Possible Contamination, Bacteria hitched a ride to Mars Options

[tty]

I think that introducing mass of cork DNA, even dead, was a mistake: wind will carry it everywhere, and everywhere we will find Earth DNA.

I don't think so. DNA is pretty unstable. In the presence of strong UV-radiation and probably an unfriendly chemical environment (to judge from the Viking results) free DNA would have a very short lifetime. Remember that even methane breaks up quickly in the martian atmosphere. In the cold Martian environment I suppose it would last quite a long time inside the cork, but we already know where that came from. Actually if the cork was sterilized the DNA may already be gone, it breaks down very fast in a hot environment.
Actually if we go looking for chemical fossils from past life on Mars DNA (and RNA) would be very bad choices. On the other hand if we do find "strange" DNA (or RNA) on Mars it would be a strong indication that life still exists there.

tty

[deglr6328]

Cork? CORK?!?!! I can't believe they used cork for the heatshield parts! I also don't know how that fact slipped by me until now. Why did they use cork? I mean how hard would it have been to synthesize a new type of hard polymer foam or something? This seems incredibly reckless and stupid to me. I could see maybe 30 years ago it was all we could come up with, but now? We know the heatshields were broken on impact and we know that this cork was spewed out all over the place when that happened. Cork is (somewhat) commonly contaminated with molds that contaminate wine which was then said to be "corked". It is also known to be colonized by various types of fungi. I really, REALLY hope they gamma sterilized them before assembly.

[Bill Harris]

A cork-epoxy-glass microbead compound is used in the ablative coating on heatshields; evidently cork is the ideal material since it has been used with heatshields since the 1960's. I can't find the specific link to the MER heatshield, but google "mer heatshield cork" for more info.

--Bill




Or read here:

http://www.unmannedspaceflight.com/index.php?showtopic=561

[edstrick]

Of note:

26-27 Jul: NAC Planetary Protection Advisory Committee Meeting

http://www.spaceref.com/calendar/calendar.html?pid=3589

"SUMMARY: In accordance with the Federal Advisory Committee Act, Public Law 92-463, as amended, the National Aeronautics and Space Administration announces a forthcoming meeting of the NASA Advisory Council (NAC), Planetary Protection Advisory Committee (PPAC). "

"SUPPLEMENTARY INFORMATION: The meeting will be open to the public up to the capacity of the room. The agenda for the meeting includes the following topics:

Planetary Protection Program Update
Solar System Exploration Overview
Mars Forward Contamination Requirements
Mars Mission Implementation Status
Mars Sample Return Mission, Planning, and Status
Future Outer Planet Missions
Planning for Future Human Missions to the Moon and Mars

[Cugel]

Personally I think that the search for life is overblown as a justification for Mars exploration.  At this point it's pretty clear that the only life we're likely to find will be microscopic, and probably related to microbes carried from Earth by meteorites.  It's also likely to only exist deep underground, where modern contamination isn't likely to affect it.  I'm inclined to stop worrying about contamination and just get on with exploring the geology.

Europa may be a different matter.

IMO the life on Mars issue is not much more than a hype. There is no life on the surface and most likely also not deep down, as we would have seen much more metabolistic gasses in that case. However, the search for life is what pays the bills! The moment you officially declare Mars dead is the moment funding for Mars research will stop. After Viking, NASA developed a very keen eye for this. You must talk and hint about it a lot, but never directly look for life on Mars.

[Guest_Myran_*]

algorimancer said:
It's also likely to only exist deep underground, where modern contamination isn't likely to affect it.

I can only say 'Hear, hear' even though I have stopped clinging at straws entirely on the matter of life on Mars. As said elsewhere im old to have lived since the days when almost every astronomical textbook described the seasonal growth of lichen on the Martian surface.
That most certainly started my life long obsssion with the planet, and its still there even after I have faced the truth that the planet are dead.
It might or might not have had life in the past, we might find the signs of that past life later, after some future lander or rover drills down a few feet into the permafrost. I would view that as icing on the cake.
Remember we are a very privileged group of people with the fantastic exploration we got here and now, one kind of exploration the writers of those textbooks from the 1960's would have given one arm and a leg to witness!

[Guest_Richard Trigaux_*]

If Marsian organisms, even microscopic, evolved into the depths, they could find hot environments rich into nutrients, like on Earth with the "black smokers", hot water springs in the bottom of the oceans. So Marsian bacteria may have evolved into forms able to survive on Earth, and may be brought to surface in hot springs. Eventually, if their "DNA" or whatever plays its role, is faster to duplicate than Earth DNA, they could overcome many microbian life on Earth. It is why a mission like Mars Sample Return can be very dangerous, if appropriate cautions are not taken (for instance the box should withstand a full speed impact on Earth, withstand corrosion and self destroy itself if it is not found)

Could martian bacteria destroy all Earth life? Several more conditions are required for this. Most likely, they could create shifts into ecosystems, or new diseases. But if they can interact with our DNA in a virus-style way, every life form is at risk.

