A Review of Different Aspects of Off-Earth Drilling

Off-Earth drilling may be assumed as the second phase of space exploration to discover the unrevealed subsurface on the planetary bodies. It accelerates future space objectives such as in-situ propellant production, mineral exploitation, and space tourism. Owing to the rampant progress in modern technology, the new drill tools mounted on the sophisticated robots are capable to drill the planetary regolith dispersed on the celestial objects; however, formidable obstacles such as microgravity, vacuum condition, and temperature fluctuation as well as the weight limitation, lack of real-time drilling analysis, and remote robot-operator communication impose pressing restrictions on the quick development of space drilling tools. In this study, research on the past and present aspects of off-Earth drilling has been implemented to illuminate the horizon of this technology in the near-term future. The context encompasses a detailed description of the limitations, applications and mechanisms of the different drilling techniques adopted for planetary bodies. A particular emphasis is put on the hydraulic power systems which have not been satisfactorily deployed in off-Earth drilling yet. The research strives to glance over the pivotal aspects of off-Earth drilling to contribute to the future drilling programs planned by the national and private space agencies.

Performance of Multiple Metagenomics Pipelines in Understanding Microbial Diversity of a Low-Biomass Spacecraft Assembly Facility

NASA planetary protection (PP) requires an assessment of the biological contamination of the potential microbial burden on spacecraft destined to explore planetary bodies that may harbor signs of life, like Mars and Europa. To help meet these goals, the performance of multiple metagenomic pipelines were compared and assessed for their ability to detect microbial diversity of a low-biomass clean room environment used to build spacecraft destined to these planetary bodies. Four vendors were chosen to implement their own metagenomic analysis pipeline on the shotgun sequences retrieved from environmental surfaces in the relevant environments at NASA’s Jet Propulsion Laboratory. None of the vendors showed the same microbial profile patterns when analyzing same raw dataset since each vendor used different pipelines, which begs the question of the validity of a single pipeline to be recommended for future NASA missions. All four vendors detected species of interest, including spore-forming and extremotolerant bacteria, that have the potential to hitch-hike on spacecraft and contaminate the planetary bodies explored. Some vendors demonstrated through functional analysis of the metagenomes that the molecular mechanisms for spore-formation and extremotolerance were represented in the data. However, relative abundances of these microorganisms varied drastically between vendor analyses, questioning the ability of these pipelines to quantify the number of PP-relevant microorganisms on a spacecraft surface. Metagenomics offers tantalizing access to the genetic and functional potential of a microbial community that may offer NASA a viable method for microbial burden assays for planetary protection purposes. However, future development of technologies such as streamlining the processing of shotgun metagenome sequence data, long read sequencing, and all-inclusive larger curated and annotated microbial genome databases will be required to validate and translate relative abundances into an actionable assessment of PP-related microbes of interest. Additionally, the future development of machine learning and artificial intelligence techniques could help enhance the quality of these metagenomic analyses by providing more accurate identification of the genetic and functional potential of a microbial community.

Absence of a long-lived lunar paleomagnetosphere

Determining the presence or absence of a past long-lived lunar magnetic field is crucial for understanding how the Moon’s interior and surface evolved. Here, we show that Apollo impact glass associated with a young 2 million–year–old crater records a strong Earth-like magnetization, providing evidence that impacts can impart intense signals to samples recovered from the Moon and other planetary bodies. Moreover, we show that silicate crystals bearing magnetic inclusions from Apollo samples formed at ∼3.9, 3.6, 3.3, and 3.2 billion years ago are capable of recording strong core dynamo–like fields but do not. Together, these data indicate that the Moon did not have a long-lived core dynamo. As a result, the Moon was not sheltered by a sustained paleomagnetosphere, and the lunar regolith should hold buried 3He, water, and other volatile resources acquired from solar winds and Earth’s magnetosphere over some 4 billion years.

Exogeology from Polluted White Dwarfs

It is difficult to study the interiors of terrestrial planets in the Solar System and the problem is magnified for distant exoplanets. However, sometimes nature is helpful. Some planetary bodies are torn to fragments and consumed by the strong gravity close to the descendants of Sun-like stars, white dwarfs. We can deduce the general composition of the planet when we observe the spectroscopic signature of the white dwarf. Most planetary fragments that fall into white dwarfs appear to be rocky with a variable fraction of associated ice and carbon. These white dwarf planetary systems provide a unique opportunity to study the geology of exoplanetary systems.

