I’ve long maintained that we’ll find compelling biosignatures on an exoplanet sooner than we’ll find them in our own Solar System. But I’d love to be proven wrong. The recent flurry of news over the interesting findings from the Perseverance rover on Mars is somewhat reminiscent of the Clinton-era enthusiasm for the Martian meteorite ALH8001. Now there are signs, as Alex Tolley explains below, that this new work will prove just as controversial. Biosignatures will likely be suggestive rather than definitive, but Mars is a place we can get to, as our rovers prove. Will Perseverance compel the sample return mission that may be necessary to make the definitive call on life?
by Alex Tolley
Overview of jezero Crater and sample site in article. Credit NASA/MSSS/USGS.
On September 10, 2025, Nature published an article that got wide attention. The authors claimed that they had discovered a possible biosignature on Mars. If confirmed, they would have won the race to find the first extraterrestrial biosignature. Exciting!
One major advantage of detecting a biosignature in our system is that we can access samples and therefore glean far more information than we can using spectroscopic data from an exoplanet. This will also reduce the ambiguity of simpler atmospheric gas analyses that are all we can do with our telescopes at present.
Figure 1. Perseverance’s path through Neretva Vallis and views of the Bright Angel formation. a, Orbital context image with the rover traverse overlain in white. White line and arrows show the direction of the rover traverse from the southern contact between the Margin Unit and Neretva Vallis to the Bright Angel outcrop area and then to the Masonic Temple outcrop area. Labelled orange triangles show the locations of proximity science targets discussed in the text. b, Mastcam-Z 360° image mosaic looking at the contact between the light-toned Bright Angel Formation (foreground) and the topographically higher-standing Margin Unit from within the Neretva Vallis channel. This mosaic was collected on sol 1178 from the location of the Walhalla Glades target before abrasion. Upslope, about 110 m distant, the approximate location of the Beaver Falls workspace (containing the targets Cheyava Falls, Apollo Temple and Steamboat Mountain and the Sapphire Canyon sample) is shown. Downslope, about 50 m distant, the approximate location of the target Grapevine Canyon is also shown. In the distance, at the southern side of Neretva Vallis, the Masonic Temple outcrop area is just visible. Mastcam-Z enhanced colour RGB cylindrical projection mosaic from sol 1178, sequence IDs zcam09219 and zcam09220, acquired at 63-mm focal length. A flyover of this area is available at https://www.youtube.com/watch?v=5FAYABW-c_Q. Scale bars (white), 100 m (a), 50 m (b, top) and 50 cm (b, bottom left). Credit: NASA/JPL-Caltech/ASU/MSSS.
Let’s back up for context. The various rover missions to Mars have proceeded to determine the history of Mars. From the Pathfinder mission starting in 1996, the first mission since the two 1976 Viking landers, the various rovers from Soujourner (1997), Spirit & Opportunity (2004), Curiosity (2012), and now Perseverance (2021), have increased the scope of their travels and instrument capabilities. NASA’s Perseverance rover was designed to characterize environments and look for signs of life in Jezero Crater, a site that was expected to be a likely place for life to have existed during the early, wet phase of a young Mars. The crater was believed to be a lake, fed by water running into it from what is now Neretva Vallis, and signs of a delta where the ancient river fed into the crater lake are clear from the high-resolution orbital images. Perseverance has been taking a scenic tour of the crater, making stops at various points of interest and taking samples. If there were life on Mars, this site would have both flowing water and a lake, with sediments that create a variety of habitats suitable for prokaryotic life, like the contemporary Earth.
Perseverance had taken images and samples of a sedimentary rock formation, which they called Bright Angel. The work involved using the Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) instrument to obtain a Raman UV spectrum of rock material from several samples. The authors claimed that they had detected 2 reduced iron minerals, greigite and vivianite, and organic carbon. The claim is that these have been observed in alkaline environments on Earth due to bacteria, and therefore prove to be a biosignature of fossil life. The images showed spots (figure 2) which could possibly be the minerals formed by the metabolism of anaerobic bacteria, reducing sulfur and iron for energy. The organic carbon in the mudstone rock matrix is the fossil remains of the bacteria living in the sediments.
Exciting, no? Possible proof that life once existed on Mars. The authors submitted a paper to Nature with the title, “Detection of a Potential Biosignature by the Perseverance Rover on Mars“. The title was clearly meant to catch the scientific and popular attention. At last, NASA’s “Follow the Water” strategy and exploration with their last rover equipped to detect biosignatures had found evidence of fossil life on Mars. It might also be a welcome boost for NASA’s science missions, currently under funding pressure from Congress.
Then the peer review started, and the story seemed less strong. Just as 30 years ago, when the announcement from the White House by the US president, Bill Clinton claimed that a Martian meteorite retrieved from the Antarctic, ALH8001, was evidence of life on Mars proved very controversial. Notably, slices of that meteorite viewed under an electron microscope showed images of what might have been some forms of bacteria. These images were seen around the world and were much discussed. The consensus was that the evidence was not unambiguous, with even the apparent “fossil bacteria” being explained as natural mineral structures.
Well, the new paper created one of the longest peer review documents I have ever read. Every claimed measurement and analysis was questioned, including the interpretation. The result was that the paper was published as the much drier “Redox-driven mineral and organic associations in Jezero Crater, Mars”. There are just 3 uses of the term biosignatures, each prefaced with the term “potential”, and the null hypothesis of abiotic origin emphasized as well. One of the three peer reviewers even wanted Nature to reject the paper, based on what might be another ALH8001 fiasco. A demand, too far.
What were the important potential biosignature findings?
Organisms extract energy from molecules via electron transfer. This often results in the compounds becoming more reduced. For example, sulfur-reducing bacteria convert sulfates (SO4) to sulfide (S). Iron may be reduced from its ferric (Fe3+) state to its ferrous (Fe2+) state. Two minerals that are often found reduced as a result of bacterial energy extraction are greigite Fe2+Fe3+2S4] and vivianite [Fe2+3(PO4)2·8H2O]. On Earth, these are regarded as biosignatures. In addition, unidentified carbon compounds were associated with these 2 minerals. The minerals were noticed as spots on the outcrop and identified with the Planetary Instrument for X-ray Lithochemistry (PIXL), which can identify elements via X-ray spectroscopy. The SHERLOC instrument identified the presence of carbon in association with these minerals.
Figure 2. An image of the rock named “Cheyava Falls” in the “Bright Angel formation” in Jezero crater, Mars, collected by the WATSON camera onboard the Mars 2020 Perseverance rover. The image shows a rust-colored, organic matter in the sedimentary mudstone sandwiched between bright white layers of another composition. The small dark blue/green to black colored nodules and ring-shaped reaction fronts that have dark rims and bleached interiors are proposed to be potential biosignatures. Credit: NASA/JPL-Caltech/MSSS.
To determine whether the carbon associated with the greigite and vivianite was organic or inorganic, the material was subjected to ultraviolet rays. Organic carbon bonds, especially carbon-carbon bonds, will respond to specific wavelengths by vibrating, like sound frequencies can resonate and break wine glasses. Raman spectroscopy is the technique used to detect the resonant vibrations of types of carbon bonds, particularly specific arrangements of the atoms and their bonds that are common in organic carbon. The spectroscopic data indicated that the carbon material was organic, and therefore possibly from decayed organisms. This would tie together the findings of the carbon and the 2 minerals as a composite biosignature. However, the reviewers also questioned the interpretation of the Raman spectrum.. The sp2 carbon bonds (120 degrees) seen in aromatic 6-carbon rings, in graphene, graphite, and commonly in biotic compounds, should show both a G-band (around 1600 cm-1) and a D-band (around 2700 cm-1), yet the spectrum only clearly showed the G-band. Did this imply that the organic carbon may not have been found? The reviewers also questioned why the biological explanation was favored over an abiotic one. No one questioned the greigite and vivianite findings, other than that they are not exclusively associated with anaerobic bacterial metabolism.
Figure 3 – Raman spectrum with interpolated curves to highlight the G-band in the 4 samples taken at the location.
So what to make of this? Clearly, the authors backed down on their more positive interpretation of their findings as a biosignature.
What analyses would we want to do on Earth?
Assuming the samples from Perseverance are eventually retrieved and returned to Earth, what further analysis would we want to do to increase our belief that a biosignature was discovered?
A key analysis would be to analyze the carbon deposits. The Raman UV spectra indicate that the carbon is organic, which is almost a given. You may recall that the private MorningStar mission to Venus will do a similar analysis but use a laser-induced fluorescence that detects aromatic rings [1]. Neither of these techniques can distinguish between abiotic and biogenic carbon. The carbon may even be in the form of common polycyclic aromatic hydrocarbons (PAH), a form that is ubiquitous and is easily formed, especially with heat.
One useful approach to distinguish the source of the carbon is to measure the isotopic ratios of the 2 stable carbon isotopes, carbon-12 and carbon-13. Living organisms favor the lighter carbon-12, and therefore, the C13/C12 ratio is reduced when the carbon is from living organisms. This must be compared to known abiotic carbon to confirm its source. This analysis requires a mass spectrometer, which was not included with the Perseverance instrument pack.
The second approach is to analyze the carbon compounds. Gas chromatography followed by infrared spectroscopy is used to characterize the compounds. Life restricts the variety of compounds compared to random reactions, and can be compared to expectations based on Assembly Theory [2], although exposure to UV and particle radiation for billions of years may make the composition of the carbon more random.
Lastly, if the carbon were once protein or nucleotide macromolecules, any chirality might distinguish its source as biotic.
Isotopic analysis can also be made on the sulfur compounds in the greigite. As with carbon, life will preferentially use lighter isotopes. Bacteria reduce sulfate to sulfide for energy, and the iron sulfide mineral, greigite, is a waste product of this metabolism. Of the 2 stable sulfur isotopes, sulfur-32 and sulfur-34, if the S34/S32 ratio is reduced, then this hints that the greigite was formed biotically.
Lastly, opening up the samples and inspecting them with an electron microscope, there may be physical signs of bacteria. However, any physical features will need to be identified unambiguously to avoid the ALH8001 controversy.
Unfortunately for these proposed analyses, the Mars Sample Return (MSR) mission has been cut with the much-reduced NASA budget. When, or whether, we get these samples for analyses on Earth is currently unknown.
