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USGS2021

Aeolian processes and landforms across the Solar System: Science and technology requirements for the next decade

Discussions of planetary atmospheric-surface interactions (including aeolian processes and phenomena and the resulting landforms) are often tied to a specific planetary body. Considering this, a series of workshops were initiated in 2008 to facilitate an interdisciplinary and interplanetary body approach to further our understanding of aeolian processes, phenomena, and landforms (Titus et al., 2008, 2010, 2012, 2015, 2017). The most recent workshop, held 12-13 May 2020, transitioned to a virtual format due to the COVID-19 pandemic, with a specific focus on the planetary aeolian community’s vision for the next decade. Discussions centered around dynamics and resulting landforms, missions and models, and facilities. Participants determined that a planetary aeolian goals-and-objectives document was needed that was inclusive of multiple planetary bodies, processes, and phenomena that all intersect where the surface meets the atmosphere. This white paper is the first iteration of that vision, with definition of Goals/Objectives that organize the broad range of existing and needed planetary aeolian studies.

Bulletin of the AAS↗
USGS2021

Solar-system-wide significance of Mars polar science

1. The North Polar Layered Deposits contain thousands of ice layers that record accumulation and climate history for at least several million years, making the most accessible and most complete climate record aside from the Earth’s – and the only one to record the impact of large obliquity shifts. 2. Mars Polar Science is a diverse and integrated system spanning much of the planet, above and below the surface: geographic poles, mid- and high-latitudes, numerous active volatile processes that interact with the near-surface, and the lower and middle atmosphere circulations, even influencing the upper atmosphere and atmospheric escape. 3. Mars polar processes serves as an analogue and scientific link to numerous solar system bodies. Mars has two volatile cycles that influence surface processes, atmospheric processes, and climate cycles. Mars, with many data sets and observations, serves as a proxy for outer planets and moons that undergo the same physics but with other volatile species. Additionally, technology designed for Mars polar exploration benefits exploration elsewhere. 4. Mars Polar and Atmospheric Science results are critical for future human exploration and in situ resources and the study of planetary habitability.

Bulletin of the AAS↗
USGS2021

Current activity on the Martian surface: A key subject for future exploration

One of the fundamental discoveries in Mars science in the last decade has been the extent and importance of current surface activity. Recent results have shifted our view of Mars from a world where the most interesting geologic events were in the distant past (similar to the Moon) to a world that undergoes active evolution and one where understanding the present is key to deciphering the planet’s history. When input was requested for the last Planetary Science Decadal Survey, some observations of surface changes had been published, but the number of detections was small and their significance not fully appreciated. Since that time, detections have proliferated, driven primarily by the long-term operation of the Mars Reconnaissance Orbiter (MRO) and the High Resolution Imaging Science Experiment (HiRISE) as well as landed observations of aeolian activity. In addition to observed changes, theory suggests that additional important surface processes are likely active but not yet observed because orbital data are limited in space and time and landed studies are rare. Understanding current Martian surface processes is a fundamental science question in itself, as it provides a test for physical and terrestrial analog-based models of specific geological processes acting under non-Earth planetary and environmental conditions. It is also an essential step for reading Mars’ geologic history and providing input to climate models: without understanding current dynamic processes, we cannot understand how they have varied during recent climate cycles, nor how they are reflected in ancient rock or modern ice records. Understanding the rates and types of current surface activity is also highly relevant to selecting geological samples, setting Planetary Protection rules, and understanding the hazards and environment that would be experienced by future human explorers.

Bulletin of the AAS↗
USGS2021

Maximizing the science and resource mapping potential of Orbital VSWIR Spectral measurements of Mars

The last 16 years witnessed a rapid growth in understanding 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) [1] and Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) [2]. Both are sensitive to water-, hydroxyl-, sulfate-, and carbonate-bearing and ferric phases that record past liquid water. As the spatial resolution of such data has improved, and supporting laboratory data have been acquired, the diversity of mineral phases that are recognized has likewise expanded. The same phases typically contain recoverable water, a resource for future human exploration, and are the only near-surface water 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 revolutionary advance in understanding the inventory, diversity, and stratigraphy of these materials can be obtained from Mars orbit, using two complementary approaches: hyperspectral imaging at ~6 meters per pixel at 0.7–4 µm, and 1 meter-per-pixel imaging at selected VSWIR wavelengths from 0.4–1.7 µm.

