It’s just like buses; you wait for ages, and then two life-molecules-in-space stories come along at once. This one’s a little closer to home than the Saturnian subsystem, though; a discovery by the Phoenix rover in 2008 encouraged scientists to re-evaluate some old Viking data:
Phoenix detected a chlorine-containing chemical called perchlorate at its landing site, near the Martian north pole. The researchers suspected that perchlorate may have produced what Viking found, destroying original soil organics and leaving behind the two chlorinated compounds, chloromethane and dichloromethane.
So the scientists performed a lab experiment. They grabbed some dirt from Chile’s Atacama Desert — widely considered to be a Martian analog environment — and spiked it with perchlorate. Then they heated the mixture up in the lab, just as the Viking landers did on Mars.
Just as with Viking, the researchers found chloromethane and dichloromethane.
“The simplest, most reasonable explanation of the Viking results is that there were organics in the soil, and they were consumed by the perchlorate,” McKay said. “I think it’s pretty convincing.”
Don’t get too excited, though:
The results don’t prove that life exists — or ever existed — on Mars. While organics are associated with life here on Earth, that’s not necessarily the case elsewhere in the solar system, McKay said.
[…]
But the prospect of Martian life may be a bit more likely now, since Viking seemingly found life’s building blocks in the planet’s red dirt more than three decades ago.
Said it before, and I’ll say it again – let’s just go there, properly, and find out for real.
OK, so we’re pretty positive about there being