Search NASA⌕ Search

Engineering topics

K M Stack

Publications and source records attributed to K M Stack.

12 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2024

Sampling the Margin Unit of Jezero Crater, Mars for Future Mars Sample Return

Mars 2020 Perseverance rover is currently exploring Jezero crater, which contains an ancient lake-delta system with a high potential for past habitability. One of Perseverance’s primary science goals is to collect a set of scientifically return-worthy samples for return to Earth (Mars Sample Return; MSR). Between February 2021 and December 2023, Perseverance has sealed 23 tubes containing 20 rock cores, 2 regolith samples and one atmosphere sample. All rock and regolith samples are accompanied by a set of observations (Sample Threshold Observation Protocol, the STOP List) performed on abrasion patches or regolith near each sample collection site. These observations are documented in the Initial Reports and the Sample Dossier (https://pds-geosciences.wustl.edu/missions/mars2020/returned_sample_science.htm). Here we provide an overview of the samples collected during the Margin campaign. The Margin unit is situated interior and adjacent to the western crater rim and exhibits a strong carbonate signal from orbital reflectance spectroscopy. Stratigraphically the unit lies beneath the previously explored curvilinear and blocky units of the fan top and is therefore older than those units. Based on its position near the crater rim and the strong carbonate detections it has been proposed to be a shoreline deposit with possible lacustrine carbonates. Alternative hypotheses include pyroclastic, fluviolacustrine and aeolian deposits. Based on rover observations a lacustrine shoreline deposit seems most likely. The planning of the Margin campaign took place during the summer of 2023, and 3-5 samples were baselined to be collected. Exploration of the Margin unit began in September 2023 and so far, two samples have been collected: the Pelican Point core at the Hans Amundsen Memorial Workspace in the Mandu Wall region , and the Lefroy Bay core at Lake Newell in the Turquoise Bay region (Fig. 1). The associated abrasion patches are Amherst Point (Pelican Point) and Bills Bay (Lefroy Bay) . Mandu Wall is interpreted to be stratigraphically lower than Turquoise Bay based on topography.

Mars sample return↗
NASA NTRS2024

Depositional History of the Upper Sequence of the Western Fan: Evidence for Late-Stage Fluvial and Potential Igneous Activity, Jezero Crater, Mars

Within Jezero crater, a 45 km diameter Noachian-aged crater on Mars, the Upper Fan group (UFg) stratigraphy records the youngest interval of sediment deposition via aqueous activity on the western fan. From orbital images, the UFg surface is characterized by ridges interpreted to be associated with channels that can be group based on orientation into distinct elongate and fan-shaped deposits. UFg deposits primarily consist of a sandstone to granule conglomerate facies covered by a lithified boulder conglomerate or dense accumulations of loose boulders along the surface. The coarse-grained nature of UFg deposits and the unconformable contact with the underlying fan stratigraphy suggest that the UFg represents a higher-energy shift from the relatively longer-lived, lower-energy aqueous systems interpreted in underlying fan stratigraphy. The Mars 2020 Perseverance rover encountered the main exposures of the UFg deposits beginning on Sol 755 and has been continuously collecting data along its northwestward traverse across the fan, enabling reconciliation of orbitally-derived geomorphology with in-situ observations from the rover and Ingenuity helicopter. This work represents a combined assessment of the geomorphology and the sedimentology and stratigraphy of the UFg in order to establish its depositional and emplacement history. Determining the origins of the Upper Fan sequence will clarify how, when, and in what order aqueous environments evolved through time within Jezero crater (e.g. crater infill, overflow, breach, and lake level drop;). Finally, this work will provide critical context for the three rock samples within the UFg sample suite.

