By Matt Schudel September 24 at 8:49 AM

Oleg Ivanovsky, a Soviet rocket scientist who played a central role in developing satellites at the dawn of the space age, including the first vehicle to carry a human being in orbit around the Earth, died Sept. 18. He was 92.

His death was announced by Roscosmos, the Russian space agency. The cause and location were not reported.

Mr. Ivanovsky worked for many years as a top engineer at the secret Soviet space facility known as Star City, where he helped design Sputnik, which was launched on Oct. 4, 1957. The unmanned satellite, just 23inches in diameter, circled the globe for three months and prompted alarm in the United States that the Soviets had taken the lead in engineering, rocketry and the Cold War in general.

A month after the first Sputnik launch, the Soviets sent Sputnik 2 into space, this time with a dog on board. The dog, named Laika, died after a few hours in orbit, apparently from heat exhaustion, but she gave much to biology, Mr. Ivanovsky said later.

We didnt know if an animal could survive for longer than a few minutes in weightlessness, he said. But from the data from Sputnik 2, we could see that she moved, and even ate, after the launch.

Encouraged that a mammal could survive in space, at least for a short time, Mr. Ivanovsky took a leading role in building a capsule that could carry a Soviet cosmonaut into orbit. A 27-year-old pilot, Yuri Gagarin, was chosen to fly the spacecraft, called Vostok 1.

In 1960, an explosion at the Soviet launch pad in Kazakhstan killed 126 people, and there were other technical setbacks along the way. Mr. Ivanovsky and other engineers estimated the chances of a successful manned flight at no more than 50-50.

Gagarin wrote a farewell letter to his wife in case he would not return from his mission, but he blithely sang a folk song as he climbed into the cockpit on April 12, 1961. His heart rate stayed at a steady 64 beats per minute while he awaited liftoff.

Mr. Ivanovsky accompanied Gagarin to the cockpit.

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Oleg Ivanovsky, Soviet engineer who was a key designer of early spacecraft, dies at 92