Hole On Mars a Pit, Not Cave

An extremely dark feature on Mars is probably just a pit – not the entrance to a deep cavern that future astronauts could call home, a new image reveals. The 150- by 157-metre feature was first noticed in an image taken by NASA's Mars Reconnaissance Orbiter on May 5 using a camera called the High Resolution Imaging Science Experiment (HiRISE). Viewed from directly overhead, the dark spot showed no evidence of walls or a floor, leading some HiRISE scientists to suspect it was the opening to a cavern.

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