Sergei Grits, file, Associated Press
FILE - In this file photo taken on Friday, Sept. 21, 2007, Boris Chertok speaks to reporters in Moscow. Chertok, who died in Moscow Wednesday at the age of 99, was one of the founders of the Soviet space program and played a key role in many Soviet space achievements.

MOSCOW — Russian rocket designer Boris Chertok, who played a key role in engineering Soviet-era space victories, has died. He was 99.

The state-controlled RKK Energiya rocket builder where he worked as a top consultant said Chertok died in Moscow on Wednesday after contracting pneumonia.

For many years, Chertok served as a deputy to the father of the Soviet space program, Sergei Korolyov. He was closely involved in putting the world's first satellite in orbit on Oct. 4, 1957, and preparing the first human flight to space by Yuri Gagarin on April, 12 1961.

Chertok was born in Lodz, Poland, when it was still part of the Russian empire and his family moved to Moscow at the start of World War I.

After graduating from the Moscow Energy Institute in 1940, he started working as an aviation engineer. When World War II ended, Chertok was selected to lead a group of Soviet experts to travel to Germany to tap the Nazi know-how in rockets. He first met Korolyov there, and the two worked closely together until Korolyov's death in 1966.

Chertok, who specialized in control systems for rockets and spacecraft, has published memoirs chronicling the rise of the Soviet space program from its early days to the moon race the Soviet Union lost to the U.S.

"Each of these first rockets was like a beloved woman for us," Chertok said at a meeting with reporters. "We were in love with every rocket, we desperately wanted it to blast off successfully. We would give our hearts and souls to see it flying."

Even the names of Chertok and other leaders of the space program were a tightly-guarded secret, and he only was permitted to travel abroad only in the late 1980s, after Soviet leader Mikhail Gorbachev liberalized the Soviet Union.

Chertok's voluminous work for the first time revealed to the public details of the endeavors which had been hidden by the veil of Soviet-era secrecy.

In recent years, he has frequently appeared on national television and participated in events marking historic achievements. Chertok made stinging criticism of the Russian leadership for losing the nation's edge in space.

"The new elite consisting of the superrich and corrupt officials feeding on windfall energy revenues don't care about the national space program," he said in an interview published earlier this year.