TP6
modeling that help to understand processes at past, present or future landing sites.
Session assets
1. Introduction
The Mars Environmental Dynamics Analyzer (MEDA) instrument onboard the Mars 2020 Perseverance rover [1] has been measuring the environmental conditions at Jezero Crater for over 1450 sols since landing, covering from Ls ~ 5° in MY 36 to Ls ~ 70° in MY 38, and it continues to operate. Here we detail MEDA’s evolving measurement strategy under changing resource constraints, describe sensor performance, and present processed data through sol 1450.
2. MEDA Measurement Strategy
MEDA’s daily measurement cadence has varied throughout the mission in response to available resources (Fig. 1). Until sol 1116, MEDA followed a nominal cadence of 1h-and-5' blocks starting at odd hours on odd sols, and even hours on even sols, with 3 to 4 SkyCam images per sol. Additional blocks were added when resources allowed. During each block, MEDA sensors operated at 1 Hz, although some sensors occasionally recorded at 2 Hz.
Figure 1. Temporal coverage through sol 1450.
A reduced cadence was implemented from sol 1197 to 1319, consisting of 5’ or 10' blocks at the start of each hour, 1 Hz sampling, and 2 SkyCam images per sol. Beginning on sol 1320, and due to Wind Sensor (WS) degradation from sand abrasion, a new nominal cadence was adopted with 30’ blocks covering hh:00-hh:30 on even sols, and hh:30-hh:00 on odd sols, two additional 30’ floating blocks to support science activities, and 2 SkyCam images. Under this cadence, the WS is only active for 15’ every 2h for a total of 4h per sol, while the Atmospheric Temperature Sensor (ATS), Thermal Infrared Sensor (TIRS), Pressure Sensor (PS), Humidity Sensor (HS), and Radiation and Dust Sensor (RDS) operate 13h per sol.
3. Sensor Performance
All MEDA sensors are operating nominally except for the WS, which has suffered progressive damage from saltating sand and dust grains (Fig. 2, left). The first major damage occurred during a dust devil encounter on sol 313, limiting WS measurements of the highest confidence to the first 313 sols. The WS was reactivated on sol 345 with reduced capability, and further failures have since occurred. Optimized methods are being developed to interpret wind conditions from the remaining sensor outputs, with plans to release these data soon.
Figure 2. (Left) WS status as of sol 1478, showing the damage to the boards and dice, color-coded by severity. (Right) DCF as a function of Ls for the upward-looking TIRS/IR3 (0.3–3 µm) and RDS/TOP7 (0.19–1.2 µm) channels during MY 36 and 37.
While TIRS and RDS continue to operate nominally, dust accumulation on them requires corrections to their readings. The Dust Correction Factor (Fig. 2, right) is used to quantify the fraction of the incoming surface radiation that reaches the RDS/TOP7 and TIRS/IR3, respectively [2,3]. While TIRS measurements available in NASA’s PDS are corrected for this effect, RDS measurements are not.
4. Processed MEDA Data through Sol 1450
Fig. 3 shows the seasonal and interannual evolution of the environmental quantities measured by MEDA. Data from TIRS, PS, WS, and ATS were calculated as averages over the first 5’ of each hour and half-hour. For the HS, only measurements taken during the first few seconds after the HS was activated (following at least ~5 minutes of inactivity) were considered to avoid heating effects [4]. Water vapor volume mixing ratio was calculated as VMR = RH × es(T)/P, where esis the saturation vapor pressure over ice. Due to low daytime RH, MEDA-derived VMR values are restricted to nighttime.
Figure 3. Environmental conditions through sol 1450. Daily maximum, mean, and minimum ground temperature (a); atmospheric pressure (b); horizontal wind speed (c); air temperature (d), where only ATS1, ATS2, and ATS3 have been considered; daily maximum relative humidity (e); and nighttime maximum water vapor VMR (f).
Fig. 4 shows the aerosol opacity retrieved from SkyCam through sol 1450. For comparison, retrievals from the ZCAM instrument [5] are also shown. After approximately sol 700, sand and dust particles accumulated on the SkyCam may have introduced outliers.
Figure 4. Aerosol opacity (dust + water ice) retrieved from SkyCam (0.691 µm) and ZCAM (0.88 µm), color-coded by acquisition time.
