Water on Mars? Eh, Maybe So. Plus: Exoplanets!

Some pictures taken last May by the Mars Phoenix Lander may show water droplets on the leg of the craft:

Phoenix landed near Mars's north pole last May, and several "self portraits" taken to assess the craft's health show material spattered on the legs.

This substance is probably saline mud that splashed up as the craft landed, study leader and Phoenix co-investigator Nilton Renno of the University of Michigan told National Geographic News.

Salt in the mud then absorbed water vapor from the atmosphere, forming the watery drops, Renno said.

Of course, it was already known that there was water underground on Mars, as shown in this detailed map of "water-equivalent hydrogen," based on data from the Mars Odyssey. This map ought to roughly correspond to amounts of water in the Martian soil.



In other astromapping news, I just found out about the Kepler mission - a NASA project that's scheduled to launch on March 6th. It's going to be looking for earth-sized planets in a large chunk of the milky way (and by large, I mean small - it will only be a narrow sector of one arm of the milky way; and by small, I mean unimaginably vast - because even this small slice of the galaxy contains over 100,000 stars). This galaxy map shows the Kepler search space (as well as our location in the milky way, in case you were curious). The mission will be using the transit method - watching for fluctuations in the brightness of stars that would indicate an Earth-sized planet is passing in front of the star. For this to work for a given star, that means the planet has to be orbiting on a plane that's lined up with the Kepler craft; otherwise a planet might be there and Kepler'd never see it. The odds of a planet lining up in this way for a given star are about 1 in 210. So...

the 1 in 210 probability means that if 100% of stars observed had Earth-like terrestrial planets, Kepler would find about 480 of them. The mission is therefore ideally suited to determine the frequency of Earth-like planets around other stars.

In other words, if this project works out, we ought to be able to determine roughly how many other Earths are out there. Fun stuff.