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This paper details a significant milestone towards maturing a buoyant aerial robotic platform, or aerobot, for flight in the Venus clouds. We describe two flights of our subscale altitude-controlled aerobot, fabricated from the materials necessary to survive Venus conditions. During these flights over the Nevada Black Rock desert, the prototype flew at the identical atmospheric densities as 54 to 55 km cloud layer altitudes on Venus. We further describe a first-principle aerobot dynamics model which we validate against the Nevada flight data and subsequently employ to predict the performance of future aerobots on Venus. The aerobot discussed in this paper is under JPL development for an in-situ mission flying multiple circumnavigations of Venus, sampling the chemical and physical properties of the planet's atmosphere and also remotely sensing surface properties., Comment: Preprint submitted to AIAA Journal of Aircraft more...

A major focus of the planetary science and astrobiology community is the understanding of planetary habitability, including the myriad factors that control the evolution and sustainability of temperate surface environments such as that of Earth. The few substantial terrestrial planetary atmospheres within the Solar System serve as a critical resource in studying these habitability factors, from which models can be constructed for application to extrasolar planets. The recent Astronomy and Astrophysics and Planetary Science and Astrobiology Decadal Surveys both emphasise the need for an improved understanding of planetary habitability as an essential goal within the context of astrobiology. The divergence in climate evolution of Venus and Earth provides a major, accessible basis for understanding how the habitability of large rocky worlds evolves with time and what conditions limit the boundaries of habitability. Here, we argue that Venus can be considered an "anchor point" for understanding planetary habitability within the context of terrestrial planet evolution. We discuss the major factors that have influenced the respective evolutionary pathways of Venus and Earth, how these factors might be weighted in their overall influence, and the measurements that will shed further light on their impacts of these worlds' histories. We further discuss the importance of Venus with respect to both of the recent decadal surveys, and how these community consensus reports can help shape the exploration of Venus in the coming decades., Comment: 23 pages, 3 figures, 1 table, accepted for publication in Nature Astronomy more...

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 from local to global scales. Astrobiologists have been proposing different habitability models for some time, with little integration and consistency among them, being different in function to those used by ecologists. Habitability models are not only used to determine if environments are habitable or not, but they also are used to characterize what key factors are responsible for the gradual transition from low to high habitability states. Here we review and compare some of the different models used by ecologists and astrobiologists and suggest how they could be integrated into new habitability standards. Such standards will help to improve the comparison and characterization of potentially habitable environments, prioritize target selections, and study correlations between habitability and biosignatures. Habitability models are the foundation of planetary habitability science and the synergy between ecologists and astrobiologists is necessary to expand our understanding of the habitability of Earth, the Solar System, and extrasolar planets., Comment: Published in Astrobiology, 21(8). arXiv admin note: substantial text overlap with arXiv:2007.05491 more...

As an end-member of terrestrial planet formation, Mercury holds unique clues about the original distribution of elements in the earliest stages of solar system development and how planets and exoplanets form and evolve in close proximity to their host stars. This Mercury Lander mission concept enables in situ surface measurements that address several fundamental science questions raised by MESSENGER's pioneering exploration of Mercury. Such measurements are needed to understand Mercury's unique mineralogy and geochemistry; to characterize the proportionally massive core's structure; to measure the planet's active and ancient magnetic fields at the surface; to investigate the processes that alter the surface and produce the exosphere; and to provide ground truth for current and future remote datasets. NASA's Planetary Mission Concept Studies program awarded this study to evaluate the feasibility of accomplishing transformative science through a New-Frontiers-class, landed mission to Mercury in the next decade. The resulting mission concept achieves one full Mercury year (~88 Earth days) of surface operations with an ambitious, high-heritage, landed science payload, corresponding well with the New Frontiers mission framework. The 11-instrument science payload is delivered to a landing site within Mercury's widely distributed low-reflectance material, and addresses science goals and objectives encompassing geochemistry, geophysics, the Mercury space environment, and surface geology. This mission concept is meant to be representative of any scientific landed mission to Mercury; alternate payload implementations and landing locations would be viable and compelling for a future landed Mercury mission., Comment: Report submitted to NASA and the Planetary Science and Astrobiology Decadal Survey more...

Over the past several decades, thousands of planets have been discovered outside of our Solar System. These planets exhibit enormous diversity, and their large numbers provide a statistical opportunity to place our Solar System within the broader context of planetary structure, atmospheres, architectures, formation, and evolution. Meanwhile, the field of exoplanetary science is rapidly forging onward towards a goal of atmospheric characterization, inferring surface conditions and interiors, and assessing the potential for habitability. However, the interpretation of exoplanet data requires the development and validation of exoplanet models that depend on in-situ data that, in the foreseeable future, are only obtainable from our Solar System. Thus, planetary and exoplanetary science would both greatly benefit from a symbiotic relationship with a two-way flow of information. Here, we describe the critical lessons and outstanding questions from planetary science, the study of which are essential for addressing fundamental aspects for a variety of exoplanetary topics. We outline these lessons and questions for the major categories of Solar System bodies, including the terrestrial planets, the giant planets, moons, and minor bodies. We provide a discussion of how many of these planetary science issues may be translated into exoplanet observables that will yield critical insight into current and future exoplanet discoveries., Comment: 53 pages, 5 figures, invited review, accepted for publication in the Journal of Geophysical Research: Planets more...