Fig. 5 shows the seasonal and interannual evolution of each surface energy budget term. Downwelling and reflected solar fluxes have been extended to the full solar range (0.19–5 mm) as described in [6]. The limited coverage of the downwelling solar flux and the sensible heat flux is due to the availability of the DCF, which has only been calculated through sol 1051 (Fig. 2, right), and to the availability of WS data. Similarly, the net heat flux into the ground has been computed only through sol 1051, based on the availability of dust-corrected downwelling solar fluxes. Daily minimum net heat flux values in MY 37 centered around Ls ~50° and 150° are caused by shadows affecting the RDS, which result in artificially low net heat flux values.
Figure 5. Surface energy budget at Jezero Crater through sol 1450. (a) Daily maximum downwelling solar flux (0.19–5 µm). (b) Daily maximum reflected solar flux (0.19–5 µm). (c) Daily maximum, mean, and minimum sensible heat flux. (d) Daily maximum, mean, and minimum downwelling longwave flux (5–80 µm). (e) Daily maximum, mean, and minimum upwelling longwave flux emitted by the surface (5–80 µm). (f) Daily maximum, mean, and minimum net heat flux.
Acknowledgments
This work has been funded by the Spanish MEC, through projects No. ESP2014-54256-C4-1-R and AYA2015- 65041-P; MCIU, No. ESP2016-79612-C3-1-R, ESP2016-80320-C2-1-R, RTI2018-098728-B-C31, RTI2018-099825-B-C31, MDM-2017-0737 and PID2021-126719OB-C41; INTA and CDTI.
References
[1] Rodríguez-Manfredi, J. A., et al. (2021). Space Sci. Rev., 217(3), 1–86. [2] Sebastián, E., et al. (2025), Acta Astronaut., 226, 791–802. [3] Vicente‐Retortillo, A., et al. (2024). Geophys. Res. Lett., 51, e2023GL107975. [4] Polkko, J., et al. (2023). J. Geophys. Res. Planets 128, e2022JE007447. [5] Bell, J. F., et al. (2021). Space Sci. Rev., 217, 24. [6] Martínez, G. M., et al. (2023). J. Geophys. Res. Planets, 128, e2022JE007537.
How to cite: Martinez, G., Manfredi, J. A., de la Torre-Juarez, M., Apéstigue, V., Gomez, F., Genzer, M., Harri, A.-M., Hieta, M., Hueso, R., Lemmon, M., McConnochie, T., Munguira, A., Newman, C., Pla-Garcia, J., Polkko, J., Sanchez-Lavega, A., Sebastian, E., Tamppari, L., Toledo, D., and Vicente-Retortillo, A.: MEDA on Mars 2020: Environmental Data and Sensor Insights through Sol 1450, EPSC-DPS Joint Meeting 2025, Helsinki, Finland, 7–13 Sep 2025, EPSC-DPS2025-1461, https://doi.org/10.5194/epsc-dps2025-1461, 2025.
Oxia Planum is the chosen landing site for the European Space Agency’s ExoMars Rosalind Franklin rover mission for its evidence of multi-episodic sustained aqueous activity and astrobiological potential[1,2]. Previous works have aimed to characterise various mineralogical and morphological units present in Oxia Planum. Two distinct clay-bearing units have been identified based on spectral and morphological variations: an orange and a blue unit [2,3]. The blue unit stratigraphically overlies the orange unit, and while they are similar texturally, they exhibit some subtle textural as well as spectral differences from one another.Compositionally, the orange unit is associated with the strongest clay signatures, while the blue unit appears to be consistent with a clay signature mixed with a mafic component[2,3]. Several hypotheses have been proposed to explain their formation, including pedogenesis, groundwater alteration, and subaqueous sedimentation of either authigenic or clastic nature[3]. However, these scenarios need to be further constrained and may also need to be further expanded to include clay formation under less warm and wet conditions on early Mars [4]. Impact craters serve as windows into the subsurface by excavating, uplifting, and exposing materials that may not be visible at the surface. In this study, we use impact craters to investigate local and regional variations in the stratigraphy of Oxia Planum.
Methods: We characterized the colour/spectral characteristics of exposed layers within a ~1.5- and a ~2.1-km crater and compared them with units on the basin floor (stars in Fig. 1). Here we use DS-corrected [8-10] multispectral data from the 3-band High Resolution Imaging Science Experiment (HiRISE) (50-60 cm/px) [11], the 4-band Colour and Stereo Surface Imaging System (CaSSIS) (4 m/px) [12], and the hyperspectral Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) (20 m/px) [13]. CRISM is no longer operational, and the data is limited, while CaSSIS and HiRISE effectively extend the detailed spectral information from CRISM across the region. By identifying specific mineral phases with CRISM and then spectrally resampling them to CaSSIS and HiRISE, we establish a method to extensively map mineralogical units.
