Barbara Cohen

NASA

We tested rover science operations strategies to determine best practices for interrogating geologic sections where the bulk composition is igneous but depositional/emplacement processes range from sedimentary to volcanic. This scenario may mirror locations on Mars interrogated by mobile vehicles (e.g., Perseverance rover in Jezero crater). Two fie...

At a Mars analog site in Utah, we tested two science operation methods for data acquisition and decision-making protocols: a scenario where the tactical day is preplanned, but major adjustments may still be made before plan delivery; and a scenario in which the sol path must largely be planned before a given tactical planning day and very few adjus...

The Perseverance rover landed in Jezero crater, Mars, to investigate ancient lake and river deposits. We report observations of the crater floor, below the crater’s sedimentary delta, finding the floor consists of igneous rocks altered by water. The lowest exposed unit, informally named Séítah, is a coarsely crystalline olivine-rich rock, which acc...

The geological units on the floor of Jezero crater, Mars, are part of a wider regional stratigraphy of olivine-rich rocks, which extends well beyond the crater. We investigate the petrology of olivine and carbonate-bearing rocks of the Séítah formation in the floor of Jezero. Using multispectral images and x-ray fluorescence data, acquired by the P...

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...

Geochronology, or determination of absolute ages for geologic events, underpins many inquiries into the formation and evolution of planets and our Solar System. Absolute ages of ancient and recent magmatic products provide strong constraints on the dynamics of magma oceans and crustal formation, as well as the longevity and evolution of interior he...

We conducted a field test at a potential Mars analog site to provide insight into planning for future robotic missions such as Mars 2020, where science operations must facilitate efficient choice of biologically relevant sampling locations. We compared two data acquisition and decision-making protocols currently used by Mars Science Laboratory: (1)...

We review the in situ geochronology experiments conducted by the Mars Science Laboratory mission's Curiosity rover to understand when the Gale Crater rocks formed, underwent alteration, and became exposed to cosmogenic radiation. These experiments determined that the detrital minerals in the sedimentary rocks of Gale are ∼4 Ga, consistent with thei...

The GHOST field tests are designed to isolate and test science-driven rover operations protocols, to determine best practices. During a recent field test at a potential Mars 2020 landing site analog, we tested two Mars Science Laboratory data-acquisition and decision-making methods to assess resulting science return and sample quality: a linear met...

We report the results of geological studies by the Opportunity Mars rover on the Endeavour Crater rim. Four major units occur in the region (oldest to youngest): the Matijevic, Shoemaker, Grasberg and Burns formations. The Matijevic formation, consisting of fine-grained clastic sediments, is the only pre-Endeavour-impact unit and might be part of t...

Following K-Ar dating of a mudstone and a sandstone, a third sample has been dated by the Curiosity rover exploring Gale Crater. The Mojave 2 mudstone, which contains relatively abundant jarosite, yielded a young K-Ar bulk age of 2.57 ± 0.39 Ga (1σ precision). A two-step heating experiment was implemented in an effort to resolve the K-Ar ages of pr...

We tested science operations strategies developed for use in remote mobile spacecraft missions, to determine whether reconnoitering a site of potential habitability prior to in-depth study (a walkabout-first strategy) can be a more efficient use of time and resources than the linear approach commonly used by planetary rover missions. Two field team...

With the advent of exoplanetary astronomy and the ongoing discovery of terrestrial-type planets around other stars, our own solar system becomes a key testing ground for ideas about what factors control planetary evolution. In particular, what allows a planet to be both within a potentially habitable zone and sustain habitability over long geologic...

Martian meteorite Elephant Moraine A79001 (EET 79001) has received considerable attention for the unusual composition of its shock melt glass, particularly its enrichment in sulfur relative to the host shergottite. It has been hypothesized that Martian regolith was incorporated into the melt or, conversely, that the S-enrichment stems from preferen...

We used a field excursion to the West Clearwater Lake Impact structure as an opportunity to test factors that contribute to the decisions a remote field team (for example, astronauts conducting extravehicular activities (EVA) on planetary surfaces) makes while collecting samples for return to Earth. We found that detailed background on the analytic...

