The authors and co-signers of the Terrestrial Planets Comparative Climatology (TPCC) mission concept white paper advocate that planetary science in the next decade would greatly benefit from comparatively studying the fundamental behavior of the atmospheres of Venus and Mars, contemporaneously and with the same instrumentation, to capture atmospheric response to the same solar forcing, and with a minimum of instrument-related variability. Leslie K Tamppari, Amanda Brecht, Kevin Baines, Paul Byrne, Brian Drouin, Larry Esposito, Scott Guzewich, Richard Hofer, Kandis Lea Jessup, Armin Kleinböhl, Tibor Kremic, Michael Mischna, Nicholas Schneider, Aymeric Spigai Leslie K Tamppari (
The Importance of Field Studies in Closing Key Knowledge Gaps in Planetary Science This white paper outlines the importance of analog field studies, goals and challenges in the next decade. It argues for robustly finding fieldwork in support of fundamental science, instrument development, and mission readiness. Patrick Whelley et al., Patrick Whelley (
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 NEED FOR RECOMMENDATIONS IN SUPPORT OF PLANETARY BODIES CARTOGRAPHIC COORDINATES AND ROTATIONAL ELEMENTS STANDARDS This paper considers how, since 1976, the International Astronomical Union Working Group on Cartographic Coordinates and Rotational Elements (WGCCRE) has made recommendations regarding coordinate systems and rotational element standards for planetary bodies that are needed for mapping and the planning, execution, and interpretation of observations. We recommend that the Planetary Science Decadal and Astrobiology Decadal Survey committee and panels (hereafter, the “Survey”) endorse the value of cartographic standards as provided by the WGCCRE, support the collection of community input as to how the services the group provides can be improved, and advocate for the modestly enhanced financial support needed to implement key improvements. 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 (
The science enabled by a dedicated solar system space telescope This whitepaper presents science themes and key questions that require a long-lasting space telescope dedicated to planetary science that can capture high-quality, consistent data at the required cadences that are free from the complicating effects of the terrestrial atmosphere and differences across observing facilities. A dedicated telescope for solar system science would a) transform our understanding of time-dependent phenomena in our solar system that cannot be studied currently under programs to observe and visit new targets and b) enable a comprehensive survey and spectral characterization of minor bodies across the solar system, which requires a large time allocation not supported by existing facilities. The time-domain phenomena to be explored are critically reliant on UV observations and include: interaction of planetary magnetospheres with the solar wind and internal plasma sources, Venus and giant planet atmospheric dynamics, icy satellite geologic activity and surface evolution, cometary evolution, and evolving ring phenomena. Such a telescope would have excellent synergy with astrophysical facilities by placing planetary discoveries made by astrophysics assets in temporal context, as well as triggering detailed follow-up observations using larger telescopes. The telescope would also support future missions to the Ice Giants, Ocean Worlds, and minor bodies across the solar system by placing the results of such targeted missions in the context of longer records of temporal activities and larger sample populations. It would engage a broad spectrum of the community and ensure that the high-resolution, high-sensitivity observations of the solar system in visible and UV wavelengths revolutionized by the Hubble Space Telescope could be extended. C.L. Young, M.H. Wong, K.M. Sayanagi, and many others. Additional coauthors are welcome! Cindy L. Young (
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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