Boris Chertok, a legendary rocket designer who was a key figure in the Soviet-era space program, died Wednesday at the age of 99.
Chertok died after contracting pneumonia just three months shy of his 100th birthday, Interfax reported.
He was among a group of engineers headed by Sergei Korolyov, a former gulag prisoner who became the father of the Soviet space age.
Together with Korolyov, Chertok helped construct Sputnik, which became the world's first satellite in orbit on Oct. 4, 1957. The world-changing event was at first underestimated by the Soviet Union, he 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 also built the rocket that sent the first man, Yury Gagarin, into space, in April 1961. They were also responsible for the first unmanned spacecraft to reach the moon and take the first photographs of its dark side.
Chertok's and Korolyov's identities and their involvement in the space program were a state secret for decades.
Chertok continued to work in the space industry until his death. For the past several years he was a consultant with the state-controlled RKK Energia rocket company.
In 2007, Chertok told The Moscow Times that he was proud of the contributions his team made to the world, paving the way for advances from satellite phones and GPS navigation systems.
"You don't know it, but many people use our science all the time," he said.