NASA's Opportunity Mars rover is investigating the edge of a crater on Mars that scientists think could once have been a lake of liquid water. The rover spotted rocks on the Endeavour Crater’s edge that has been suggested as being eroded in place by the wind or transported by a flood.
According to Deccan Chronicle, the features were discovered just outside the crater’s rim crest above Perseverance Valley -- an area carved into the rim’s inner slope. The Opportunity research team is planning to steer the rover down the valley after finishing a walkabout survey of the region above it.
"The walkabout is designed to look at what's just above Perseverance Valley," Deputy Principal Investigator of the Opportunity mission Ray Arvidson said. "We see a pattern of striations running east-west outside the crest of the rim.”
Arvidson has added that the team wants to study whether the rocks are transported or in-place rocks. He also mentioned the possibility that the site “was the end of a catchment where a lake was perched against the outside of the crater rim.” Furthermore, the rocks could have been brought in by a flood that breached the rim and then spilled into the crater. Consequently, the valley down the inner side of the rim was carved.
The expert has suggested another likelihood as well, where the region was fractured by the impact that had led to the creation of the Endeavour Crater. Thereafter, the fractures were filled by rock dikes and now the effects of wind erosion on those filled fractures can be seen.
Incidentally, the Opportunity rover has been exploring sites near and on the western rim of the 22 kilometers wide Endeavour Crater since 2011. At the moment, the Opportunity team is studying images of the Perseverance Valley, captured from the rim, to plan the rover’s route.