NASA rover yet to find methane on Mars
nature.com
nature.com
http://www.dlr.de/dlr/en/desktopdefault.aspx/tabid-10081/151...
However, my understanding is that these have such slow rates of growth that they might not be terribly good at "enriching" the Martian atmosphere, at least in their current natural form.
Not many things could destroy both Earth and Mars, except the expanding of the Sun in 5 billion years and maybe the fusion Andromeda/MilkyWay in 4 billion years if we're not lucky. Also aliens.
Edit: interesting to read: http://en.wikipedia.org/wiki/Terraforming_of_Mars
If something happens and they do evolve fast enough to pose a threat, perhaps they will evolve fast enough to realize that two planets with intelligent life are better than one.
(Dolphins and some others seem smart, too, but they wouldn't venture to other planets.)
You could try to introduce a weakness to a particular poison (one that is not actually poisonous to anything you might want to introduce later), but that would be selected out against pretty fast. And genedrift would probably remove it even before you actually introduce the poison.
A vital dependency on some specific substance wouldn't work either. For one thing, you'd have to provide that substance Mars-wide, and also there would be a strong selection pressure to get around that dependency.
You could try to come up with some other timing methods. But genetical engineering is not magic.
And while you might kill 90% of a population, or 99% or perhaps even 99.9%, you won't kill them all.
You could build the architecture of the genome such that any minor mutation to the "death gene" immediately kills the organism. You could probably get it to the point that it would require $n$ simultaneous point mutations to disable the "death gene" without killing the organism. What you'd really want to worry about is whole chunks of genome being deleted (either through a serious accident in reproduction or a virus). You'd want to design the genome such that each part checks the others parts (hell just use checksums SHA3 is available now), if any part comes up bad, the organism dies.
tl;dr It should be possible to freeze evolution (or just freeze particular gene's) using modern cryptographic techniques.
The latter might not be a problem on Mars. But in such a harsh environment you do not only have to worry about competition, but about surviving at all.
Hmmm. Kind of a bummer Monday morning thought.
I can't imagine the degree of confusion which led someone to say that it's possible for Mars' atmosphere to contain a negative concentration of methane.
No, it really can't. If it looks like it is, you're using a symmetric distribution function (probably a normal distribution) in a context where its assumptions do not hold.
I mean we're talking about a whole planet here, with the possibility of canyons, valleys, underground structures which may have who knows what trapped inside them.
Maybe there are tons of gases trapped and hidden inside the surface of Mars and the atmosphere is devoid of it because over millions of years, those things escaped into space?
I know I'm probably missing something here.
UPDATE: Okay, here we go: Various campaigns in the last decade have claimed to detect martian methane at levels as intriguingly high as 30 parts per billion1 and 45 parts per billion2. But more perplexing was the way that the methane signals sometimes appeared as hotspots, or plumes, and then disappeared — implying both a sudden injecton, as well as an unknown process to destroy the methane quickly, which would otherwise mix in the atmosphere and persist. Skepticism for these claims has abounded (See “Curiosity set to weigh in on Mars methane puzzle” ).