My view on the findings
If the findings and the interpretation of their compositions is correct, then this would probably be the most convincing, but still not unambiguous biosignature to date. If the samples are returned to Earth and the findings are extended with other analyses, then we probably would have detected fossil life on Mars. In my opinion, that would validate the idea that Martian life existed, and further exploration is warranted. We would then want to know if that life was similar or different from terrestrial life to shed light on abiogenesis or panspermia between Earth and Mars. As the formation of the Moon would have been very destructive, if life emerged on Mars and was spread to Earth, this might provide more time for living cells to evolve compared to the conditions on Earth. It would also stimulate the search for subsurface life on Mars, where interior heat and water between rock grains would support such a niche habitat as it does on Earth.
It seems a pity that without an MSR, we may have the evidence for Martian fossil life, packaged for analysis, but kept frustratingly remote and unavailable, mere millions of kilometers distant.
The paper is Hurowitz, J.A., Tice, M.M., Allwood, A.C. et al. “Redox-driven mineral and organic associations in Jezero Crater, Mars.” Nature 645, 332–340 (2025). https://doi.org/10.1038/s41586-025-09413-0
Other readings
Tolley A, (2022) Venus Life Finder: Scooping Big Science web: https://www.centauri-dreams.org/2022/06/03/venus-life-finder-scooping-big-science/
Walker, S. I., Mathis, C., Marshall, S., & Cronin, L. (2024). “Experimentally measured assembly indices are required to determine the threshold for life.” Journal of the Royal Society Interface, 21(220). https://doi.org/10.1098/rsif.2024.0367
Twenty years ago I thought life on Mars was impossible, but now it might be possible that Mars was wet long enough to have produced life. If not, then I doubt there is any non indigenous life there. Getting a sample from ancient subsurface ice or rock where water once ran is ideal. I agree with the justification for going there to find life.
If Mars’ warm, wet period ended about 3.5 bya, I don’t know what evidence of life we could find. Stromatolite bands in rocks like those in Australia? I cannot imagine there is any organic material representing DNA/RNA/proteins. If the carbon the rover instruments detected was some remains of life, it must have been exposed for possibly billions of years. What could be left other than a carbon isotope ratio? Chiral compounds become racemic after a much shorter time, especially if exposed. If the samples are ever returned to Earth, it will be interesting to see what tests can be done to determine their origin.
If life was once on Mars, perhaps it may still be extant in the crust, protected from the cold, dry, low atmospheric pressure on the surface. Deep drilling into the crustal rocks, perhaps where water is still liquid, might be an option, perhaps when a base is established, sometime this century. Perhaps the best approach is to drill sideways into a canyon rock face if there is evidence that water is seeping out periodically, or perhaps closer to the northern pole where water is closer to the surface, and the depth is shallower where there is a warm spot. It may be a long shot, but if the base needs to drill for water anyway, one might as well do some science as well.
As Jezero crater once had water, perhaps that might be a good location to drill deep below the surface sediments to reach rocks that are above freezing. Deep drilling is a non-trivial operation, and currently well beyond the capability of robots.
The Jezero crater appeared to be a good site for this investigation and it has been conducted pretty much as planned. Perhaps what more we could expect from the Perseverance mission is that an effective means to obtain the samples thus far be worked out. But I have to wonder if Jezero is going to reveal much more about life to this Rover. It it something akin to the dilemma left by Viking biochemical tests, only with treads.
So what’s an alternative?
Mars does still have a hydrosphere, suggesting that somewhere subsurface there should be “pooling: of H2O. I hesitate to say liquid water, but water is transported about Mars somehow and more than one way. Considering how much we have heard about trying to sample fluids on Europa or Enceladus, it ought to be easier to drill into a possible liquid water table on Mars and check for biological traces. A subsurface element of the hydrosphere just might circulate more organic chemical evidence of previous less sterilized eras or perhaps even leads to where hot springs host some form of what we would consider extremophiles on Earth.
The surface, as indicated, gives some indication of previous eras where life might have been responsible for tracks, or chemical formations, agreed. But if this surface has been in much the same state as it is now for a billion years or even hundred million years, perhaps our searches for ancient life are handicapped by comparison with a subsurface environment that appears to belch methane now and then, perhaps seasonally.
Of course, there is still an underlying assumption or two here. We could investigate to determine whether there was never any life, some primitive form of life earlier, or some primitive life still remaining subsurface. And if that last possibility sounds absurd, consider how much has been said in behalf of investigating Ceres further, because it might have had a more Mars like environment eons ago.
From another angle, it is one thing to get to Mars via a fleet of LOX-CH4 powered rockets. But it is another thing to survive on surface or subsurface resources until there is an opportunity to launch back. For not only is there the matter of testing for life, but also how portable water is under a chemically volatile surface influenced by high doses of UV. Contamination of the water table in arid regions on Earth is bad enough. No reason to expect tapping into a water source that is already distilled. Do we really know what we are in for if a crew has to get by out there for a martian year?
@wdk
Yes, humans living on teh surface of Mars will not be trivial.
I don’t believe the water problem is severe. Standard heating, filtration, and cleaning should create a supply of potable water, if needed some minerals if it has to be distilled for safety.
It will not be possible to prove life never existed on Mars. In teh short term, we can either find evidence of past life, or if we are very lucky, extant life. We might need large populations living on Mars for centuries before there is sufficient work to state that life has never emerged on Mars. By that time, I would expect contamination and terraforming projects to have totally muddled the situation on the surface and in the immediate subsurface. Given Zubrin’s stated POV and that of others, similarly-minded libertarians, there will be little interest in doing life searches.
While KSM’s Mars trilogy had various factions on Mars, some wanting to preserve its state, I suspect that this may not happen with the Martian population. Less philosophical ideals and more rugged living due to teh harshness of the environment.
A modification of Zubrin’s Mars Direct plan makes sense with methalox propulsion. Perseverance is already testing kit to turn CO2 and water to methane and oxygen as fuel and oxidizer. An unmanned Starship could do that in advance, guaranteeing an early return flight if needed. Extra O2 can be extracted from the perchlorates that contaminate the Martian regolith.
Now, what the population is going to do to generate the income for trade to ensure Earth keeps supplies coming is another story.
Life might not exist today since Mars is very inhospitable. The time is a problem as Alex Tolley has mentioned. Mars did not have a giant impact like Earth so that gives a little more time to evolve than on Earth. There might be fossils also in lakes, and ancient ocean beds in the permafrost where they might not have been damaged by solar radiation, etc. Fossils are still possible and we might have to go there and take some rock samples back from many places.
@geofrey
Even a hint that a separate abiogenesis occurred will be very important for astrobiologists searching for life on exoplanets. Buried fossil bacterial artifacts, or minerals that could only be the product of life, would be welcome.
AI Overview
+17
In deep-sea marine sediments, microbes have been found to persist for millions of years with an exceptionally slow metabolic rate, suggesting potential doubling times on the order of thousands to tens of thousands of years. Scientists have even coined the term “aeonophiles” to describe organisms that are obligated to grow slowly over extended periods.
This extreme slow growth, almost like a state of suspended animation, is a survival strategy in environments with very limited resources. Unlike bacteria in a lab culture that can double in minutes, these microbes exist in conditions of profound energy limitation.
Deep-sea microbes
Research on microbes in deep subseafloor sediments has revealed astonishingly long lifecycles.
100-million-year survival: A 2020 study reported the resuscitation of aerobic microorganisms from sediments collected from the South Pacific Gyre, a nutrient-poor region of the ocean. The sediments, dated to between 4.3 and 101.5 million years old, contained microbes that had been metabolically active, albeit at an extremely low rate.
Multi-year doubling times: In certain deep marine sediments, the mean generation time for microbial communities has been estimated to be tens to thousands of years. Some uncultured clades like Bathyarchaeota and Thermoprofundales have estimated doubling times of several years.
Subsurface bacteria and archaea
Life in the deep terrestrial and oceanic subsurface is characterized by similar slow metabolic rates due to a lack of nutrients, space, and energy.
Long-lived permafrost microbes: Microbes isolated from Siberian permafrost have remained viable for over 100,000 years.
Deep subsurface fluids: In places like the Timmins mine in Canada, fluids can be trapped for over a billion years, allowing for the possibility of life persisting on this timescale.
Ancient salt deposits: In one controversial study, bacteria were reportedly isolated and revived from a 250-million-year-old salt inclusion. While there is ongoing debate about contamination, the findings suggest the potential for extreme longevity in some bacteria.
Why these microbes live so slowly
In these nutrient-poor, energy-limited habitats, microbes have adapted to minimize their energy consumption.
Maintenance metabolism: A large portion of their minimal energy is likely used for cell repair and maintenance rather than for growth and reproduction.
Slow growth, not dormancy: Studies have shown that many of these organisms are not simply dormant, but are metabolically active and dividing, though at an exceptionally slow pace.
Survival traits: This slow-growth strategy allows them to endure long periods of starvation and environmental stress, making them some of the most enduring life forms on Earth.
We are unlocking how frozen microbes stay alive for 100,000 years
It is amazing – and even a bit frightening – how long certain organisms can last. Of course, this bodes well for any native microorganisms on Mars who might be surviving and even thriving deep (?) under the surface of the Red Planet. After all, Mars also has huge regions of subsurface ice water.
This also makes me wonder: If these “simple” creatures can live for ages without consciously trying, what could an advanced intelligent species do in terms of longevity?
Speaking of long lives…
A recent record for this incredible ability to exist in a living state is 100 million years by some aerobic bacteria found under deep sea sediments in the Pacific Ocean:
https://www.scientificamerican.com/article/100-million-year-old-seafloor-sediment-bacteria-have-been-resuscitated/
Even more recently, scientists have found two-billion-year-old microorganisms buried in some igneous rocks from South Africa that may still be alive!
https://link.springer.com/article/10.1007/s00248-024-02434-8
And I love this animated speculation on Martian life courtesy of Walt Disney from 1957…
https://www.youtube.com/watch?v=m8pjloU1XL4&t=1s
I find it curious that some of these organisms would therefore be longer lived than the sea floor where they reside. Are they migratory? No, that’s not a serious question, just demonstrating the unreasonableness of superficial evidence of long lived organisms.
The Pacific Ocean is older than the 100 million years of the microbes found in teh sediment. Whether or not the calculations are correct, the finding cannot be discounted by the age of the ocean.
Billion-year-old microbes is another matter, unless they are still reproducing at a slow rate that stays within bounds.
I we cryo-preserved microbes as cells and not spores, and protected them from external damage, how long could they last? If nothing else, it implies that microbes embedded in frozen rocks or comets could survive long journeys across interstellar space, making a mockery of our concerns of warm, complex animal survival of even a century questionable.
