Question about Mars landers.

Is there any record of or rumor that we put organic material on anything we’ve sent to Mars?

Who knows. . .bacteria, vegetable matter, whatever.

I know that Mars is pretty low-light, low-moisture, but we tend to view “life” as quite resilient.

This is a possibility that people take quite seriously, actually, as evidenced by this 150-page white paper on the subject. The executive summary gives a pretty good overview of the issue, and it’s only a few pages.

Thanks. The summary is an interesting read.

I didn’t realize that we were so worried about contaminating Mars. I was thinking that “they” might think it was “fun” to start a new ecosystem there.

I wonder if their concerns about forward contamination are because it would interfere with their search for life, or simply because they think there’s something ethically wrong with sending our bacteria to a new planet.

NASA has a Planetary Protection Office that deals with this issue.

That’s interesting too.

Still, it brings up a couple more questions. Here’s a quote:

So, is the main rationale of avoiding contamination so that we might be able to colonize in the future?

Is the rationale so that we can study early/other life and we don’t want to contaminate that? (this is kind of what that quote implies)

Is the rationale just a widely held, more noble belief that we shouldn’t spread our “disease” without first fully understanding the consequences?

All of the above, really. Why assume there is one simplistic bit of reasoning involved?

I’m just going on distant memory, but I believe that when the Viking lander was doing it’s soil tests in the mid 1970s, there was some initial excitement when it appeared that there might be some organic matter found. Upon further study, they determined that it was just some residue from some cleaning fluid used to clean the equipment.
So the strict answer to the OP is that yes, organic matter was sent to Mars, but only a negligible trace inside the lander.

Is there any evidenc that earth life/bacyeria could survive on Mars? it seems to me that the surface of mars is probably the best sterilizing environment there is-cold, dry, and bombarded by UV and cosmic rays.
I’ve heard that some bacteria managed to survive on the moon landers, but contaminating the surface? probably not likely.

No reason, but I’d also think there are little devils on a lot of shoulders saying, “let’s throw a bunch of shit at the wall and see what sticks.”

They want to keep the landers clean so that if they get a positive hit for “life”, they will be certain it’s not life that came along with the lander. Why spend all that time (some of the scientists spend a good deal of their entire career on one mission) and money to hunt for life if you weren’t certain what you found wasn’t a bugger somebody stuck to the lander?

As for not contaminating other bodies just to see if it’d be cool, the Galileo probe was crashed into Jupiter on purpose so it wouldn’t risk contaminating any of Jupiter’s moons with biological material from Earth. When they send probes to look for life on these moons, it wouldn’t be of any value if the life there was from a crashed probe.

Not to mention all the oxygen that isn’t in the atmosphere. The ordinary bacteria that humans carry wouldn’t stand a chance.

There are some anaerobic bacteria species that could, maybe, survive on the Martian surface — but I’m fairly confident we’ve never sent any such thing to Mars deliberately, and it’s hard to see how they would end up there accidentally.

Though such devils might be around, heeding their voices is considered unprofessional, to say the least. More likely, a terminating offense. It could make for a good laugh down in the cafeteria though.

Here’s a NASA Document on procedures to be followed for extraterrestrial missions (probes). See in particular section A.2.2, “Category IV (Mars Landers)”.

There are some lichens which could probably handle it. They can withstand temperatures of hundreds of degrees below freezing, and need very little CO[sub]2[/sub] and no external oxygen. They might not actually grow at those extreme sub-zero temperatures, but parts of Mars do occasionally rise above the melting point of ice. But it’s unlikely that anything we might accidentally send to Mars would be able to take hold.

Europa, one of Jupiter’s moons, is another story. It’s quite possible that Europa has life right now (depending on what the probability is of life arising in the first place), and even if it doesn’t, it would probably be fairly hospitable for many opportunistic Eathly microbes (the same sort that would hitch a ride on the lunar landers). So anything that we send to Europa, we’re going to have to be exceedingly careful to sterilize very thoroughly first.

