OTD in Space – March 17: U.S. Launches Its Second Satellite, Vanguard 1

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On Saint Patrick's Day in 1958, the U.S. Navy launched Vanguard 1, the first solar-powered satellite and the oldest artificial satellite currently orbiting the Earth. [‘On This Day in Space’ Video Series on Space.com](https://www.space.com/39251-on-this-day-in-space.html)

The main purpose of this mission was to test a new three-stage rocket. Vanguard 1 was the fourth satellite ever launched into space (following Sputniks 1 and 2 and Explorer 1). It looks a lot like a miniature version of Sputnik. Vanguard 1 was tiny compared to the satellites that came before it. It's about the size of a grapefruit and weighs only 3 pounds. Solar technology allowed the satellite to transmit signals to Earth for 7 years, while battery-powered satellites couldn't even last a month. Scientists think the satellite will deorbit by the year 2198 after spending 240 years in space.

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