Amazingly, the question asked for centuries, and asked scientifically for over a century, still has no answer: Does Mars have life? Even the possibility of surface or near-surface life at Mars has not been scientifically answered. Conversely, the surface of Mars has not been proven sterile. So should we return samples of Mars to Earth without even knowing if the samples contain microbes or other life?
There are at least six significant but controversial signs that Mars has surface or near-surface life. (See Overview of Mars page via the menu at the upper right). However, to scientifically declare Mars has life, definitive proof would be required. I’m interested to collect the opinions of people, especially amateur astronomers, to the question: Does Mars have life? Also, does that opinion affect your concern of the danger of a Mars pathogen or invasive species being returned to Earth in the upcoming Mars Sample Return program?
Mars has no atmospheric protection against Lethal Ultraviolet radiation, thus the (less) likelihood of living pathogens being brought back to earth.
it’s hypothesis when it’s yet to be proved and theory when the evidence supports the hypothesis.
Secondly. That’s why we have gone to Mars to collect samples to study.
‘Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying.’-Arthur C. Clarke
While I understand your point of view since there is zero evidence of definitive life, we have found very curious results. I’d suggest looking into what test samples from previous missions prompted the perseverance mission. It seems very obvious to the experts there was liquid water at one point. Mars is very old but it is growing increasingly likely that it may have been habitable for some forms of life even if just microbial. Obviously perseverance placement in an ancient dried lake bed with evidence of flowing water (rivers) feeding into it is an excellent place to search. Normally our rovers avoid this type of terrain so being able to land inside instead should provide us something. I’d also suggest to check out what we been observing in Venus’s atmosphere! Looks like that will be another mission happening to learn more. I don’t disagree with you on the facts but there is promising data in our solar system let alone when you imagine the statistical probabilities!
Dr. Gilbert Levin discovered microbiotic life in the soil of Mars in 1976 with the Labeled Release experiment. Met EVERY preset requirement for declaring life existed on Mars. Every objection to the reality of the discovery has been reversed & overcome – still denied.
There is 0 evidence of life anywhere outside of Earth. Every “possible indication” of life on Mars is also caused by geochemical processes. It is completely sterile and poses no threat. Everything else is science fiction.
We already have numerous meteorites proven to come from Mars. Also some scientists believe that is where life on earth originated in the first place -also from space in general. Probably the greatest danger here is Earth contaminating Mars, not the other way around.
I don’t personally think life on Mars has ever existed. It is definitely a possibility. I just wonder, when life arises at the right time it grows very rapidly. So my thought is that most likely either Mars is full of dead life and a few modern extremophiles, or that it has had no signs of life. If the first case is true I would imagine past missions would’ve found something.
I think that it is possible that in the early stages of life Mars could’ve went through such harsh changes that life was snuffed out, in that case finding the signs of life would be very challenging. Regardless of life I’m sure the perseverance team will learn exiting new things about Mars.
P.s. I don’t study biology so my thoughts on astrobiology have no weight.
Stuff from Mars already arrives on earth all the time. If anything could have done anything it would have already done it.
Perhaps. But even ALH84001 didn’t prove that, but even given that some Mars life has made it to Earth via meteors (lithopanspermia), how can we be sure that random collection represents what Perseverance will collect?
We came from Mars
Warning, I am not an astrobiologist. Though I did meet a couple once backcountry skiing, and was not impressed. Mars IMO, is most likely dead. I believe life is very rare, very special and that puts me at odds with the mainstream. There is argument that life originated on Earth or Mars and found it’s way to the other world. Sort of panspermia. Or we may have contaminated Mars already. I’d take the latter. In either case that will prove out. Native Martian life would be a fascinating opportunity to discover if the building blocks of life, proteins and such could be manipulated differently.
My niece worked on Perseverance. The whole family is watching! Who knows what it will find?
Not life as we know it. Concerned about possible bacteria/viruses being returned to Earth?
Seems likely there is life (on Mars), doesn’t it?
Based on what we have learned from Curiosity, the near-surface mudstones at Gale crater have been cooked by ionizing radiation for tens of millions of years, leading to destruction and significant oxidation of the organics there.
At the Committee on Space Research (COSPAR) conference (Australia, 2021, though virtual due to Covid), I specifically asked a Mars Curiosity scientist who presented results “Is it clear from the results (of analysis by Curiosity on Mars) that the samples could NOT have contained dormant cells or bacteria?”
