Earthlings going to Mars!
I have written many times over 30-some years about why I'm quite convinced, based on the results of the Viking experiments in 1976 and supported by a lot of new evidence since then, that living organisms exist on Mars today. (Examples include my book, and articles in The Atlantic, Wired, New Scientist, etc.) We'll certainly have the proof within the next couple of decades, and we'll see if I've been right about this (along with a few others, including Viking scientist Gil Levin, and former NASA scientist Robert Jastrow).
I also think it's pretty likely, though by no means proven, that Terrestrial life may actually have originated on Mars, and that primitive microbes were first brought here by meteorites blasted off by asteroid impacts on Mars. We'll find that out eventually too. And it's also almost certain that living organisms from Earth have already contaminated the surface of Mars (see this story, for example).
But in the meantime, a new and very interesting experiment on a Russian spacecraft to be launched this October will be testing part of that hypothesis -- the ability of microbial life to survive the radiation, zero-g, the shock of blastoff and so on of an interplanetary trip. Four vials of organisms will be carried to Mars (actually, to the surface of its moon Phobos), and then brought back to Earth for analysis. The experiment is happening thanks to the Planetary Society.
There's a good story with some of the details here. It sounds like a good selection of organisms they're testing. The results should be very interesting.
I certainly hope it works -- unlike the last attempt to send a biologically-interesting experiment to Mars, a (fairly crude, simple) followup to the Viking labeled release life-detection test that was carried aboard the Russian Mars 96 probe (in guess what year?), which alas ended up somewhere in the Atacama desert of northern Chile after a launch failure and was never found.
They'll also be bringing back to Earth some soil from Phobos, which could be quite interesting -- and which is a much better idea than bringing back Mars soil, which I think would be premature at this point, given the danger of potential contamination (if, as I've just been ranting on about, there is life there now that's closely related to us).
I'm excited about this new mission, and I hope it all succeeds.