I first heard about long-lived microbes in the deep ocean sediments about a decade or so ago. Since then, the discoveries of very slow metabolizing microbes have increased. Preservation of microbes has also been demonstrated by revived microbes millions of years old, which is fascinating as this means that functioning biology can be maintained rather than the organisms leaving fossil traces. Very X-Files.
I have wondered whether these microbes could provide a useful genomic sequence clock to calibrate against their more contemporary and active examples of the species.
More relevant to this post is whether it is possible that microbes in the subsurface glaciers have survived and might be extracted when drilling into the subsurface glaciers for water sources on Mars.
Thank you for this post!👍🏼
Finding the fox by its footprints or a missing chicken and a few feathers near the coop.
After his first adventure recovering tiny metallic globules from the sea floor where an interstellar meteor went down, Avi Loeb was contemplating a second expedition to look for bigger chunks, but that adventure didn’t materialize. I was hoping that they might find a well-preserved alien thumb drive or solid state drive or some such techno-artifact. Maybe one may yet be found on a forthcoming interstellar asteroid or comet.
Robin Datta – I don’t know what happened to Avi Loeb. When he started his now very off-road adventure, he said he was mainly doing this so that mainstream science would include extraterrestrial explanations into the current science paradigms. Instead, he reminds me more of Eric von Daniken and the infamous ancient astronauts ideas from the 1970s.
Sadly, Loeb is also reminding me of Harvard professor John Mack who studied those who claim to have been abducted by aliens and got lost along the way…
https://www.psychologytoday.com/us/articles/199403/the-harvard-professor-the-ufos?msockid=295f0603348667a51b4e15a235c56636
There is a very good reason why science is so rigorous. Pseudoscience doesn’t need any more help – it already has way too many supporters as it is. This isn’t just an inconvenience or even amusing: It is a genuine threat to our society.
Maybe the Chinese can bring back the samples for us…
https://www.livescience.com/space/mars/if-there-is-a-space-race-chinas-already-winning-it-nasa-unlikely-to-bring-mars-samples-back-to-earth-before-china-does-experts-say
There first attempt to land a rover on Mars was a success:
https://www.space.com/tianwen-1.html
And they have also returned samples of lunar regolith from both our natural satellite’s near and far sides:
https://en.wikipedia.org/wiki/Chinese_Lunar_Exploration_Program
Well done article, Alex. You clearly laid out the details of this important discovery for the field of extraterrestrial life and the need to get those samples back to Earth – either that or we send an advanced biolab there.
What are your thoughts on percholates and how they might affect life on Mars, especially the kind that is might actually be living there now?
https://ntrs.nasa.gov/api/citations/20190028297/downloads/20190028297.pdf
https://www.sciencedirect.com/science/article/pii/S0019103524003063
https://www.seattletimes.com/opinion/crucial-evidence-about-life-on-mars-is-stuck-on-mars/
@LJK
The chlorate and perchlorates are fairly toxic to terrestrial plants. I am old enough to recall that sodium chlorate was sold as a weedkiller. On Mars, as they are produced by surface conditions, it is probable that they do not extend deeply into the regolith, the depth depending on the turnover of the regolith.
Having said that, terrestrial prokaryotes can use chlorates and perchlorates for energy and are therefore suitable for detoxifying the Martian regolith for agriculture.
There is a CD post about remediating the Martian regolith: Mars Agriculture – Knowledge Gaps for Regolith Preparation.
As for indigenous Martian life, there are two possibilities. Firstly, they live in niches well away from the surface in crustal rocks where the conditions allow for liquid water. Secondly, like terrestrial organisms that can use these molecules, there could be life just beneath the surface, protected from radiation, but utilizing the chlorates as an energy source.
It would be ironic if the Viking mission actually detected these microbes, but the findings were dismissed. We have been very careful to avoid doing biology on Mars for 50 years. Maybe now is the time to start thinking about it again.
This article goes into great detail on the Viking biology experiments and how they came about…
https://www.drewexmachina.com/2022/07/28/nasas-viking-mission-the-search-for-life-on-mars-the-experiments/
You may also find this video of interest…
https://www.youtube.com/watch?v=9s9UXXAmlTg
It is unfortunate how gun-shy NASA became after the ambiguous Viking results. They just had an incomplete view of the makeup of the Martian surface at the time, which in one way should have been expected considering no one had successfully landed on the Red Planet before.
I was also surprised that Viking didn’t have better methods of conducting a geological and mineralogical analysis of the Martian surface: One might think that would have been a top-tier priority in the search for life there.
Then again, when InSight landed on Mars in 2018, the mission team somehow didn’t take into account that there might be obstructing rocks under the Martian surface when they attempted to burrow seismology sensors into it, go figure.
We are talking about 1960s and early 1970s technology for teh Viking landers. I can tell you that labs in those days were very primitive by comparison to today, with very little knowledge of molecular biology. Just for reference, the structure of DNA was elucidated just 22 years earlier, genetics was studied with no understanding of what genes were, and my university had no courses on molecular biology, just biochemistry. A few proteins had been painstakingly sequenced. Electronics were still very simple. Programmable ICs with CPUs and memory were being introduced when Viking was on Mars. I can only guess at what was available when Viking was being designed. Just compare the Viking science instruments to those on Perseverance with roughly the same spacecraft mass. Today, we can pack optical spectrometers, gas chromatography, mass spectrometers, and even tiny microscopes on a probe, and control them with sophisticated software that can analyze the data locally if desired. Look at old 1960 movies of scientists staring down basic microscopes. Today, those scopes can do far more, and if portability is desired, there are tiny microscopes offering 40-100x magnification. If we had a tiny microscope with 1000x magnification, we could resolve bacteria, and that could be packed onto an icy moon probe/lander.
Since we don’t yet know if life exists or what its molecular biology is, we cannot yet sequence its DNA/RNA/proteins. But if life exists, we will be able to do that once we have the knowledge. Imagine doing environmental “alien DNA” analysis from a sub-ice-crust ocean submersible, or even a plume sampler at the surface. The first Nature/Science article about the results will be sensational. Then it will be ho-hum.
Yes, but what about analyzing the mineral composition of the Martian surface itself? I am not talking about looking for any life signs here, only the reachable inorganic contents of the ground around the Viking landers.
Are you saying that even in 1976 we lacked the technology to determine what the planet’s surface was made of geologically?
@LJK
No, I am not saying that. What I am saying is:
1. Instruments have both improved, become smaller, and can do analyses that were not possible before. In some cases, e.g., classifying minerals, we can do that remotely with new laser-based instruments, which previously took human expertise, eyeballing, and chemical treatments. Consider. It needed an Apollo astronaut trained in geology and geologist approaches to find teh famous “genesis rock” on the Moon. Now a rover can do that, albeit more slowly than a human in a spacesuit. As we move forward, more and more analyses that require bringing back samples will be done remotely. Indeed, when we have interstellar probes, the only thing sent back to Earth will be information, certainly no samples.
2. As I said before, how we do biology now is very different than what was done in the 1970s. We can probe biology in ways unthinkable back then. It was bust 35 years ago when teh human genome project was started, and 25 years ago when it was completed. Today, you can run a complete human genome sequence for less than $1000. You can also sequence DNA with a device the size of a cigarette packet. Genomic phylogeny (as used in the LUCA paper) is a post-2000 technique due to the low cost of DNA sequencing. Gene expression studies – also an end-of-century development. We can gene engineer organisms using CRISPR, a technique that succeeds the old restriction enzyme approach, vastly improving the accuracy of replacement and finally allowing this technique to be used in the clinic.
What does this mean for the search for life? Viking could only do basic biology experiments – growth, metabolic outputs – the sort of experiments that were done in student labs. It wasn’t much more sophisticated than looking at pond water samples with a good magnifying glass and a basic microscope. The concept of C13/C12 isotope analysis of organic material was unknown (AFAIK). Most biological material analysis required samples, separating components in a centrifuge, and running chemicals or fractionation columns to separate and detect components and functionality. None of that could be put on a langer, even if there were large, complex organisms within trappable reach. Of course, if that were the case, a simple camera would be all that was needed to detect extant life.
Even now, we still need to bring rock samples back to Earth to be analyzed by equipment too large to put on a probe, such as an electron microscope. We cannot yet do carbon isotope analysis in the field. We also need domain experts to work on physical samples. Machines still have limitations, and will always do so for the foreseeable future. However, technology is constantly improving, and we can expect our machines to do more remotely in the future. The adage that a spacesuited human can do the work faster is rapidly ending. The ground speed of Mars rovers has increased rapidly, and the Ingenuity helicopter has shown that it can exceed human walking (and driving?) speed on Mars. Remote science labs in space are the future. The only issue is whether humans are better off also being in space with them where possible, or not.
UMass Researchers Help ID New Mineral on Mars, Providing Insight on the Red Planet’s Potential to Have Supported Life
Identifying the mineral on Mars’ surface has eluded scientists for decades
Researchers from the University of Massachusetts Amherst are part of a team that has identified a unique mineral on Mars, described in Nature Communications.
Named ferric hydroxysulfate, the mineral provides clues about the Martian environment and history of the planet, including the possibility of former lava, ash or hydrothermal activity.
The full article here…
https://www.umass.edu/news/article/umass-researchers-help-id-new-mineral-mars-providing-insight-red-planets-potential
The paper online here…
https://www.nature.com/articles/s41467-025-61801-2
To quote:
“Temperature, pressure and conditions such as pH are all very important indications of what the paleoclimate was,” says Parente. He is excited about the new level of detail scientists have for understanding the Red Planet through this research. “The presence of this mineral puts a lot more nuance on what was going on. Parts of Mars have been chemically and thermally active more recently than we once believed—offering new insight into the planet’s dynamic surface and its potential to have supported life.”
It strikes me as near insane that Perseverance’s Martian samples will sit there, waiting to be picked up for lack of a few billion dollars.
Whether finings are positive, negative, panspermic, or unique; their analysis would change our understanding of biogenisis across the universe.
Humans to Mars yes, but send “Fed Ex”to get that package!
Better yet, collaborate with the European, Chinese, and Indian space agencies to bring back the goods.
As I posted in this thread above, the Chinese are seriously planning to return samples of the Martian surface to Earth. Their recent mission efforts at Luna and Mars indicate they could do it.
https://www.livescience.com/space/mars/if-there-is-a-space-race-chinas-already-winning-it-nasa-unlikely-to-bring-mars-samples-back-to-earth-before-china-does-experts-say
I wonder if that will energize the US to get the samples back? China is already overtaking the US in several technology and science endeavors. A successful Mars sample return by China could be a “Sputnik” moment for the US.
