Is there life on Mars?

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1. 1

   Biological Validation and Agnostic Experiments for Extant and Extinct Microbial Life within the Martian Subsurface.

   Astrobiology (Perl et al.)Published Jul 15, 2026Checked Oct 3, 2026

   “These advances enable mission concepts centered on microbiological processes that facilitate identification of both active life and preserved biosignatures through measurements of metabolism and associated biochemical markers that, on Mars, are more likely to be retained below the surface. Terrestrially, although biological processes can exert a significant influence on Earth's crust, the presence of habitable conditions does not necessarily imply the existence of cellular life. The Viking missions constituted the first direct life-detection experiments on Mars but produced equivocal outcomes, prompting subsequent exploration strategies to emphasize surface habitability rather than direct biological testing. Leveraging progress in subsurface microbiology and planetary exploration, we contend that Mars missions are now poised to shift toward direct tests for extant microbial activity in the subsurface, with metabolic processes serving as a broadly applicable indicator of life.”

2. 2

   Viking's Astrobiological Legacy: A Philosophical Framework for Searching for Molecular Biosignatures.

   Astrobiology (Buckner & Wilhelm)Published Jun 30, 2026Checked Oct 3, 2026

   “James Lovelock was the first to lay out a physical and chemical basis for searching for life beyond Earth, based on the observation that the molecular features and patterns in classes of organics differ for compounds formed through biological versus nonbiological processes. This approach shaped the Viking molecular analysis experiment designed to search for organics, including potential signs of extinct or extant life, and it still remains fundamentally viable today. In the five decades since Viking, many missions have uncovered new information about the martian organic inventory, geological landscape, and changes to habitability over time, while advances in organic geochemistry on Earth enabled scientists to identify even more differences between biotic and abiotic organics, solidifying the utility of Lovelock's physical and chemical approach in the search for extraterrestrial life. Key Words: Search for Mars' Organics-Mars-Biosignatures-Life detection-Biomarkers. Astrobiology 26, 72S-78S.”

3. 3

   Biosignature stability in space enables their use for life detection on Mars

   Science Advances (Baqué et al.)Published Sep 7, 2022Checked Oct 3, 2026

   “Two rover missions to Mars aim to detect biomolecules as a sign of extinct or extant life with, among other instruments, Raman spectrometers. However, there are many unknowns about the stability of Raman-detectable biomolecules in the martian environment, clouding the interpretation of the results. To quantify Raman-detectable biomolecule stability, we exposed seven biomolecules for 469 days to a simulated martian environment outside the International Space Station. Ultraviolet radiation (UVR) strongly changed the Raman spectra signals, but only minor change was observed when samples were shielded from UVR. These findings provide support for Mars mission operations searching for biosignatures in the subsurface. This experiment demonstrates the detectability of biomolecules by Raman spectroscopy in Mars regolith analogs after space exposure and lays the groundwork for a consolidated space-proven database of spectroscopy biosignatures in targeted environments.”

4. 4

   Mars sample return campaign: biological risk and a proposed sample safety assessment protocol.

   Applied and environmental microbiology (McDonnell et al.)Published May 27, 2026Checked Oct 4, 2026

   “Returning surface samples from Mars to Earth has been a major planetary science objective, with the potential for the detection of microbiological life and the possibility of improving our understanding of the origins of life. The National Aeronautics and Space Administration and the European Space Agency assembled a team to assess the level of risk that returned samples could contain potential biohazards. The team was chartered with optimizing previous sample safety assessment strategies, defining what constitutes a biological hazard, developing a protocol to test for biohazards, and establishing a statistical framework to determine if samples may be safe for release from a high-containment facility. This report presents the biological context for a proposed three-step protocol for testing returned samples, including how to determine if microorganisms are present, and if they could be (or were recently) alive.”

5. 5

   Strong nickel enrichment co-located with redox-organic interactions in Neretva Vallis, Mars.

