Most of the unmanned probes that the United States sent to the Moon in the 1960s had one main goal: pave the way for astronauts to land on the Moon by the end of the decade. These craft squeezed in some good research, but science wasn't their main goal.
But by the time the last robotic lander took flight, the priority had changed. Everything was ready for the Apollo astronauts, so NASA sent Surveyor 7 to a tricky site in the Moon's southern hemisphere -- a spot near one of the Moon's youngest big craters. It landed there 40 years ago this month.
Tycho is the most prominent crater on the Moon. It's surrounded by long, bright streaks known as "rays." They probably formed from the impact that gouged out the crater itself. More about the crater tomorrow.
Tycho is located in a region of the Moon that hadn't been explored before, known as the highlands. Surveyor 7 took pictures of the region, dug into the soil, and measured the composition of the soil and rocks. It found that the highlands are made of a different kind of rock from the dark volcanic plains that previous landers had studied.
During its first lunar day -- about 14 Earth days -- Surveyor 7 transmitted almost 21,000 pictures. But the extreme cold of the lunar night -- which also lasted 14 Earth days -- crippled the lander. It snapped only a handful of pictures during the second day before its batteries failed -- ending a scientifically ambitious look at the Moon.
Script by Damond Benningfield, Copyright 2007
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