While minor glitches continue to effect the mission of the Phoenix Mars Mission, there’s some fairly big news from the Red Planet today. A small trench dug by the lander four days ago exposed some small, white clumps of something—possibly just salt, but possibly frozen water. Looking again at the trench today, scientists discovered that the chunks had disappeared. Scientists believe that the chunks sublimated, which is basically when something evaporates directly from a solid into a gas (without passing through a liquid phase). Apparently salt doesn’t do this, but water does.
NASA and the University of Arizona have(and ) claiming, essentially, that water ice exists on Mars. I’d be willing to bet they’re right, but I’ll wait for direct evidence rather than an indirectly-observed sublimation before I buy into it 100 percent. Scientists shouldn’t be jumping to conclusions . . . the disappearance of the white material could be sublimation, but then again it could be something else (in four days, I’m sure some white, non-water substances could melt into a liquid and be reabsorbed into the soil, for example). You can’t conclude that the material is water ice unless a) its sublimation was directly observed or b) you test it directly.
I’m sure one of those is on the scientists’ to-do list, along with checking out that flagpole I mentioned the other week.
Update 7/31/2008: The findings have been confirmed; there is water on Mars.