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."

Comments

Re:Nonbiological methane production

[Rei]

> Actually, the deal with the methane is this:
Its lifetime in the atmosphere
> is ~ 350 (earth) years.

300-600. On Titan, it's about 10 million earth years - a ~20,000fold difference. However Mars has methane at 10.5 parts per *billion*, while Titan has 2-5% methane; methane on Titan is over *3 million* times more concentrated. Consequently, Mars is actually producing a rather small amount of inorganic methane compared to Titan. Titan has the advantage of being in deep-freeze, of course, but it's still an example of how huge quantities of methane can remain subsurface and be released steadily on a geologically inactive (presumedly) world.

> Thus, for the amount of methane detected, either there was recent (years ago,
> not Ma or even Ka) volcanic activity

Incorrect. There are many ways methane can be released inorganically; they're just not known by your average slashdotter. There's methane hydrates, which only need variations in temperature to outgas (which we know happen on Mars, and have happened to an extreme extent over its history). There are dozens of subsurface reactions apart from vulcanism that can produce methane - for example, it is an *expected* product of low temperature fluid-rock interaction; all it takes is enough low-level residual heat to melt ice:

http://www.lpi.usra.edu/meetings/lpsc2005/pdf/23 32 .pdf

However, even concerning vulcanism itself, the jury is still quite out. There is evidence of recent vulcanism on Mars, as you hinted to:

http://www.space.com/scienceastronomy/solarsyste m/ mars_volcano_011113.html

Contrary to how you tried to make it sound, 10 MY is very recent geologically. I see no reason to suspect that, if volcanoes have been erupting that recently, that it's suddenly going to peter out at the exact time (geologically speaking) that humans start observing the planet.

> Hydrocarbon deposits would require life to have existed in the past,

Not true. Hydrocarbons form in all sorts of circumstances; you can get short chains from UV interaction with methane alone. You can even have hydrocarbons formed from such basic reactions as the subduction of calcium carbonate and water in with Iron(II) oxide. Hydrocarbons are all over the place; for example, the Saturnian system is littered with organic "goo" (not just on Titan, but all over the place, from Phoebe to the rings).

People here just seem way too ready to grasp onto anything that could remotely be a product of life - even if it's something that forms inogranically all across our solar system, and is constantly outgassed from dead worlds.

Positive Viking Lander Results

[north.coaster]

For some years now, the principle investigator for the 1976 Viking Lander Labeled Release Experiment has claimed that his experiment did find evidence of life on Mars. The problem is that the results from the other Viking experiments was inconsistent with this, so NASA decided that the LRE detected a non-biological chemical reaction.

Is this new data about methane consistent with the Viking LRE data?