[
{
"id": "authors:8bc7k-h7505",
"collection": "authors",
"collection_id": "8bc7k-h7505",
"cite_using_url": "https://authors.library.caltech.edu/records/8bc7k-h7505",
"type": "article",
"title": "Testing of SLUSH ice penetrating probe in Europa, Enceladus, and Mars environments",
"author": [
{
"family_name": "Stolov",
"given_name": "Leo"
},
{
"family_name": "Lang",
"given_name": "Caleb"
},
{
"family_name": "Zacny",
"given_name": "Kris"
},
{
"family_name": "Mellerowicz",
"given_name": "Boleslaw"
},
{
"family_name": "Palmowski",
"given_name": "Joseph"
},
{
"family_name": "Bywaters",
"given_name": "Kathryn"
},
{
"family_name": "Sheeran",
"given_name": "Frank"
},
{
"family_name": "van Susante",
"given_name": "Paul"
},
{
"family_name": "Ehlmann",
"given_name": "Bethany L.",
"orcid": "0000-0002-2745-3240",
"clpid": "Ehlmann-B-L"
}
],
"abstract": "Europa and Enceladus conceal global liquid-water oceans beneath ice shells several kilometers thick, and Mars holds thick polar ice deposits that may cover localized layers of liquid water or brine. These subsurface environments are primary targets in the search for past or present life in the solar system. The Search for Life Using Submersible Heated drill (SLUSH) probe is a hybrid, thermo-mechanical probe capable of penetrating through the ice to reach the subsurface liquid water. To improve efficiency and drilling speed, SLUSH combines the two existing methods for traveling through ice: thermal (melting) and mechanical (cutting). \"Slushing\" uses rotary-percussive drilling to break the ice into chips (the fragmented ice cuttings produced by the drill) and heat to partially melt these chips into a slush, enabling efficient transport behind the probe. A scaled prototype of the SLUSH probe has been developed to compare the three drilling methods (thermal, mechanical, and thermo-mechanical or slushing). Testing was conducted in relevant ambient pressure and vacuum environments using \"warm\" (260 K) and \"cryogenic\" (130 K) ice. An analytical thermal model is applied to estimate the idealized performance of a conventional melt probe as an upper-bound baseline, and a conceptual power-balance framework is introduced that decomposes the slushing power requirement into mechanical and thermal contributions relative to this baseline. Initial testing demonstrated the feasibility of the slushing approach across all three environments and identifies key design drivers for future optimization.
",
"doi": "10.3389/frspt.2026.1887929",
"issn": "2673-5075",
"publisher": "Frontiers Media SA",
"publication": "Frontiers in Space Technologies",
"publication_date": "2026-08-06",
"volume": "7",
"pages": "1887929"
},
{
"id": "authors:xp4p0-m6024",
"collection": "authors",
"collection_id": "xp4p0-m6024",
"cite_using_url": "https://authors.library.caltech.edu/records/xp4p0-m6024",
"type": "article",
"title": "Aluminum Phyllosilicate and Jarosite Formation Through Alteration of Reworked Al/Si-Rich Volcaniclastic Sediments in Nili Fossae, Mars",
"author": [
{
"family_name": "Baker",
"given_name": "S. R.",
"orcid": "0009-0001-7705-3261",
"clpid": "Baker-Samantha-R"
},
{
"family_name": "Ehlmann",
"given_name": "B. L.",
"orcid": "0000-0002-2745-3240",
"clpid": "Ehlmann-B-L"
}
],
"abstract": "\n
Aluminum phyllosilicates occur in 1–10s of km2 exposures of Noachian (∼3.7 Ga) rock across Mars and typically appear stratigraphically above Fe/Mg-phyllosilicates. These units have been proposed to represent pedogenic basalt weathering sequences. We examine Al-phyllosilicates in the Nili Fossae region, combining mineral maps generated from imaging spectroscopy with digital elevation models and high-resolution imagery to determine mineral assemblages, their geologic relationships, and their history of formation. We find that the Al-phyllosilicate is dominantly kaolinite and lacks associated Fe oxide. The Al-phyllosilicates typically have a distinct texture relative to Fe/Mg-phyllosilicate units, indicating an unconformity, and two different protoliths rather than formation as a pedogenic weathering sequence. Layers in some kaolinite deposits and their preferential association with sedimentary basins suggest reworked sedimentary material. The most plausible source is an Al/Si-enriched (non-basaltic) airfall volcanic deposit. We detect sparse jarosite closely associated with kaolinite but not Fe/Mg-phyllosilicate. We interpret that the jarosite, which is metastable under present surface conditions, formed from reaction between Fe-enriched fluids and S that is found sufficiently only within the kaolinite-bearing protolith. Collectively, these observations suggest less intense near-surface oxidative weathering than the basalt pedogenesis hypothesis, namely, an upper bound of several million cumulative years of aqueous activity in Nili Fossae that largely ended after the formation of jarosite. Detection of Al-phyllosilicate-bearing float rocks in nearby Jezero Crater by the Perseverance Rover shows that sample return has potential to conclusively determine processes and environmental conditions forming Nili Fossae's distinctive Al-phyllosilicates.
\n
Satellite data have been used to estimate the three\u2010dimensional orientation of features on Mars inferred to be bedding planes to support interpretations of deposit characteristics and depositional environments. Opportunities to ground\u2010truth these estimates and to understand the geologic information recorded by surfaces measured from orbit are limited to landing sites. We developed a generalized workflow for calculating surface orientations from measured apparent dip angles and look directions that may be applied to photographs. We then performed a quantitative comparison of five orbiter\u2010derived plane fits of scarps, light\u2010toned bands, and other layer\u2010like features exposed in outcrops in Jezero crater's western fan with both orientations and up\u2010close geologic interpretations of the same features using images taken by the Perseverance rover. Orbiter\u2010derived orientation estimates almost always fall within orientation constraints set by apparent dip angles and dip directions seen in two or more rover images. Additionally, the rover\u2010 and orbiter\u2010based orientation solutions often overlap within mutual uncertainties. However, only one of five features traced from orbit was confirmed in rover images to constitute an actual single bed, indicating that our ability to distinguish hierarchical stratigraphic elements, lithologies, and stratal structures from orbit is limited. Thus, in situ investigation at sub\u2010decimeter\u2010scale with landed spacecraft that can view strata in cross\u2010section will often be required to definitively distinguish stratigraphic elements that are characteristic of depositional environment. Nevertheless, certain outcrop characteristics such as distinct tonality and moderate\u2010to\u2010steep inclination are discernible from orbit and allow for the characterization of the orientation of beds or self\u2010similar packages of strata.
",
"doi": "10.1029/2026ea005086",
"issn": "2333-5084",
"publisher": "American Geophysical Union",
"publication": "Earth and Space Science",
"publication_date": "2026-08",
"series_number": "8",
"volume": "13",
"issue": "8",
"pages": "e2026EA005086"
},
{
"id": "authors:77j2x-fth80",
"collection": "authors",
"collection_id": "77j2x-fth80",
"cite_using_url": "https://authors.library.caltech.edu/records/77j2x-fth80",
"type": "article",
"title": "Lunar Trailblazer Spacecraft Tracking and Mission Recovery Attempt: Characterization of Status and Behavior of a Non-Cooperative Object in Cis-Lunar Space",
"author": [
{
"family_name": "Ehlmann",
"given_name": "B. L.",
"orcid": "0000-0002-2745-3240",
"clpid": "Ehlmann-B-L"
},
{
"family_name": "Bellerose",
"given_name": "J."
},
{
"family_name": "Lantoine",
"given_name": "G.",
"orcid": "0000-0002-9528-0011"
},
{
"family_name": "Furlan",
"given_name": "E.",
"orcid": "0000-0001-9800-6248",
"clpid": "Furlan-Elise"
},
{
"family_name": "Scire",
"given_name": "E.",
"orcid": "0000-0003-1468-5357",
"clpid": "Scire-Elena"
},
{
"family_name": "Fajardo\u2010Acosta",
"given_name": "S.",
"orcid": "0000-0001-9309-0102",
"clpid": "Fajardo\u2010Acosta-Sergio"
},
{
"family_name": "Bennett",
"given_name": "L.",
"clpid": "Bennett-L"
},
{
"family_name": "Sanchez Net",
"given_name": "M."
},
{
"family_name": "Lazio",
"given_name": "T. J. W.",
"clpid": "Lazio-T-J-W"
},
{
"family_name": "Brozovi\u0107",
"given_name": "M.",
"orcid": "0009-0007-3493-2139"
},
{
"family_name": "Masiero",
"given_name": "J.",
"orcid": "0000-0003-2638-720X",
"clpid": "Masiero-Joseph"
},
{
"family_name": "Steckel",
"given_name": "A. V.",
"orcid": "0000-0003-1345-8240",
"clpid": "Steckel-Amanda-V"
},
{
"family_name": "Burke",
"given_name": "P. A.",
"orcid": "0000-0002-6736-4138"
},
{
"family_name": "Kimura",
"given_name": "M.",
"orcid": "0000-0001-8135-9207",
"clpid": "Kimura-Masahiko"
},
{
"family_name": "Foxman",
"given_name": "S.",
"clpid": "Foxman-S"
},
{
"family_name": "Zaw",
"given_name": "M. P. M.",
"clpid": "Zaw-M-P-M"
},
{
"family_name": "Lee",
"given_name": "L. M.",
"orcid": "0009-0003-9667-9483"
},
{
"family_name": "Clarke",
"given_name": "F."
},
{
"family_name": "Hauge",
"given_name": "M."
},
{
"family_name": "McDonald",
"given_name": "D."
},
{
"family_name": "Adler",
"given_name": "J.",
"orcid": "0009-0006-7265-2747",
"clpid": "Adler-Judy"
},
{
"family_name": "Strauss",
"given_name": "R."
