This review reports Curiosity’s scientific results and operational status during mission years 9–12 on Mars, covering August 2020–August 2024.

Major scientific findings

• Organic molecules: SAM’s first thermochemolysis experiment detected more than 20 aromatic and cyclic organic compounds—including benzene, toluene, naphthalene derivatives, sulfur-bearing organics, and ester/carboxylic-acid-related compounds—in clay-rich rocks of Glen Torridon. These findings strengthen the evidence that ancient lake and lake-margin sediments preserved organic matter for billions of years.
• Clay-to-sulfate transition: Curiosity directly investigated the orbital clay-sulfate transition on Mount Sharp. The transition corresponds to a broad environmental change from predominantly lacustrine and river/shoreline settings to increasingly arid, aeolian environments. The shift toward aridity was not uniform: wet-dry cycles, fluctuating groundwater, and intermittent surface water continued.
• Mg sulfate-bearing unit: CheMin identified magnesium sulfate minerals, including the first detection on Mars of starkeyite—a polyhydrated Mg sulfate—and also detected kieserite, a monohydrated Mg sulfate. These minerals likely formed through brine concentration and later dehydration. The unit is dominated by wind-deposited sediments, although some intervals preserve evidence of shallow water and lakes.
• Ancient ice-free lake: Wave ripples in the Amapari Marker Band indicate that an ice-free lake existed during the early Hesperian period, despite the generally arid conditions recorded by surrounding strata.
• Carbonates and climate: Many sulfate-unit samples are enriched in siderite, an iron carbonate, at levels consistent with chemical sedimentation. This may represent a substantial portion of Mars’ previously “missing” carbonate and suggests atmospheric CO₂ sequestration into minerals.
• Gediz Vallis: The canyon and associated alluvial deposits record numerous later fluvial and debris-flow events, occurring after Mount Sharp’s older strata had been deposited, lithified, and eroded. Bright clasts in the canyon were identified as native elemental sulfur, the first such detection on Mars.
• Atmosphere and radiation: Curiosity continued long-term monitoring of dust, winds, clouds, atmospheric composition, and radiation. It observed high-altitude noctilucent and iridescent clouds and completed radiation measurements spanning an entire solar cycle, including the mission’s largest measured dose rate during a May 2024 solar particle event.

Mission performance

During years 9–12, Curiosity:

• Traveled 9.1 km and climbed approximately 450 m.
• Reached a total traverse distance of 32.4 km and elevation gain of about 850 m.
• Drilled and analyzed 15 samples, bringing the mission total to 48.
• Conducted 1,083 ChemCam target analyses and 605 APXS analyses.

Rover and instrument status

All ten scientific instruments continued to return valuable data, although with important limitations:

• ChemCam: Laser operations were restricted after degradation of its high-voltage subsystem.
• Left Mastcam: A filter wheel failure eliminated narrow-band multispectral imaging through that camera.
• DAN: Its active neutron generator failed, but passive neutron measurements remain available.
• SAM: One gas-chromatograph column became obstructed; another column is being used instead.
• CheMin: Remaining sample-cell capacity is limited because several cells are clogged, though procedural changes have extended their usability.
• The rover also continues to cope with wheel wear, degraded computer redundancy, aging brakes, and declining MMRTG power.

Future plans

The mission planned to investigate:

1. A regional “boxwork” ridge network thought to record ancient groundwater flow.
2. Higher portions of the Mg sulfate-bearing unit.
3. A major unconformity and overlying yardang-forming unit, potentially recording a significant climatic or depositional hiatus.

Overall, the review concludes that Curiosity remains scientifically productive and capable of addressing major questions about Mars’ ancient habitability, climate evolution, water history, organic preservation, and subsurface fluid activity despite substantial aging and resource constraints.

The experiment employed an innovative approach to analyze Martian soil samples, leveraging the SAM instrument’s pyrolysis gas chromatography–mass spectrometry (GC-MS) capabilities combined with TMAH derivatization chemistry. By doing so, the scientists successfully stabilized and identified a wide array of organic molecules that are otherwise difficult to detect due to the harsh oxidative conditions of the Martian surface. This methodological advancement separates the recent findings from prior analyses that either detected limited organics or faced ambiguities caused by surface perchlorates and cosmic radiation.

Significantly, the organic compounds identified include a variety of carboxylic acids, amines, and unique nitrogen-containing species, pointing to complex carbon-based chemistry beyond simple hydrocarbons. These molecules were discovered in sedimentary samples drilled from ancient lakebed deposits within Jezero Crater, the rover’s landing site, which is hypothesized to have supported aqueous environments billions of years ago. This context bolsters the argument that Mars may have once possessed conditions conducive to prebiotic chemistry or even microbial life.