Bulletin of the AAS↗
USGS2021

A Next Generation Lunar Orbiter mission

The Moon is the scientific foundation for our knowledge of the early evolution and impact history of the terrestrial planets. Over the last decades the lunar science community has made significant progress in addressing key lunar science and exploration goals, while defining many new high-priority scientific questions regarding the formation and evolution of the Moon. On a broad scale, the last Planetary Decadal Survey defined three scientific objectives to guide studies of the inner planets and Moon. These objectives address the origins and diversity of terrestrial planets, the evolution of life on terrestrial planets, and climate processes on Earth-like planets [1]. Many of these objectives carry forward into exploration goals of a renewed lunar human exploration program, and urgently addressing these objectives will enable the rapid development of exploration plans. A large (Flagship or New Frontiers class) Next Generation Lunar Orbiter (NGLO) mission would address the last Planetary Decadal Survey objective of understanding the origin and diversity of terrestrial planets by studying the geochemistry and geology of the Moon at an unparalleled resolution compared to other lunar mission datasets. Also, NGLO would address the objective of studying the evolution of life on terrestrial planets by furthering knowledge about the composition and distribution of volatile elements on the lunar surface and better characterizing the past and present-day impact rates in the inner Solar System in order to better understand the original delivery of water to Earth. Key exploration goals, including identifying the nature and distribution of lunar volatiles (i.e., water, ice), mapping and characterizing potentially valuable lunar resources, and establishing a human presence on the Moon, also would be addressed by NGLO.

Bulletin of the AAS↗
USGS2021

The role of the Next Generation Lunar Scientists and Engineers (NextGen) group in lunar science and exploration

Founded in 2008, the Next Generation Lunar Scientists and Engineers (NextGen) is a group of students and early career professionals who have a vision and passion for lunar science and exploration. NextGen organizes professional development opportunities through workshops and networking events that are designed to provide resources and training for scientists and engineers so that they are prepared to lead international lunar science and exploration programs. NextGen also provides a network of professional support and opportunities for the younger generation to lead in the field and to learn from more experienced generations of lunar scientists and engineers. Members of NextGen are actively engaged in scientific research, mission formulation/execution, community outreach, and professional activities. With the United States on the brink of a new era of lunar exploration, and many international space agencies preparing to send spacecraft to the Moon, NASA and the lunar community have recognized the importance of training and nurturing the next generation of lunar scientists and engineers. As the future workforce, it is imperative that students and early career professionals receive continued and increased support from NASA, industry, and the lunar community as a whole.

Bulletin of the AAS↗
USGS2021

Mars science helicopter: Compelling science enabled by an aerial platform

This whitepaper describes two conceptual vehicle designs, including possible tradeoffs within those designs, which would enable a wide array of innovative science investigations. In addition to describing vehicle capabilities, flight characteristics, and the breadth of enabled science for the two helicopter designs, we also introduce three mission concepts that showcase investigations made possible by MSH. We conclude with recommendations concerning the future of rotorcraft exploration at Mars.

Bulletin of the AAS↗
USGS2021

GANGOTRI mission concept on the glacial key to the Amazonian climate of Mars

The GANGOTRI mission concept would investigate in situ the geologic origins of midlatitudinal Martian glaciers, as underlain by Amazonian climate evolution, by riddling the ice with a hybrid thermo-mechanical drill for deep englacial sampling. GANGOTRI would use regolith compositional measurements to characterize ice-regolith interaction, and stable isotope measurements to characterize fundamental exchange processes of major ice reservoirs. Meanwhile, geophysical observations would cross-calibrate composition.