},
{
"family_name": "Trilling",
"given_name": "D."
},
{
"family_name": "Edwards",
"given_name": "C. S.",
"orcid": "0000-0002-8096-9633"
},
{
"family_name": "Nolan",
"given_name": "M. C.",
"orcid": "0000-0001-8316-0680"
},
{
"family_name": "Lyster",
"given_name": "D."
},
{
"family_name": "Robinson",
"given_name": "L.",
"orcid": "0009-0005-7612-5613"
},
{
"family_name": "Klesh",
"given_name": "A. T."
},
{
"family_name": "Seybold",
"given_name": "C. C."
}
],
"abstract": "\n
Unexpectedly following launch, the Lunar Trailblazer mission experienced software anomalies that led it to orient solar panels away from the sun and lose communication with Earth. This paper describes efforts to determine the spacecraft state and attempt recovery of the mission's science at the Moon. First, ground observatories at optical and radar wavelengths were engaged to maintain custody of the spacecraft and knowledge of its trajectory. Second, viability of recovery of the mission science objectives was established via testbed work to understand system behavior in fault conditions and determination of trajectories and maneuvers that would enable lunar orbit insertion. Third, optical photometry and radar doppler broadening were employed to determine Lunar Trailblazer's spin and orientation, using approaches similar to those in asteroid studies, to establish when solar panels might again receive sufficient power to boot the spacecraft and initialize its radio. Fourth, X-band-capable groundstations in addition to the NASA Deep Space Network were engaged to monitor for the spacecraft's radio carrier signal nearly continually, including crowd-sourced monitoring and tip-and-cue style commanding. Lunar Trailblazer left the Earth-Moon system and is in a 14-year Earth return, heliocentric orbit. As it moved further away from Earth prospects for recovery became formidable; ultimately, the ability of the telecom system to return telemetry to Earth would have been insufficient to enable actions to recover the spacecraft, and the recovery attempt ended 6 July 2025. Lunar Trailblazer's mission recovery efforts illuminate capabilities in characterizing a 1–3.5 m3 size non-cooperative object in cis-lunar space.
\n
The Lunar Trailblazer (LTB) spacecraft launched on 27 February 2025, toward a planned low\u2010lunar orbit. Eleven hours into its mission, contact with Trailblazer was lost, and recovery efforts began. Estimating the orientation and angular velocity state of Trailblazer was central for recovery to determine whether and when the vehicle could be contacted again. This work documents a method to estimate Trailblazer's attitude state using only ground\u2010based optical telescopes. This data is cheap to collect and scales favorably with distance compared to radar data. We rely on photometric light curves, time histories of Trailblazer's observed brightness. The process of estimating Trailblazer's orientation and angular velocity from this data is known as light curve inversion. Light curve attitude inversion, in addition to inherent ambiguities caused by symmetries in the observed object's geometry and the geometry of the observation, is sensitive to the object's assumed surface materials. In this paper, we study the impact of surface material accuracy using two light curves of Trailblazer acquired by the 4.2\u2010m aperture Lowell Discovery Telescope in Arizona on 10 March 2025 and the 8.1\u2010m aperture Gemini South observatory in Chile on 9 April 2025. We produce two sets of solutions for each light curve: one using material properties derived from a solar radiation pressure model of the LTB, and a second using materials fit to laboratory reflectometry of Trailblazer's materials. We qualitatively compare solutions for both cases and perform a sensitivity analysis to quantify the dependence between the attitude solutions and material property errors.
",
"doi": "10.1029/2025ea004733",
"issn": "2333-5084",
"publisher": "American Geophysical Union",
"publication": "Earth and Space Science",
"publication_date": "2026-07",
"series_number": "7",
"volume": "13",
"issue": "7",
"pages": "e2025EA004733"
},
{
"id": "authors:rzx5t-tj741",
"collection": "authors",
"collection_id": "rzx5t-tj741",
"cite_using_url": "https://authors.library.caltech.edu/records/rzx5t-tj741",
"type": "article",
"title": "Spatially distributed complex organic matter detected in an ancient river valley in Jezero crater, Mars",
"author": [
{
"family_name": "Murphy",
"given_name": "Ashley E.",
"orcid": "0000-0003-2533-6224"
},
{
"family_name": "Uckert",
"given_name": "Kyle",
"orcid": "0000-0002-0859-5526"
},
{
"family_name": "Hand",
"given_name": "Kevin P.",
"orcid": "0000-0002-3225-9426"
},
{
"family_name": "Bhartia",
"given_name": "Rohit",
"orcid": "0000-0002-1434-7481"
},
{
"family_name": "Bykov",
"given_name": "Sergei V.",
"orcid": "0000-0002-6161-0027"
},
{
"family_name": "Hickman-Lewis",
"given_name": "Keyron",
"orcid": "0000-0001-8014-233X"
},
{
"family_name": "Jakubek",
"given_name": "Ryan S.",
"orcid": "0000-0001-7880-9422"
},
{
"family_name": "Lee",
"given_name": "Carina",
"orcid": "0000-0001-8151-3438"
},
{
"family_name": "McCubbin",
"given_name": "Francis M.",
"orcid": "0000-0002-2101-4431"
},
{
"family_name": "Minitti",
"given_name": "Michelle E.",
"orcid": "0000-0003-4715-4544"
},
{
"family_name": "Pascuzzo",
"given_name": "Alyssa",
"orcid": "0000-0003-0180-1371"
},
{
"family_name": "Siljestr\u00f6m",
"given_name": "Sandra",
"orcid": "0000-0002-4975-6074"
},
{
"family_name": "Sharma",
"given_name": "Sunanda",
"orcid": "0000-0001-8822-7960"
},
{
"family_name": "Steele",
"given_name": "Andrew",
"orcid": "0000-0001-9643-2841"
},
{
"family_name": "Williford",
"given_name": "Kenneth H.",
"orcid": "0000-0003-0633-408X"
},
{
"family_name": "Abbey",
"given_name": "William",
"orcid": "0000-0002-0555-6599"
},
{
"family_name": "Asher",
"given_name": "Sanford A.",
"orcid": "0000-0003-1061-8747"
},
{
"family_name": "Barnes",
"given_name": "Robert",
"orcid": "0000-0001-7864-4824"
},
{
"family_name": "Barr",
"given_name": "Parker A.",
"orcid": "0009-0007-7050-2590"
},
{
"family_name": "Bell",
"given_name": "James F.",
"orcid": "0000-0002-2006-4074"
},
{
"family_name": "Beyssac",
"given_name": "Olivier",
"orcid": "0000-0001-8879-4762"
},
{
"family_name": "Bosak",
"given_name": "Tanja",
"orcid": "0000-0001-5179-5323"
},
{
"family_name": "Bramble",
"given_name": "Michael S.",
"orcid": "0000-0002-9440-4756"
},
{
"family_name": "Brown",
"given_name": "Adrian",
"orcid": "0000-0002-9352-6989"
},
{
"family_name": "Broz",
"given_name": "Adrian P.",
"orcid": "0000-0003-1843-6702"
},
{
"family_name": "Buckner",
"given_name": "Denise",
"orcid": "0000-0002-5160-5857"
},
{
"family_name": "Cardarelli",
"given_name": "Emily L.",
"orcid": "0000-0001-5451-2309"
},
{
"family_name": "Carsten",
"given_name": "Joseph L."
},
{
"family_name": "Corpolongo",
"given_name": "Andrea",
"orcid": "0000-0002-8623-358X"
},
{
"family_name": "Czaja",
"given_name": "Andrew",
"orcid": "0000-0002-2450-0734"
},
{
"family_name": "Edgington",
"given_name": "Scott G. C."
},
{
"family_name": "Ehlmann",
"given_name": "Bethany L.",
"orcid": "0000-0002-2745-3240",
"clpid": "Ehlmann-B-L"
},
{
"family_name": "Farley",
"given_name": "Kenneth A.",
"orcid": "0000-0002-7846-7546",
"clpid": "Farley-K-A"
},
{
"family_name": "Fornaro",
"given_name": "Teresa",
"orcid": "0000-0001-7705-9658"
},
{
"family_name": "Fries",
"given_name": "Marc",
"orcid": "0000-0003-2761-6692"
},
{
"family_name": "Gonz\u00e1lez-Burgos",
"given_name": "Roxana"
},
{
"family_name": "Gupta",
"given_name": "Sanjeev",
"orcid": "0000-0001-6415-1332"
},
{
"family_name": "Haney",
"given_name": "Nikole C.",
"orcid": "0000-0001-5405-3616"
},
{
"family_name": "Hug",
"given_name": "William",
"orcid": "0000-0002-0403-9979"
},
{
"family_name": "Huggett",
"given_name": "Joshua",
"orcid": "0009-0002-0244-9613"
},
{
"family_name": "Hurowitz",
"given_name": "Joel A.",
"orcid": "0000-0002-5857-8652"
},
{
"family_name": "Imbeah",
"given_name": "Samara",
"orcid": "0000-0003-2921-1840"
},
{
"family_name": "Clark",
"given_name": "Joanna"
},
{
"family_name": "Jones",
"given_name": "Alexander J.",
"orcid": "0009-0005-4752-4543"
},
{
"family_name": "Kah",
"given_name": "Linda C.",
"orcid": "0000-0001-7172-2033"
},
{
"family_name": "Kennedy",
"given_name": "Megan R.",
"orcid": "0000-0001-5076-6395"
},
{
"family_name": "Lee",
"given_name": "Steven W.",
"orcid": "0009-0009-1477-0616"
},
{
"family_name": "Maki",
"given_name": "Justin",
"orcid": "0000-0002-7887-0343"
},
{
"family_name": "Nixon",
"given_name": "Brian",
"orcid": "0000-0001-6224-229X"
},
{
"family_name": "N\u00fa\u00f1ez",
"given_name": "Jorge I.",
"orcid": "0000-0003-0930-6674"
},
{
"family_name": "Osterhout",
"given_name": "Jeffrey T.",
"orcid": "0000-0001-8523-0072",
"clpid": "Osterhout-Jeffrey-T"
},
{
"family_name": "Phelan",
"given_name": "Nicole D.",
"orcid": "0000-0002-5587-5723"
},
{
"family_name": "Phua",
"given_name": "Yu Yu",
"orcid": "0000-0001-9660-1991"
},
{
"family_name": "Ravine",
"given_name": "Michael A.",
"orcid": "0000-0003-4810-7352"
},
{
"family_name": "Hollis",
"given_name": "Joseph Razzell",
"orcid": "0000-0002-6239-694X"
},
{
"family_name": "Scheller",
"given_name": "Eva",
"orcid": "0000-0002-9981-5802"
},
{
"family_name": "Schulte",
"given_name": "Mitchell D."