[The current mania of hyperscaling the GenAI development to reach AGI/SI may well collapse the US stock market and damage the economy, and could even allow China to become dominant. I hope sanity will prevail, but the current US zeitgeist seems to be following the 1930s German experience with regard to science (and art), and look where that led.]
I will be surprised if there is not life on Mars. If it did not evolve independently, it would have probably arrived from Earth via panspermia, probably around 4 bya.
At this time, the surface of Mars and shallow bodies of water would have been too oxidizing for it to survive, but deeper bodies of water like the Great Northern Ocean would most likely have been anaerobic in their lower reaches. As Mars dried out and froze, this life would have retreated, following the liquid layer into the crust becoming like the slow metabolizing aeonophiles deep in Earth’s crust today.
The question will be is the life we find native, or did it come from Earth, or did Earth’s life come from Mars?
@Dave
What is the evidence for this? The atmosphere was still mostly CO2, possibly with hydrogen, and warm enough to maintain liquid water oceans and seas. Even if photolysis of H2O was generating some free O2, it seems unlikely to have created enough to be oxidizing. Even the Earth’s oceans failed to become decently oxidizing for a couple of billion years until the iron was finally oxidized and free O2 could accumulate.
Supposing we find extant life on Mars, could we determine if it was indigenous or came from Earth, or vice versa, if its biology was effectively identical to terrestrial life? If nothing else, it may stimulate research into whether paleo conditions on Mars could be more or less favorable to abiogenesis than Earth.
I wonder if the impact that formed the Hellas Basin disrupted if not outright destroyed any major life forms that were present on Mars at that time – as well as disrupted either their further evolution or potential to exist later on?
References:
https://marspedia.org/Hellas_Planitia
https://www.sciencedirect.com/science/article/abs/pii/S0012821X25003656
And then there is this…
https://www.astronomy.com/science/mars-moon-phobos-may-have-formed-from-a-giant-impact/
We should probably check for fossils, and maybe life, on the Martian satellites as well.
The mineralization is all oxidized species. Sulfur is in the form of sulfate, not FeS if the surface was reducing. Iron is in its ferric state Fe3+ not Ferrous state Fe2+.
And most importantly Manganese is in its 4+ state not its 2+ state. This is the marker used on Earth to tell whenEarth’s oceans became full aerobic.
@Dave
But are the oxidized minerals we see from 4 bya, or more recently, after the loss of the surface water?
Yes, that is the case. Sulfates and carbonates need water to form. The most interesting case is the Mg4+. Curiosity found a pond bed about 4 billion years old, and at what had been the surface of the pond, Mg was in the 4+ state, while at the bottom of the pond, Mg was in its 2+ state. This is an almost certain indication there was an atmosphere with some level of Oxygen in it.
Somebody has done a paper on this, but I haven’t got around to reading it yet.
Life can’t be ruled out until we get some Mars rocks. Fossils will of course be indigenous. The question is was Mars hospital long enough or not for life to survive.
Time to Revisit the Viking Mars Lander, Search for Life Results
By Leonard David
February 21, 2025
https://www.leonarddavid.com/time-to-revisit-the-viking-mars-lander-search-for-life-results/
Some relevant quotes…
The most significant change since those 1970s experiments were conducted was the discovery of high levels of perchlorate on Mars. Perchlorate, plus abiotic oxidants, explains the Viking results and there is no requirement to postulate life on Mars.
“The discovery of perchlorate on Mars by the Phoenix mission has provided a basis for explaining the results of the Viking Landers,” the newly issued paper notes. “Thermal decomposition of perchlorate in the ovens of the [Viking] instrument can explain the lack of organics detected. Accumulation of hypochlorite in the soil from cosmic ray decomposition of perchlorate can explain the reactivity seen when nutrient solutions were added to the soil in the Viking Biology Experiments.”
However, the paper adds, “a non-biological explanation for the Viking results does not preclude life on Mars.”
Revisit the results
The just-released paper — The Viking biology experiments on Mars revisited – has been authored by noted Mars researchers Christopher McKay, Richard Quinn and Carol Stoker. All three authors are from the space science division of NASA’s Ames Research Center at Moffett Field, California, near San Francisco.
“With Mars sample return on the horizon and the prospect of future missions to Mars, perhaps even including life detection instruments, it may be timely to revisit the results of the Viking Biology Experiments,” the research team suggests. “Since Viking landed on Mars, many things have changed, and many things have not. What has not changed in the past 50 years is our understanding of the limits of life in cold and dry environments.”
In a communiqué with Christopher McKay, he told Inside Outer Space: “It is important to note that we are not saying that the Viking results imply ‘no life on Mars.’ Nor are we saying the Viking results imply there is life on Mars.”
McKay said that their core point is that the Viking results are saying there is perchlorate and other oxidants on Mars, “and that is what the Viking biology experiments responded to.”
What this means is that the results of the Viking Biology experiments can’t be used to justify an approach to astronaut health and safety or a sample and/or astronaut quarantine policy for return to Earth that assumes no life on Mars.
…
Good targets
In summing up their research paper, they conclude that the perchlorate model for the Viking results “does not prove that there is no life on Mars, nor does it imply that the continued search for evidence of life on Mars, past or present, is pointless.”
Indeed, as the research team suggests, “we strongly argue for the search for evidence of extant life in future missions. Good targets are salt deposits and polar ground ice.”
I was incorrect about the possibility of remote testing of carbon isotopes C-13, C-12 on Mars. The failed ESA Beagle 2 mission lander could do that:
Source: Beagle 2.
As for the NASA missions, look at the various science packages on a series of rovers starting with Sojourner in 1997.
Sojourner (1997)
Spirit & Opportunity(2004)
Curiosity (2012)
Perseverance (2021)
It is also worth looking at the computer limitations on teh rovers. They used relatively early computers compared to comparable home computers at the same time, probably due to the lead time for the design.
Compare to the Chinese Mars rover:
Zhurong (2021)
Comparison of embedded computer systems on board the Mars rovers
A new article on China possibly returning the Perseverence biosphere to Earth…
https://www.space.com/astronomy/mars/could-china-return-the-perseverance-rovers-possible-biosignature-sample-from-mars
The discussion above covers a wide range of evidence and hypotheses in the absence so far of sample retrieval. Some of it was related to..
Long lived and low metabolic rate microbial life here on Earth in ocean sediments: the inference that martian equivalents could exist even now subsurface.
And if there was primitive life on Mars, did it originate there or here?
Well, I would think that the odds are better that the meteoritic Fedex shipping works better from Mars to Earth than vice-versa. But I don’t think we should leave out the possibility that life in the solar system and its early neighboring stars fits into this picture as well.
A lot of evidence from other spacecraft such as the Bennu and Japanese mission to asteroid Ryugu. Precursors to life were abundant in both cases, especially the first.
At one time or another tardigrades were examined as to how good a spacefaring species they might be. Maybe they have/had cousins that actually could have done the job.
But since we all have a fascination with Alpha Centauri “today”, it is practically a standing argument against life transport from one star system to another. In the sun’s earlier days, however, it was likely that it formed amid more close neighbors which dispersed out of a relatively much more dense and rich cloud or interstellar medium. Xenophiles might have been with us all along as well as our interplanetary interstellar neighbors in the ancient gas cloud.
So, in summary, if present day “bacterial” life can be detected on Mars, or traces of its existence can be found from eons ago, I don’t think we should discount its more than local nature – beside its possible connection to life on Earth.
Speaking of life somewhat at the other end of the tree from the roots, the passing of Jane Goodall has been noted widely these past few days – and one of her early discoveries was that the chimpanzees she observed had a tendency to construct tools from stems or shoots to draw out termites from their mounds for dinner.
Doing it since before ‘we” discovered agriculture, farming or the wheel. And just how was this “technology” passed down?
So much else about her career seems to leave that observation in the background. And yet it’s there. Tools made for maybe a million years – but left at the same threshold. We can put that into our Drake equation considerations and smoke it. Language of some nature exists here too. A step or two toward communication across the sky.
This flicker of consciousness is similar to ours in many ways biologists would not have acknowledged decades ago. So many inherent qualities of consciousness that could be biological – or chance. But odds decrease for the latter. As wasteful as nature might seem, there are elements that suggest it values purposes we can understand or sympathize with. If we were to discover life or its remains on Mars, I can’t anticipate as yet how, but I hope that we will be able to imitate Goodall’s respect for and ability to gain insight from it.
We don’t know how long that tool was used, although it is very probable that it was a meme passed down through observation of tool-using chimps. We don’t even know if it appeared before chimps split off from earlier ancestor species, even further back in time.
Paleolithic homo species made the same stone tools for 3 million years, so it is quite conceivable it may have been a similar length of time for chimps, which split off from the homo line over 8 mya.
We also know of more recent memes being developed by primates, and IIRC, one of the ape species taught ASL passed that to her offspring. [One day, Caesar will appear.]
@wdk
Panspermia within a system might be possible on the solar wind blowing off bacteria in the upper atmosphere. If so, that might allow a better chance of Earth seeding Mars, or even Venus seeding Earth.
If microbes can survive for millions of years, then it may be more likely that panspermia could exist between stars now that we have evidence of 3 interstellar objects arriving in our system, with expectations that newer telescopes will discover many more. We also know that stars periodically make close encounters with ou.r system, reducing the time for material swaps. What then is the probability of microbes making a multi-light-year journey and reaching the Earth, and vice versa? Does it require microbes to be ejected in rocks from an impact, or can microbes be seeding the KBO and Oort objects, which are then ejected by passing stars? A biological study of icy moon surfaces might provide some answers if it could be shown that there were microbes with the same terrestrial biology. KBO life would remove any issue of independent biogenesis. I expect that paleo diseases will become a sub-discipline this century as we build libraries of ancient pathogens and viruses.
It would be ironic if Hoyle and Wickramasinghe were right that comets contained life (viruses), but inferred this for the wrong reasons (virus outbreaks on Earth from close encounters).
A.T.,
When the thought occurred to me about fitting chimpanzees into the Drake equation, there was a flash for a moment about somehow changing the input diagram… And then it vanished. But it was something akin to the Earth having more cards on the table in the equation or the ramp up to communication than we might normally acknowledge simply factoring probabilities. A rigged casino slot machine perhaps.
But the other “panspermia” element would most likely be close the beginning of Earth’s history. Were we to witness solar system formation early days, what would an unclouded dark sky look like? It would have stars, of course, but a lot of them a lot closer and in a considerably denser interstellar medium.
When I was searching around my old textbooks on stellar and planetary origins, the ones I have were published long before exoplanets were discovered. Interactions like Oumuamua were not considered.