[tty]

If Marsian organisms, even microscopic, evolved into the depths, they could find hot environments rich into nutrients, like on Earth with the "black smokers", hot water springs in the bottom of the oceans. So Marsian bacteria may have evolved into forms able to survive on Earth, and may be brought to surface in hot springs. Eventually, if their "DNA" or whatever plays its role, is faster to duplicate than Earth DNA, they could overcome many microbian life on Earth. It is why a mission like Mars Sample Return can be very dangerous, if appropriate cautions are not taken (for instance the box should withstand a full speed impact on Earth, withstand corrosion and self destroy itself if it is not found)

Could martian bacteria destroy all Earth life? Several more conditions are required for this. Most likely, they could create shifts into ecosystems, or new diseases. But if they can interact with our DNA in a virus-style way, every life form is at risk.

Very very unlikely. Remember that nearly all microorganisms are completely harmless. It takes very special adaptations to circumvent immune defences and actually infect another species. Martian bugs are not likely to be that closely related to us.

Virus are even more unlikely. They reproduce by injecting their DNA into a cell, incorporating themselves into the cell's DNA and using its biochemical facilities to make copies of themselves. This requires exquisite adaptation to work, and viruses (fortunately) don't often manage to jump species barriers even among us closely related terran life-forms.

Also if it could happen it would already have happened. Martian meteorites have been arriving for four billion years without self-destruct facilities. Shades of Hoyle and Wackramasinghe.

tty

[Guest_Richard Trigaux_*]

Also if it could happen it would already have happened. Martian meteorites have been arriving for four billion years without self-destruct facilities.

tty

that bacteria could survive a several million years space travel is only an hypothesis until now, not an established fact. It has been proposed only to explain a strange life form, the nanobacteria, which are even not recognized by all the scientists as they are much smaller that the minimum size expected for a bacteria.

Shades of Hoyle and Wackramasinghe.

???

Very very unlikely. Remember that nearly all microorganisms are completely harmless. It takes very special adaptations to circumvent immune defences and actually infect another species. Martian bugs are not likely to be that closely related to us.

Marsian bug may be very dangerous by creating ecological unbalance. For instance if they could live into the soil, they could take the place of humus bacteria and destroy all our food resources. And if they are made of something else than our usual amino acids, they could be invisible for our immune systems and develop anywhere uncluding in our bodies, creating dangerous diseases without immune responses.

Virus are even more unlikely. They reproduce by injecting their DNA into a cell, incorporating themselves into the cell's DNA and using its biochemical facilities to make copies of themselves. This requires exquisite adaptation to work, and viruses (fortunately) don't often manage to jump species barriers even among us closely related terran life-forms.

OK not viruses which are very specialized. But if a martian "something" feeds with proteins or DNA without our cell barriers are able to stop it, a bit like the prions, abnormal proteins able to pervert normal proteins and propagate like an infection, we are all dead.


Numerous scenarios are possible for Marsian life hampering or destroying Earth life, some predictable, other we can even not imagine. This is why we cannot bet that what will be in the sample return capsule does not pose a dreadfull threat for us all. Even the surface of the capsule should be thoroughly sterilized before sending it to Earth.

With my opinion the safest scenario is to send the capsule on a trajectory where the Moon places it in Earth orbit, never aiming at Earth itself. It will be more costy to recover it, but safer than to send it direct on the ground, especially in the case where recovery fails. We never know, for instance a war or a major natural catastrophe breaks up during the travel... At least with this scenario the capsule is left in space and not rusting in some desert, releasing death fifty years later.

[Chmee]

that bacteria could survive a several million years space travel is only an hypothesis until now, not an established fact.

Well, any life on Mars ia also just a hyposthesis as well. Over time as we know more and more about Mars the area where life could possibly reside has shrunk considerably. In the 1890's it was (almost) accepted wisdom that a civilization was there. In the 1950's - 60's it was "known" that plants or lichen came and went with the seasons. In the 1970's, until Viking, it was thought that life could be in the soil on the surface. Still nothing.

Now we are left with the only possibility that life is deep underground. It seems that life is always "just around the corner" on Mars but as soon as we look around it and it is not there , we just come up with even more unlikely scenarios of where it might be. I am sure once we start drilling the surface and do not find life, people will say we did not drill in the right place or deep enough and that life is really in the mantle not the crust, etc, etc.