The response was “That’s an interesting qustion. I would say No, it is not clear. We can not from the organic compound range we have detected with SAM on Curiosity, we can not determine the origin of these compounds. It is compatible with chemistry, it is compatible with life, and we do not have a way to differentiate both origins.”
I imagine the only life they might find would be mold spores, which are probably all over the near solar system anyway.
Considering how long living organisms can survive in an environment which doesn’t protect them from the sun’s radiation plus, the need for FOOD during that time, there’s vey little chance anything’s up there that’d live for even 100 years let alone thousands of years… More than likely, if they bring something back in a sample container, it’s because the sample container carried it up there in the first place… But, we’ll see.
Richard P., some organisms go dormant for a time. Estimated that if Mars bacteria has d radiodurans DNA repair mechanisms, it could remain dormant on Mars for two million years before the ionizing radiation would destroy it. Yup, we’ll see (but I’d rather learn what we’re dealing with on Mars or even on the ISS first.) Thanks and be well!
I fully think that life is in our solar system other than on Earth. Life will be abundant in the universe. This is about finding and bringing bacteria, on Mars, that is still viable. Is it possible…yes. but so is getting hit by a meteor…
Have you seen the movie “life” on Netflix? Pretty much a horror drama about exactly this- A Mars specimen gets out of hand.
Dan B. That’s right, except, according to NASA, the samples will be brought directly to Earth and not tested on the ISS for safety. Also, I don’t expect an alien like the one in the move, but even an invasive bacteria could be very bad for Earth!
I don’t know who he knew. He worked on so many classified projects he never talked about his co-workers
Yes, my father (who was part of the design and testing team for Viking) always said the results were not entirely negative.
When they were building the equipment, they realised they hadn’t tested it outside of the lab. They used it on earth dirt. The test came back negative. They found that one of the test steps killed everything ?
John F. , interesting! Did he know Dr. Gil Levin? He had one of the life detection experiments aboard Viking and has maintained the positive results of his experiment were not due to soil composition but were in fact signs of life. Thank you very much for your comments. I do list the Viking results as one of the six controversial signs of life on the “Overview of Mars” page
No, Mars is sterile and there are decontamination steps.
John F., how do you know Mars is sterile? In fact that is not known and probably not true. There are six controversial signs that Mars has life listed on the “Overview of Mars” page.
As for decontamination, there are no plans to decontaminate the samples prior to return to Earth (or immediately after) – a main purpose of the samples is to look for life or signs of life.
“Curiosity rover measured ionizing radiation levels of 76 mGy per year. This level of ionizing radiation is sterilizing for dormant life on the surface of Mars. It varies considerably in habitability depending on its orbital eccentricity and the tilt of its axis. If the surface life has been reanimated as recently as 450,000 years ago, then rovers on Mars could find dormant but still viable life at a depth of one meter below the surface, according to an estimate. Even the hardiest cells known could not possibly survive the cosmic radiation near the surface of Mars since Mars lost its protective magnetosphere and atmosphere.”
No. Mars is a sterile planet. It has been since it lost its atmosphere.
Tom S. that is incorrect. Mars has a thin atmosphere.
It is unlikely that there are microbes on Mars. The environment there, low pressure toxic atmosphere and high ionizing radiation, could be used to sterilize surgical instruments.
As a chemist I am not concerned about contamination (to) Earth, as near surface Martian samples will certainly prove sterile with no organic carbon. The presence of peroxides and superoxides in the surface minerals, and the influence of far ultraviolet light would make surface life impossible…
I would only be more hesitant if life were to be discovered deep below the surface of Mars, probably in microbial form. and transported to Earth. This is still a possibility of course…
Dr., some counterpoints: as for UV sterilizing the surface, UV will be blocked by as little as 1 millimeter of regolith (Finding 3-7 in “A New Analysis of Mars Special Regions…, ASTROBIOLOGY V. 14. Number 11, 2014, coauthored by 25 respected scientists.) As for the presence of peroxides and superoxides in the surface minerals, this is a conclusion made from just a couple of sites on Mars, and Mars certainly has different surface compositions in different locations, as is obvious by simply observing the differing light and dark regions. And lastly, the dark regions have been excluded (due to the treaty designation of “Special Regions”) from exploration because of the high liklihood that either Earth microbes or indigineous Mars life could survive there. So your conjecture of a sterile Mars surface from available data is difficult to support.