The Allende meteorite ( which fell to Earth 07 February 1969) was about the only evidence for interstellar interaction. Reviewing the webpage, it has pre-solar grains or CAIs _”calcium–aluminium-rich inclusions”. The lead isotope 204 and 207 ratios in Allende and other carbonaceous chondrite meteorites attest to a solar system age of about 4.56 billion years back, but there are other inclusions of other nature in the Allende
remains include older time settings.
If this is interstellar material, it is reasonable to think that less of this sort of material would be around in the early solar system, or otherwise we wouldn’t be able to establish a 4.6 billion year birthmark to begin with. But on the other hand, it is a piece of evidence that other stars were not that far away from the birthday party either.
Based on traces of calcium, barium and neodymium isotopes, as early as 1977 a case was built that the solar system’s formation was triggered by a supernova explosion 2 million years prior that provided a compressive shockwave.
Now given the shockwave and the absence as yet of our friend the sun, additional inclusions in Allende were
“..small amount(s) of carbon (including graphite and diamond), and many organic compounds, including amino acids, some not known on Earth. Iron, mostly combined, makes up about 24% of the meteorite. Unpublished detailed study in 2020 have purportedly identified iron and lithium-containing protein of extraterrestrial origin, hemolithin, first such discovery in meteorite.”
I don’t want to get too carried away by the Wikipedia anecdotal material at the end. However, I think this does make a case for the sun being surrounded by a
medium condensed by a shock, a medium with refuse from earlier galactic populations of stars – and that once this cloud contracted, the stars formed within were a lot closer neighbors than Alpha Centauri and Sol are now. We have an Oort Cloud and Kuiper Belt these days, but I would wager that the debris medium between the sun and the next star was orders of magnitude closer and denser and that was likely the case in almost all directions, assuming our sun was well embedded in the region. Findings from asteroid Bennu and Ryugu sample missions seem to suggest something akin to that too: complex organic chemistry smeared all over pebbles from the early solar system.
Before Apollo when I was a teenager, sometimes there were news reports about scientific committees stressing their preferences for space missions vs. what would turn into Apollo. A recurring priority was sampling a comet for life’s building blocks. The Allende was still on its way here, but I can see where the science “panelists” were coming from now.
According to this recent article from The Planetary Society, the piece claims there are “roughly one trillion billion million objects reside in interstellar space — that’s a 1 followed by 27 zeros.”
https://www.planetary.org/articles/where-do-3i-atlas-and-other-interstellar-visitors-come-from
If this number is accurate or just close – and they do not state where they got this estimate from, please note – then the odds that at least some interstellar debris will contain life on it are pretty good and thus good for the concept of galactic panspermia.
That we have confirmed only three interstellar objects since 2017 only means that we really need to ramp up and modernize our astronomical observing efforts. No wonder SETI has yet to find anything since 1960.
https://astrobiology.com/2025/10/waking-up-microbes-trapped-in-permafrost-for-up-to-40000-years.html
Waking Up Microbes Trapped In Permafrost For Up To 40,000 Years
By Keith Cowing
Press Release
University of Colorado at Boulder
October 4, 2025
In a new study, a team of geologists and biologists led by CU Boulder resurrected ancient microbes that had been trapped in ice—in some cases for around 40,000 years.
The study is a showcase for the planet’s permafrost. That’s the name for a frozen mix of soil, ice and rocks that underlies nearly a quarter of the land in the northern hemisphere. It’s an icy graveyard where animal and plant remains, alongside plentiful bacteria and other microorganisms, have become stuck in time.
That is, until curious scientists try to wake them up.
The group discovered that if you thaw out permafrost, the microbes within will take a while to become active. But after a few months, like waking up after a long nap, they begin to form flourishing colonies.
“These are not dead samples by any means,” said Tristan Caro, lead author of the study and a former graduate student in geological sciences at CU Boulder. “They’re still very much capable of hosting robust life that can break down organic matter and release it as carbon dioxide.”
Caro and his colleagues published their findings in September in the journal JGR Biogeosciences.
The research has wide implications for the health of the Arctic, and the entire planet, added study co-author Sebastian Kopf.
Today, the world’s permafrost is thawing at an alarming rate because of human-caused climate change. Scientists worry this trend could kick off a vicious cycle. As permafrost thaws, microbes living in the soil will begin to break down organic matter, spewing it into the air as carbon dioxide and methane—both potent greenhouse gases.
Robyn Barbato of the Cold Regions Research and Engineering Laboratory drills a sample from the walls of the Permafrost Tunnel. Credit Tristan Caro
“It’s one of the biggest unknowns in climate responses,” said Kopf, professor of geological sciences at CU Boulder. “How will the thawing of all this frozen ground, where we know there’s tons of carbon stored, affect the ecology of these regions and the rate of climate change?”
Long slumber
To explore those unknowns, the researchers traveled to a one-of-a-kind location, the U.S. Army Corps of Engineers’ Permafrost Tunnel. This research facility extends more than 350 feet into the frozen ground beneath central Alaska.
When Caro entered the tunnel, which is about as wide as a mine shaft, he could see the bones of ancient bison and mammoth sticking out from the walls.
“The first thing you notice when you walk in there is that it smells really bad. It smells like a musty basement that’s been left to sit for way too long,” said Caro, now a postdoctoral researcher at the California Institute of Technology. “To a microbiologist, that’s very exciting because interesting smells are often microbial.”
In the current study, the researchers collected samples of permafrost that was a few thousand to tens of thousands of years old from the walls of the tunnel. They then added water to the samples and incubated them at temperatures of 39 and 54 degrees Fahrenheit—chilly for humans, but downright boiling for the Arctic.
“We wanted to simulate what happens in an Alaskan summer, under future climate conditions where these temperatures reach deeper areas of the permafrost.” Caro said.
With a twist: The researchers relied on water made up of unusually heavy hydrogen atoms, also known as deuterium. That allowed them to track how their microbes drank up the water, then used the hydrogen to build the membranes made of fatty material that surround all living cells.
Arctic summers
What they saw was surprising.
In the first few months, these colonies grew at a creep, in some cases replacing only about one in every 100,000 cells per day. In the lab, most bacterial colonies can completely turn over in the span of a few hours.
But by the six-month mark, that all changed. Some bacterial colonies even produced gooey structures called “biofilms” that you can see with the naked eye.
Caro said these microbes likely couldn’t infect people, but the team kept them in sealed chambers regardless.
He added that the colonies didn’t seem to wake up that much faster at hotter temperatures. The results could hold lessons for thawing permafrost in the real world: After a hot spell, it may take several months for microbes to become active enough that they begin to emit greenhouse gases into the air in large volumes.
In other words, the longer Arctic summers grow, the greater the risks for the planet.
“You might have a single hot day in the Alaskan summer, but what matters much more is the lengthening of the summer season to where these warm temperatures extend into the autumn and spring,” Caro said.
He added there are still a lot of open questions about these microbes, such as whether ancient organisms behave the same at sites around the world.
“There’s so much permafrost in the world—in Alaska, Siberia and in other northern cold regions,” Caro said. “We’ve only sampled one tiny slice of that.”
Microbial Resuscitation and Growth Rates in Deep Permafrost: Lipid Stable Isotope Probing Results From the Permafrost Research Tunnel in Fox, Alaska, Journal of Geophysical Research Biogeosciences
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2025JG008759
Astrobiology
@LJK
The observation that it took months to “wake” up the bacteria is both interesting and important. Bacterial cultures are often assumed to rapidly develop colonies in 24 hours, especially pathogens that infect mammals. But if they take months, then any lander or rover doing a life experiment on Mars needs to be running for months before determining whether life is present or not.
I would also mention that the vast majority of bacteria cannot be cultured, so it is possible that Viking-adjacent life experiments may be a waste of time. But, if we can get a DNA sample, then we are “off to races”, as environmental DNA collection and analysis does not need culturing, just a successful replication by PCR. This does require knowledge that the DNA uses the same bases, which may mean that we do need a real colony sample to extract and sequence the DNA. [What if any of the 4 bases are not the same, but different? What if the sugar-phosphate backbone is different? If so, then current technology will not work, but maybe we can design a PCR that will work?]
All this applies to any life on that uncountable number of interstellar objects.
Do we have any estimate of the fraction of objects (meteorites or comets) that contact the Earth? Also, with comets, how often does the Earth pass through a comet’s tail (both volatiles and dust tails)? This may be important when we determine the number of ISOs that can enter our solar system and contact the Earth, bringing material that could include life. An answer per 10 million years might indicate whether panspermia was a probable proximate cause of life appearing on Earth or not, depending on whether they have life [0…1]. The last, like a Drake Equation probability, is an unknown, but might well be making comets and icy moons viable objects to take samples for life, culturing them in laboratories over time to determine if any organisms exist and are alive. [Ice can be melted, and filters used to trap any bacteria and discard other abiotic objects.]
https://astrobiology.com/2025/10/exomars-rosalind-franklin-mars-rover-sample-processing.html
ExoMars Rosalind Franklin Mars Rover Sample Processing
By Keith Cowing
Status Report
ESA
October 6, 2025
The intricate mechanisms of the most sophisticated laboratory on Mars are revealed in Episode 4 of the ExoMars Rosalind Franklin series, called “Sample processing.”
The Rosalind Franklin rover’s drill has a maximum reach of two metres – deeper than any other mission has ever attempted on the Red Planet. This depth allows access to well-preserved organic material from four billion years ago, when conditions on the surface of Mars were more like those on infant Earth.
Broadcast quality footage — ESA
After receiving a sample from the drill, Rosalind’s laboratory must prepare the sample to make a detailed study of its mineral and chemical composition. The rover’s Analytical Laboratory Drawer (ALD) mechanisms execute a pre-programmed choreography of sample manipulations to make sure that the instruments can do their job.
The ExoMars Rosalind Franklin mission is part of Europe’s ambitious exploration journey to search for past and present signs of life on Mars.
For the latest mission updates, visit ESA’s ExoMars website and our FAQ section.
Astrobiology
https://astrobiology.com/2025/10/curtin-university-powers-a-global-push-to-find-life-on-mars-and-advance-autonomy.html
Curtin University Powers A Global Push To Find Life On Mars And Advance Autonomy
By Keith Cowing
Press Release
Curtin University
October 6, 2025
https://astrobiology.com/2025/10/rocket-test-proves-bacteria-survive-space-launch-and-re-entry-unharmed.html
Rocket Test Proves Bacteria Survive Space Launch And Re-entry Unharmed
By Keith Cowing
Press Release
RMIT University
October 7, 2025
A world-first study has proven microbes essential for human health can survive the extreme forces of space launch.