The choice to use TMAH was critical, as this reagent facilitates in situ methylation, transforming otherwise labile organic acids into methyl esters, which are much more stable and amenable to detection. This derivatization technique is established on Earth for its efficacy in environmental organic analysis but had not been employed in planetary exploration until now. The ability to perform such complex chemical enhancement directly on Mars marks a watershed moment in extraterrestrial chemistry research.

Crucially, the team’s analytical pipeline incorporated rigorous blank runs and contamination controls to ensure the Martian origin of the organics. The detection thresholds and isotopic compositions reflect minimal terrestrial interference, confirming the findings as indigenous to Mars. The presence of nitrogen-bearing organics suggests not just basic carbon chemistry but potential biologically relevant molecules, which have motivated intense discussions about Mars’ past habitability.

Furthermore, the distributions of these organic molecules across different samples indicate spatial heterogeneity that mirrors diverse depositional environments on ancient Mars. The sediment layers show signatures indicative of alteration by water-rock interactions, supporting the hypothesis that the detected organics have been subjected to, and preserved by, aqueous processes. This scenario paints a picture of a chemically dynamic early Mars potentially capable of sustaining life’s precursors.

The implications extend into astrobiology, opening new doors for examining Mars’ organic inventory with a fresh lens. While detection does not prove biology, these complex molecules serve as a tantalizing proxy for understanding the planet’s potential to host microbial ecosystems or at least to have undergone prebiotic organic evolution. This study revitalizes efforts to target upcoming missions to similar lakebed environments and subsurface contexts where organics might be sheltered from degradation.

Additionally, the integration of SAM’s TMAH experiment exemplifies how instrument innovation and chemistry-driven methodologies can dramatically enhance planetary exploration capabilities. This “chemical magnifying glass” effect, wherein low-abundance, volatile, or reactive organics become detectable, sets a precedent for designing future Mars landers and rovers with more sophisticated organic detection suites.

It is anticipated that comparative studies between Martian organics and those found in carbonaceous chondrites or cometary materials will further refine interpretations of the Red Planet’s carbon cycle and its sources of organic matter. Did these compounds originate from endogenous geochemical processes, exogenous delivery via meteorites, or potential biological pathways? Such questions now gain fresh relevance and urgency.

Mars’ surface radiation and oxidative soil chemistry had long been considered formidable obstacles for preserving organic matter, leading some to doubt the feasibility of detecting complex organics in situ. This new study challenges that notion decisively, demonstrating that with targeted chemical enhancements, valuable organic data can be extracted despite the inhospitable environment. This plays a pivotal role in guiding future sample return strategies.

The research team also noted that the detection of diverse organic molecules via TMAH derivatization complements previous non-derivatized approaches, together constructing a multi-dimensional picture of Mars’ organic chemistry. This combined data enhances the interpretation of Mars’ geochemical history and informs models of planetary evolution and potential bio-signature preservation.

Looking ahead, these findings underscore the necessity for further chemical innovation in planetary missions, especially regarding the capture and preservation of delicate organic compounds in extraterrestrial settings. Instruments that can apply in situ derivatization and other chemical treatments could become standard, vastly expanding the scope of astrobiological exploration on Mars and beyond.

The study marks an exhilarating chapter not only in Mars exploration but in astrochemistry, planetary science, and the enduring quest to answer one of humanity’s most profound questions: is life unique to Earth, or did it arise elsewhere in the cosmos? The diverse Martian organics exposed by this first SAM TMAH experiment draw us much closer to that answer, igniting both scientific intrigue and public imagination.

This transformative discovery heralds the arrival of a new era of Martian chemical analysis, blending technological ingenuity with scientific perseverance. As data continue to stream in from ongoing rover operations, the tantalizing puzzle of Mars’ organic chemistry — and its potential biological significance — promises many more enthralling revelations in the years to come.

Subject of Research: Organic molecules on Mars detected using the SAM instrument’s TMAH experiment.

Article Title: Diverse organic molecules on Mars revealed by the first SAM TMAH experiment.

Article References:
Williams, A.J., Eigenbrode, J.L., Millan, M. et al. Diverse organic molecules on Mars revealed by the first SAM TMAH experiment. Nat Commun 17, 2748 (2026). https://doi.org/10.1038/s41467-026-70656-0

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s41467-026-70656-0