Mars 2020↗
NASA NTRS2023

The Complex Exhumation History of Jezero Crater Floor Unit and Its Implication for Mars Sample Return

During the first year of NASA's Mars 2020 mission, Perseverance rover has investigated the dark crater floor unit of Jezero crater and four samples of this unit have been collected. The focus of this paper is to assess the potential of these samples to calibrate the crater-based Martian chronology. We first review the previous estimation of crater-based model age of this unit. Then, we investigate the impact crater density distribution across the floor unit. It reveals that the crater density is heterogeneous from areas which have been exposed to the bombardment during the last 3 Ga to areas very recently exposed to bombardment. It suggests a complex history of exposure to impact cratering. We also display evidence of several remnants of deposits on the top of the dark floor unit across Jezero below which the dark floor unit may have been buried. We propose the following scenario of burying/exhumation: the dark floor unit would have been initially buried below a unit that was a few tens of meters thick. This unit then gradually eroded away due to Aeolian processes from the northeast to the west, resulting in uneven exposure to impact bombardment over 3 Ga. A cratering model reproducing this scenario confirms the feasibility of this hypothesis. Due to the complexity of its exposure history, the Jezero dark crater floor unit will require additional detailed analysis to understand how the Mars 2020 mission samples of the crater floor can be used to inform the Martian cratering chronology.

Mars 2020↗
NASA NTRS2023

In Situ Geologic Context Mapping Transect on the Floor of Jezero Crater From Mars 2020 Perseverance Rover Observations

In situ geologic context mapping based on rover and helicopter observations provides documentation of a nearly continuous record of geology and exposed surface structure over a 120 m-wide corridor along the traverse of the Mars 2020/Perseverance rover. The results record the geologic context of Mars 2020 campaign sites and sample sites, including the local extent of bedrock outcrops, stratigraphy, attitude, and structure from imaging and rover-based remote sensing, and outcrop lithology based on in situ proximity science. Mapping identifies a sequence of igneous lithologies including (a) early mafic, possibly intrusive, rocks; (b) pervasively fractured and deeply altered massive bedrock of undetermined protolith; (c) buried and exhumed lava flows with pahoehoe and aa textures; (d) several varieties of regolith; and (e) small impact craters.

Mars 2020↗
NASA NTRSDate not supplied

Topographic Trends of the Geologic Units in Jezero Crater: Lake Levels, Potential Shorelines, and the Crater Floor Units

The Mars2020 Perseverance rover continues to explore the crater floor of Jezero crater working to understand the origins of these different crater floor geological units. Here, we model and analyze the modern and paleo-topography of various facets of Jezero crater to better constrain the evolution and origins of the various units and features observed. In general, we find that that a) the evidences for lake levels are largely unconstrained and are primarily supported by the outflow channel, western delta, and Kodiak, b) so far no convincing evidence has been found for continuous lake terraces (i.e., shorelines), and c) the contact surface of the lobate Crater Floor Fractured Rough (Cf-fr)unit dips to the southeast.

S F Sholes↗
NASA NTRSDate not supplied

Exploring the Jezero Crater Floor: Overview of Results from the Mars 2020 Perseverance Rover’s First Science Campaign

The Perseverance rover embarked on its first science campaign after landing in Jezero crater on February 18, 2021 and completing ~90 days of commissioning and Ingenuity helicopter activities. During this first campaign, Perseverance explored a large swath of Jezero’s crater floor, investigating and sampling several of the topographically lowest, and potentially oldest, rocks within the crater. Crater floor units: Perseverance explored the Máaz and Séítah formations (previously mapped as the Crater Floor Fractured Rough; Cf-fr and Crater Floor Fractured 1; Cf-f-1 units[1]). These are both widespread units in the crater that potentially correlate with units outside Jezero [2-4]. The Máaz fm. was distinguished from orbit by its mafic composition and densely cratered surface, and has various hypothesized origins, including lava flows[2] and volcaniclastic airfall [3]. The Máaz fm. is important for providing age/stratigraphic constraints on the Jezero western delta. If igneous, returned Máaz fm. samples may aid in calibrating the Mars crater chronology [2,5]and understanding Mars paleomagnetism and early igneous processes(see [6]). The Séítah fm. is olivine-bearing and has been interpreted to be related to a regional unit exposed along the inner rim of Jezero crater walls and occurs more broadly in the Nili Planum and Nili Fossae region. The olivine-bearing unit and its possible correlatives has a wide range of hypothesized origins including volcaniclastic airfall, impact melt, or aeolian and fluvial deposits [2-4,7,8]. The Séítahfm.is likely the oldest unit accessible to Perseverance and represents an important part of Jezero’s pre-delta-lacustrine history. As in the Máaz fm., the lithochemistry of the samples will help studies of early Mars igneous processes. The olivine-and carbonate-bearing components of this unit may also signify habitable conditions early in Jezero’s history, samples of which would be of high geochemical and astrobiological significance, as well as for understanding the martian carbon cycle(see [9]).