Open questions in lunar science (invited talk)

<p>The Earth’s Moon is a cornerstone and keystone in the understanding of the origin and evolution of the terrestrial, Earth-like planets.  It is a cornerstone in that most of the other paradigms for the origin, modes of crustal formation (primary, secondary and tertiary), bombardment history, role of impact craters and basins in shaping early planetary surfaces and fracturing and modifying the crust and upper mantle, volcanism and the formation of different types of secondary crust, and petrogenetic models where no samples are available, all have a fundamental foundation in lunar science.  The Moon is a keystone in that knowledge of the Moon holds upright the arch of our understand of the terrestrial planets. It is thus imperative to dedicate significant resources to the continued robotic and human exploration of this most accessible of other terrestrial planetary bodies, and to use this cornerstone and keystone as a way to frame critical questions about the Solar System as a whole, and to explore other planetary bodies to modify and strengthen the lunar paradigm.   </p> <p>What is the legacy, the long-term impact of our efforts? The Apollo Lunar Exploration Program revealed the Earth as a planet, showed the inextricable links of the Earth-Moon system, and made the Solar System our neighborhood. We now ask: What are our origins and where are we heading?: We seek to understand the origin and evolution of the Moon, the Moon’s links to the earliest history of Earth, and its lessons for exploration and understanding of Mars and other terrestrial planets. A basis for our motivation is the innate human qualities of curiosity and exploration, and the societal/species-level need to heed Apollo 16 Commander John Young’s warning that “Single-planet species don’t survive!”. These perspectives impel us to learn the lessons of off-Earth, long-term, long-distance resupply and self-sustaining presence, in order to prepare for the exploration of Mars and other Solar System destinations. </p> <p>Key questions in this lunar exploration endeavor based on a variety of studies and analyses (1-3) include:</p> <p>-How do planetary systems form and evolve over time and when did major events in our Solar System occur?</p> <p>How did planetary interiors differentiate and evolve through time, and how are interior processes expressed through surface-atmosphere interactions?</p> <p>-What processes shape planetary surfaces and how do these surfaces record Solar System history?</p> <p>-How do worlds become habitable and how is habitability sustained over time?</p> <p>-Why are the atmospheres and climates of planetary bodies so diverse, and how did they evolve over time?</p> <p>-Is there life elsewhere in the Solar System?</p> <p>Specific lunar goals and objectives will be outlined in this broad planetary science context.</p> <p> </p> <p>References: 1. Carle Pieters et al. (2018) http://www.planetary.brown.edu/pdfs/5480.pdf, 2. Lunar Exploration Analysis Group, https://www.lpi.usra.edu/leag/. 3) Erica Jawin et al. Planetary Science Priorities for the Moon in the Decade 2023-2033: Lunar Science is Planetary Science.</p>

Survival of presolar p-nuclide carriers in the nebula revealed by stepwise leaching of Allende refractory inclusions

The 87Rb-87Sr radiochronometer provides key insights into the timing of volatile element depletion in planetary bodies, yet the unknown nucleosynthetic origin of Sr anomalies in Ca-Al–rich inclusions (CAIs, the oldest dated solar system solids) challenges the reliability of resulting chronological interpretations. To identify the nature of these Sr anomalies, we performed step-leaching experiments on nine unmelted CAIs from Allende. In six CAIs, the chemically resistant residues (0.06 to 9.7% total CAI Sr) show extreme positive μ84Sr (up to +80,655) and 87Sr variations that cannot be explained by decay of 87Rb. The extreme 84Sr but more subdued 87Sr anomalies are best explained by the presence of a presolar carrier enriched in the p-nuclide 84Sr. We argue that this unidentified carrier controls the isotopic anomalies in bulk CAIs and outer solar system materials, which reinstates the chronological significance of differences in initial 87Sr/86Sr between CAIs and volatile-depleted inner solar system materials.

Shock effects in feldspars: An overview

ABSTRACT Feldspars are the dominant mineral in the crust of most terrestrial planetary bodies, including Earth, Earth’s moon, and Mars, as well as in asteroids, and thus in meteorites. These bodies have experienced large numbers of hypervelocity impact events, and so it is important to have a robust understanding of the effects of shock waves exerted on feldspars. However, due to their optical complexity and susceptibility to weathering, feldspars are underutilized as shock barometers and indicators of hypervelocity impact. Here, we provide an overview of the work done on shocked feldspars so far, in an effort to better frame the current strengths and weaknesses of different techniques, and to highlight some gaps in the literature.