Must Read: Russia celebrates nostalgic 50th anniversary of Sputnik launch

MOSCOW - Russia on Thursday celebrated the 50th anniversary of the Sputnik launch that opened the space age, with officials seeking to revive the glory of the Soviet program, although some experts worry about a loss of momentum for new missions.

Goose-stepping guards and medal-bedecked space veterans laid flowers at the tomb of the father of the Soviet space program, Sergei Korolyov, at the foot of the Kremlin wall.

'We are rightly proud that it was our nation that opened the way to stars for the humanity,' President Vladimir Putin said in a statement marking the launch of Sputnik, Earth's first artificial satellite, on Oct. 4, 1957.

The launch of the beachball-sized satellite caused a global furor and prompted the U.S. to build up its own space program quickly, entering a race it ultimately won when Apollo 11 astronaut Neil Armstrong set foot on the moon in July 1969.

NASA's top official hailed the achievements of both countries - and their cooperation of recent years.

'Without Sputnik, there would have been no Apollo,' NASA Administrator Michael Griffin said in a speech at a gathering of Russian and foreign space scientists. 'We have much learned from each other and I think we can go farther together than either of us can go separately.'

Sputnik was born as an impromptu byproduct of a frantic Soviet effort to develop an intercontinental ballistic missile capable of slamming a heavy hydrogen warhead into the United States. The R-7 missile's high thrust and payload capacity, unmatched at the time, made it the perfect vehicle to launch objects into orbit.

Korolyov, the visionary head of the Soviet rocket program and a tough manager, persuaded a reluctant Soviet leadership and top military brass to launch the first satellite into orbit.

Aware of U.S. plans to launch a satellite in 1958, Korolyov's team built a simple satellite in less than three months.