Representative orange and blue unit CRISM spectra (FRTs 9A16 & 810D) were collected from sites 1,3 and 4 (Fig. 1) and resampled to the responses of CaSSIS for direct comparisons with image-derived CaSSIS and HiRISE spectra [14,15].
Fig. 1. HRSC-MOLA overlain on CTX and with a spectral map of clay detections in magenta[16]. The latest 2028 landing ellipses (yellow) and bounding circle (black) are shown. Black stars indicate the locations of craters (1 & 2) and basin floor (3 & 4) for spectral analysis.
Results and Discussion: Previous mapping [5], reveals as many as 7 orange and 5 blue layers to date (location 2) (Fig. 2). Crater rim formation is a complicated process with the possibility of an overturned strata. However, any overturned flap would be limited to the uppermost section of the crater wall.
Fig. 2 Crater wall exposures. (a), (b) HiRISE IRB ESP_073652_1980 location #1 with mapped units; (c), (d) HiRISE IRB ESP_077041_1980 location #2 with mapped units.
The presence of multiple alternating layers raises questions about their origin—whether they represent the same or different units—and how these materials have evolved over time. Our spectral results show overall consistency in spectral shape between the three datasets, despite differences in their spectral and spatial resolution.
Fig. 3. Comparisons of DS-corrected CRISM (solid lines), CRISM resampled to CaSSIS (asterisk), CaSSIS (squares), and HiRISE (diamonds) spectra of the (a) orange unit and (b) blue unit from crater walls #1 and #2 and basin floor #3 and #4.
We compared the orange and blue units present in the basin floor (#3 & #4) and the crater walls (#1 & #2). The spectra show generally consistent nature of the units in the VNIR wavelengths. Contrary to the reported olivine component in the blue unit, the 810D spectra do not show any significant deflections towards the IR (#4; Fig. 3) [3]. Similarly, the blue unit lacks an IR deflection at ~950 nm in CaSSIS and HiRISE. It has a striking similarity with the orange unit which warrants further investigation. Due to the coarse resolution and limited coverage of CRISM, we could not extract a representative spectrum for the blue unit from the crater walls.
Well-exposed craters at lower elevations expose thicker units than ones at higher elevations (Fig. 3). These observations provide further constraints on the origin of the clays and favour a formation by erosion-transport-deposition sourced from the adjacent Noachian highlands, transported through valley systems, and eventually deposited in Oxia Planum [5].
We observe multiple alternating orange and blue units in craters across the Oxia Planum regionthat vary in number and thickness as a function of the location and local elevation [5,6], which differs from previous reports of one blue unit atop a singular orange one [2,3,7]. By further establishing a correlation between the number and thickness of these units as a function of location and elevation, we intend to reconstruct the clay-associated stratigraphy of Oxia. This would provide further insights into the provenance and origin of the clay units of the Oxia basin and the surrounding region.
References: [1] Vago J. L. et al. (2017) Astrobiology, 17 (6-7), 471-510. [2] Quantin-Nataf C. et al. (2021) Astrobiology, 21(3), 345-366. [3] Mandon L. et al. (2020) Astrobiology, 21(4), 464-480. [4] Tornabene L. L. et al. (2013) JGR: Planets, 118, 994–1012. [5] Srivastava et al. (2024) Xth Mars, 3233. [6] Srivastava et al. (2025) 56th LPSC, 1798. [7] Parkes – Bowen A. et al. (2022) PSS, 214. [8] Tornabene L. L. et al. (2018) Space Sci. Rev., 214. [9] Rangarajan V. G. et al. (2023) Icarus, 115849. [10] Tornabene L. L. et al. (2023) LPSC 54, p.2727. [11] McEwen A. S. et al. (2007) JGR: Planets, 112(E5), E05S02. [12] Thomas N. et al. (2017) Space Sci Rev, 212. [13] Murchie S. et al. (2007) JGR, 112, E05S03. [14] Tornabene L. L. et al. (2024) Xth Mars, 3318. [15] Tornabene et al. (2025) EPSC. [16] Carter et al. (2023) Icarus, 115164.
How to cite: Srivastava, A., Tornabene, L., Osinski, G., Caudill, C., Rangarajan, V. G., Fawdon, P., McNeil, J., Grindrod, P., Hauber, E., Davis, J., and Pajola, M.: Multi-scale Spectral Characterization of Clay-Rich Crater Walls in Oxia Planum, EPSC-DPS Joint Meeting 2025, Helsinki, Finland, 7–13 Sep 2025, EPSC-DPS2025-1001, https://doi.org/10.5194/epsc-dps2025-1001, 2025.
