Opportunity at Endeavour Crater...

The Mars rover Opportunity is already hard at work in the Endeavour Crater, which it only recently reached after years of travel.  It's already finding things never before seen on Mars, like the rock at right:

This is a clue ... that we may be dealing with a hydrothermal system here," Squyres said. "We may be dealing with a situation where water has percolated or flowed or somehow moved through these rocks -- maybe as vapor or maybe as liquid. We don't know yet.

 Go, Opportunity, go!