On this day: August 21

Published On: Aug 20 2012 02:02:16 PM CDT   Updated On: Aug 21 2014 01:00:00 AM CDT

Lincoln and Douglas square off for the first time, Oldsmobile begins production, Hawaii becomes a state, and The Mona Lisa and the Mars Observer go missing, all on this day.

OTD August 21 - Mars Observer
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NASA

1993: NASA loses contact with the Mars Observer spacecraft three days before it was to reach orbit around Mars. The fate of the spacecraft remains unknown. The mission, which was intended to study the Martian surface, atmosphere, climate and magnetic field, cost $980 million.

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