Introduction
The search for life is a key driver of Mars exploration, yet the detection of organic compounds on Mars remains sparse. High UV and ionizing radiation levels near the surface destroy organic compounds, leading to an underground search such as that planned for the Rosalind Franklin rover’s 2 m drill. Strong oxidizing agents have been suggested to explain conflicting Viking experiments’ non-detection results, adding further stress to any organic compounds. Such agents have since been identified in the form of perchlorate [ClO4-] salts in the martian regolith (Hecht et al. 2009). Nevertheless, small amounts of organic matter have been identified at the near surface in Gale crater on Mars with the Sample Analysis at Mars (SAM) instrument package on the Curiosity rover (e.g. Freissinet et al. 2025). However, it remains unclear whether these compounds formed on Mars or whether they are remnants of meteorite input. To tighten constraints on this assessment, we need to understand how the meteorite organic inventory evolves once it is exposed to the martian environment. Here we reacted organic compounds from a carbonaceous chondrite with perchlorate salts at levels measured in the martian regolith and analyzed the organic compounds before and after reaction with a non-targeted Liquid Chromatography Mass Spectrometry (LC-MS) metabolomics approach.
Materials and Methods
Crushed samples of the carbonaceous CM2 chondrite Jbilet Winselwan (JW) were exposed to magnesium perchlorate salts. This meteorite was found in the Western Sahara in 2013 and contains ~2 wt% organics. Measured amounts of perchlorate at the Phoenix landing sites are about 20 times the estimated amount of organic matter from meteorite input. The crushed meteorite samples were exposed to 1x, 20x and 100x perchlorate anion concentration treatments, meaning that the 20x treatment reflects the concentration on Mars. All experiments were conducted under anoxic conditions. Organics were then extracted with a series of non-polar to polar solvents and analysed with Hydrophilic Interaction Liquid Chromatography (HILIC) followed by mass spectrometry using an Orbitrap mass analyzer. Data was processed using MetaboAnalyst v6.0 (Scheltema et al. 2011; Smith et al.2006; Pang et al. 2024).
Results and Discussion
A Principal Component Analysis (PCA) was conducted on the LC-MS data to evaluate the effects of progressive perchlorate treatment on the JW meteorite organic inventory. The first two principal components account for 73.9% of the variance in the dataset (PC1: 59.5%, PC2: 14.4%). The trend in PC1 (Figure 1) reflects the treatment gradient across the experiment, with a vertical trend visible from untreated to 100x perchlorate treatment. In contrast, PC2 (14.4%) does not follow a linear pattern, with the 20x perchlorate treatment exhibiting positive loadings and the 100x exhibiting negative loadings, while untreated meteorite and 1x clustered around a loading of zero. We are investigating the possible causes for the organic distribution in 20X being so distinct from the 100X along the PC2 axis - particularly since the 20X concentration matches that of Mars - and will present the results of this work at the meeting.
Additionally we created a clustered heat map of the top 75 most abundant compounds in the perchlorate treatment experiment (Figure 2). The heatmap shows compounds behave differently when the meteorite is subjected to increased perchlorate treatment. Many compounds are resistant to smaller or moderate (20x) perchlorate treatments but are destroyed with 100x treatments. However, there are many compounds which increase in concentration with increased perchlorate treatment. This could be either liberation of compounds from macromolecule material or mineral matrix, or new compounds generated by in situ reactions during the course of the experiment. This result requires further investigation.
Conclusions
Our results indicate that Mars’ organic matter input from meteorites interacts with the martian environment, changing its composition. Inspection of individual compounds putatively detected suggest that some astrobiologically relevant compounds (e.g., N bearing polar molecules) are formed when perchlorate reacts with the CM2 organics, whilst others are destroyed.
LC-MS appears to maintain the structure of organic compounds despite the presence of oxidising agents. Our results suggest this technique reduces the detection ambiguity that would otherwise be associated with perchlorate oxidation and ultimately compound destruction in GC-MS ovens. This makes it a valuable tool for future Mars sample return.
References
Hecht, M.H. et al. (2009) Detection of Perchlorate and the Soluble Chemistry of Martian Soil at the Phoenix Lander Site. Science 325, 64-67.
Freissinet, C. et al. (2025) Long-chain alkanes preserved in a Martian mudstone. PNAS 122, 13 e2420580122.
Scheltema, R. et al. (2011) PeakML/mzMatch: A file format, Java library, R library, and tool-chain for mass spectrometry data analysis. Analytical Chemistry 83, 2786-2793.
