MOSCOW, Dec. 14 (UPI) -- Boris Chertok, a rocket designer and a key figure in the Soviet-era space program who helped build Sputnik, died of pneumonia, officials said. He was 99.
Chertok died Wednesday, three months shy of his 100th birthday, The Moscow Times reported.
He was one of a group of engineers led by Sergei Korolyov, a former gulag prisoner who became the father of the Soviet space program. He was one of the designers of Sputnik, the world's first satellite, launched into orbit Oct. 4, 1957.
The achievement, which shocked the United States and much of the world, was at first underestimated in his own country, Chertok said.
"Neither we, nor our media first grasped the historical significance of our feat," Chertok said in a 2007 interview with The Moscow Times.
Korolyov's team of engineers also built the rocket that launched Yuri Gagarin as the first man into space in April 1961.
The identities of Korolyov, Chertok and other engineers were kept a Russian state secret for many years, unknown in the West.