Slashdot Mirror
The Indirect Case For Life On Mars
Deinhard writes "Space.com is reporting that '[a] pair of NASA scientists told a group of space officials at a private meeting here Sunday that they have found strong evidence that life may exist today on Mars, hidden away in caves and sustained by pockets of water.' It is all based on methane signatures and not direct observation. Now plans for using the Genesis Device on Mars are out ... unless this is just a particle of preanimate matter caught in the matrix."
If ancient life can be discovered under Antarctic ice, nothing is unpossible.
Given our accessibility and coverage on earth, we didn't know about this ancient life until recently.
And now we only have few rovers on Mars...
Rock that crushes, Paper & Scissors that don't matter.
Years ago we were told that the best place to find life on Mars would be under rocks where there could be lichen-like lifeforms. It would shield them from the harmful UV and solar radiation effects. But so far JPL hasn't used the Instrument Deployment Device (the remote "arm") to turn over a rock and examine what's under it with the microscopic imager. They've looked all over the exposed surface of rocks and even dug small trenches in the soil and examined that. Perhaps they don't want to break it, but still I would like for them to at least try to look under a rock or two. There might be something interesting there!
According to http://www.newscientist.com/article.ns?id=dn7014 the scientists have not only detected methane, but also formaldehyde, which was measured at levels of 130 parts per billion. From the article:
He thinks that the gas is being produced by the oxidation of methane and estimates that 2.5 million tonnes of methane per year are needed to produce it. "I believe that until it is demonstrated that non-biological processes can produce this, possibly the only way to produce so much methane is life," he says. "My conclusion is there must be life in the soil of Mars."
Bruce
Exactly. Which is more likely to find life on mars - sending a stack of insturments to one spot on Mars (with the benefits of reduced latency and perhaps better local navigational ability - the two benefits that humans provide), or sending 50 stacks of insturments (with the option of having different insturments in each group, and the further benefit that you can stagger launches and thus send higher-tech insturments on each successive trip) each to different parts of the planet?
Heck, there's even proposals for robotic missions to "hop" across wide ranges of Mars via multiple takeoff/landing cycles, taking samples and examining the soil in each location. Such a mission would be many times more expensive if it had to carry humans, life support, food, etc, but is feasable for a robot-only mission.
Really, the only thing humans get you is slightly better local mobility and much reduced latency, and neither of those are particularly critical issues. The "baggage" that comes with people - tons of food, water, air, shielding, housing, etc - can't really justify the mobility and latency benefits.
"Well, then fire it up and show me what this..." (sigh)
I think it's the significant temporal VARIATION of methane content in the atmosphere of Mars that is peaking interest in this theory, not just the presence ot methane.
Evidence of methane and its coverage with water can be expained in at least one trivial way. Note Mars atmospheric composition:
C02: 95%
H2O: 0.03%
Now huge ultraviolet radiation breaks down H2O and CO2 to loose hydrogen/oxygen/carbon atoms (this process along with mars weak gravity is co-responsible for mars losing its once dense atmosphere). Additionally there is huge evidence of Electrical Discharge On The Martian Surface
Try simple high school science project: Load a container with water and CO2, add electrodes to create some discharge ('lightning') and you'll have your own PanGea in a bottle.
After some time all sorts of 'organic' chemicals will be present in the bottle along with most common methane (but also alcohols, higher carbohydrates and more complex molecules). I would think decent scientist would at least mention such possibility in reocurring articles on 'OH-OH methane is evidence of life on mars'
Actually, the deal with the methane is this:
Its lifetime in the atmosphere is ~ 350 (earth) years. Thus, for the amount of methane detected, either there was recent (years ago, not Ma or even Ka) volcanic activity, or there is life currently producing the methane. Either of these two speculations is valid.
Your other suggestions are valid also, but require something to help them release their trapped methane. Ices/clathrates need to be melted, which means they need energy input. Hydrocarbon deposits would require life to have existed in the past, and would require something to release just the methane form rather than a bunch of other stuff. i.e., we would see other (than just methane) evidence for a degassing hydrocarbon resevoir.