},
{
"family_name": "Sephton",
"given_name": "Mark A.",
"orcid": "0000-0002-2190-5402"
},
{
"family_name": "Simon",
"given_name": "Justin I.",
"orcid": "0000-0002-3969-8958"
},
{
"family_name": "Srivastava",
"given_name": "Anushree",
"orcid": "0009-0008-3713-5490"
},
{
"family_name": "Stack",
"given_name": "Kathryn M.",
"orcid": "0000-0003-3444-6695",
"clpid": "Stack-Kathryn-M"
},
{
"family_name": "Van Beek",
"given_name": "Jason",
"orcid": "0000-0002-6772-4914"
},
{
"family_name": "Weiss",
"given_name": "Benjamin P.",
"orcid": "0000-0003-3113-3415"
},
{
"family_name": "Wiens",
"given_name": "Roger",
"orcid": "0000-0002-3409-7344"
},
{
"family_name": "Williams",
"given_name": "Amy J.",
"orcid": "0000-0001-6299-0845"
},
{
"family_name": "Wogsland",
"given_name": "Brittan V.",
"orcid": "0000-0002-7829-5094"
},
{
"family_name": "Yingst",
"given_name": "R. Aileen",
"orcid": "0000-0002-0628-4265"
}
],
"abstract": "Using a Raman spectrometer onboard the Perseverance rover, we report the heterogeneous distribution of organic carbon within mudstones located in an ancient river valley on Mars. Measurements of two mudstones show hundreds of organic detections, making this the most robust organic detection in Jezero crater thus far, and, to our knowledge, the only detection of macromolecular carbon on a natural rock surface on Mars. Spectra of the interior of one rock reveal an association of organics with secondary carbonate and sulfate minerals, whereas another rock exhibits an association of organics with primary silicate-dominated matrix. Although in situ Raman analyses cannot determine whether these organics denote abiotic or biotic sources, the organic association with both depositional and diagenetic minerals and the detection of organics on the martian surface suggests that the organics observed ubiquitously at the Bright Angel outcrop may be resistant to radiation and oxidation or have been relatively recently exposed.",
"doi": "10.1126/sciadv.adx0047",
"pmcid": "PMC13292988",
"issn": "2375-2548",
"publisher": "American Association for the Advancement of Science",
"publication": "Science Advances",
"publication_date": "2026-06-26",
"series_number": "26",
"volume": "12",
"issue": "26",
"pages": "eadx0047"
},
{
"id": "authors:165xn-2hf21",
"collection": "authors",
"collection_id": "165xn-2hf21",
"cite_using_url": "https://authors.library.caltech.edu/records/165xn-2hf21",
"type": "article",
"title": "The Lunar Trailblazer Lunar Thermal Mapper Instrument",
"author": [
{
"family_name": "Bowles",
"given_name": "Neil E.",
"orcid": "0000-0001-5400-1461"
},
{
"family_name": "Ehlmann",
"given_name": "Bethany L.",
"orcid": "0000-0002-2745-3240",
"clpid": "Ehlmann-B-L"
},
{
"family_name": "Evans",
"given_name": "Rory"
},
{
"family_name": "Warren",
"given_name": "Tristram J."
},
{
"family_name": "Eshbaugh",
"given_name": "Henry H.",
"orcid": "0009-0007-1984-750X"
},
{
"family_name": "King",
"given_name": "Greg"
},
{
"family_name": "Mir",
"given_name": "Waqas"
},
{
"family_name": "Habib",
"given_name": "Namrah",
"orcid": "0000-0001-7131-251X"
},
{
"family_name": "Shirley",
"given_name": "Katherine",
"orcid": "0000-0003-0669-7497"
},
{
"family_name": "Clarke",
"given_name": "Fraser"
},
{
"family_name": "Bourgenot",
"given_name": "Cyril",
"orcid": "0000-0002-0458-9321"
},
{
"family_name": "Howe",
"given_name": "Chris",
"orcid": "0009-0004-0059-2162"
},
{
"family_name": "Nowicki",
"given_name": "Keith",
"orcid": "0000-0001-6946-5365"
},
{
"family_name": "Henderson",
"given_name": "Fiona H. M."
},
{
"family_name": "Edwards",
"given_name": "Christopher S.",
"orcid": "0000-0002-8096-9633"
},
{
"family_name": "Klima",
"given_name": "Rachel L.",
"orcid": "0000-0002-9151-6429"
},
{
"family_name": "Hanna",
"given_name": "Kerri Donaldson",
"orcid": "0000-0001-5592-4292"
},
{
"family_name": "Seybold",
"given_name": "Calina C.",
"clpid": "Seybold-Calina-C"
},
{
"family_name": "Klesh",
"given_name": "Andrew T.",
"clpid": "Klesh-Andrew-T"
},
{
"family_name": "Thompson",
"given_name": "David R.",
"orcid": "0000-0003-1100-7550",
"clpid": "Thompson-David-R"
},
{
"family_name": "Furlan",
"given_name": "Elise",
"orcid": "0000-0001-9800-6248",
"clpid": "Furlan-Elise"
},
{
"family_name": "Scire",
"given_name": "Elena",
"orcid": "0000-0003-1468-5357",
"clpid": "Scire-Elena"
},
{
"family_name": "Adler",
"given_name": "Judy S.",
"orcid": "0009-0006-7265-2747",
"clpid": "Adler-Judy-S"
},
{
"family_name": "Elkington",
"given_name": "Nicholas"
},
{
"family_name": "Vitkova",
"given_name": "Aria",
"orcid": "0000-0001-9872-7811"
},
{
"family_name": "Temple",
"given_name": "Jon"
},
{
"family_name": "Woodward",
"given_name": "Simon",
"orcid": "0009-0000-7011-9988"
}
],
"abstract": "\n
The Lunar Thermal Mapper (LTM) instrument is a UK Space Agency funded infrared radiometer designed and built for the National Aeronautics and Space Administration Lunar Trailblazer mission launched in February 2025. LTM is a pushbroom imaging filter radiometer with 15 channels that cover the wavelength range from 6.25 to 100 μm with a 40–70 m/pixel ground sampling. Lunar Trailblazer's mission is to understand the form, abundance and distribution of water across the lunar surface. LTM provides an independent measure of temperature to investigate thermal effects on water's mapped distribution as well as an independent measure of surface mineralogy. The LTM instrument's 15 infrared channels include four broadband temperature sensing channels (6.25–12.5, 12.5–25, 25–50 and 50–100 μm) plus 11 additional narrow band (∼40 cm−1) filters from ∼7–10 μm to map and discriminate silicate composition. We review the LTM design and calibration campaign at the University of Oxford's Space Instrumentation facility and show that the instrument has sensitivity from 400 K with a Noise Equivalent Temperature Difference of <0.1 K to <1 K at 110 K for typical integration times (e.g., 30 Hz readout) from a nominal 70–130 km lunar orbit design altitude.
\n
The Lunar Trailblazer mission launched in February of 2025 with the goal of characterizing lunar surface water through a targeted campaign. One instrument on the mission, the Lunar Thermal Mapper (LTM), was tasked with measuring the surface temperature to compare with maps of the form and abundance of water on the lunar surface. LTM's secondary science goals were to identify regolith composition and thermophysical properties as exhibited by mid\u2010infrared spectral features. Here we show the utility of LTM in distinguishing lunar regolith composition with its 11 narrow bands. Five spectral parameter products were developed to aid in early identification of regions of interest for follow\u2010on spectral analyses. These products include the Christiansen feature (CF) value, weighted absorption center (WAC) value, WAC band depth, Transparency Roll\u2010off, and a Diviner CF value equivalent. These products would be used mainly to flag these regions for more detailed follow\u2010up study with the entire spectral capabilities of the mission instrumentation.
