Solar sails to take flight

For decades, scientists and science fiction writers alike have floated the idea of using solar sails to propel spacecraft across vast distances. One of those advocates was the late astronomer Carl Sagan. In honor of Sagan's 75th birthday, the Planetary Society, which Sagan co-founded in 1980, announced a series of forthcoming solar sail experiments. Funded by a wealthy, and anonymous, donor, the group will launch their LightSail system three times over the next few years. The first two missions will be in Earth orbit, and the target of the third is about 900,000 miles away, in a popular "hang out" zone for traditional satellites collecting scientific data.

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