Smith, C. et al. (2006) XCMS: Processing mass spectrometry data for metabolite profiling using nonlinear peak alignment, matching, and identification. Analytical Chemistry 78, 779-787.
Pang, Z. et al. (2024) MetaboAnalyst 6.0: towards a unified platform for metabolomics data processing, analysis and interpretation. Nucleic Acids Res 52, W398-W406.
Figure 1. PCA of the meteorite treatment. PC1 (59.5%) accounts for most of the variance with a clear progression of the perchlorate treatment. PC2 (14.4%) is less clear showing high variation at the extreme ends of the treatment.
Figure 2. A clustered heatmap of the concentrations of the compounds in the meteorite perchlorate treatment. The bottom section shows compounds that have increased with the increased addition of meteorite compounds. The middle section are compounds that are semi resistant or decrease with perchlorate treatment.
How to cite: Tait, A. W., O'Brien, A. C., Hallis, L. J., Morrison, D., Regnault, C., Blackburn, G., Hagermann, A., and Schröder, C.: Reaction of perchlorate with meteorite organic compounds – implications for organic molecule characterization on Mars, EPSC-DPS Joint Meeting 2025, Helsinki, Finland, 7–13 Sep 2025, EPSC-DPS2025-1224, https://doi.org/10.5194/epsc-dps2025-1224, 2025.
Introduction
The Jezero fan delta has been well studied ever since the Mars 2020’s Perseverance rover landed in the crater in February 2021. There is now a comprehensive understanding of the architecture of the delta thanks to both in situ and orbital imagery; the fan formed in a closed lake as a Gilbert-type delta, showcasing the distinctive topset-foreset-bottomset tripartite [1].
Now that Jezero western fan is better understood, we would like to know if the Jezero delta architecture is relevant elsewhere on Mars: can we find similar geometries? Is Jezero the rule or the exception? To begin to try to answer this question, we focused on another martian sedimentary structure of similar size and volume: the Eberswalde sedimentary fan.
The Eberswalde crater (24.3° S, 326.5°E), located immediately northeast of the Holden crater, along the fluvial network connecting Argyre Planitia to Ares Vallis displays a spectacular fan shaped feature (~115 km²) with meandering channels in its westernmost part, that was most likely emplaced during the Late Noachian [2] in a closed-basin lake [3]. The volume of the fan is similar to that of Jezero’s western delta, the thickness of sediment is about 50 to 100 m in both cases [2], which makes it an interesting starting point for the comparison of Jezero to other martian sedimentary fans.
Methods
This study focuses on the geomorphological and stratigraphic analysis of the Eberswalde fan using orbital imagery. The HiRISE coverage of the Eberswalde crater is really good, due to the crater being previously considered among the potential landing sites of MSL and Mars 2020 missions. Thanks to HiRISE data, we have access to images with a resolution of up to 0.25 m/pix on the whole fan area.
The HiRISE orthoimages were taken as stereo pairs, which allowed creating stereo-derived DTM, giving access to topographic information. Contour lines and topographic profiles can therefore be extracted on the QGIS software. The dip angles of the outcropping layers can also be measured using the DTM on QGIS, thanks to the Three-Points-Method plugin, which extracts the elevation data from three points placed along the layer and calculates the dip angle and strike of said layer. Dipping layers were already observed by Goudge et al. (2018) [4] before rover data, showing that it is possible to observe them from orbit.
Results
On orbital imagery of the Eberswalde sedimentary fan, extensive meandering inverted channels are visible (Figure 1). It is possible to distinguish five lobes that were emplaced at different periods in time (Figure 1) [2]. The shape of the river channels on the Eberswalde fan differs from that of the channels on the Jezero delta, where they are rectilinear [5]. This indicates a difference in the fluvial regime responsible for the emplacement of these channels.
Figure 1: Map of the meandering inverted channels on the Eberswalde sedimentary fan and their stratigraphic relationships, from oldest to youngest lobes (coloured scale) [2]. White box represents the studied area of Figure 2. (HiRISE – MRO).
The beds outcropping at the front of the Eberswalde fan have dips mostly around 0° to 5°, occasionally reaching up to 8°, and almost always follow the contour lines (Figure 2a). These outcropping strata are therefore mostly subhorizontal, there are no steeply inclined layers at the front of the fan that would correspond to Gilbert-type foreset strata (Figure 2) as was observed in Jezero delta [1].
Two main phases can be distinguished from the orbital data: a lacustrine phase, with the subhorizontal beds outcropping at the front, and the fluvial (meandering) phase occurring afterwards.