",
"doi": "10.1029/2025ea004590",
"issn": "2333-5084",
"publisher": "American Geophysical Union",
"publication": "Earth and Space Science",
"publication_date": "2026-05",
"series_number": "5",
"volume": "13",
"issue": "5",
"pages": "e2025EA004590"
},
{
"id": "authors:vza8e-r7y53",
"collection": "authors",
"collection_id": "vza8e-r7y53",
"cite_using_url": "https://authors.library.caltech.edu/records/vza8e-r7y53",
"type": "article",
"title": "Post-Acquisition Image-Based Localization for High Resolution Thermal and Visible/Shortwave Infrared Images With Application to the Lunar Trailblazer Mission",
"author": [
{
"family_name": "Gauld",
"given_name": "Kevin D.",
"orcid": "0009-0004-2276-2791",
"clpid": "Gauld-Kevin-D"
},
{
"family_name": "Dickson",
"given_name": "James L.",
"orcid": "0000-0003-2090-160X"
},
{
"family_name": "Warren",
"given_name": "Tristam J.",
"orcid": "0000-0003-3877-0046"
},
{
"family_name": "Yang",
"given_name": "Jihoon",
"orcid": "0009-0005-1065-2998",
"clpid": "Yang-Jihoon"
},
{
"family_name": "Bowles",
"given_name": "Neil",
"orcid": "0000-0001-5400-1461"
},
{
"family_name": "Ehlmann",
"given_name": "Bethany L.",
"orcid": "0000-0002-2745-3240",
"clpid": "Ehlmann-B-L"
}
],
"abstract": "The Lunar Trailblazer mission aimed to assess the presence of water on the lunar surface using imaging spectroscopy in visible shortwave infrared (VSWIR) coupled with high-resolution multispectral imaging in thermal midwave-infrared (MWIR), captured simultaneously over the same target from orbit around the Moon with two different instruments. Uncertainties in clock timing, instrument models, and instrument pointing knowledge manifest as geospatial offsets between the two data sets that must be corrected in post-processing to enable co-registration, tying the acquired images to their precise latitudes and longitudes on the Moon. This work describes an algorithmic approach to co-registering and geolocalizing images after acquisition without high precision instrument and spacecraft pointing models, the Iterative Matching Pipeline for Post-Acquisition Image Localization (IMPPAIL), utilizing previously acquired data for development. We use Lunar Orbiter Laser Altimetry (LOLA) and Kaguya data to make shaded relief maps as the basemap on which to project data. To test our processing pipeline prior to Lunar Trailblazer data collection, we use Moon Mineralogy Mapper (M3) data for VSWIR images and simulated MWIR images. When demonstrated on these data sets, IMPPAIL produces a 98% success rate registering VSWIR data to LOLA/Kaguya shaded relief maps and successfully co-registered MWIR and VSWIR in all four simulation cases. We include a code package with software tools allowing this algorithm to be used for a variety of data sets across many other missions.
",
"doi": "10.1029/2025ea004594",
"issn": "2333-5084",
"publisher": "American Geophysical Union",
"publication": "Earth and Space Science",
"publication_date": "2026-05",
"series_number": "5",
"volume": "13",
"issue": "5",
"pages": "e2025EA004594"
},
{
"id": "authors:x3a79-cpg81",
"collection": "authors",
"collection_id": "x3a79-cpg81",
"cite_using_url": "https://authors.library.caltech.edu/records/x3a79-cpg81",
"type": "article",
"title": "Calibration and Performance of the High Resolution Volatiles and Minerals Moon Mapper (HVM\u00b3) on Lunar Trailblazer",
"author": [
{
"family_name": "Thompson",
"given_name": "David R.",
"orcid": "0000-0003-1100-7550"
},
{
"family_name": "Ehlmann",
"given_name": "Bethany L.",
"orcid": "0000-0002-2745-3240",
"clpid": "Ehlmann-B-L"
},
{
"family_name": "Green",
"given_name": "Robert O.",
"orcid": "0000-0001-9447-3076"
},
{
"family_name": "Allen",
"given_name": "Gregory D."
},
{
"family_name": "Bender",
"given_name": "Holly"
},
{
"family_name": "Copley\u2010Woods",
"given_name": "Djuna"
},
{
"family_name": "Eastwood",
"given_name": "Michael"
},
{
"family_name": "Helmlinger",
"given_name": "Mark"
},
{
"family_name": "Hummel",
"given_name": "Christopher"
},
{
"family_name": "Keller",
"given_name": "Jared"
},
{
"family_name": "Klesh",
"given_name": "Andrew"
},
{
"family_name": "McKinley",
"given_name": "Ian"
},
{
"family_name": "Moore",
"given_name": "Bradley D."
},
{
"family_name": "Mouroulis",
"given_name": "Pantazis"
},
{
"family_name": "Nadgauda",
"given_name": "Shriya"
},
{
"family_name": "Sondheim",
"given_name": "Michael"
},
{
"family_name": "Rodriguez",
"given_name": "Jose"
},
{
"family_name": "Sarture",
"given_name": "Charles"
},
{
"family_name": "Seybold",
"given_name": "Calina"
},
{
"family_name": "Singh",
"given_name": "Vritika"
},
{
"family_name": "Smith",
"given_name": "Christopher"
},
{
"family_name": "Sullivan",
"given_name": "Peter"
},
{
"family_name": "Vinckier",
"given_name": "Quentin"
},
{
"family_name": "Williamson",
"given_name": "Walton"
},
{
"family_name": "Zareh",
"given_name": "Shannon Kian G."
},
{
"family_name": "Bowles",
"given_name": "Neil"
},
{
"family_name": "Dapremont",
"given_name": "Angela M.",
"orcid": "0000-0003-0343-7382"
},
{
"family_name": "Donaldson Hanna",
"given_name": "Kerri L.",
"orcid": "0000-0001-5592-4292"
},
{
"family_name": "Edwards",
"given_name": "Christopher S.",
"orcid": "0000-0002-8096-9633"
},
{
"family_name": "Felder",
"given_name": "Emily",
"orcid": "0009-0004-0986-7345"
},
{
"family_name": "Furlan",
"given_name": "Elise",
"orcid": "0000-0001-9800-6248",
"clpid": "Furlan-Elise"
},
{
"family_name": "Gharibian",
"given_name": "Garni"
},
{
"family_name": "Haberle",
"given_name": "Christopher"
},
{
"family_name": "House",
"given_name": "Martha"
},
{
"family_name": "Klima",
"given_name": "Rachel L.",
"orcid": "0000-0002-9151-6429"
},
{
"family_name": "Miura",
"given_name": "Jasper",
"orcid": "0000-0002-2672-2605",
"clpid": "Miura-Jasper"
},
{
"family_name": "Pieters",
"given_name": "Carle",
"orcid": "0000-0003-1671-8415"
},
{
"family_name": "Scire",
"given_name": "Elena",
"orcid": "0000-0003-1468-5357",
"clpid": "Scire-Elena"
},
{
"family_name": "Wilk",
"given_name": "Kierra",
"orcid": "0000-0002-7149-7144"
}
],
"abstract": "This article reports on the initial calibration and performance of the High-resolution Volatiles and Minerals Moon Mapper (HVM³), slated for launch on the National Aeronautics and Space Administration's Lunar Trailblazer mission. HVM³ is an imaging spectrometer measuring from 600 to 3,600 nm with 10-nm spectral sampling and 50–90 m/pixel ground sampling. The mission goal is to understand the form, abundance, and distribution of water across the lunar surface and the lunar water cycle, accomplished by measuring the distinct absorptions of water ice, adsorbed H\u2082O, and OH/hydroxl while controlling for thermal effects with HVM³. HVM³ also has the ability to measure mineralogical composition. HVM³ has been assembled, tested and calibrated in preparation for launch and integrated on the Lunar Trailblazer spacecraft. We review the HVM³ design, calibration process, results, and implications for Lunar Trailblazer science goals. We find HVM³’s radiometric sensitivity is sufficient to confidently measure 1% differences in absorption band strengths under direct solar illumination in single pixel data. In addition, HVM³ has the radiometric precision to discriminate different species of volatile absorptions at irradiances of 1 W m\u207b², which will enable mapping and discriminating water ice or other volatiles within most of the Moon's Permanently Shadowed Regions using terrain-scattered illumination.
",
"doi": "10.1029/2025ea004456",
"issn": "2333-5084",
"publisher": "American Geophysical Union",
"publication": "Earth and Space Science",
"publication_date": "2026-05",
"series_number": "5",
"volume": "13",
"issue": "5",
"pages": "e2025EA004456"
},
{
"id": "authors:bka10-psm67",
"collection": "authors",
"collection_id": "bka10-psm67",
"cite_using_url": "https://authors.library.caltech.edu/records/bka10-psm67",
"type": "article",
"title": "Photometric and Spectral Characterization of Spacecraft Materials With Application to Lunar Trailblazer",
"author": [
{
"family_name": "Steckel",
"given_name": "A. V.",
"orcid": "0000-0003-1345-8240",
"clpid": "Steckel-Amanda-V"
},
{
"family_name": "Ehlmann",
"given_name": "B. L.",
"orcid": "0000-0002-2745-3240",
"clpid": "Ehlmann-B-L"
}
],
"abstract": "If a spacecraft loses contact with Earth, ground\u2010based observatories can collect observations to assist the recovery effort by providing information on spacecraft location and state. Optical observations converted to a light curve of spacecraft magnitude over time show the spin period and/or orientation of the spacecraft. For definitive interpretation, knowledge of the spacecraft's shape and reflectance properties are required. We conducted laboratory measurements of the visible/near\u2010infrared reflectance of common spacecraft materials (multilayer insulation (MLI), bare aluminum, solar cell, coated composite solar panel backing) at different orientations under controlled lighting conditions using a spectrogoniometer to obtain wavelength\u2010dependent characterization of material photometric properties for comparison with ground based optical observations. The materials are representative of the Lunar Trailblazer (LTB) spacecraft, which experienced an anomaly after launch and had several optical observations of the spacecraft collected during the recovery effort. All four materials are dark with reflectances <0.2 in most scattering geometries. We find that the BR\u2010127 coated panel shows a broad forward reflection with a 50x specular peak, aluminum and MLI exhibit strong forward\u2010scattering (>100x specular peak) with a small diffuse component, and the solar cell stands out with sharp specular peaks at the illumination angle together with a strong reflectance near 850–900 nm and a quasi\u2010periodic oscillation. This data set is available to constrain observations of future spacecraft.
