Launch of Vanguard 1

What’s the oldest manmade satellite still in orbit today? The answer: Vanguard 1, launched by the US Naval Research Laboratory on this day in 1958. Dubbed “the grapefruit satellite” by Soviet Premier Nikita Khrushchev, Vanguard 1 was the second American satellite to go into space and the fourth overall. It was the first satellite to use solar panels—a good thing, because the satellite’s other power source, chemical batteries, died after 19 days. Vanguard 1 made important measurements about the not-quite-spherical shape of Earth. The satellite’s solar-powered transmitter remained operational until 1964. Today solar panels supply energy to the International Space Station and dozens of satellites and space probes. Unlike its predecessors, Vanguard 1 remains in orbit to this day. Though it won’t stay spaceborne for 2000 years as its developers originally calculated, it still has another 200 years or so before it burns up in Earth’s atmosphere. (h/t Paul Coxon on Twitter)

Date in History: 17 March 1958