1/n OK, so about that NASA news. They found organic molecules a few cm under the surface. That’s interesting. Mind you, organic = carbon based, not necessarily life.
2/n It *might* indicate past life on Mars, or (far more likely IMO) it just means some ingredients for life were around.
3/n It’s not huge breaking news, I think, but more incremental steps taken towards figuring out if Mars was capable of hosting life way back when.
4/n I’m more interested in the methane. They found that its presence in the atmosphere goes up and down with seasons, by quite a bit (factor of 3).
5/n Methane is produced biologically on Earth (from life) but also geologically (from not-life). So we can’t say what’s causing it on Mars…
6/n … but the seasonal variation is interesting. Life on Earth is seasonal! But so is incoming sunlight, and Mars has huge seasonal variations in its atmosphere (lots of CO2 thaws in summer).
7/n Methane is delicate and breaks down easily, so seeing any means it’s being made somehow. The question is how. This seasonal change gives a nice clue, but isn’t definitive.
8/n So we can’t say “AHA!” to this news, but more like, “Hey, cooooool!” to it. It’s progress toward understanding, but we’re a ways from understanding just yet.
9/9 So if someone says “We found life on Mars!” they are jumping to a rather large conclusion. If we ever do find life there it probably won’t be anything super obvious, but rather the end of a series of subtle steps built up over time. /fin
10/9 (Dangit! Forgot to add): Phoenix lander found perchlorates on Mars, which tend to react with organic molecules and destroy them. So finding organics is pretty cool. I guess that means perchlorates must not be ubiquitous.
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