We review some key issues pertaining to NASA's Research and Analysis programs, and offer recommended actions to mitigate or resolve these issues. In particular, we recommended that NASA increases funding to support a healthy selection rate (~40%) for R&A programs, which underpin much scientific discovery with NASA mission data, and on which the majority of the U.S. planetary science community relies (either in part or wholly). We also recommend additional actions NASA can take to ensure a more equitable and sustainable planetary science research community in the U.S., including supporting the next generations of planetary researchers, working to minimize biases in peer review, and reducing the burden of scientists as they prepare R&A proposals., Comment: 8 pages, 3 figures, white paper prepared for the NASEM Planetary Science and Astrobiology Decadal Survey 2023-2032 more...

The key goals of the astrobiology community are to identify environments beyond Earth that may be habitable, and to search for signs of life in those environments. A fundamental aspect of understanding the limits of habitable environments and detectable signatures is the study of where such environments can occur. Thus, the need to study the creation, evolution, and frequency of environments hostile to habitability is an integral part of the astrobiology story. The study of these environments provides the opportunity to understand the bifurcation between habitable and uninhabitable conditions on planetary bodies. The archetype of such a planet is Earth's sibling planet, Venus, which provides a unique opportunity to explore the processes that created a completely uninhabitable environment and thus define the conditions that rule out bio-related signatures. We advocate a continued comprehensive study of our neighboring planet, to include models of early atmospheres, compositional abundances, and Venus-analog frequency analysis from current and future exoplanet data. Critically, new missions to Venus that provide in-situ data are necessary to address the major gaps in our current understanding, and to enable us to take the next steps in characterizing planetary habitability., Comment: White paper submitted in response to the solicitation of feedback for the "2020 Planetary Science and Astrobiology Decadal Survey" by the National Academy of Sciences more...

The field of exoplanetary science has emerged over the past two decades, rising up alongside traditional solar system planetary science. Both fields focus on understanding the processes which form and sculpt planets through time, yet there has been less scientific exchange between the two communities than is ideal. This white paper explores some of the institutional and cultural barriers which impede cross-discipline collaborations and suggests solutions that would foster greater collaboration. Some solutions require structural or policy changes within NASA itself, while others are directed towards other institutions, including academic publishers, that can also facilitate greater interdisciplinarity., Comment: 8 pages; white paper submitted to the Planetary Science and Astrobiology Decadal Survey 2023-2032 more...

We advocate for establishing key scientific priorities for the future of Mercury exploration, including the development of specific science goals for a landed mission. We support the Mercury science community in fostering closer collaboration with ongoing and planned exoplanet investigations. The continued exploration of Mercury should be conceived as a multi-mission, multi-generational effort, and that the landed exploration of Mercury be a high scientific priority in the coming decade., Comment: 8 pages, 6 figures, white paper prepared for the NASEM Planetary Science and Astrobiology Decadal Survey 2023-2032 more...

Icy satellites represent compelling astrobiological targets, but their rocky interiors must be better characterized. Fundamental research programs and thematic workshops promoting ocean world interdisciplinarity are key. Future missions to icy satellites should explicitly include objectives to characterize interfaces between rock and water or high-pressure ices., Comment: 7 pages, 2 figures, prepared for the NASEM Planetary Science and Astrobiology Decadal Survey 2023-2032 more...

This is a white paper submitted to the Planetary Science and Astrobiology Decadal Survey. The Exoplanets in our Backyard meeting was born out of a recognition of the value and potential of interdisciplinary, cross-divisional exoplanet and solar system research, and to encourage and grow the community of researchers working at this intersection. This first-ever inter-assessment group (AG) meeting (organized by members of the Venus Exploration, Outer Planets, and Exoplanet AGs, or VEXAG, OPAG, and ExoPAG, respectively), successfully brought together solar system and exoplanetary scientists from different backgrounds and NASA divisions, fostered communication between researchers whose paths had never crossed at a meeting before, and spurred new collaborations. The meeting was held at the Lunar and Planetary Institute in Houston, TX on February 5-8, 2020 immediately following the OPAG meeting hosted at the same location. The meeting was attended by approximately 110 scientists on site, and 20-30 online participants. The success of this meeting should be capitalized upon and its momentum carried forward to promote fruitful scientific and programmatic discussion, partnerships, and research going forward. This white paper summarizes the meeting, and discusses the findings and action items that resulted., Comment: A White Paper for the Planetary Science and Astrobiology Decadal Survey 2023-2032 more...

The search for exoplanetary life must encompass the complex geological processes reflected in an exoplanet's atmosphere, or we risk reporting false positive and false negative detections. To do this, we must nurture the nascent discipline of "exogeoscience" to fully integrate astronomers, astrophysicists, geoscientists, oceanographers, atmospheric chemists and biologists. Increased funding for interdisciplinary research programs, supporting existing and future multidisciplinary research nodes, and developing research incubators is key to transforming true exogeoscience from an aspiration to a reality., Comment: Submitted as white paper to 2023-2033 Planetary Science and Astrobiology Decadal Survey; Updated to include all co-authors more...

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 from 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., Comment: White Paper for the Planetary Science and Astrobiology Decadal Survey 2023-2032 more...

Some human mission trajectories to Mars include flybys of Venus. These flybys provide opportunities to practice deep space human operations, and offer numerous safe-return-to-Earth options, before committing to longer and lower-cadence Mars-only flights. Venus flybys, as part of dedicated missions to Mars, also enable human-in-the-loop scientific study of the second planet. The time to begin coordinating such Earth-to-Mars-via-Venus missions is now, Comment: A White Paper for the Planetary Science and Astrobiology Decadal Survey 2023-2032. 7 pages +cover page, 2 figures +cover image more...