Space agencies are planning to send crews to Mars within decades but sustaining life on the red planet would be more difficult if important bacteria die during the flight.
Now an Australian-led study has found the spores of Bacilus subtilis, a bacterium essential for human health, can survive rapid acceleration, short-duration microgravity and rapid deceleration.
The spores of bacteria were launched high into the sky, then studied once their rocket fell back to earth, in what is believed to be the first study of its kind in real conditions outside the lab.
Study co-author Distinguished Professor Elena Ivanova from RMIT University said the findings add to our overall understanding of how living organisms respond to the unique environment of space.
“Our research showed an important type of bacteria for our health can withstand rapid gravity changes, acceleration and deacceleration,” Ivanova said.
“It’s broadened our understanding on the effects of long-term spaceflight on microorganisms that live in our bodies and keep us healthy.
“This means we can design better life support systems for astronauts to keep them healthy during long missions.
“Researchers and pharmaceutical companies can also use this data to conduct innovative life science experiments in microgravity.”
Although humans have been living on board space stations for short stints since the 1970s, bacteria like B. subtilis are important to sustain healthy human life over decades, which will be needed for a future Mars colony. B. subtilis bacteria contribute towards support the immune system, gut health and blood circulation.
The test
For the study, researchers blasted the spores to the edge of space in a sounding rocket subjected to several extreme conditions in a short time including rapid acceleration, deceleration and very low gravity.
Although B. subtilis is known to be tougher than other microbes, testing this variety sets a benchmark for further study on other, more delicate, organisms.
During the launch, the rocket experienced a maximum acceleration of about 13 g – 13 times the force of Earth’s gravity – during the second stage burn phase.
After reaching an altitude of about 260 kilometres, the main engine cut off, initiating a period of weightlessness called microgravity that lasted for more than six minutes.
Upon re-entry into the Earth’s atmosphere, the payload experienced extreme deceleration, with forces up to 30 g while spinning about 220 times per second.
After the flight, spores showed no changes in their ability to grow and their structure stayed the same, indicating a key microbe for human health can survive the journey.
RMIT space science expert Associate Professor Gail Iles said understanding how microorganisms survive in space is crucial for the future of space travel.
“This research enhances our understanding of how life can endure harsh conditions, providing valuable insights for future missions to Mars and beyond,” she said.
“By ensuring these microbes can endure high acceleration, near-weightlessness and rapid deceleration, we can better support astronauts’ health and develop sustainable life support systems.”
Benefits for life on Earth
Understanding the limits of microbial survival could lead to innovations in biotechnology, where microorganisms are used in extreme environments on Earth.
“Potential applications of this research extend far beyond space exploration,” Ivanova said.
“They include developing new antibacterial treatments and enhancing our ability to combat antibiotic-resistant bacteria.
“We’re a while away from anything like that but now we have a baseline to guide future research.”
Iles said the findings add to our overall understanding of how living organisms respond to the unique environment of space.
“Microbes play essential roles in sustaining human health and environmental sustainability, so they’re an essential factor of any long-term space mission,” she said.
“Broader knowledge of microbial resilience in harsh environments could also open new possibilities for discovering life on other planets.
“It could guide the development of more effective life-detection missions, helping us to identify and study microbial life forms that could thrive in environments previously thought to be uninhabitable.”
Space industry links
RMIT collaborated with space tech firm ResearchSat and drug delivery company Numedico Technologies on the research, which involved transporting the bacteria from Melbourne to Sweden.
The launch was hosted by the Swedish Space Corporation and featured a custom 3D-printed microtube holder developed by ResearchSat and RMIT.
The sample was prepared and later analysed at the RMIT Microscopy and Microanalysis Facility, which houses state-of-the-art electron microscopes, surface analysis and microanalysis instrumentation.
Now the team is seeking further funding to further facilitate researching life sciences in microgravity, which could lead to improvements in drug delivery, discovery and chemistry. For more information, email research.partnerships@rmit.edu.au.
‘Effects of Extreme Acceleration, Microgravity, and Deceleration on Bacillus subtilis Onboard a Suborbital Space Flight’(open access) is published in npj Microgravity. DOI: 10.1038/s41526-025-00526-4
https://www.nature.com/articles/s41526-025-00526-4
Astrobiology, Space biology
That test was one expensive and unnecessary experiment. It could have been done on the ground. Furthermore, a few minutes of microgravity is immaterial compared to months of microgravity and exposure to radiation. And the experiment was done on spores, not live bacteria. Is this the new “gold standard science” the administration speaks of?
https://astrobiology.com/2025/10/preliminary-planning-for-mars-sample-return-msr-curation-activities-in-a-sample-receiving-facility-srf.html
Preliminary Planning For Mars Sample Return (MSR) Curation Activities in a Sample Receiving Facility (SRF)
By Keith Cowing
Status Report
Astrobiology via Pub Med
October 9, 2025
The Mars Sample Return Planning Group 2 (MSPG2) was tasked with identifying the steps that encompass all the curation activities that would happen within the MSR Sample Receiving Facility (SRF) and any anticipated curation-related requirements. An area of specific interest is the necessary analytical instrumentation.
The SRF would be a Biosafety Level-4 facility where the returned MSR flight hardware would be opened, the sample tubes accessed, and the martian sample material extracted from the tubes. Characterization of the essential attributes of each sample would be required to provide enough information to prepare a sample catalog used in guiding the preparation of sample-related proposals by the world’s research community and informing decisions by the sample allocation committee.
The sample catalog would be populated with data and information generated during all phases of activity, including data derived concurrent with Mars 2020 sample-collecting rover activity, sample transport to Earth, and initial sample characterization within the SRF. We conclude that initial sample characterization can best be planned as a set of three sequential phases, which we have called Pre-Basic Characterization (Pre-BC), Basic Characterization (BC), and Preliminary Examination (PE), each of which requires a certain amount of instrumentation.
Data on specific samples and subsamples obtained during sample safety assessments and time-sensitive scientific investigations would also be added to the catalog. There are several areas where future work would be beneficial to prepare for the receipt of samples, which would include the design of a sample tube isolation chamber and a strategy for opening the sample tubes and removing dust from the tube exteriors.
Preliminary Planning for Mars Sample Return (MSR) Curation Activities in a Sample Receiving Facility (SRF), Astrobiology via Pub Med
Preliminary Planning for Mars Sample Return (MSR) Curation Activities in a Sample Receiving Facility (SRF), Astrobiology via Pub Med (open access)
https://www.liebertpub.com/doi/10.1089/AST.2021.0105?url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org&rfr_dat=cr_pub++0pubmed
Astrobiology
https://astrobiology.com/2025/10/mars-crater-deposits-reveal-a-history-of-shrinking-ice-volumes-through-ages.html
Mars Crater Deposits Reveal A History Of Shrinking Ice Volumes Through Ages
By Keith Cowing
Press Release
Okayama University
October 10, 2025
Mars craterfill deposits showing varying intensities and topographies (cross sections). Crater locations are shown in Figure 2A. (A) Thin and laterally restricted fill with deposits concentrated in the southwestern region (34.40°E, 31.30°N). The zoomed-in image in the center-left shows lineated terrain (marked with white arrows), similar to glacial flutes, indicating possible downslope boulder movement from the southwestern part of the crater. On the right, it shows the absence of ridges on the northeastern part. (B) Moderately thick and laterally extensive fill at Ismenius Cavus (17.10°E, 33.50°N) with moraines (white arrows in inset) and a ring-mold crater (red rectangle in inset). (C) Thick and laterally extensive fill (41.40°E, 30.15°N) featuring brain terrain and glacial flow patterns. Double-headed red arrow marks the southwestern ridge width, while black arrows represent ridge widths in the western and eastern part of the crater, respectively. Photos are from the CTX camera onboard the Mars Reconnaissance Orbiter. (D–F) Schematics of low, mid, and high-intensity fills, matching the craters in A–C, respectively, showing southwestern deposition trends. — Geology
For decades, scientists have been curious about how much water Mars once had and what led to its gradual transformation into the dry planet we see today.
A new study published online on September 2, 2025, in the Geology journal, sheds light on this mystery by looking deep inside martian craters, which act like “ice archives” that store a frozen record of the planet’s past. These craters reveal that Mars went through repeated ice ages over hundreds of millions of years; however, with each cycle, the amount of remaining ice decreased steadily.
The study was led by Associate Professor Trishit Ruj from Institute for Planetary Materials, Okayama University, Japan, along with Dr. Hanaya Okuda from Kochi Institute for Core Sample Research, Japan, Dr. Hitoshi Hasegawa from Kochi University, Japan, and Professor Tomohiro Usui from Institute of Space and Astronautical Science, Japan. By studying the glacial landforms preserved in craters between 20°N and 45°N latitude, the team was able to reconstruct how Mars stored and lost its water through time.
Dr. Ruj explains, “Mars went through repeated ice ages, but the amount of ice deposited in craters steadily shrank over time. These icy ‘time capsules’ not only reveal how Mars lost its water but also mark places where future explorers might tap into hidden ice resources.”
To investigate this, the researchers analyzed high-resolution images from NASA’s Mars Reconnaissance Orbiter. They focused on craters with indicative signs of glaciation, such as ridges, moraines (piles of debris left behind by glaciers), and brain terrain (a pitted, maze-like surface formed by ice-rich landforms). By comparing the shapes and orientations of these features with climate models, they found that ice consistently clustered in the colder, shadowed southwestern walls of craters. This trend was consistent across various glacial periods, ranging from approximately 640 million to 98 million years ago.
The results show that Mars didn’t just freeze once—it went through a series of ice ages driven by shifts in its axial tilt, also known as obliquity. Unlike Earth, Mars’ tilt can swing dramatically over millions of years, redistributing sunlight and triggering cycles of ice build-up and melting. These changes shaped where water ice could survive on the planet’s surface. Over time, however, each cycle stored less ice, pointing to a gradual planetary drying.
The team highlights the significance of these findings: “By tracing how Mars stored and lost its ice, this study guides future explorers to water supplies and offers insights that can be applied to Earth’s changing environment.”
The implications of this work extend far beyond understanding martian climate. Hidden ice deposits could be important for future human missions to Mars. Buried ice can be used for drinking water, converted into oxygen for breathing, and split into hydrogen and oxygen to make rocket fuel—a process known as in-situ resource utilization (ISRU). This would allow astronauts to live off the land rather than carry all their supplies from Earth, making long-term missions more practical and affordable.
“Knowledge of long-lived ice deposits helps identify safe and resource-rich regions for future robotic and crewed landings,” notes Prof. Usui.