   Nature communications (Manelski et al.)Published Mar 31, 2026Checked Oct 4, 2026

   “In 2024, NASA's Perseverance rover explored Neretva Vallis, an ancient river channel that once transported water into Jezero crater. There, the rover encountered Mg-poor mudstones with diverse alteration features. In 32 rock targets in Neretva Vallis, nickel (Ni) was detected by the SuperCam instrument with concentrations in individual rocks as high as ~1.1 weight percent - the highest abundance ever seen in bedrock on Mars. In this work, we describe and contextualize these Ni enrichments using outcrop-scale imagery and petrographic-scale elemental maps provided by the PIXL instrument. We find Ni enrichment in Fe-sulfides and their weathering products. The geochemistry and morphology of Neretva Vallis Fe-sulfides are similar to pyrite present in terrestrial Archean and Paleoproterozoic sedimentary rocks. As an essential element for terrestrial microbial life, the proximity of Ni enrichments to reduced sulfur and organic matter adds to the interest in bringing back to Earth the rock sample collected by Perseverance at this location, which could provide key insights into complex redox chemistry on early Mars.”

6. 6

   The search for life signatures on Mars by the Tianwen-3 Mars sample return mission.

   National science review (Hou et al.)Published Oct 21, 2024Checked Oct 4, 2026

   “We present the proposed strategic study, 'Integrated elements for Martian life signature exploration', to support the sampling and identification of any potential biosignatures in compliance with the engineering constraints of the Tianwen-3 mission.”

7. 7

   Emergence of biosignatures on Earth and implications for life detection.

   Proceedings of the National Academy of Sciences of the United States of America (Barge et al.)Published Aug 14, 2026Checked Oct 3, 2026

   “Thus, the emergence of biosignatures and their formation context are critical considerations for mission interpretations, especially where there is no obvious pervasive biosphere. Here, we provide a structured approach for interpreting chemical states across the continuum of OCE on a planetary body. We distinguish between universal biosignatures of a world vs. specific biosignatures that are tied to environmental or temporal conditions of that world. We then consider how the evolution of a planetary body would impact the expression of these signatures over time. The detection of active prebiotic chemistry-that is, signatures that fall in the ambiguous transition between prebiotic and living systems-would be a hallmark discovery, providing insight into life's origins and justifying investment in further exploration of such worlds. Leveraging Earth as an example, we suggest that while mission observations may be more challenging to interpret than previously thought, they may also open doors to a more productive exploration of our planetary neighbors.”

8. 8

   The chemistry of habitable oceans in the Solar system.

   Nature communications (Hao et al.)Published Jun 29, 2026Checked Oct 4, 2026

   “Liquid water exists on the Earth and several other planetary bodies in our solar system. The chemical character of these aqueous reservoirs is central to evaluating their habitability. Here, we synthesize the chemical features of water reservoirs and their biological implications on the modern Earth. We then outline constraints on the evolutionary history of Earth's ocean chemistry and discuss its interplay with the biosphere. Furthermore, we examine the inferred chemical environments of water bodies on early Mars, dwarf planet Ceres, Jupiter's moon Europa and Saturn's moons Enceladus and Titan. We conclude by outlining priority questions for future planetary habitability studies.”

9. 9

   Biosignatures on Mars: What, Where, and How? Implications for the Search for Martian Life

   Astrobiology (Westall et al.)Published Nov 1, 2015Checked Oct 3, 2026

   “Obtaining nutrition from the same kinds of sources as early terrestrial chemotrophic life and living in the same kinds of environments, the fossilized traces of the latter serve as useful proxies for understanding the potential distribution of martian chemotrophs and their fossilized traces. Thus, comparison with analog, anaerobic, volcanic terrestrial environments (Early Archean >3.5-3.33 Ga) shows that the fossil remains of chemotrophs in such environments were common, although sparsely distributed, except in the vicinity of hydrothermal activity where nutrients were readily available. Moreover, the traces of these kinds of microorganisms can be well preserved, provided that they are rapidly mineralized and that the sediments in which they occur are rapidly cemented. We evaluate the biogenicity of these signatures by comparing them to possible abiotic features. Finally, we discuss the implications of different scenarios for life on Mars for detection by in situ exploration, ranging from its non-appearance, through preserved traces of life, to the presence of living microorganisms. KEY WORDS: Mars-Early Earth-Anaerobic chemotrophs-Biosignatures-Astrobiology missions to Mars.”