Sputnik 1 came perilously close to suffering the same fate as the United States’ TV3 satellite, which was destroyed in a launch failure on Dec. 6, 1957.
Sputnik 1 was lofted by an R-7 rocket, which consisted of four first-stage boosters — known as Blocks B, V, G and D — strapped onto a core second stage (Block A). During the launch, the Block G booster’s main engine reached its intended thrust levels later than expected.
“As a result, 6.5 seconds after the launch, the rocket started to pitch, deviating around 1 degree from the nominal trajectory 8 seconds after the liftoff,” Zak wrote . “In the effort to correct the increasing pitch angle, steering engines No. 2 and [No.] 4 on the core stage rotated as much as 8 degrees; similar engines on strap-on boosters of Block V and D rotated as much as 17-18 degrees, while tail air rudders rotated 10 degrees.
“Only a split second remained, after which the flight control system would terminate the flight of the underpowered rocket,” he added. “Fortunately, the engine finally reached normal performance, and [the] rocket fully returned to nominal trajectory some 18-20 seconds after the liftoff.”
Sputnik 1 eventually settled into an elliptical orbit, which took the satellite as close to Earth’s surface as 142 miles (228 kilometers) and as far away as 588 miles (947 km). The satellite zipped around Earth every 96 minutes.
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