1958-05-15 Sputnik 3
Sputnik 3 was launched on May 15th, 1958 at 7:12 a.m. UTC from Site No. 1 at Baikonur Cosmodrome. Sputnik 3 was Object D, designed to be Earth’s first satellite, but with so much scientific equipment it had a mass of 1327 kilograms, leading it to be delayed in favor of lighter payloads. Like Sputnik 1 and 2, it was launched on a Sputnik launcher – a modified R-7 – but this version was the slightly more powerful 8A91 rather than the 8K71.
Sputnik 3 had an array of instruments to measure pressure, cosmic rays, magnetic fields, micrometeorites, and the composition of the atmosphere. It was also supposed to measure the radiation belts, but it wasn’t able to do so because of a recording instrument failure. Explorer 3, almost identical to Explorer 1 except for an instrument fix, had been able to definitively discover the Van Allen belts a month and a half earlier.
An initial launch of an Object D satellite failed on April 27th after one and a half minutes. That satellite was actually recovered mostly intact, but couldn’t be reused. Thankfully, there was a backup payload and launcher.
The backup Object D reached an orbit of 217 by 1864 kilometers at a 65.18 degree inclination. It ultimately decayed back into the atmosphere on April 6th, 1960.
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