Wikipedia:Reference desk/Archives/Science/2024 February 1

= February 1 =

Life on Mars
Let's say that at some point in the future and after enough search scientists conclude that there is no life on Mars, at all, nor has there ever been. And then it is proposed to bring life ourselves. Of course, no animals or plants can survive in Mars as it is, but is there any bacteria that may survive and thrive there, if just released and left on its own? Cambalachero (talk) 00:49, 1 February 2024 (UTC)


 * There are probably no Earthly microbes that would thrive at the surface of Mars, as it is dry, often very cold, and exposed to high levels of radiation. There might be some that could endure in those conditions, though likely in a dormant or mostly dormant state.  However, the considerations change dramatically if you consider the subsurface.  At several kilometers of depth, the Martian lithosphere is likely warm enough for liquid water and shielded from space radiation.  Conditions suggest that many of the bacteria found in the deep subsurface of Earth would also find the deep subsurface of Mars hospitable.  Dragons flight (talk) 02:17, 1 February 2024 (UTC)
 * Not bacteria, but tardigrades could probably hack it for a while, but the lack of water and nutrients might prevent their long-term survival. See:
 * Can tardigrades theoretically survive on Mars?
 * Spacesuits optional for 'water bears' 
 * Alansplodge (talk) 12:23, 1 February 2024 (UTC)
 * Lichen as well might have a chance so it's fairly certain lots of strange single celled ones can survive no problem. NadVolum (talk) 12:45, 1 February 2024 (UTC)
 * There are a thing called water bears. They are real life aliens from space. 23.24.81.162 (talk) 22:07, 1 February 2024 (UTC)
 * Froget about the reply you did think of that. 23.24.81.162 (talk) 22:08, 1 February 2024 (UTC)
 * Some organisms—those that can thrive in extreme conditions on Earth—have been considered as potential candidates for life on Mars. Some extremophiles, such as certain types of bacteria and archaea, can withstand extreme temperatures, high levels of radiation, and other inhospitable conditions.
 * One example is Deinococcus radiodurans, a bacterium known for its ability to survive high levels of radiation. Harvici  ( talk ) 03:07, 2 February 2024 (UTC)


 * As I recall, Carl Sagan talked about the possibility of terraforming Mars. It would require creating a greenhouse effect, to hold in warmth and moisture. ←Baseball Bugs What's up, Doc? carrots→ 06:24, 2 February 2024 (UTC)


 * There are organizations inside of NASA tasked with Planetary Protection - (not to be confused with the similarly-named, totally-different task of Planetary Defense).
 * "Planetary Protection is the practice of protecting solar system bodies from contamination by Earth life..."
 * That NASA website has a lot of information about the objectives, methods, and accomplishments that are used to make sure that life does not accidentally spread.
 * From one of the resources linked, here is a 2021 COSPAR official statement of policy COSPAR POLICY ON PLANETARY PROTECTION. The goal is "to protect “special regions” on Mars, which were defined as “a region within which terrestrial organisms are likely to propagate, or a region which is interpreted to have a high potential for the existence of extant Martian life forms.”"  In other words, in direct answer to the original question - scientists are actively studying specific conditions in specific areas on Mars to fully understand (and control for) any possibility of Earth life-forms that might spread there.
 * Nimur (talk) 18:52, 2 February 2024 (UTC)
 * I wanna throw in my two cents. The other respondents basically covered the topics of tardigrades and the deinococcus radiodurans, i actually don't believe lichen would make it for long... the thing is, Mars is as barren as it gets. There's literally nothing there. Said tardigrades or other minor organisms could probably survive there for years, but there's nothing to go on, any scarce supply of nutrients would be exhausted fairly quickly. It's basically sending them over there so they could barely exist. No kind of thriving would be possible, there's just nothing there. --Ouro (blah blah) 20:33, 2 February 2024 (UTC)
 * Dryness, a relatively high radiation level and relative coldness are not only reasons why the terrestrial life cannot survive on Mars. What is more important is that the Mars environment probably lacks any energy sources necessary for life to survive. In addition this environment is chemically very hostile to life: there is an abundance of chlorine compounds (e.g. perchlorates, chlorates and elemental chlorine) that are normally used as disinfectants on Earth. Ruslik_ Zero 20:46, 2 February 2024 (UTC)
 * That's very narrow view. Seeing what evolution did on Earth, it is almost certain that if life started at Mars warm period, they adjusted to the conditions wherever the temp rises over 4 c in the summer. Zarnivop (talk) 03:26, 3 February 2024 (UTC)
 * The OP's question is not about native Martian life, but about how native Earth life would fare if released on Mars. I think Ruslik is correct: the answer to the OP's question is "not well". Double sharp (talk) 14:36, 3 February 2024 (UTC)
 * Well, it's clear that you need some kind of thermal energy source in order for life (as we know it) to start in order to keep the water liquid. But you need nutrients (which are energy sources that have to be digested) in any case. --Ouro (blah blah) 05:48, 3 February 2024 (UTC)
 * True, and both exist on Mars. On the equator, the temperature is 0 c in average. This means that during the martian day, temperatures rise above 0, and likely above 4 c - that's means water ice -> water. This is with direct dun - which provides energy. As for nutrients, primary life forms only require minerals, co2, light and water. Some primary organisms on Earth developed alternate energy production means (We actually found | lithobacteria 2 km deep in rocks on Earth). Zarnivop (talk) 12:53, 3 February 2024 (UTC)
 * The problem is that under Martian ambient conditions the boiling point of pure water is lower that the melting point. So, the ice quickly sublimates before any water can appear. The water can exist only in form of a heavy brine saturated with various (often toxic) salts. Ruslik_ Zero 13:13, 4 February 2024 (UTC)
 * On earth some lichen can continue photosynthesizing and growing within ice at down to minus 20 degrees centigrade. And there's some life growing in the salt crystals in the various salt flats around earth and the brine of the Dead Sea. NadVolum (talk) 17:41, 4 February 2024 (UTC)
 * Dead Sea's water indeed contains a small number of bacteria and archaea but usually in place where salinity is lower. But you should take into account that Dead Sea is not nearly as toxic as any possible Martian brine. So, on Mars no terrestrial microorganism can possibly survive. Ruslik_ Zero 20:30, 4 February 2024 (UTC)
 * Hellas Planitia would barely support liquid water. Double sharp (talk) 15:17, 5 February 2024 (UTC)
 * There are some microbes that can grow via perchlorate reduction. Double sharp (talk) 15:21, 5 February 2024 (UTC)
 * The problem is not perchlorates themselves but their radiolysis products. Ruslik_ Zero 20:02, 5 February 2024 (UTC)
 * Thanks for the paper! In that case, I agree: ClO2 nails the door shut. Double sharp (talk) 08:22, 6 February 2024 (UTC)
 * Extensive exposed layers of clean ice may have been found in the mid-latitudes and at 11.9 degrees from its equator there is evidence of a geothermal mantle plume  at Cerberus Fossae. Deeper, warmer water with fewer salts than its desert-like soils will allow would mean... Hell, it is even possible that Mars's life hitched a ride along time ago and colonized our hydrothermal vents. Modocc (talk) 16:56, 6 February 2024 (UTC)