Here, we revisit the impactites of the West Clearwater Lake impact structure following a 2014 expedition; the first field study of this structure for 40 years.

Using the Mars Exploration Rover Opportunity, we have compiled one of the first field geologic maps on Mars while traversing the Noachian terrain along the rim of the 22-km diameter Endeavour crater (Lat -2° 16’ 33”, Long -5° 10’ 51”). In situ mapping of the petrographic, elemental, structural, and stratigraphic characteristics of outcrops and rock...

Executive Summary: Grain-scale lithology pro-vides diagnostic data allowing interpretation of geolog-ic environments. However, current rover platforms do not provide the appropriate resolution at an actionable distance; or conversely, when current platforms make high resolution observations, they are too late to be actionable (they serve the purpos...

Hawkeye, a mast-mounted, 2-megapixel RGB color camera with a focusable macro lens, is a simple, heritage-rich investigation that provides hand lens scale lithology from actionable distances, maximizing the efficiency of landed or roving vehicles.

en Geochronology is a fundamental measurement for planetary samples, providing global and solar system context for the conditions prevailing on the planet at the time of major geological events. The potassium (K)‐Argon (Ar) laser experiment (KArLE) will make in situ noble gas geochronology measurements aboard planetary robotic missions such as rove...

We used MER-derived semi-autonomous rover science operations strategies to determine best practices suitable for remote semi-autonomous lunar rover geology. Two field teams studied two glacial moraines as analogs for potential ice-bearing lunar regolith. At each site a Rover Team commanded a human rover to execute observations based on common MER s...

Processes, environments, and the energy associated with the transport and deposition of sand at Gusev crater are characterized at the microscopic scale through the comparison of statistical moments for particle size and shape distributions. Bivariate and factor analyses define distinct textural groups at 51 sites along the traverse completed by the...

Determining the accuracy/precision of volume measurements of laser-generated pits to better understand the ablation process for isotope abundance calculations.

KArLE will provide absolute K-Ar ages by combining LIBS and mass spectrometry measurements made on a single pit in a core sample taken by the Mars 2020 rover.

Crystalline impact-melt samples were created in high-temperature environments by relatively large craters and, as such, give additional constraints on the nature of the impacts that created them. This article provides new 40Ar-39Ar ages of impact-melt clasts in howardites and shows that these clasts formed on the HED parent body, 4 Vesta, within th...

The Moon experienced an intense period of impacts about 4 Gyr ago. This cataclysm is thought to have affected the entire inner Solar System and has been constrained by the radiometric dating of lunar samples: 40Ar-39Ar ages reflect the heating and degassing of target rocks by large basin-forming impacts on the Moon. Radiometric dating of meteorites...

Basaltic outcrops / Newberries, breccias, and veins / Clays still elusive.

The last five years have seen a boom in exploration of the Solar System. Barbara Cohen explains that the biggest gains have been right here on Earth.

Over the last 5 years, NASA has invested in development and risk-reduction activities for a new generation of planetary landers capable of carrying instruments and technology demonstrations to the lunar surface and other airless bodies. The Robotic Lunar Lander Development Project (RLLDP) is jointly implemented by NASA Marshall Space Flight Center...

The nature of the lunar Late Heavy Bombardment (LHB), a period of increased bombardment of the Moon 3.9Gyr ago, continues to be debated because many lunar samples provide only circumstantial evidence about the epoch of large basin formation. Independent constraints can be placed by meteorite 40Ar-39Ar ages reset in asteroid impact events. The best...

We are developing a capability to make in situ geochronology measurements using existing, flight-heritage components. Our goal is to determine the age of planetary samples to ±100 m.y., sufficient to address a wide range of high-priority science.

We describe a in situ triple coincidence life detection/characterization and Rb-Sr/K-Ar geochronology mission concept using a MER to mid-sized rover.

Martian Veins After more than 7 years of traveling across the Meridiani Planum region of Mars, the Mars Exploration rover Opportunity reached the Endeavour Crater, a 22-km-impact crater made of materials older than those previously investigated by the rover. Squyres et al. (p. 570 ) present a comprehensive analysis of the rim of this crater. Locali...

We report on field tests at two glacial moraines (analogs for ice-bearing lunar regolith) where we tested science operational strategies used on Mars to determine best practices for conducting remote semi-autonomous rover geology on the Moon.