",
"doi": "10.1029/2025ea004732",
"issn": "2333-5084",
"publisher": "American Geophysical Union",
"publication": "Earth and Space Science",
"publication_date": "2026-03",
"series_number": "3",
"volume": "13",
"issue": "3",
"pages": "e2025EA004732"
},
{
"id": "authors:rbec6-txz82",
"collection": "authors",
"collection_id": "rbec6-txz82",
"cite_using_url": "https://authors.library.caltech.edu/records/rbec6-txz82",
"type": "article",
"title": "Shortwave Infrared Microimaging Spectroscopy of the Martian Meteorites",
"author": [
{
"family_name": "Miura",
"given_name": "J. K.",
"orcid": "0000-0002-2672-2605",
"clpid": "Miura-Jasper-Kenzo"
},
{
"family_name": "Ehlmann",
"given_name": "B. L.",
"orcid": "0000-0002-2745-3240",
"clpid": "Ehlmann-B-L"
},
{
"family_name": "Greenberger",
"given_name": "R.",
"orcid": "0000-0003-1583-0261",
"clpid": "Greenberger-Rebecca"
},
{
"family_name": "Cutts",
"given_name": "E."
}
],
"abstract": "\n
Until samples from the Martian surface are successfully brought to Earth, meteorites represent the only opportunity to perform laboratory analyses on Martian material. Microimaging spectroscopy of the Martian meteorite suite provides a valuable means to better understand infrared data collected remotely from the Martian surface. This rapid and non-destructive method surveys compositional and textural relationships within and between meteorite samples. We expand upon existing documentation of the spectral variability of the Martian meteorites by presenting a publicly accessible data set of over 1.2 million 1.0–2.5 μm spectra at 250 μm/pixel scale, from 144 imaged faces of 78 pieces of 54 distinctly named Martian meteorites. These meteorites include 2 chassignites, 6 nakhlites, 43 shergottites, 2 polymict breccias and 1 orthopyroxenite. Analysis of the spectral diversity results in the definition of 17 spectral classes on the basis of (a) color properties of the samples in false color with channels identified at spectrally significant wavelengths for mafic mineralogy, (b) a 3-step classification process comprised of a two-step unconstrained (orthogonal) Sequential Maximum Angle Convex Cone endmember extraction, Spectral Angle Mapping, and consolidation of the endmembers and their classified spectra into mineralogically significant groups, (c) band center position of the pyroxene 2 μm absorption, and (d) distribution and abundance of hydration/hydroxylation absorptions at 1.4 and 1.9 μm. Careful inspection of the spectra and processed data reveals compositional textures that are invisible to the naked eye, rare spectral phases, two distinct populations of high-calcium pyroxenes, and evidence of secondary aqueous alteration.
\n
\n
The Lunar Trailblazer smallsat mission High-resolution Volatiles and Minerals Moon Mapper (HVM3) science instrument was designed to acquire targeted spectral image cubes of the lunar surface at visible to shortwave infrared (VSWIR) wavelengths (0.6–3.6 μm) in an effort to understand the distribution, abundance, and form (OH, H2O, ice) of lunar water, as well as the lunar water cycle. The Lunar Trailblazer mission end was declared in July 2025. Here, we describe the formulation and testing of VSWIR spectral parameters in preparation for previously anticipated returned data from HVM3 using global image cubes and mosaic data from the Moon Mineralogy Mapper (M3) imaging spectrometer, HVM3's predecessor, and the Deep Impact spacecraft. We expand upon the existing M3 global spectral parameter library, test the efficacy of presented parameters individually and alongside existing M3 spectral parameters, provide examples of quantitative thresholds intended to indicate robust mineral detections, and discuss the spectral parameter limitations. We demonstrate that newly formulated and existing parameters capture lunar mineral diversity well and serve as a reliable indicator of lunar surface hydration, making them useful for existing and future scientific analysis using lunar orbital remote sensing data sets.
\n
\n
The “Barbarian” L-type asteroids are purported to contain a high abundance of calcium–aluminum inclusions (CAIs), the oldest solar system solids, based on the dominance of the mineral spinel in their near-infrared spectra. We observed a sample of five objects of this class at 5–28 μm with the Medium-Resolution Spectrometer mode of the Mid-Infrared Instrument on the James Webb Space Telescope. The spectra indicate high-porosity (85%–97% porosity) particulate regolith (<30 μm particles) made up of Mg-rich crystalline olivine (Fo 80–100), with an additional component that could be spinel or amorphous olivine. The spectra of these objects closely resemble that of the oxidized CV3 chondrite Allende. The asteriod spectra additionally exhibit features at 5.75, 6.2, and 7.55 μm that are not definitively identified but may arise from infall of C-bearing materials. These data complement existing visible to near-infrared data of the same targets, which indicate the presence of spinel and minimal hydroxylation, demonstrating the value of multiwavelength spectroscopy to get a more complete picture of the surface compositions of asteroids. The multiwavelength data consistently demonstrate a strong resemblance between the L-type asteroids and CV3 (or possibly CO3) chondrites. The spectra do not require an enhancement in CAI content above that of CV3 chondrites, but the lack of laboratory data prevents a quantitative constraint on CAI content for now. The dominance of crystalline olivine with a high Mg/Fe ratio, and minimal evidence for hydration suggest either an anhydrous formation in the inner solar system, or formation in the outer solar system followed by high-temperature alteration and dehydration.
\n
\n
Primitive asteroids and carbonaceous chondrites (CCs) record the history of processes in the early solar system. Visible and shortwave infrared (VSWIR) spectroscopy of primitive asteroids and bulk-powdered CCs has identified shared spectral features suggestive of shared parent body origins. However, bulk powder CC spectra are spatially unresolved and destroy textures, which hinders tying shared spectral features to particular phases, petrologic contexts, and alteration histories. This study analyzes 20 CCs measured using microimaging hyperspectral VSWIR spectroscopy, recording over 700,000 individual spectra at the ∼80 μm/pixel scale. We compare CC spectral features with asteroids using the Expanded Bus-DeMeo taxonomy. We introduce a spectral processing pipeline using Savitzky-Golay filtering to better capture subtle spectral features, reduce noise and enhance comparisons between asteroid classes and CC subgroups and constituent phases. Key findings include a close spectral match between CM chondrites and Cgh-class asteroids, as well as between CV3 chondrites and L-class asteroids. Unaltered, iron-bearing silicate CC components are similar to “stony” asteroid spectral classes. Furthermore, taxonomy-based separation of CC spectra also identifies features unique to CCs, for example, oxidized iron signatures in CR2 chondrite NWA 7502 and other samples indicative of terrestrial weathering. Together these CC data show that primary and secondary Fe-bearing minerals drive the separations in the asteroid classes expressed in the Expanded Bus-DeMeo taxonomy. These findings also underscore the value of microimaging spectroscopy and statistically motivated frameworks in conducting larger surveys to interrogate the shared record of alteration in the early solar system. The data set is released for further study.
\n
\n
CM (Mighei-type) carbonaceous chondrites host abundant OH/H2O-bearing phyllosilicates formed from water-rock reactions in primitive planetesimals. Their infrared (IR) spectral features resemble those of C-type asteroids, making laboratory analyses of CMs essential for interpreting asteroid observations. However, CM chondrites are often breccias composed of lithologies with variable degrees of aqueous alteration, complicating their interpretation. Here we use in situ analytical techniques to characterize spectral-compositional relationships for phyllosilicates in 8 CM lithologies across two meteorite samples. Micro-Fourier Transform Infrared (μ-FTIR) spectra collected from phyllosilicate-rich matrix regions show that band positions of the 3-μm feature and Si-O stretch Reststrahlen band (RB) systematically vary with alteration. Additional data from spatially correlated electron microprobe and μ-FTIR measurements tie spectral variations to specific cation substitutions in serpentines: the 3-μm feature shifts from 2.78 to 2.70 μm with increased Mg/Fe in octahedral sites, and the Si-O stretch RB shifts from 10.8 to 9.8 μm with increased Si/Fe3+ in tetrahedral sites. Co-variation of these features across the studied CM lithologies defines two successive alteration stages: (1) the Si-O stretch RB and 3-μm feature shift to longer and shorter wavelengths, respectively, as Mg- and cronstedtite-rich phyllosilicates form from incipient chondrule alteration; (2) Si-O stretch RB shifts to shorter wavelengths as Mg-serpentines replace cronstedtite and Mg-rich chondrules. These patterns align with inferred changes in composition and redox state for altering fluids on the CM parent body. Similar features in the spectra of C-type asteroids may reveal information about conditions of aqueous alteration and constrain models of their evolution.
\n
JWST's MIRI LRS provides the first opportunity to spectroscopically characterize the surface compositions of close-in terrestrial exoplanets. Models for the bare-rock spectra of these planets often utilize a spectral library from R. Hu et al., which is based on room-temperature reflectance measurements of materials that represent archetypes of rocky planet surfaces. Here we present an expanded library that includes hemispherical reflectance measurements for a greater variety of compositions, varying textures (solid slab, coarsely crushed, and fine powder), as well as high-temperature (500–800 K) emissivity measurements for select samples. We incorporate this new library into version 6.3 of the open-source retrieval package PLATON and use it to show that planetary surfaces with similar compositions can have widely varying albedos and surface temperatures. We additionally demonstrate that changing the texture of a material can significantly alter its albedo, making albedo a poor proxy for surface composition. We identify key spectral features—the 5.6 μm olivine feature, the transparency feature, the Si-O stretching feature, and the Christiansen feature—that indicate silicate abundance and surface texture. We quantify the number of JWST observations needed to detect these features in the spectrum of the most favorable super-Earth target, LHS 3844 b, and revisit the interpretation of its Spitzer photometry. Lastly, we show that temperature-dependent changes in spectral features are likely undetectable at the precision of current exoplanet observations. Our results illustrate the importance of spectroscopically resolved thermal emission measurements, as distinct from surface albedo constraints, for characterizing the surface compositions of hot, rocky exoplanets.