Beyond space travel, the study also offers lessons for our own planet. The shrinking ice on Mars is a planetary-scale example of climate change, showing how water systems respond to long-term environmental shifts. The same imaging and modeling tools used in this research can also help scientists monitor glaciers, permafrost, and hidden water reservoirs on Earth, where the effects of climate change are already visible. “Mars serves as a natural laboratory for understanding how ice behaves over vast timescales. The insights we gain here can sharpen our understanding of climate processes on Earth as well,” emphasizes Dr. Hasegawa.
In conclusion, the discovery of multi-stage glaciations paints a picture of Mars as a planet that once cycled through periods of icy abundance, only to see its frozen reserves steadily diminish. These findings not only enrich our understanding of Mars’ past but also help chart a path forward for its exploration. By learning from the red planet’s icy history, humanity may one day unlock the resources needed to survive and thrive on another world.
Long-term and multi-stage ice accumulation in the martian mid-latitudes during the Amazonian, Geology (open access)
https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G53418.1/660985/Long-term-and-multi-stage-ice-accumulation-in-the
Astrobiology, Astrogeology
It is remarkable what inferences can be made about the Martian climate and glaciers from high-resolution, orbital imagery. While I don’t think any of the crater locations were investigated by any of the rovers, it would be good to get some ground truth to verify the imaging analysis, and hopefully even use this to find the glaciers and extract cores for analysis.
As with the protocol described for handling the MSR samples, sometime in the future, carefully preserved cores might be sent back to Earth for analysis, just as we do with Antarctic and Greenland ice cores. On Mars, those cores might preserve not just 100s of thousands of years of climate and environmental data, but potentially billions (3?) of years. If there was indigenous life on Mars, or life delivered from Earth or elsewhere, that might be trapped in the ice, it should be amenable to analysis. What a treasure to uncover!
https://astrobiology.com/2025/10/mars-sample-return-msr-sample-receiving-facility-srf-assessment-study-msas.html
Mars Sample Return (MSR) Sample Receiving Facility (SRF) Assessment Study (MSAS)
By Keith Cowing
Status Report
NASA
October 16, 2025
The Mars Sample Return (MSR) campaign, initiated in 2020 with the launch of the Perseverance Rover, is an international partnership between NASA and the European Space Agency (ESA) to return Martian geological samples to Earth for scientific study in the early 2030s.
Not only is MSR the first mission to bring samples back to Earth from an-other planet, it is the first time since Apollo 14to have a mission classified as a Category V: Restricted Earth Return by the NASA Planetary Protection Office due to the possibility that the samples could harbor extra-terrestrial life.
https://astrobiology.com/wp-content/uploads/2025/10/Mars-Sample-Return-MSR-Sample1.png
Notional MSR Campaign architecture The cartoon is intended to demonstrate functional steps for the MSR Campaign and, other than the Mars 2020 Mission, may not represent the final campaign mission architecture. — PNAS via PubMed
As a result of this classification, the Sample Receiving Facility (SRF)must not only pro-vide a pristine environment to ensure samples are protected from terrestrial contamination for scientific investigations, it must also provide high-containment (biosafety level 4 [BSL-4]-equivalence)to isolate the samples from Earth’s biosphere until the samples are deemed safe for release and/or sterilized.
https://astrobiology.com/wp-content/uploads/2025/10/Mars-Sample-Return-MSR-Sample2.png
This illustration shows the proposed process for safely recovering, containing, and transporting Mars samples gathered by NASA’s Perseverance Mars rover after they are returned to Earth as part of the joint NASA/ESA (European Space Agency) Mars Sample Return Campaign.– NASA source
Mars Sample Return (MSR) Sample Receiving Facility (SRF) Assessment Study (MSAS), NASA NTRS Abstract
Preliminary Planning for Mars Sample Return (MSR) Curation Activities in a Sample Receiving Facility (SRF), NASA / Astrobiology via University of Las Vegas (open access)
https://oasis.library.unlv.edu/cgi/viewcontent.cgi?article=1543&context=geo_fac_articles
Astrobiology
https://astrobiology.com/2025/10/probing-the-geological-setting-of-exoplanets-through-atmospheric-analysis-using-mars-as-a-test-case.html
Probing The Geological Setting Of Exoplanets Through Atmospheric Analysis: Using Mars As A Test Case
By Keith Cowing
Status Report
astro-ph.EP
October 16, 2025
One of the frontier research fields of exoplanetary science is the study of the composition and variability of exoplanetary atmospheres.
This field is now moving from the gas giant planets towards the smaller and colder telluric planets, and future instruments like ANDES will focus on the observations of the atmosphere of telluric planets in the habitable zone in reflected light. These future observations will possibly find variable signals due to the view of different hemispheres of the planet.
Particularly, the strength of the signal may be linked to the thickness of the atmospheric layer probed, and therefore to the average altitude variations of the planetary surface, that are related to the global geodynamic evolution of the planet. To better prepare for the interpretation and exploitation of these future data, we used Mars as a Solar System analog of a spatially resolved telluric exoplanet.
We observed the reflected light of Mars with the high-resolution near-infrared (NIR) spectrograph GIANO-B (widely used in exoplanetary atmospheric studies) during a 3 month period: we studied the spatial and temporal variations of the Martian CO2 signal using the least-squared deconvolution technique (LSD), to mimic as closely as possible the standard exoplanetary atmospheric analysis.
We linked the variations found to the well-known Martian geological surface characteristics: we found a clear dependence of the strength of the CO2 signal with the thickness of the Martian atmospheric layer by comparing the retrieved CO2 signal with the altitudes of our pointings. The proposed strategy is promising: it proved to be effective on Mars and may shed light on the variations in the strength of atmospheric signal of telluric exoplanets.
Monica Rainer, Evandro Balbi, Francesco Borsa, Paola Cianfarra, Avet Harutyunyan, Silvano Tosi
Comments: 44 pages, 18 figures, accepted for publication on Icarus
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2510.09305 [astro-ph.EP] (or arXiv:2510.09305v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2510.09305
Focus to learn more
Submission history
From: Monica Rainer
[v1] Fri, 10 Oct 2025 11:53:16 UTC (1,643 KB)
https://arxiv.org/abs/2510.09305
Astrobiology, Astrogeology
https://astrobiology.com/2025/10/yeast-survives-martian-conditions.html
Yeast Survives Martian Conditions
By Keith Cowing
Press Release
Indian Institute of Science (IISc)
October 15, 2025
Any life on Mars in the past, present, or future would have to contend with challenging conditions including, among others, shock waves from meteorite impacts and soil perchlorates—highly oxidizing salts that destabilize hydrogen bonds and hydrophobic interactions.
Purusharth I. Rajyaguru and colleagues subjected Saccharomyces cerevisiae, which is a widely used model yeast, to shock waves and perchlorates. The authors chose the yeast in part because it has already been studied in space. When stressed, yeast, humans, and many other organisms form ribonucleoprotein (RNP) condensates, structures made of RNA and proteins that protect RNA and affect the fates of mRNAs.
When the stressor passes, the RNP condensates, which include subtypes known as stress granules and P-bodies, disassemble. The authors simulated Martian shock waves at the High-Intensity Shock Tube for Astrochemistry (HISTA) housed in the Physical Research Laboratory in Ahmedabad, India. Yeast exposed to 5.6 Mach intensity shock waves survived with slowed growth, as did yeast subjected to 100 mM sodium salt of perchlorate (NaClO4)—a concentration similar to that in Martian soils.
Yeast cells also survived exposure to the combined stress of shock waves and perchlorate stress. In both cases, the yeast assembled RNP condensates. Shock waves induced the assembly of stress granules and P-bodies; perchlorate caused yeast to make P-bodies but not stress granules. Mutants incapable of assembling RNP condensates were poor at surviving the Martian stress condition.
Transcriptome analysis identified specific RNA transcripts perturbed by Mars-like conditions. According to the authors, the results show the importance of yeast and RNP condensates in understanding the effects of Martian conditions on life.
https://astrobiology.com/wp-content/uploads/2025/10/Yeast-Survives-Martian-conditions1.png
Model depicting the importance of RNP condensate in mediating survival under Mars-like stress condition. In wild-type cells, sodium perchlorate stress causes cell wall damage and protein misfolding, which coincides with P-body assembly and stabilization of stress-related transcripts (SPI1, ROM2, SSE2, ERO1, and SSA1). This enables maintenance of cell wall integrity and protein folding, thereby promoting survival. In contrast, P-body assembly mutants fail to form condensates, leading to decreased abundance of these transcripts and heightened sensitivity to perchlorate stress. — PNAS Nexus
Ribonucleoprotein (RNP) condensates modulate survival in response to Mars-like stress conditions, PNAS Nexus (open access)
https://academic.oup.com/pnasnexus/article/4/10/pgaf300/8285101?login=false
Astrobiology
https://astrobiology.com/2025/10/are-there-living-microbes-on-mars-check-the-ice.html
Are There Living Microbes on Mars? Check The Ice.
By Keith Cowing
Press Release
Penn State
October 17, 2025
Frozen in time, ancient microbes or their remains could be found in Martian ice deposits during future missions to the Red Planet.
By recreating Mars-like conditions in the lab, a team of researchers from NASA Goddard Space Flight Center and Penn State demonstrated that fragments of the molecules that make up proteins in E. coli bacteria, if present in Mars’ permafrost and ice caps, could remain intact for over 50 million years, despite harsh and continuous exposure to cosmic radiation. In the study, published in Astrobiology, the researchers encouraged future missions searching for life on Mars to target locations with pure ice or ice-dominated permafrost for exploration, as opposed to studying rocks, clay or soil.
“Fifty million years is far greater than the expected age for some current surface ice deposits on Mars, which are often less than two million years old, meaning any organic life present within the ice would be preserved,” said co-author Christopher House, professor of geosciences, affiliate of the Huck Institutes of the Life Sciences and the Earth and Environment Systems Institute, and director of the Penn State Consortium for Planetary and Exoplanetary Science and Technology. “That means if there are bacteria near the surface of Mars, future missions can find it.”
Samples of E. coli mixed with water ice and Martian sediment were cooled to minus 60 degrees Fahrenheit, then blasted with an equivalent of 20 million years of cosmic radiation at Penn State’s Radiation Science and Engineering Center. Credit: Provided by Alexander Pavlov. All Rights Reserved.
The research team, led by corresponding author Alexander Pavlov, a space scientist at NASA Goddard — who completed a doctorate in geosciences at Penn State in 2001 — suspended and sealed E. coli bacteria in test tubes containing solutions of pure water ice. Other E. coli samples were mixed with water and ingredients found in Mars sediment, like silicate-based rocks and clay.