In this work we provide a new interpretation of Ar-Ar ages of HED meteorites that may significantly affect their implications for the collisional evolution of Vesta.

Most main belt asteroids hit each other too slowly to produce much heat or reset Ar-Ar ages. Instead, we show LHB-era impact heating events likely came from asteroids pushed onto deep Earth-crossing orbits by late giant planet migration.

Desert Research and Technology Studies (Desert RATS) is a multi-year series of hardware and operations tests carried out annually in the high desert of Arizona on the San Francisco Volcanic Field. These activities are designed to exercise planetary surface hardware and operations in conditions where long-distance, multi-day roving is achievable, an...

Background We tested the science operational strategy used for the Mars Exploration Rover (MER) mission on Mars to determine its suitability for conducting remote geology on the Moon by conducting a field test at Cerro de Santa Clara, New Mexico. This region contains volcanic and sedimentary products from a variety of provenances, mimicking the var...

Our understanding of the composition of Ceres is driven by remote sensing of its surface. We review spectral observations of Ceres over wavelengths from the ultraviolet to the radio, as well as non-spectral data such as thermal inertia, photometric properties, radar experiments, and surface variability. We also discuss the closest likely meteorite...

Chemical, mineralogic, and lithologic ground truth was acquired for the first time on Mars in terrain units mapped using orbital Mars Reconnaissance Orbiter's High Resolution Imaging Science Experiment (MRO HiRISE) image data. Examination of several dozen outcrops shows that Mars is geologically complex at meter length scales, the record of its geo...

Touching the surface / Lander designs grant access / To dazzling worlds .

We investigate EETA79001 impact melt using S, Ni, and Cl --- all strong indicator elements of martian soil. If soil is a contributor to Lithology C's S budget it should also contribute Ni and Cl. Our work suggests no soil component is necessary to explain the Lithologu C composition.

We report the first lunar occurrence of keiviite-(Y) with formula (Y,REE)2Si2O7 in troctolitic anorthosite 76335,59. It has been characterized by EPMA utilizing new analytical methods.

We have begun a program of ground-based lunar observation in the 2-4 µm region, following up on the discovery of water in the lunar regolith. We will present the results from our first observing run, focusing on the Reiner Gamma region.

Lunar poles harbor / Strange and wonderful ices / Awaiting our touch.

The Desert Research and Technology Studies (D-RATS) field tested two models of human-in-the-loop remote field geology: one based on the Apollo science backroom that integrated tactical and strategic decisions, and one that separated tactical and strategic processes as utilized during the Mars Exploration Rovers (MER) and Mars Phoenix Scout missions...

We have used visible and near-infrared Panoramic Camera (Pancam) spectral data acquired by the Opportunity rover to analyze 15 rock fragments at the Meridiani Planum landing site. These spectral results were then compared to geochemistry measurements made by the in situ instruments Mössbauer (MB) and Alpha Particle X-ray Spectrometer (APXS) to dete...

Numerous loose rocks with dimensions of a few centimeters to tens of centimeters and with no obvious physical relationship to outcrop rocks have been observed along the traverse of the Mars Exploration Rover Opportunity. To date, about a dozen of these rocks have been analyzed with Opportunity's contact instruments, providing information about elem...

We report ⁵³Mn–⁵³Cr and ²⁶Al–²⁶Mg isotopic data, obtained by in-situ SIMS analysis, for feldspathic clasts in polymict ureilites DaG 319 and DaG 165. The analyzed clasts belong to the “albitic lithology,” the most abundant population of indigenous feldspathic materials in polymict ureilites, and are highly fractionated igneous assemblages of albiti...

NASA Marshall Space Flight Center (MSFC) and The Johns Hopkins University Applied Physics Laboratory (APL) have been conducting mission studies and performing risk reduction activities for NASA's robotic lunar lander flight projects. This paper describes some of the lunar lander concepts derived from these studies conducted by the MSFC/APL Robotic...

We present initial findings from a high-resolution electron microprobe study of impact melt from martian meteorite EET A79001. We investigate martian soil composition, near-surface processes, and the generation of impact melt.