I’m currently reading a biography of Carl Sagan, who if not one of the earliest thinkers in this area was certainly one of the most active and strenuous advocates of sterilizing space probes, and all of these considerations were given more or less equal weight. It’s true, as you suspect, that there used to be a lot of folks who just wanted to try stuff for the hell of it to see what might happen (what would “stick,” as you say), but the arguments of Sagan et al. won the day a while back and you don’t hear so much from those types any more.

Apollo 12 landed only a few hundred yards away from Surveyor 3, an unmanned probe that had previously touched down on the Moon. The astronauts brought back a couple components from the lander, and it was discovered that living microbes had survived the two and half years sitting on the Moon.

And the Moon’s an environment that, if anything, is harsher than on Mars. I agree that simply surviving is a long way from reproducing and spreading, however.

NASA may sterilize their Martian landers and I expect that the ESA does too. But there’s at least one Martian lander that was not sterilized.

Back in the 70s (I believe it was about the same time that the Viking missions were happening), the Soviets sent a lander (well, more of a crash-lander), whose name I forget, to Mars. It didn’t produce much useful data since it quit sending back telemetry almost immediately upon landing, so you don’t hear much about it even if you study Mars. But the point is, they didn’t have the budget to sterilize it before launch. So it probably carried at least some bacteria or other microbes to Mars.

Now those microbes may still be viable (as the ones from Surveyor 3 were) but conditions are so dry on Mars that they can’t be growing and reproducing. Any contamination is probably limited to the inside of that lander and possibly to nearby areas.

Interesting thread! I will contribute what I can though I’m sleepy- but I’ll be back (no doubt with actual references)!

It is the combination of these stressors that really makes it hard for a microbe to survive on the martian surface. There are microbes that can survive (at least in a dormant state) the cold, dry conditions of Mars, but when you combine that with the UV radiation, even the hardiest of earth microbes are killed. Keep in mind though that the UV flux at the martian surface is not unmitigated; the (albeit thin) atmosphere absorbs some of the harsher (shortwave) UV radiation. If one or more of these stressors can be alleviated, the chance for survival jumps.

The interesting part of this comes when you allow for a covering of rock or regolith. It only takes a thin covering (think ~millimeters) to effectively filter out enough UV radiation for microbes to survive (I believe Cockell et al, 2005 Astrobiology used chroococcidiopsis and got greater longevity at martian conditions than previous experiments using bacillus subtilis. 1mm regolith covering at Mars temp and pressure.) There is a sweet spot where UV radiation is filtered out but visible light can still penetrate, theoretically providing a habitable zone for phototrophic microbes- provided they can get everything they need from that environment. So a microbe would have to survive the sterilization processes on earth, survive the journey, entry though the martian atmosphere (if that part of the spacecraft was exposed), then get quickly deposited under the regolith at the perfect distance for its nucleic acids to remain intact. Tricky! I’m not suggesting this is the only mechanism for microbial delivery- just an interesting one.

Planetary protection protocols (at least for Mars) rely on the sterilizing UV radiation at the surface to take care of some of the microbial hitchhikers. Anything penetrating the surface falls into a stricter category on the planetary protection plan (or it did last time I looked- could have changed by now). There is an effort to keep things as ‘clean’ as possible, but highly sensitive equipment, or tools which will be digging into the soil, are specially treated (heat, biobarriers) to minimize the possibility of microbial contamination.

I am not a microbiologist, but from what I’ve seen in the astrobio literature, the dessication and cold resistant microbes go into a kind of dormant state for survival. However, if you want a microbe to survive prolonged radiation, you want it to be capable of rapidly repairing its DNA. If it can, then the pressing issue is basically instantaneous radiation dose- ie how much UV can it get in any one short period of time (then it can repair). If it is in some kind of dormant state and can’t rapidly repair its DNA, then the issue becomes one of accumulated radiation dose- ie can it repair the damage done to it by UV after it reawakens after a much longer session of exposure. Deinococcus radiodurans is particularly resistant to radiation because it has a fast nucleic acid repair mechanism- it only concerns itself with instantaneous dose (first studied for its X-ray resistance, now of importance in planetary protection). Chroococcidiopsis is the same way.

Here I am, posting to GQ, without proofreading. What am I thinking??