",
"doi": "10.3847/1538-4357/ada9eb",
"issn": "0004-637X",
"publisher": "American Astronomical Society",
"publication": "Astrophysical Journal",
"publication_date": "2025-03-10",
"series_number": "2",
"volume": "981",
"issue": "2",
"pages": "130"
},
{
"id": "authors:wq6e8-att05",
"collection": "authors",
"collection_id": "wq6e8-att05",
"cite_using_url": "https://authors.library.caltech.edu/records/wq6e8-att05",
"type": "article",
"title": "Episodic warm climates on early Mars primed by crustal hydration",
"author": [
{
"family_name": "Adams",
"given_name": "Danica",
"orcid": "0000-0001-9897-9680",
"clpid": "Adams-Danica-J"
},
{
"family_name": "Scheucher",
"given_name": "Markus"
},
{
"family_name": "Hu",
"given_name": "Renyu",
"orcid": "0000-0003-2215-8485",
"clpid": "Hu-Renyu"
},
{
"family_name": "Ehlmann",
"given_name": "Bethany",
"orcid": "0000-0002-2745-3240",
"clpid": "Ehlmann-B-L"
},
{
"family_name": "Thomas",
"given_name": "Trent B.",
"orcid": "0000-0003-2457-2890"
},
{
"family_name": "Wordsworth",
"given_name": "Robin",
"orcid": "0000-0003-1127-8334"
},
{
"family_name": "Scheller",
"given_name": "Eva"
},
{
"family_name": "Lillis",
"given_name": "Rob"
},
{
"family_name": "Smith",
"given_name": "Kayla"
},
{
"family_name": "Rauer",
"given_name": "Heike"
},
{
"family_name": "Yung",
"given_name": "Yuk L.",
"orcid": "0000-0002-4263-2562",
"clpid": "Yung-Y-L"
}
],
"abstract": "Geological records indicate that the surface of ancient Mars harboured substantial volumes of liquid water, a resource gradually diminished by processes such as the chemical alteration of crustal materials by hydration and atmospheric escape. However, how a relatively warm climate existed on early Mars to support liquid water under a fainter young Sun is debated. Greenhouse gases such as H2 in a CO2-rich atmosphere could have contributed to warming through collision-induced absorption, but whether sufficient H2 was available to sustain warming remains unclear. Here we use a combined climate and photochemical model to simulate how atmospheric chemistry on early Mars responded to water–rock reactions and climate variations, as constrained by existing observations. We find that H2 outgassing from crustal hydration and oxidation, supplemented by transient volcanic activity, could have generated sufficient H2 fluxes to transiently foster warm, humid climates. We estimate that Mars experienced episodic warm periods of an integrated duration of ~40 million years, with each event lasting ≥105 years, consistent with the formation timescale of valley networks. Declining atmospheric CO2 via surface oxidant sinks or variations in the planet’s axial tilt could have led to abrupt shifts in the planet’s redox state and transition to a CO-dominated atmosphere and cold climate.
",
"doi": "10.1038/s41561-024-01626-8",
"issn": "1752-0894",
"publisher": "Nature Publishing Group",
"publication": "Nature Geoscience",
"publication_date": "2025-02",
"series_number": "2",
"volume": "18",
"issue": "2",
"pages": "133-139"
},
{
"id": "authors:ys33m-22y21",
"collection": "authors",
"collection_id": "ys33m-22y21",
"cite_using_url": "https://authors.library.caltech.edu/records/ys33m-22y21",
"type": "article",
"title": "Inorganic interpretation of luminescent materials encountered by the Perseverance rover on Mars",
"author": [
{
"family_name": "Scheller",
"given_name": "Eva L.",
"orcid": "0000-0002-9981-5802"
},
{
"family_name": "Bosak",
"given_name": "Tanja",
"orcid": "0000-0001-5179-5323"
},
{
"family_name": "McCubbin",
"given_name": "Francis M.",
"orcid": "0000-0002-2101-4431"
},
{
"family_name": "Williford",
"given_name": "Kenneth",
"orcid": "0000-0003-0633-408X"
},
{
"family_name": "Siljestr\u00f6m",
"given_name": "Sandra",
"orcid": "0000-0002-4975-6074"
},
{
"family_name": "Jakubek",
"given_name": "Ryan S.",
"orcid": "0000-0001-7880-9422"
},
{
"family_name": "Eckley",
"given_name": "Scott A.",
"orcid": "0000-0002-2692-2164"
},
{
"family_name": "Morris",
"given_name": "Richard V.",
"orcid": "0000-0003-1413-4002"
},
{
"family_name": "Bykov",
"given_name": "Sergei V.",
"orcid": "0000-0002-6161-0027"
},
{
"family_name": "Kizovski",
"given_name": "Tanya",
"orcid": "0000-0001-8188-9769"
},
{
"family_name": "Asher",
"given_name": "Sanford",
"orcid": "0000-0003-1061-8747"
},
{
"family_name": "Berger",
"given_name": "Eve",
"orcid": "0000-0002-9902-439X"
},
{
"family_name": "Bower",
"given_name": "Dina M.",
"orcid": "0000-0002-4275-1318"
},
{
"family_name": "Cardarelli",
"given_name": "Emily L.",
"orcid": "0000-0001-5451-2309"
},
{
"family_name": "Ehlmann",
"given_name": "Bethany L.",
"orcid": "0000-0002-2745-3240",
"clpid": "Ehlmann-B-L"
},
{
"family_name": "Fornaro",
"given_name": "Teresa",
"orcid": "0000-0001-7705-9658"
},
{
"family_name": "Fox",
"given_name": "Allison",
"orcid": "0000-0002-5952-4170"
},
{
"family_name": "Haney",
"given_name": "Nikole",
"orcid": "0000-0001-5405-3616"
},
{
"family_name": "Hand",
"given_name": "Kevin",
"orcid": "0000-0002-3225-9426",
"clpid": "Hand-Kevin"
},
{
"family_name": "Roppel",
"given_name": "Ryan",
"orcid": "0000-0002-1782-1388"
},
{
"family_name": "Sharma",
"given_name": "Sunanda",
"orcid": "0000-0001-8822-7960",
"clpid": "Sharma-Sunanda"
},
{
"family_name": "Steele",
"given_name": "Andrew",
"orcid": "0000-0001-9643-2841"
},
{
"family_name": "Uckert",
"given_name": "Kyle",
"orcid": "0000-0002-0859-5526",
"clpid": "Uckert-Kyle"
},
{
"family_name": "Yanchilina",
"given_name": "Anastasia G.",
"orcid": "0000-0003-3782-6343"
},
{
"family_name": "Beyssac",
"given_name": "Olivier"
},
{
"family_name": "Farley",
"given_name": "Kenneth A.",
"orcid": "0000-0002-7846-7546",
"clpid": "Farley-K-A"
},
{
"family_name": "Henneke",
"given_name": "Jesper",
"orcid": "0000-0002-3195-7417"
},
{
"family_name": "Heirwegh",
"given_name": "Chris",
"orcid": "0009-0002-8234-7288",
"clpid": "Heirwegh-Chris"
},
{
"family_name": "Pedersen",
"given_name": "David A. K."
},
{
"family_name": "Liu",
"given_name": "Yang",
"orcid": "0000-0003-0308-0942",
"clpid": "Liu-Yang"
},
{
"family_name": "Schmidt",
"given_name": "Mariek E.",
"orcid": "0000-0003-4793-7899"
},
{
"family_name": "Sephton",
"given_name": "Mark",
"orcid": "0000-0002-2190-5402"
},
{
"family_name": "Shuster",
"given_name": "David",
"orcid": "0000-0003-2507-9977"
},
{
"family_name": "Weiss",
"given_name": "Benjamin P.",
"orcid": "0000-0003-3113-3415"
}
],
"abstract": "A major objective of the Mars 2020 mission is to sample rocks in Jezero crater that may preserve organic matter for later return to Earth. Using an ultraviolet Raman and luminescence spectrometer, the Perseverance rover detected luminescence signals with maximal intensities at 330 to 350 nanometers and 270 to 290 nanometers that were initially reported as consistent with organics. Here, we test the alternative hypothesis that the 330- to 350-nanometer and 270- to 290-nanometer luminescence signals trace Ce3+ in phosphate and silicate defects, respectively. By comparing the distributions of luminescence signals with the rover detections of x-ray fluorescence from P2O5 and Si-bearing materials, we show that, while an organic origin is not excluded, the observed luminescence can be explained by purely inorganic materials. These findings highlight the importance of eventual laboratory analyses to detect and characterize organic compounds in the returned samples.
",
"doi": "10.1126/sciadv.adm8241",
"pmcid": "PMC11423895",
"issn": "2375-2548",
"publisher": "American Association for the Advancement of Science",
"publication": "Science Advances",
"publication_date": "2024-09-25",
"series_number": "39",
"volume": "10",
"issue": "39",
"pages": "eadm8241"
},
{
"id": "authors:1k6kh-fjs61",
"collection": "authors",
"collection_id": "1k6kh-fjs61",
"cite_using_url": "https://authors.library.caltech.edu/records/1k6kh-fjs61",
"type": "monograph",
"title": "The Mysterious Interior of Uranus: Final Report of the 2023 KISS Study",
"author": [
{
"family_name": "Hofstadter",
"given_name": "Mark David",
"orcid": "0000-0002-3208-3918",
"clpid": "Hofstadter-M-D"
},
{
"family_name": "Helled",
"given_name": "Ravit"
},
{
"family_name": "Stevenson",
"given_name": "David J.",
"orcid": "0000-0001-9432-7159",
"clpid": "Stevenson-D-J"
},
{
"family_name": "Ehlmann",
"given_name": "Bethany",
"orcid": "0000-0002-2745-3240",
"clpid": "Ehlmann-B-L"
}
],
"abstract": "Determining the internal structure of Uranus is a key objective for planetary science. Knowledge of Uranus’s bulk composition and the distribution of elements is crucial to understanding its origin and evolutionary path. In addition, Uranus represents a poorly understood class of “intermediate-mass planets” (intermediate in size between the relatively well studied terrestrial and gas giant planets), which appear to be very common in the Galaxy. As a result, a better characterization of Uranus will also help us to better understand exoplanets in this mass and size regime.
