The Opportunity science team has decided to next take the rover into the floor of Endeavour Crater.
The gully chosen as the next major destination slices west-to-east through the rim about half a mile (less than a kilometer) south of the rover’s current location. It is about as long as two football fields. “We are confident this is a fluid-carved gully, and that water was involved,” said Opportunity Principal Investigator Steve Squyres of Cornell University, Ithaca, New York. “Fluid-carved gullies on Mars have been seen from orbit since the 1970s, but none had been examined up close on the surface before. One of the three main objectives of our new mission extension is to investigate this gully. We hope to learn whether the fluid was a debris flow, with lots of rubble lubricated by water, or a flow with mostly water and less other material.”
The team intends to drive Opportunity down the full length of the gully, onto the crater floor. The second goal of the extended mission is to compare rocks inside Endeavour Crater to the dominant type of rock Opportunity examined on the plains it explored before reaching Endeavour.
If it is the gully I think, it is the slope visible in the panorama I created for this rover update two weeks ago. The science team has named the mound they have been studying Spirit Mound. The ridge line, visible in the panorama and to the south of the rover in the overhead view provided in the same September 27 rover update, has been dubbed Wharton Ridge. It is also possible that the entrance gully is the gully to the south of Wharton Ridge. Based on the information NASA has provided, I am not sure.
Either way, I had guessed that they would work their way south to Wharton Ridge along the edge of the crater rim, and then retreat away from the crater floor to do more study of the interior crater rim. It appears they have decided that the rover can safely descend the slope to enter the crater floor itself, and they aren’t going to wait any longer to do it.