Bulletin of the AAS↗
USGS2021

Science and technology requirements to explore caves in our Solar System

We are in the incipient phase of exploring the subterranean realm of our Solar System. Planetary caves research offers interdisciplinary, cross-planetary body investigations spanning geology, climatology, astrobiology, robotics, and human use. Caves are of great importance in advancing our understanding of planetary processes and the search for life beyond Earth. Given these advances, a diverse and interdisciplinary community of planetary caves researchers has emerged. Their activities have been partially documented by a series of workshops and conferences over the last thirteen years (Titus & Boston, 2012; Wynne et al, 2016; Titus et al., 2020, submitted). These meetings brought together scientists and engineers from around the world to discuss both science needs (i.e., geology, habitability, and astrobiology), as well as engineering challenges (e.g., mobility, navigation, and communications) for cave research on other planetary bodies. It was determined at the last planetary caves conference that a goals and/or roadmap document, like those of the Assessment and Advisory Groups, was needed. This white paper is our initial conception of such an effort.

Bulletin of the AAS↗
USGS2021

Mid-latitude ice on Mars: A science target for planetary climate histories and an exploration target for in situ resources

In the last decade, aided by the high-resolution data and long-term monitoring by NASA’s Mars Reconnaissance Orbiter (MRO) and other spacecraft, extensive evidence has emerged supporting the presence of abundant H2O ground ice throughout much of the mid-latitudes of Mars. Growing evidence indicates that much of this ice is relatively pure, exists within a few meters of the surface, and reaches lower latitudes than previously thought, potentially providing an accessible record of the recent climate and a large in situ resource for future human exploration of Mars. We are reaching the limits of currently available datasets, however, just as we are starting to unlock the climate record and determine the water resources contained within the Martian mid-latitudes. A comprehensive understanding of the nature of this ice would significantly enhance our understanding of Mars’ climate history and total water budget, as well as the effects of orbital/axial forcing on volatiles. In this regard, Mars is a testbed for comparative planetary climate studies, including for exoplanets; these studies are particularly valuable because Mars has many similarities to Earth but lacks the complicating effects of oceans and a biosphere, such that orbital/axial forcing dominates climate variability. Quantifying the volumes, distribution, and properties of the water ice are crucial for addressing two overarching questions in the next decade: 1. What climate record is preserved in mid-latitude ice deposits on Mars? 2. How accessible is the ice as a resource for future exploration? New missions will enable us to capitalize on the major discoveries of the last decade and take the next giant leap in the upcoming decade to address these questions.

Bulletin of the AAS↗
USGS2021

Summary of the final report from the Ice and Climate Evolution Science Analysis group (ICE-SAG)

The Ice and Climate Evolution Science Analysis Group (ICE-SAG) was convened by the Mars Exploration Program Analysis Group (MEPAG) in fall 2018, with the aims of (1) identifying and prioritizing fundamental science questions related to the recent and ongoing evolution of Mars volatiles and climate, and (2) exploring new mission approaches that could address these high-priority science questions during the coming decade (2023–2032). In this white paper, we summarize the ICE-SAG final report via a selection of report materials and provide broad context for the content of this MEPAG-generated report (which is likely a reference mentioned within a number of other, community-based white papers).

Bulletin of the AAS↗
USGS2021

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 impact effects from the impact of an asteroid. The effects usually considered are: blast, overpressure shock, thermal radiation, cratering, seismic shaking, ejecta, and tsunami (e.g. Hills & Goda, 1993; Collins et al., 2005, Rumpf et al., 2017). These first-order effects typically are localized in time and diminish with increased distance from the impact (or air burst) location. However, there are delayed effects that will propagate through time and occur in areas not immediately affected by the initial impact. These delayed effects include, but are not limited to, down-stream and down-wind effects. Down-stream effects could occur months after the impact as sediment and debris are washed into reservoirs, potentially impacting water quality for populations not originally affected by the impact event. Down-wind effects could deposit dust and debris hundreds or thousands of kilometers down-wind, reducing insolation and ultimately settling out over large areas which could include cropland. Depending on when this occurs, significant damage could occur to croplands, thus reducing or eliminating whole sections of the global food chain. In addition, depending on the amount of ashfall, the deposition of dust and debris could cross watershed boundaries and thus affect water quality for a larger population than just those who live in the initial impacted watershed. For most smaller asteroid impacts, these delayed effects can be neglected. However, there are likely a class of impacts (e.g. impactor size and composition, impact location and time of year) where failure to consider these effects could complicate post-impact relief and recovery efforts. For example, evacuation of the population within the initial damage zone from an impact to a city down-stream could exacerbate water quality issues and water usage months later. An impact in western Nebraska might have minimal civil defense requirements for evacuation (due to the low population density) but the down-wind effects could disrupt both the economic health of the American Midwest while threatening global food security. Understanding when these time-delayed and geographically displaced effects become relevant is key to successful civil defense and recovery planning.

