The Lunar Geophysical Network Mission

The National Academy’s current Planetary Decadal Survey (NRC, 2011) prioritizes a future Lunar Geophysical Network (LGN) mission to gather new information that will permit us to better determine how the overall composition and structure of the Moon inform us about the initial differentiation and subsequent evolution of terrestrial planets

Key technologies and instrumentation for subsurface exploration of ocean worlds

In this chapter, the key technologies and the instrumentation required for the subsurface exploration of ocean worlds are discussed. The focus is laid on Jupiters moon Europa and Saturns moon Enceladus because they have the highest potential for such missions in the near future. The exploration of their oceans requires landing on the surface, penetrating the thick ice shell with an ice-penetrating probe, and probably diving with an underwater vehicle through dozens of kilometers of water to the ocean floor, to have the chance to find life, if it exists. Technologically, such missions are extremely challenging. The required key technologies include power generation, communications, pressure resistance, radiation hardness, corrosion protection, navigation, miniaturization, autonomy, and sterilization and cleaning. Simpler mission concepts involve impactors and penetrators or, in the case of Enceladus, plume-fly-through missions

Corrigendum: Subsurface Microbial Habitats in an Extreme Desert Mars-Analog Environment (Frontiers in Microbiology, (2019), 10, (69), 10.3389/fmicb.2019.00069)

10.3389/fmicb.2019.02129Frontiers in Microbiology10212

Airfall on Comet 67P/Churyumov-Gerasimenko

We here study the transfer process of material from one hemisphere to the other (deposition of airfall material) on an active comet nucleus, specifically 67P/Churyumov-Gerasimenko. Our goals are to: 1) quantify the thickness of the airfall debris layers and how it depends on the location of the target area, 2) determine the amount of H2O and CO2 ice that are lost from icy dust assemblages of different sizes during transfer through the coma, and 3) estimate the relative amount of vapor loss in airfall material after deposition in order to understand what locations are expected to be more active than others on the following perihelion approach. We use various numerical simulations, that include orbit dynamics, thermophysics of the nucleus and of individual coma aggregates, coma gas kinetics and hydrodynamics, as well as dust dynamics due to gas drag, to address these questions. We find that the thickness of accumulated airfall material varies substantially with location, and typically is of the order 0.1-1 m. The airfall material preserves substantial amounts of water ice even in relatively small (cm-sized) coma aggregates after a rather long (12 h) residence in the coma. However, CO2 is lost within a couple of hours even in relatively large (dm-sized) aggregates, and is not expected to be an important component in airfall deposits. We introduce reachability and survivability indices to measure the relative capacity of different regions to simultaneously collect airfall and to preserve its water ice until the next perihelion passage, thereby grading their potential of contributing to comet activity during the next perihelion passage

Meeting the Technical Challenges of Measurements in the Martian Subsurface

Recent advances across disciplines have demonstrated the breadth and diversity of life in Earth’s subsurface. Key science questions and scientific context for the exploration of the Martian subsurface are ummarized in the companion abstract [1]. Coupling those advances with the history and nature of subsurface fluids on Mars [e.g. 2, 3] presents a compelling case for advancing our knowledge of the subsurface [4]. While the subsurface is regarded as one of the next frontiers for Mars exploration [4, 5], accessing the subsurface presents challenges. The compelling nature of the science questions for the subsurface and their complementarity to ongoing surface exploration and sample return missions necessitate an evaluation of subsurface access strategies. Subsurface processes, highly dependent on crustal porosity and local permeability, inevitably contribute to surface properties of the atmosphere, hydrosphere, and any possible biosphere [4]. Mars subsurface exploration opens the door to measurements of gas fluxes, fracture systems, and geochemical properties vital to understanding past and present Mars. It also lays the foundation for self-sufficient human settlements beyond our own planet and provides an emerging potential for synergistic collaborations with the rising commercial space sector and traditional mining companies. Our understanding of the Martian subsurface and the technologies for exploring it, with a dual focus on the search for signs of extinct and extant life, and resource characterization and acquisition, have matured enough for serious consideration of subsurface studies as part of future robotic missions to Mars

Scientific Rationale for Exploration of the Marian Subsurface

The subsurface of Mars is likely the longest-lived habitable environment accessible to exploration within the coming decade that could host ancient biosignatures of past life or even extant microbial life [1]. Here we consider 3 aspects of subsurface exploration on Mars and address the driving science questions: 1) the crustal environment and spatial architecture of Mars; 2) the nature of subsurface volatiles and transport pathways; and 3) implications for habitability of the Martian subsurface. The technological aspects of subsurface access are addressed in a companion abstract [2]

In Situ Geochronology for the Next Decade: Mission Designs for the Moon, Mars, and Vesta

Geochronology is an indispensable tool for reconstructing the geologic history of planets, essential to understanding the formation and evolution of our solar system. Bombardment chronology bounds models of solar system dynamics, as well as the timing of volatile, organic, and siderophile element delivery. Absolute ages of magmatic products provide constraints on the dynamics of magma oceans and crustal formation, as well as the longevity and evolution of interior heat engines and distinct mantle/crustal source regions. Absolute dating also relates habitability markers to the timescale of evolution of life on Earth. However, the number of terrains important to date on worlds of the inner solar system far exceeds our ability to conduct sample return from all of them. In preparation for the upcoming Decadal Survey, our team formulated a set of medium-class (New Frontiers) mission concepts to three different locations (the Moon, Mars, and Vesta) where sites that record solar system bombardment, magmatism, and habitability are uniquely preserved and accessible. We developed a notional payload to directly date planetary surfaces, consisting of two instruments capable of measuring radiometric ages, an imaging spectrometer, optical cameras to provide site geologic context and sample characterization, a traceelement analyzer to augment sample contextualization, and a sample acquisition and handling system. Landers carrying this payload to the Moon, Mars, and Vesta would likely fit into the New Frontiers cost cap in our study (∼$1B). A mission of this type would provide crucial constraints on planetary history while also enabling a broad suite of complementary investigations 2021. The Author(s). Published by the American Astronomical Society. © 2021. The Author(s). Published by the American Astronomical Society.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]