The problem is that we can never "prove" that life does not exist on Mars (you cannot prove a negative). It seems clear that there is no life on Mars' surface and if any life exists below the surface it would have to be in very small quantities since we would have detected the gases associated with biological activity in the atmosphere by now.

Therefore we should not let contamination issues overly affect our exploration of Mars. Yes, reasonable precations should be taken like clean rooms and sterilization when needed, but to put a blanket ban on all manned landings or sample returns makes no sense and is not supported by the evidence to date.

[tty]

that bacteria could survive a several million years space travel is only an hypothesis until now, not an established fact.

There is no law in celestial mechanics that a martian meteorite has to spend millions of years before reaching Earth.
Just to get a handle on numbers and probabilities. I seem to remember that a total of 18 martian meteorites have been identified so far. Assuming (very optimistically) that the number of meteorites in scientific collections is equal to one average years crop of meteorites falling to Earth that sums to about 7*10^10 Martian meteorites since the late heavy bombardment!

And if they are made of something else than our usual amino acids, they could be invisible for our immune systems and develop anywhere uncluding in our bodies, creating dangerous diseases without immune responses.

I should think that would make the immune system react very strongly. In any case a life-form containing other amino acids than earthlife would be harmless since it couldn't possibly feed and procreate here.

tty

[tedstryk]

"Marsian bug may be very dangerous by creating ecological unbalance."


Should Mars have life at all, it would be a much less complex ecosystem. I think the real risk here is that our own microbes will destroy any such martian microbes before we can study them. I think the risk of the reverse of this happening is too insignificant to worry about.

[edstrick]

An essential point is that there are probably essentially two types of life-bearing planets.

1) Planets with cryptic life, possibly abundant and profuse, but in a hidden, protected ecosystem. Martian life, if present, is probably restricted primarily to the probable watertable, concentrated in areas of "geo" thermal heating and active chemistry. Europa life, if present is in the probable brine layer between the ice-crust and the rock-mantle. It may have periods of flourishing during episodic tidal heatnig cycles. In both cases, life does not dominate the open surface environment and controle the chemistry and physical properties of the surface and atmosphere.

2.) Profusely life-bearing planets. Earth. See the "Gaea Hypothesis" stuff by Lovelock and Margolis <sp?> for an extreme take on the ideas.

I don't seem to see this point made in discussions of exobiology. Type 1 planets probably outnumber type 2 by hundreds to tens of thousands to one, but we can only voice prejudice on the odds so far.

[Cugel]

Interesting idea. According to the latest biological ideas, the Earth actually is of both types! This theory claims that most of life (in mass and in numbers) can be found deep below the surface, up to 3 or 5 kilometers deep. Life on top of the surface should be regarded as 'icing on the cake'. From time to time, the icing is destroyed and for a short while the Earth is a pure type 1 planet. (Like after the impact that created the Moon or when our planet is covered with ice from pole to pole) However, it doesn't take long for those critters underground to find their way up and colonize the surface once more.

This leads to the conclusion that every living planet is actually of type 1 and only under very special conditions (liquid water on the surface) can it migrate to the surface. The question is whether Mars is a prime candidate for such underground life. I think the icy moons of Jupiter and Saturn are better candidates, as they possess lots of active vulcanism and the perfect chemistry.

The good news is of course that within 2 years we will know if there is liquid water under the surface of Mars! (With 2 ground penetrating radars in orbit that shouldn't be too much to ask...)

[Bob Shaw]

An essential point is that there are probably essentially two types of life-bearing planets. 

1) Planets with cryptic life

2) Profusely life-bearing planets

I don't seem to see this point made in discussions of exobiology.  Type 1 planets probably outnumber type 2 by hundreds to tens of thousands to one, but we can only voice prejudice on the odds so far.

I think you're right, but with the caveat that the second group of planets is actually a sub-set of the first - even on Earth, the visible surface macro-ecology appears to be grossly out-performed by the bugs which live well below our feet. What we tend to describe as a 'less complex' cryptic ecology may well be a highly evolved and highly efficient system, which our prejudiced world-view fails to acknowledge.

As well-preserved life-bearing rocky material may travel quite quickly between the terrestrial planets and planetary bodies (not to mention asteroids and comets, KBOs, moons...) then I, for one, would be quite surprised *not* to find some form of life-as-we-would-know-it-if-we-could-be-bothered-to-look in most potential ecological niches. As for which came first, and the relationships between the various branches, well, that's a fascinating set of questions for once we have some samples!