\n
Recognizing the importance of Uranus, a Keck Institute for Space Studies (KISS) workshop was held in September 2023 to investigate how we can improve our knowledge of Uranus’s internal structure in the context of a future Uranus mission that includes an orbiter and a probe. The scientific goals and objectives of the recently released Planetary Science and Astrobiology Decadal Survey were taken as our starting point. We reviewed our current knowledge of Uranus’s interior and identified measurement and other mission requirements for a future Uranus spacecraft, providing more detail than was possible in the Decadal Survey’s mission study and including new insights into the measurements to be made. We also identified important
knowledge gaps to be closed with Earth-based efforts in the near term that will help guide the design of the mission and interpret the data returned.
\n
Our report focuses on the following topics:
• Uranus’s atmosphere (noble gas, elemental, and molecular abundances and the pressure-temperature profile)
• Its gravity field and interior models
• The planet’s magnetic field, heat flux, and energy balance
• The potential for Uranian seismology
\nIn the words of the Decadal Survey, the Uranus Flagship mission can produce “transformative, breakthrough science across a broad range of topics.” We argue that to fulfill its promise, great progress should be made in terms of mission design, theoretical calculations, numerical modeling, experiments, ground-based observations, and bringing communities together to plan the mission and interpret the data it returns.
",
"doi": "10.7907/1k6kh-fjs61",
"publisher": "Keck Institute for Space Studies",
"publication_date": "2024-09-03"
},
{
"id": "authors:h6pv6-fhf02",
"collection": "authors",
"collection_id": "h6pv6-fhf02",
"cite_using_url": "https://authors.library.caltech.edu/records/h6pv6-fhf02",
"type": "article",
"title": "The CRISM investigation in Mars orbit: Overview, history, and delivered data products",
"author": [
{
"family_name": "Seelos",
"given_name": "Frank P.",
"orcid": "0000-0001-9721-941X"
},
{
"family_name": "Seelos",
"given_name": "Kimberly D.",
"orcid": "0000-0001-7236-0580"
},
{
"family_name": "Murchie",
"given_name": "Scott L.",
"orcid": "0000-0002-1616-8751"
},
{
"family_name": "Novak",
"given_name": "M. Alexandra Matiella"
},
{
"family_name": "Hash",
"given_name": "Christopher D."
},
{
"family_name": "Morgan",
"given_name": "M. Frank"
},
{
"family_name": "Arvidson",
"given_name": "Raymond E.",
"orcid": "0000-0002-2854-0362"
},
{
"family_name": "Aiello",
"given_name": "John"
},
{
"family_name": "Bibring",
"given_name": "Jean-Pierre"
},
{
"family_name": "Bishop",
"given_name": "Janice L."
},
{
"family_name": "Boldt",
"given_name": "John D."
},
{
"family_name": "Boyd",
"given_name": "Ariana R."
},
{
"family_name": "Buczkowski",
"given_name": "Debra L.",
"orcid": "0000-0002-4729-7804"
},
{
"family_name": "Chen",
"given_name": "Patrick Y."
},
{
"family_name": "Clancy",
"given_name": "R. Todd",
"orcid": "0000-0002-2673-9992"
},
{
"family_name": "Ehlmann",
"given_name": "Bethany L.",
"orcid": "0000-0002-2745-3240",
"clpid": "Ehlmann-B-L"
},
{
"family_name": "Frizzell",
"given_name": "Katelyn",
"orcid": "0000-0002-6103-0057"
},
{
"family_name": "Hancock",
"given_name": "Katie M."
},
{
"family_name": "Hayes",
"given_name": "John R."
},
{
"family_name": "Heffernan",
"given_name": "Kevin J."
},
{
"family_name": "Humm",
"given_name": "David C.",
"orcid": "0000-0003-1520-261X"
},
{
"family_name": "Itoh",
"given_name": "Yuki"
},
{
"family_name": "Ju",
"given_name": "Maggie"
},
{
"family_name": "Kochte",
"given_name": "Mark C."
},
{
"family_name": "Malaret",
"given_name": "Erick"
},
{
"family_name": "McGovern",
"given_name": "J. Andrew"
},
{
"family_name": "McGuire",
"given_name": "Patrick",
"orcid": "0000-0001-6592-4966"
},
{
"family_name": "Mehta",
"given_name": "Nishant L."
},
{
"family_name": "Moreland",
"given_name": "Eleanor L.",
"orcid": "0000-0003-0210-7576"
},
{
"family_name": "Mustard",
"given_name": "John F.",
"orcid": "0000-0003-2509-0287"
},
{
"family_name": "Nair",
"given_name": "A. Hari"
},
{
"family_name": "N\u00fa\u00f1ez",
"given_name": "Jorge I.",
"orcid": "0000-0003-0930-6674"
},
{
"family_name": "O'Sullivan",
"given_name": "Joseph A."
},
{
"family_name": "Packer",
"given_name": "Liam L."
},
{
"family_name": "Poffenbarger",
"given_name": "Ryan T."
},
{
"family_name": "Poulet",
"given_name": "Francois"
},
{
"family_name": "Romeo",
"given_name": "Giuseppe"
},
{
"family_name": "Santo",
"given_name": "Andrew G."
},
{
"family_name": "Smith",
"given_name": "Michael D."
},
{
"family_name": "Stephens",
"given_name": "David C."
},
{
"family_name": "Toigo",
"given_name": "Anthony D."
},
{
"family_name": "Viviano",
"given_name": "Christina E.",
"orcid": "0000-0003-1601-2105"
},
{
"family_name": "Wolff",
"given_name": "Michael J."
}
],
"abstract": "The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on the Mars Reconnaissance Orbiter (MRO) collected hyperspectral images of the Martian surface and atmosphere from September 27, 2006, through May 7, 2022. Over that time, nearly twenty scientific investigations were completed, most of which arose as a result of the findings from previous investigations. Two review papers published in 2009 (Murchie et al., 2009a, b) described the initial two-year investigation during MRO's Primary Science Phase, its key findings, and the CRISM data products that were developed and released to the community through that time. Here we describe the conduct and evolution of the CRISM investigation since then, which includes MRO's Extended Science Phase and first five Extended Missions. We document the physical changes in the instrument as it aged, including capabilities that were lost as well as new modes of operation not initially envisioned; the new science questions that were investigated and their key findings; anatomy of the extensive collection of data products that have been released to the Planetary Data System; the \"final\" radiometric calibration; high-order derived products produced from high-resolution targeted observations and global mapping campaigns; and data processing and analysis tools which have been developed and released by the CRISM team.",
"doi": "10.1016/j.icarus.2023.115612",
"issn": "0019-1035",
"publisher": "Elsevier",
"publication": "Icarus",
"publication_date": "2024-09-01",
"volume": "419",
"pages": "115612"
},
{
"id": "authors:21131-8bt66",
"collection": "authors",
"collection_id": "21131-8bt66",
"cite_using_url": "https://authors.library.caltech.edu/records/21131-8bt66",
"type": "article",
"title": "Characterization of the particle size distribution, mineralogy, and Fe mode of occurrence of dust-emitting sediments from the Mojave Desert, California, USA",
"author": [
{
"family_name": "Gonz\u00e1lez-Romero",
"given_name": "Adolfo",
"orcid": "0000-0003-0977-6019"
},
{
"family_name": "Gonz\u00e1lez-Fl\u00f3rez",
"given_name": "Cristina",
"orcid": "0000-0002-3603-3088"
},
{
"family_name": "Panta",
"given_name": "Agnesh",
"orcid": "0000-0002-7953-8334"
},
{
"family_name": "Yus-D\u00edez",
"given_name": "Jes\u00fas",
"orcid": "0000-0002-8124-1492"
},
{
"family_name": "C\u00f3rdoba",
"given_name": "Patricia",
"orcid": "0000-0003-0596-4354"
},
{
"family_name": "Alastuey",
"given_name": "Andres",
"orcid": "0000-0002-5453-5495"
},
{
"family_name": "Moreno",
"given_name": "Natalia",
"orcid": "0000-0003-1488-2561"
},
{
"family_name": "Hern\u00e1ndez-Chiriboga",
"given_name": "Melani"
},
{
"family_name": "Kandler",
"given_name": "Konrad",
"orcid": "0000-0002-8268-6557"
},
{
"family_name": "Klose",
"given_name": "Martina",
"orcid": "0000-0001-8190-3700"
},
{
"family_name": "Clark",
"given_name": "Roger N.",
"orcid": "0000-0002-7021-1220"
},
{
"family_name": "Ehlmann",
"given_name": "Bethany L.",
"orcid": "0000-0002-2745-3240",
"clpid": "Ehlmann-B-L"
},
{
"family_name": "Greenberger",
"given_name": "Rebecca N.",
"orcid": "0000-0003-1583-0261",
"clpid": "Greenberger-Rebecca-N"
},
{
"family_name": "Keebler",
"given_name": "Abigail M.",
"clpid": "Keebler-Abigail-M"
},
{
"family_name": "Brodrick",
"given_name": "Phil",
"orcid": "0000-0001-9497-7661",
"clpid": "Brodrick-Philip-G"
},
{
"family_name": "Green",
"given_name": "Robert",
"orcid": "0000-0001-9447-3076",
"clpid": "Green-Robert-O"
},
{
"family_name": "Ginoux",
"given_name": "Paul",
"orcid": "0000-0003-3642-2988"
},
{
"family_name": "Querol",
"given_name": "Xavier",
"orcid": "0000-0002-6549-9899"
},
{
"family_name": "P\u00e9rez Garc\u00eda-Pando",
"given_name": "Carlos",
"orcid": "0000-0002-4456-0697"
}
],
"abstract": "\n
\n
Constraining dust models to understand and quantify the effect of dust upon climate and ecosystems requires comprehensive analyses of the physiochemical properties of dust-emitting sediments in arid regions. Building upon previous studies in the Moroccan Sahara and Iceland, we analyse a diverse set of crusts and aeolian ripples (n=55) from various potential dust-emitting basins within the Mojave Desert, California, USA. Our focus is on characterizing the particle size distribution (PSD), mineralogy, aggregation/cohesion state, and Fe mode of occurrence. Our results show differences in fully and minimally dispersed PSDs, with crusts exhibiting average median diameters of 92 and 37 µm, respectively, compared to aeolian ripples with 226 and 213 µm, respectively. Mineralogical analyses unveiled strong variations between crusts and ripples, with crusts being enriched in phyllosilicates (24 % vs. 7.8 %), carbonates (6.6 % vs. 1.1 %), Na salts (7.3 % vs. 1.1 %), and zeolites (1.2 % and 0.12 %) and ripples being enriched in feldspars (48 % vs. 37 %), quartz (32 % vs. 16 %), and gypsum (4.7 % vs. 3.1 %). The size fractions from crust sediments display a homogeneous mineralogy, whereas those of aeolian ripples display more heterogeneity, mostly due to different particle aggregation. Bulk Fe content analyses indicate higher concentrations in crusts (3.0 ± 1.3 wt %) compared to ripples (1.9 ± 1.1 wt %), with similar proportions in their Fe mode of occurrence: nano-sized Fe oxides and readily exchangeable Fe represent ∼1.6 %, hematite and goethite ∼15 %, magnetite/maghemite ∼2.0 %, and structural Fe in silicates ∼80 % of the total Fe. We identified segregation patterns in the PSD and mineralogy differences in Na salt content within the Mojave basins, which can be explained by sediment transportation dynamics and precipitates due to groundwater table fluctuations described in previous studies in the region. Mojave Desert crusts show similarities with previously sampled crusts in the Moroccan Sahara in terms of the PSD and readily exchangeable Fe yet exhibit substantial differences in mineralogical composition, which should significantly influence the characteristic of the emitted dust particles.