Bulletin of the AAS↗
USGS2021

A critical gap: In situ measurements of surface-atmosphere interactions from outside earth

This white paper demonstrates five points: (1) The lack of robust measurements of the vertical gradients of natural boundary layers and transport fluxes on other planetary bodies precludes adequate estimation of aeolian and other meteorological processes throughout our Solar System (§1). (2) Thus, there exist critical knowledge gaps within high-priority planetary science questions that motivate the need for in situ aeolian and other meteorological measurements on an extraterrestrial surface (§2). (3) Such measurements would be timely, because they will greatly enhance the utility of existing climate data/models, while also contributing to improved design, safety, and effectiveness of near-future missions (§3). (4) Acquisition of these next-generation measurements from Mars is technologically feasible within the coming decade (including via small spacecraft) (§4, 6) and (5) such measurements would also significantly contribute towards addressing key Mars science questions (§5). Our implicit recommendation is that this type of in situ science be considered in definition of high-priority planetary science questions and prioritization of mission concepts.

Bulletin of the AAS↗
USGS1955

1950 and 1951 eruptions of Mihara Yama, O Shima Volcano, Japan

Mihara Yama is the active central cone of O Shima Volcano on the island of O Shima, Tokyo Prefecture, Japan. The outer slopes of O Shima Volcano compose most of the island. Their crest is a somma, about 600 km in altitude and 3 km in diameter, which encloses a caldera. Mihara Yama rises from the southern part of the caldera to an altitude of 755m. It is a truncated cone with a crater 800 m in diameter. Before the eruption in 1950 the crater contained an inner pit approximately 300 m in diameter and 165 m deep. Mihara Yama erupted on July 16, 1950, after 10 years of quiescence. Activity continued until September 24. Eruption resumed on February 4, 1951, and continued until April 2, after which activity was intermittent until the eruption ceased on June 28. In 1950 molten basalt was ejected explosively accompanied at times by flows. Two successive cinder cones formed from the accumulation of ejecta, some of which were hurled as high as 500 m. Lava filled the inner pit and crater, and a small amount overflowed into the caldera. About 52,000,000 metric tons of material was erupted. In 1951 six successive small cones developed. Beginning February 21 the principal cone formed. Lava overflowing the crater rim solidified mostly as aa and covered nearly 2 square km of the caldera floor. The intermittent activity during the final 3 months consisted of nine brief periods of eruption, a few of which were relatively violent. Between eruptions and especially after the final eruption the crater floor subsided. In 1951 about 20,000,000 metric tons of material was erupted.

O Shima Volcano↗
USGS1969

Nuées Ardentes of the 1968 Eruption of Mayon Volcano, Philippines

Mayon Volcano, southeastern Luzon, began a series of explosive eruptions at 0900 April 21, 1968, and by May 15 more than 100 explosions had occurred, at least 6 people had been killed, and roughly 100 square km had been covered by more than 5 cm of airfall ash, blocky ash flows, and a lava flow. All material crupted was porphyritic augite-hypersthene andesite. Explosions from the summit crater (elevation 2460 m) ejected large quantities of ash and incandescent blocks to a height exceeding 600 m and produced ash-laden clouds which rose to heights of 3 to 10 km. Backfall of the coarser material fed nuées ardentes which repeatedly swept down ravines on all sides of the volcanic cone. The velocity of one nuée ardente ranged from 9 to 63 m per sec. The largest nuées descended to the southwest and reached as far as 7 km from the summit. An aa lava flow also descended 3 1/2 km down this flank. The nuées ardentes deposited pyroclastic flows that contained large breadcrust-surfaced blocks averaging about 30 cm across, but occasionally reaching 25 m in greatest dimension. These blocks were still very hot in their interiors several days later. Surrounding the pyroclastic flows is a seared zone as much as 2 km wide, but averaging a few hundred meters, in which vegetation is charred and splintered, but over which only a thin layer of airfall ash was deposited.

Mayon Volcano↗