A close-up of the rectangular rock called 'Flat Top' from NASA's Mars Pathfinder (MPF) rover Sojourner in July, 1997.

A close-up of the rectangular rock called "Flat Top."

Photojournal note: Sojourner spent 83 days of a planned seven-day mission exploring the Martian terrain, acquiring images, and taking chemical, atmospheric and other measurements. The final data transmission received from Pathfinder was at 10:23 UTC on September 27, 1997. Although mission managers tried to restore full communications during the following five months, the successful mission was terminated on March 10, 1998.

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