Recent talk about the possibility of finding evidence of life on Mars makes me wonder: Isn’t it possible that the Mars probes sent to our neighboring planet from Earth carry, or carried, living microorganisms with them which were thus imported? I have no idea whether there are any habitats, of any scale whatsoever, where these organisms could reproduce (AFAIK the current level of knowledge is that there is ice on Mars, but no liquid water), but I assume past probes could also have imported tiny amounts of water which could function as a tiny breeding ground for bacteria.
So is it possible that the enthusiasm about the discovery of life on Mars which some people hope for to occur in the close future will be much ado about the discovery of life which we ourselves brought to the planet? I assume they decontaminate probes before launching them, but the first American and Soviet missions to land on the surface of the planet were in the early 1970s, and I doubt they were much concerned about this risk back then.
The probes are sterilized like crazy before being packed in a hermetically-sealed capsule and shot off into interplanetary space. Doesn’t discount the possibility that some wacky spores or something survived on the probe’s surface and are right now growing on Mars and plotting the destruction of Earth — but it’s extremely unlikely anything could survive the process, and the beating an organism would take in an unshielded, uninsulated capsule in space.
First point, all space probes, and satellites, are constructed in “clean rooms” to minimize any chance of contamination by dust, microbes or other microscopic contaminants. After construction the payloads are stored in hermetically sealed containers, again to prevent contamination. This isn’t meant to keep space or target planets uncontaminated - just something that’s done because the tolerances are such for the moving parts on these devices, that the potential for a mote of dust to bollix up the works are so high. But the upshot of all this is that the effect will be to make the initial biological contamination that the OP is concerned about highly unlikely.
Then, as ignis_glaciesque says, the environments that the contaminant will have to survive to get to the destination planet often include years in interplanetary vacuum. I’m not au fait on the orbits used to get payloads to Mars, but it’s not impossible that at least some of them have gone inside the Earth’s orbit for a time. And the closer to the sun an object in space gets the hotter the average temperature that the sun-facing surfaces will get. ISTR that in earth orbit, the surfaces on the Space Shuttle approach 170 C. Which is hotter than many autoclaves get.
Then, too, the Viking probes, since they were specifically looking for life on Mars were put through additional concerns to ensure sterility - to keep from bollixing up the experiments. But those are only two probes.
The short answer, though, remains that while it’s not impossible for something to piggy-back on a probe, and survive the trip. It’s highly unlikely - on the rough order of probability of winning the Lottery unlikely - that it will or has happened.
Of course, if you’d asked me 25 years ago whether there could be ecosystems based on something other than photosynthesis (If only through several removes.) I would have said, “No.” And then gotten very red in the face when the black smoker ecosystems were discovered.
I don’t think that’s the case for all satellites. My sister worked on a satellite project for the European Space Agency, and she included a lock of her hair in the satellite so it would go into space. I’m pretty sure she wasn’t violating any major rules - lots of people did similar stuff.
However, that satellite was of course just designed to go into orbit and eventually burn up in the Earth’s atmosphere. Interplanetary probes are a whole different ball game, and are strictly sterilised.
Though, I can imagine circumstances where there was a sealed void in the satellite for such lightweight bonus payloads - without actually compromising the clean room environment for the satellite as a whole. AIUI the tolerances for the moving parts on even earth orbiting satellites are such that random hairs could cause major problems.
Actually, just googling the words “contaminating mars microbes” brings up a lot of hits. Here’s the results of a 2005 study that said NASA’s methods of cleaning spacecraft just ain’t cutting it.
Microbes are routinely shot into space on satellites and space vehicles. You just can’t get them all. Deinococcus radiodurans is a common earth microbe which can easily survive the trip to Mars. Just check out the radiation stuff. It can repair itself after having it’s DNA ripped apart by a dose that is 500 times what would be fatal to humans, and a dose 3700 times what is fatal to humans will only kill 66% of them.
Surveyor 3 landed on the moon in 1967. When astronauts recovered the camera in 1969 and brought it back to earth, they found a colony of earth microbes inside that had been thriving for the past 2.5 years on the moon.
Is Mars being contaminated by our probes? I don’t know, but it is surely possible. But just as interestingly, Earth and Mars are continuously exchanging rocks and debris thrown into space by comet and asteroid impacts. It would be extremely surprising if the planets weren’t contaminating each other by that route, and probably more so than what few microbes our probes may bring every few years.
just one more factoid on the subject. With the present Phoenix lander even greater care was taken to sterilize the machine. For instance the digging scoop, because it is the one part of the machine that is designed to actually touch the surface of Mars (besides the landing pads of course), went through additional sterilization steps and in fact was packaged in a special envelope to keep it from getting anything on it from the rest of the (already sterile) machine. NASA works hard at this. And one reason is that viruses and microbes are just so incrediably hard to kill when you are cleaning a machine you want to work afterwards. There is a treaty specifying that any country sending a probe to another planet has to meet minimum standards of sterile.
And of course what was said upthread. rocks from all the planets have already traveled to all the other (OK the other inner) planets through meteor strikes. Contamination has already happened. But NASA is doing it’s best to not add to the problem.
Most of this has been mentioned before. . . but to underscore-
The degree of cleanliness for the rover/probe/instruments depends on the habitability potential (past and present) of the body it’s visiting, the smaller scale area it will be interacting with (like the Phoenix scoop), and potential for sterilization entering or at the target site (UV sterilization at the surface of Mars, or heat sterilization upon entry for the outer shell of probes.) We have most certainly taken microbes to Mars- it’s just not possible to get some of the equipment that sterile without harming it, especially if you want to kill spore-formers and biofilms. (500 deg C dry heat for ~seconds is one benchmark, NASA has others depending on the situation.) And in most cases, it’s just not necessary to sterilize on Earth until every microbe is dead- the inhospitable environment it’s being sent to can take care of that for us. IIRC, the rovers achieved sterilization of an order of magnitude better than required (some number of microbes per square cm on surfaces.)
Sorry no citations for microbes we’ve sent- I can look up stuff when I get to work where I’ve got reference material and a university subscription to all the usual journals if need be. To take a look at NASA’s guidelines for mission cleanliness, see NASA Planetary Protection office.
This document (not a PDF) is actually an interesting read (okay, for me)- An Astrobiology Strategy for the Exploration of Mars. It was published by the Space Studies Board of the National Academies- if you are a scientist or at an academic institution, you can order some of their publications for free at their website. Particularly interesting for those into space policy.
I’m pretty sure she wasn’t violating any major rules - lots of people did similar stuff.