The researchers froze the samples and transferred them to a gamma radiation chamber at Penn State’s Radiation Science and Engineering Center, which was cooled to minus 60 degrees Fahrenheit, the temperature of icy regions on Mars. Then, the samples were blasted with radiation equivalent to 20 million years of cosmic ray exposure on Mars’ surface, vacuum sealed and transported back to NASA Goddard under cold conditions for amino acid analysis. Researchers modelled an additional 30 years of radiation for a total 50-million-year timespan.
In pure water ice, more than 10% of the amino acids — the molecular building blocks of proteins — from the E. coli sample survived the simulated 50-million-year timespan, while the samples containing Mars-like sediment degraded 10 times faster and did not survive. A 2022 study by the same group of researchers at NASA found that amino acids preserved in a 10% water ice and 90% Martian soil mixture were destroyed more rapidly than samples containing only sediment.
“Based on the 2022 study findings, it was thought that organic material in ice or water alone would be destroyed even more rapidly than the 10% water mixture,” Pavlov said. “So, it was surprising to find that the organic materials placed in water ice alone are destroyed at a much slower rate than the samples containing water and soil.”
That degradation could be due to a slippery film that forms in areas where ice touches minerals, the researchers hypothesized, allowing radiation to reach and destroy amino acids.
“While in solid ice, harmful particles created by radiation get frozen in place and may not be able to reach organic compounds,” Pavlov said. “These results suggest that pure ice or ice-dominated regions are an ideal place to look for recent biological material on Mars.”
In addition to testing for conditions on Mars, researchers also tested organic material in temperatures similar to those on Europa, an icy moon of Jupiter, and Enceladus, an icy moon of Saturn. They found that these even colder temperatures further reduced the rate of deterioration.
Those results are encouraging to NASA’s Europa Clipper mission, Pavlov said, which will explore the ice shell and ocean of Europa, the fourth largest of Jupiter’s of 95 moons. Europa Clipper launched in 2024 and is traveling 1.8 billion miles to reach Jupiter in 2030. It will conduct 49 close flybys of Europa to assess whether there are places below the surface that could support life.
For exploring ice on Mars, the 2008 NASA Mars Phoenix mission was the first to excavate down and capture photos of ice in the Mars equivalent of the Arctic Circle.
“There is a lot of ice on Mars, but most of it is just below the surface,” House said. “Future missions need a large enough drill or a powerful scoop to access it, similar to the design and capabilities of Phoenix.”
In addition to House and Pavlov, the co-authors include Zhidan Zhang, a retired lab technologist in the Penn State Department of Geosciences; and Hannah McLain, Kendra Farnsworth, Daniel Glavin, Jamie Elsila and Jason Dworkin, all researchers at NASA Goddard.
NASA’s Planetary Science Division Internal Scientist Funding Program through the Fundamental Laboratory Research work package at Goddard Space Flight Center supported this research.
Slow Radiolysis of Amino Acids in Mars-Like Permafrost Conditions: Applications to the Search for Extant Life on Mars, Astrobiology (open access)
https://www.liebertpub.com/doi/10.1177/15311074251366249
Astrobiology
https://astrobiology.com/2025/10/an-introduction-to-mars-terraforming-2025-workshop-summary.html
An Introduction To Mars Terraforming – 2025 Workshop Summary
By Keith Cowing
Status Report
astro-ph.IM
October 22, 2025
Terraforming Mars is an age old science fiction concept now worth revisiting through the lens of modern science and technology.
This document serves as a summary of contemporary ideas about Mars terraforming, prepared for attendees of the 2025 Green Mars Workshop. It presents one illustrative story of how Mars might be transformed into a habitable world.
The story is told in reverse, beginning with possible planetary endpoints and tracing backward to the steps required to reach them.
Along the way, it highlights alternative approaches, critical unknowns and research priorities, and the near-term applications and benefits of terraforming research for planetary science, climate engineering, and sustainable technologies on Earth.
Devon Stork, Erika DeBenedictis
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP); Geophysics (physics.geo-ph)
Cite as: arXiv:2510.07344 [astro-ph.IM] (or arXiv:2510.07344v1 [astro-ph.IM] for this version)
https://doi.org/10.48550/arXiv.2510.07344
Focus to learn more
Submission history
From: Erika DeBenedictis
[v1] Tue, 7 Oct 2025 19:47:12 UTC (20,280 KB)
https://arxiv.org/abs/2510.07344
Astrobiology, Astrogeology
https://astrobiology.com/2025/10/mysterious-gullies-on-mars-appear-to-have-been-dug-but-by-whom-or-what.html
Mysterious Gullies On Mars Appear To Have Been Dug, But By Whom Or What?
By Keith Cowing
Press Release
Utrecht University
October 22, 2025
https://astrobiology.com/wp-content/uploads/2025/10/Mysterious-Gullies-On-Mars.png
Two examples of Martian dunes with linear dune gullies. North is up in both images. (a) Linear dune gullies on a dune field in Galle crater (HiRISE image ESP_077477_1280_MIRB). (b) Linear dune gullies on a dune field in an unnamed crater in the centre of Hellas Planitia (HiRISE image ESP_051770_1345). — Geophysical Research Letters
Did life really exist on Mars after all? Unfortunately, there is no conclusive evidence for this yet. Nevertheless, it would seem that some form of life was the driving force behind the mysterious Martian dune gullies.
Earth scientist Dr Lonneke Roelofs from Utrecht University has investigated how these gullies were formed. In a test setup, she observed that blocks of CO2 ice ‘dug’ these gullies in a unique way. “It felt like I was watching the sandworms in the film Dune.”
Other researchers had previously suspected that these blocks could play a role in the formation of the gullies. Roelofs has now proven this by having CO2 ice blocks actually dig those gullies in an experiment – a phenomenon that we do not know here on Earth and that had never been observed by anyone before.
Sublimation
Ice forms on the dunes during the Martian winter when it is minus 120 degrees Celsius. At the end of winter, the dune slopes heat up and blocks of ice break off, some of which are up to a metre long. Due to the thin atmosphere and the large temperature difference between the warm dune sand and the ice, the bottom side of the ice immediately turns into gas, a process referred to as sublimation. As a kilo of gas requires far more space than the same weight of ice, the ice explodes, so to speak.
“In our simulation, I saw how this high gas pressure blasts away the sand around the block in all directions”, says Roelofs. As a result, the block digs itself into the slope and becomes trapped in a hollow surrounded by small ridges of settled sand. “However, the sublimation process continues, and so the sand keeps on being blasted in all directions.” Due to this process, the block gradually moves downwards, leaving a long, deep gully with small sand ridges on either side behind it. This is exactly the type of gully that is also found on the Red Planet.
Video footage from the experiments – watch the ice blocks dig themselves in…
https://www.youtube.com/watch?v=PVCU6_5hl-0
Landscape formation
Roelofs preparing her experiments at the Mars Chamber…
https://astrobiology.com/wp-content/uploads/2025/10/Mysterious-Gullies-On-Mars1.jpg
Lonneke Roelofs investigates the processes that form the landscape on the planet Mars. For example, last year she published her research into sublimation of CO2 ice as a driver of Martian debris flows.
https://www.uu.nl/en/news/surprising-insights-about-debris-flows-on-mars
These flows cut deep gullies on crater walls. “But the gullies from this research looked different”, explains Roelofs. “Therefore, a different process was behind this, but which? That is what I set out to discover.”
Mars chamber
Together with master student Simone Visschers, she travelled to the English city of Milton Keynes to solve the mystery behind these unusual sand gullies. The Open University has a ‘Mars chamber’: a facility for simulating Martian conditions. Financial support from the British Society of Geomorphology made the visit possible. “We tried out various things by simulating a dune slope at different angles of steepness. We let a block of CO2 ice fall from the top of the slope and observed what happened”, states the researcher.
“After finding the right slope, we finally saw results. The CO2 ice block began to dig into the slope and move downwards just like a burrowing mole or the sandworms from Dune. It looked very strange!”
When the CO2 ice (still visible at the bottom) has left a trail through the sand, with the characteristic levees on the sides of the gully. The bend in the gully is probably due to a small disturbance in the sand bed.
From ice to gullies
But how exactly do these blocks of ice form? “The CO2 ice blocks form on the desert dunes halfway down the southern hemisphere of Mars. During the winter, a layer of CO2 ice forms over the entire surface of the dune field, sometimes up to a thickness of 70 cm! In spring, this ice begins to warm up and sublimate. The last remnants of this ice are located on the shaded side of the dune tops, and that is where the blocks break off from once the temperature is high enough. Once the blocks reach the bottom of the slope and stop moving, the ice continues to sublimate until all the CO2 has evaporated. What remains is a hollow in the sand at the bottom of the dune.”
https://astrobiology.com/wp-content/uploads/2025/10/Mysterious-Gullies-On-Mars2.jpg
Why Mars?
Why does this planet fascinate people so much? “Mars is our nearest neighbour. It is the only rocky planet close to the ‘green zone’ of our solar system. This zone lies exactly far enough from the Sun to make the presence of liquid water possible, which is a prerequisite for life. Questions about the origin of life, and possible extra-terrestrial life, could therefore be solved here”, says Roelofs.
“Also, conducting research into the formation of landscape structures of other planets is a way of stepping outside the frameworks used to think about the Earth. This allows you to pose slightly different questions, which in turn can deliver new insights for processes here on our planet.”
Article
Lonneke Roelofs, Simone R. Visschers, Susan Conway et al., ‘Sliding and burrowing blocks of CO2 create sinuous “linear dune gullies” on Martian dunes by explosive sublimation-induced particle transport’, Geophysical Research Letters…
https://doi.org/10.1029/2024GL112860 (open access)
Astrobiology, astrogeology
Spinning, spinning, spinning to Mars
In the 1980s, a group of scientists and engineers developed a Mars mission concept that had significant influence. Dwayne Day examines that concept and its staying power.
https://www.thespacereview.com/article/5085/1
Spinning, spinning, spinning to Mars
by Dwayne A. Day
Monday, October 20, 2025
In 1984, a group of scientists, engineers, and graduate students meeting in Colorado for a conference and led by a core group of enthusiasts who a journalist nicknamed the “Mars Underground,” developed a concept for a human mission to Mars.
Because the group included an artist named Carter Emmart who sketched and later illustrated the phases of the Mars mission, for at least a decade or longer that Mars concept appeared in books and even novels as the way that humans would explore the Red Planet. It influenced both the culture and thinking about human missions to Mars.