Geology topics

Research about Earth, Mars

Source-linked reports with geographic coverage including Earth, Mars.

4 recordsLinked to original sources

USGS2026

The Sand AbrasioN Device for Aeolian Research (SANDAR): A new experimental device for investigating how wind transport affects sand on Earth and Mars

On Earth and Mars, aeolian transport causes sand grains to become abraded, resulting in mineralogic and textural changes. Understanding how sands evolve, or mature, with transport via experimental studies is important for understanding the origins, geologic history, and cycling of sediments, as well as dust production. Previous experimental works have used a variety of methods to simulate aeolian transport in the laboratory, but practical limitations and similitude concerns have limited such research. Here, we present and validate the Sand AbrasioN Device for Aeolian Research (SANDAR), a modified air mill that uses pressurized air to circulate sand around a small abrasion chamber, simulating the effects of aeolian transport. This device is re-circulating to simulate long-distance transport, and it allows for repeated analyses of well-constrained sediment samples, revealing their evolution over time. It is compatible with the grain sizes (74–500 μm) and grain impact velocities (∼0.6–3.7 m/s) typically expected for natural aeolian environments, and is also adaptable for diverse applications simulating different wind conditions. We show that the SANDAR achieves similitude of kinetic energy with respect to saltating sand on both Earth and Mars. SEM and optical microscope imaging reveal that the SANDAR produces microtextures on the surfaces of sand grains similar to those found with natural aeolian transport, demonstrating that it effectively simulates the mechanical effects of aeolian processes. Thus, the SANDAR is a valid tool for use in experimental research to improve our understanding of sedimentary processes across the Solar System.

Aeolian Research↗

USGS2025

The abiotic background as a central component of a Sample Safety Assessment Protocol for Mars Sample Return

Martian rock and regolith samples are being collected and cached by NASA’s Perseverance rover, with the goal of returning them to Earth as soon as the mid-2030s. Upon return, samples would be housed in a sample receiving facility under biological containment to prevent exposing Earth’s biosphere to any potential biohazards that might be present. Samples could be released from high containment for scientific investigations if they are found to be safe or are sterilized. The Sample Safety Assessment Protocol Tiger Team (SSAP-TT) was convened by the Sample Receiving Project between August 2023 and August 2024 and tasked with the development of a Sample Safety Assessment Protocol (SSAP). The result of this work is a proposed three-step protocol, supported by Bayesian statistical hypothesis testing, to assess the risk as to whether returned samples contain modern martian biology that could represent a biohazard. The proposed protocol outlines procedures to determine whether the samples could be safely released from high containment without sterilization or require a “hold and review” step. This article presents the central concept of the SSAP approach—comparing returned samples to the abiotic baseline. Organic molecules, which exist throughout the solar system, can have either biotic or abiotic origins. However, biotically produced organic molecules exhibit distinct complexity, distribution, and abundance characteristics that differentiate them from those formed through abiotic chemistry. The proposed protocol would examine the organic inventory of returned samples by using multiple techniques, including morphological and spectral assessments, to determine whether any signals exceed the abiotic baseline; that is, whether the organic molecular inventory could be explained solely by abiotic chemical synthesis. This approach provides a rigorous, yet feasible, safety assessment protocol by using modern techniques while minimizing sample consumption. We also identify key areas for future research and development, which include detection limits and further characterization of the martian abiotic background.

Astrobiology↗

USGS2022

It’s time for focused in situ studies of planetary surface-atmosphere interactions

A critical gap in planetary observations has been in situ characterization of extra-terrestrial, present-day atmospheric and surface environments and activity. While some surface activity has been observed and some in situ meteorological measurements have been collected by auxiliary instruments on Mars, existing information is insufficient to conclusively characterize the natural processes via concurrent and high-resolution measurement of environmental drivers and activity. Thus, many atmospheric, aeolian, and other surface processes models – which are used to generate key constraints on science and exploration in many areas of planetary investigation—such as surface exposure/erosion estimates, landscape interpretation, and modeling dust storm development—remain untested under non-Earth conditions. Analogous terrestrial processes are often studied intensively via numerical modeling that integrates empirical results from laboratory and/or field studies of process-response interactions between the atmosphere and relevant surface landforms. Incorporation of such in situ measurements into model development has significantly advanced our understanding of atmosphere-surface interactions and related geomorphic processes on Earth, and is poised to do so on other planets. However, to date, such testing and refinement have not been possible in other planetary environments, partially because investigations of this sort require new technologies, mission architectures, and operations designs (e.g., different from large rovers focused on geochemical investigations) to fully address the key gaps in our understanding while keeping cost and risk low. Fortunately, technological developments in the areas of surface access, instrumentation, and onboard processing/memory now enable small spacecraft to accommodate meteorological and aeolian instrumentation that could collect the needed measurements to fill this critical gap while remaining within typical small spacecraft resource budgets. Furthermore, maturity of our understanding of the broader geologic and atmospheric context on Mars provides a ready framework for ingestion of discrete ground truth measurements into our understanding of the broader and multi-scale martian natural systems and processes. These advancements make addressing key science questions with novel mission concepts feasible, promising results that would significantly advance our understanding of extraterrestrial surface-atmosphere interactions. This summary follows from a community-generated white paper for the ongoing Planetary Science/Astrobiology Decadal Survey, small spacecraft concept development at JPL, and numerous JPL and community discussions.

Conference Paper↗

USGS1979

The Palomar planet-crossing asteroid survey, 1973-1978

Photographic coverage of about 80,000 deg 2 of sky with the Palomar 46-cm Schmidt camera has yielded 12 new planet-crossing asteroids as well as many objects in the main asteroid belt. The estimated population of planet-crossing asteroids includes ∼100 Atens, 700 ± 300 Apollos, 1000–2000 Amors, 10,000 ± 5000 Mars crossers, and ∼5000 Mars grazers.

Icarus↗