Mars 2020↗
NASA NTRSDate not supplied

An Orbital Photogeologic Map of the Jezero Crater Rim: Diverse Targets for Mars 2020 Future Exploration.

The Perseverance rover on the Mars 2020 mission is currently collecting samples in Jezero crater for potential future return to Earth by the Mars Sample Return (MSR) mission. Jezero is a 45 km diameter mid- to late-Noachian-aged crater selected for its diverse geology and potential for preserving evidence of ancient life. The rover is approaching the crater rim, an area of interest for its potential to preserve diverse lithologies representative of a large period of geologic history. It has significant astrobiological potential, as it may preserve evidence of uplifted deep crust and ancient hydrothermal environments. Impact megabreccia in the crater rim may be exhumed pre-Noachian crust from the Isidis impact, which would likely be the oldest materials ever investigated by a rover on Mars. Additionally, the rim hosts outcrops of the regionally extensive and potentially volcanic olivine/carbonate unit and mafic capping unit, which could have implications for the evolution of Mars volcanism. Regional maps have delineated the lithologies present in and around Jezero as a whole. The largest scale that the crater rim geology has been mapped is 1:5000.

M C Deahn↗
NASA NTRSDate not supplied

Diversity, Equity, Inclusion and Accessibility Initiatives on the Mars 2020 Science Team and Implications for NASA Planetary Science Missions

For the first time, the most recent NASA Decadal Survey for Planetary Science and Astrobiology includes an entire chapter devoted to the state of the profession[1]. Understanding that people are NASA’s greatest resource, it specifically looked into is-sues of Diversity, Equity, Inclusion, and Accessibility (DEIA) to make recommendations for recruiting and retaining the best talent. It calls on both NASA leadership and the NASA community to engage with these recommendations to advance the state of the profession.

DEIA↗
NASA NTRSDate not supplied

Astrobiological Potential of Rocks Acquired By the Perseverance Rover at the Front of the Western Sediment Fan in Jezero Crater, Mars.

Major objectives of the Perseverance rover mission include identifying past habitable environments, collecting rocks that are likely to preserve biosignatures and using the rover’s instruments to look for potential biosignatures in these rocks. The recognition of the > 3.5 billion-year old habitable environments in Jezero crater, Mars (Fig. 1); promised that the mission could achieve these objectives. The western sedimentary fan deposit, the hydrated minerals therein and the carbonate minerals at the margin of this fan were identified as particularly compelling areas in which to search for the signs of past life and collect the oldest aqueously deposited rocks from another planet.

Mars 2020↗
NASA NTRSDate not supplied

The Scientific Significance of Potential Samples From the Jezero Crater Rim

The Mars 2020 Perseverance rover has been exploring Jezero crater, Mars to characterize the geology,assess the potential for rocks to represent ancient habitable environments and/or preserve biosignatures, and collect a suite of scientifically compelling samples for return to Earth (Farleyet al.,2020).Thus far, Perseverance has collected samples that represent the diversity of igneous materials encountered on the crater floor and a suite of aqueously deposited sedimentary rocks from the fanand margin units(Simon et al., 2023; Bosak et al., 2024). When the rover ascendsthe crater rimit will encounter rocktypesthat are not included in the current sample cache. These include rocks fromthe Noachian whose mineralogical, geochemical, and geochronological recordswould greatly expand our understanding of early Mars. Some of the exposures are understood to come from subsurface aquifers that may represent the most ancient potentially habitablesubsurfaceenvironmentson Mars(Ehlmann et al., 2024). Samples ofthese rocks will add uniquescientific value tothe sample cache and to the Mars sample returnprogramby addressing outstanding questions in Mars science including potential habitability and how the climate and the interior of the planet evolved through time.

Mars 2020↗