Another Sign of Water on Mars

NASA’s Spirit rover has discovered more evidence of water on Mars, a high concentration of salt in a trench dug by the rover in the Gusev Crater region it has been exploring.

“We have found more evidence of salts, more evidence for the action of water -- much more compelling evidence than we found anywhere else at Gusev,” said principal scientist Steven Squyres of Cornell University.

The salts could have been formed by water percolating through the subsurface, dissolving minerals from rocks, he said.

“Now, we are not talking about big standing bodies of liquid water. You don’t need a lake to do this. You can perfectly well do this with small amounts of water percolating through the soil,” he said.

Spirit’s findings have shown that water activity at Gusev was less extensive than at Opportunity’s landing site in the Meridiani Planum region, which mission officials say was once drenched.

On Thursday, meanwhile, Opportunity “dipped its toes” into the Endurance crater to determine whether it would be able to get back out again if it entered the stadium-sized hole in the Martian plain.

The craft went just far enough over the rim of the crater so that all six of its wheels were inside, then backed out. Engineers determined that Opportunity’s wheels slipped on the crater wall less than expected, giving them confidence that it could go to the bottom of the crater to conduct an examination of the soil, then exit once more.