\n
\n
\n
The Mars 2020 Perseverance rover has explored fluvio-lacustrine sedimentary rocks within Jezero crater. Prior work showed that igneous crater floor Séítah and Máaz formations have mafic mineralogy with alteration phases that indicate multiple episodes of aqueous alteration. In this work, we extend the analyses of hydration to targets in the Jezero western fan delta, using data from the SHERLOC (Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals) Raman spectrometer. Spectral features, for example, sulfate and hydration peak positions and shapes, vary within, and across the crater floor and western fan. The proportion of targets with hydration associated with sulfates was approximately equal in the crater floor and the western fan. All hydrated targets in the crater floor and upper fan showed bimodal hydration peaks at ∼3,200 and ∼3,400 cm−1. The sulfate symmetric stretch at ∼1,000 cm−1 coupled with a hydration peak at ∼3,400 cm−1 indicate that MgSO4·nH2O (2 < n ≤ 5) is a likely hydration carrier phase in all units, perhaps paired with low-hydration (n ≤ 1) amorphous Mg-sulfates, indicated by the ∼3,200 cm−1 peak. Low-hydration MgSO4·nH2O (n = 1–2) are more prevalent in the fan, and hydrated targets in the fan front only had one peak at ∼3,400 cm−1. While anhydrite co-occurs with hydrated Mg-sulfates in the crater floor and fan front, hydrated Ca-sulfates are observed instead at the top of the upper fan. Collectively, the data imply aqueous deposition of sediments with formation of salts from high ionic strength fluids and subsequent aridity to preserve the observed hydration states.
\n
\n
The Mars Reconnaissance Orbiter and its Context Camera (CTX) have acquired more than 100,000 separate panchromatic images that capture nearly the entire surface of Mars at ∼5–6 m/pixel. This paper describes a data processing workflow used to generate the first contiguous global mosaic of CTX data, which represents a large improvement in spatial resolution over existing 100 m/pixel contiguous global mosaics. We describe the overarching strategy for the mosaic's construction, which was to maximize the scientific utility of a continuous mosaic that is 5.7 trillion pixels in size. The pipeline used for data processing prioritized traceability and reproducibility of the final mosaic, such that the provenance of all pixels is reported, equipping scientists with information to differentiate mosaic artifacts from surface landforms and to incorporate critical image metadata into their analyses. The CTX data set synthesized into a global CTX mosaic facilitates ready analysis and provides a new capability in transitioning global studies of Mars from high-resolution investigations of individual images to systematic studies of the entire Martian surface at outcrop-resolving quality without regard to image boundaries.
\n
\n
\n
Characterising the physico-chemical properties of dust-emitting sediments in arid regions is fundamental to understanding the effects of dust on climate and ecosystems. However, knowledge regarding high-latitude dust (HLD) remains limited. This study focuses on analysing the particle size distribution (PSD), mineralogy, cohesion, iron (Fe) mode of occurrence, and visible–near infrared (VNIR) reflectance spectra of dust-emitting sediments from dust hotspots in Iceland (HLD region). Extensive analysis was conducted on samples of top sediments, sediments, and aeolian ripples collected from seven dust sources, with particular emphasis on the Jökulsá basin, encompassing the desert of Dyngjunsandur. Both fully and minimally dispersed PSDs and their respective mass median particle diameters revealed remarkable similarities (56 ± 69 and 55 ± 62 µm, respectively). Mineralogical analyses indicated the prevalence of amorphous phases (68 ± 26 %), feldspars (17 ± 13 %), and pyroxenes (9.3 ± 7.2 %), consistent with thorough analyses of VNIR reflectance spectra. The Fe content reached 9.5 ± 0.40 wt %, predominantly within silicate structures (80 ± 6.3 %), complemented by magnetite (16 ± 5.5 %), hematite/goethite (4.5 ± 2.7 %), and readily exchangeable Fe ions or Fe nano-oxides (1.6 ± 0.63 %). Icelandic top sediments exhibited coarser PSDs compared to the high dust-emitting crusts from mid-latitude arid regions, distinctive mineralogy, and a 3-fold bulk Fe content, with a significant presence of magnetite. The congruence between fully and minimally dispersed PSDs underscores reduced particle aggregation and cohesion of Icelandic top sediments, suggesting that aerodynamic entrainment of dust could also play a role upon emission in this region, alongside saltation bombardment. The extensive analysis in Dyngjusandur enabled the development of a conceptual model to encapsulate Iceland's rapidly evolving high dust-emitting environments.
\n
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Ground-based observations of \"Barbarian\" L-type asteroids at 1–2.5 μm indicate that their near-infrared spectra are dominated by the mineral spinel, which has been attributed to a high abundance of calcium-aluminum inclusions (CAIs)—the first solids to condense out of the protoplanetary disk during the formation of the solar system. However, the spectral properties of these asteroids from 2.5–5 μm, a wavelength region that covers signatures of hydrated minerals, water, and organics, have not yet been explored. Here, we present 2–5 μm reflectance spectra of five spinel-rich asteroids obtained with the NIRSpec instrument on the James Webb Space Telescope. All five targets exhibit a ∼2.85 μm absorption feature with a band depth of 3%–6% that appears correlated in strength with that of the 2 μm spinel absorption feature. The shape and position of the 2.85 μm feature are not a good match to the 2.7 μm feature commonly seen in carbonaceous CM meteorites or C-type asteroids. The closest spectral matches are to the Moon and Vesta, suggesting commonalities in aqueous alteration across silicate bodies, infall of hydrated material, and/or space weathering by solar wind H implantation. Lab spectra of CO/CV chondrites, CAIs, as well as the minerals cronstedtite and spinel, also show a similar feature, providing clues into the origin of the 2.85 μm feature.
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We reassessed several orbital topographic data sets for the Perseverance rover landing site at Jezero Crater, Mars to better understand its floor units. Tens-of-meters deep topographic anomalies occur in the volcanic floor of Jezero crater and are not a result of impact cratering. Eight km-scale steep escarpment-bounded depressions may be locations of paleotopographic highs that were embayed by the volcanic floor lava flows, forming inverted topography from either contemporaneous upward inflation of embaying lavas or later deep scour due to differential erosion over 107−9 years. Five multi km-scale shallow-sloped depressions linked by channel-like forms may record locations of buried paleolakes and channels that predate the volcanic floor units or a drained magma system. These results indicate Jezero experienced multiple closed-basin or dry phases, allowing erosion of the crater floor and creation of topography, which provides new geologic context for the samples gathered by Perseverance.
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Sulfur plays a major role in martian geochemistry and sulfate minerals are important repositories of water. However, their hydration states on Mars are poorly constrained. Therefore, understanding the hydration and distribution of sulfate minerals on Mars is important for understanding its geologic, hydrologic, and atmospheric evolution as well as its habitability potential. NASA's Perseverance rover is currently exploring the Noachian-age Jezero crater, which hosts a fan-delta system associated with a paleolake. The crater floor includes two igneous units (the Séítah and Máaz formations), both of which contain evidence of later alteration by fluids including sulfate minerals. Results from the rover instruments Scanning Habitable Environments with Raman and Luminescence for Organics and Chemistry and Planetary Instrument for X-ray Lithochemistry reveal the presence of a mix of crystalline and amorphous hydrated Mg-sulfate minerals (both MgSO4·[3–5]H2O and possible MgSO4·H2O), and anhydrous Ca-sulfate minerals. The sulfate phases within each outcrop may have formed from single or multiple episodes of water activity, although several depositional events seem likely for the different units in the crater floor. Textural and chemical evidence suggest that the sulfate minerals most likely precipitated from a low temperature sulfate-rich fluid of moderate pH. The identification of approximately four waters puts a lower constraint on the hydration state of sulfate minerals in the shallow subsurface, which has implications for the martian hydrological budget. These sulfate minerals are key samples for future Mars sample return.
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