The volcanism argument is very difficult to sustain because we don't see evidence for it NOW (however, as my advisor is always looking for opportunities to point out, "absence of evidence is not evidence of absence."). I like the volcanism argument because I like volcanism, but the most recent flow fields are 10 Ma, and seem to have been the last gasp of a dying planet. Unless they released a LOT of methane into the atmosphere, the current methane is not from those flows.
The life argument has some major problems, but it's at least worth investigating. There needs to be some sort of energy to maintain these putative methanogens, and that's one of the issues right now (we don't know where to look for life because we don't see any* evidence for subsurface energy).
We can't directly look for concentrations of methane because the in situ measurements would provide something like 1 PPM, and averaged through the atmosphere would be undetectably low compared with the amount of the methane in the (presumed well-mixed) atmosphere (ppb).
* There are small east-west trending fissures (canyons) that may be the best places to search for life-sustaining energy because they collect daytime sunlight but don't effeciently reemit it at night, thus increasing their temperatures relative to the surroundings and possibly conducting heat to the subsurface and possibly collecting enough heat to sustain life. . . I'll let you know in a week or so if this pans out. . .
And as such, methane hydrates or underground hydrocarbon deposits would vary over time as well. In fact, I can't think of an inorganic methane scenario which *wouldn't* be affected by, say, temperature.
"Well, then fire it up and show me what this..." (sigh)
...what if we brought life to mars?
Those who know, do not speak. Those who speak, do not know. ~Lao Tzu
You said: "IIRC, Mars is geologically (or "areologically," if you prefer) dead -- obviously it had significant volcanic activity a long time ago, as evidenced by Olympus Mons, but none that we've ever detected going on now or in the recent past."
The idea that Mars is geologically dead is based on old data. After the Mars Global Surveyor mission, alot of new information came about. One of the estimates was that Mars had volcanic activity about 20 million years ago. Considering a 4.5 billion year existance, 20 million years is hardly dead. This data was from crater counting. Older structures will have many craters and younger structures will have few craters. Obviously this has a fairly large margin of error (but a 2 billion year old structure still won't be confused with a 20 million year old structure). New studies from the Mars Express mission have said that vulcanism may have occured as early as 4 million years ago. This tends to support the idea that volcanos on Mars are dormant, not dead.
As far as having a magnetic field or having plate tectonics, yes Mars is dead. Mars may have had plate tectonics (which in general is due to convection of the mantle) in one localized region in its early history, but there is no evidence of it now.
Recent studies of gullies, volcanism, and the planet's precession tend to indicate that Mars may be alot more active than we think.
Suddenly, the hairy finger of a familiar monkey tapped me on the shoulder. It was time.--G. T.
Scientists releasing papers and ideas, especially ones that are obviously controversial, before the peer review/publication process has been completed is poor science. While the peer review process is not perfect with the potential to overemphasize mediocre/bad work or miss good work, the system is the checks and balances upon which science has relied for decades to ensure quality work.
For an example of how releasing scientific results to the media before it is fully evaluated can have disastrous effects, check out cold fusion.
Jeez, this is so transparent.
Not necessarily. Back in the 1960s James Lovelock (of Gaia Hypothesis fame) was working for NASA on detecting life on other planets. He reasoned that to detect life all you needed to do was to see if the atmospheric chemistry was far from equilibrium. He used Earth as his example explaining that the presence of highly reactive oxygen and other clues indicates life. He suggested to NASA that a 1000 inch telescope be built to get detailed chemistry information on the other planets to determine if there was life without the need to send probes. NASA turned it down.
So the presence of methane on Mars is not a trivial thing.
Is the "possibility of life" a grant magnet? Of course, so is cancer, HIV, etc. Doesn't mean they don't have something important to say.
Bitter and proud of it.
It wasn't so much that the results from the other Viking experiments were inconsistent with life -- they weren't -- but that they could be explained by non-life processes (such as superoxide chemistry). The labeled-release experiment's results required a lot more handwaving to be explained that way.
I used to explain that the Viking biology experiments package was very carefully designed to answer the question "is there life on Mars?". The two Vikings landed, carefully performed their experiments, and broacast back the message "could you repeat the question?".
Of course, if Martian soil were that rich in superoxides, it's hard to imagine methane lasting even 300 years.
-- Alastair