Sputnik 2 weighed 508 kg, six times Sputnik 1

Sputnik 2 weighed 508.3 kg (about 1,120 lb), roughly six times the 83.6 kg of Sputnik 1, and the Soviet Union launched it on November 3, 1957, less than a month after the first satellite.

Sputnik 1 was a polished sphere carrying little more than radio transmitters. Sputnik 2 stood about 4 metres (13 ft) tall and carried instruments for measuring solar radiation and cosmic rays, plus a pressurised cabin for the dog Laika, the first animal to orbit Earth.

Half a ton against a few kilograms

The mass gap mattered more to the Cold War than the dog did. NASA’s own timeline puts America’s first satellite, Explorer 1, at 14 kg when it flew in January 1958, and Vanguard 1 at just 1.47 kg that March. Sputnik 2 outweighed Explorer 1 about 36 times and Vanguard 1 about 350 times; Vanguard’s intended payload had been a mere 3.5 pounds. Because the rockets that lofted satellites could also carry nuclear warheads, every extra kilogram in orbit read in Washington as a measure of Soviet missile power.

What really happened to Laika

Soviet publications first claimed that Laika died painlessly after a week in orbit. That account did not survive. NASA’s history of animals in space says there was no time to work out any reentry plan and that she expired after a few hours. Later accounts blamed overheating, which NASA has said may have happened because the thermal control system did not work properly and some insulation tore loose during launch.

The spacecraft’s batteries died on November 10, 1957, and it fell silent. It kept circling until April 14, 1958, when it burned up in the atmosphere after roughly 2,570 orbits and 162 days in space.