On October 4, 1957, Americans were stunned when they learned--in no uncertain terms-- that the U.S. had been one-upped by the Soviet Union. The Russians had lofted the first earth-orbiting satellite, Sputnik 1.

Forty years later, Sputnik does not seem like much as spacecraft go. A shiny aluminum sphere barely bigger than a basketball and weighing just 184 pounds, Sputnik was too small to be visible but its spent third stage booster, tumbling along behind, could be seen from the ground. And Sputnik's taunting beeps as it blazed over the U.S. every 96 minutes at an astonishing speed of 17,000 miles per hour made its presence painfully obvious. Claire Booth Luce, then a member of Congress and wife of the publisher of Time magazine, termed Sputnik a "raspberry" from Russia.

Sputnik had a brief life in space, determining the density of the upper atmosphere as part of the International Geophysical Year (IGY), an international scientific collaboration to study Earth. Its radio transmitters, which were sending signals to Earth, went silent after 21 days. Sputnik's orbit decayed, and it burned up in the atmosphere on January 4, 1958--92 days after its launch.

But coming at the height of the cold war and less than a year after Soviet Premier Nikita Khrushchev told Western diplomats, "We will bury you," the tiny satellite had a powerful political and symbolic significance. It chilled the military, who were awed at the apparent power of the Soviet ICBM rocket that pushed it into orbit and ushered in both the space race, culminating in the Apollo moon missions of the 1960s, and the space age.

President Dwight D. Eisenhower attempted to diminish the importance of Sputnik by referring to it as "one small ball in the air," but on July 29, 1958, he signed the legislation that created the National Aeronautics and Space Administration (NASA), which was founded on October 1. Another program, the National Defense Education Act (NDEA), was started in September 1958 as a crash effort to train scientists and engineers. As the U.S. geared up, the budget of the National Science Foundation nearly tripled from 1958 to 1959, then doubled again by 1962.

After two failed attempts, the U.S. managed to launch its first IGY satellite, . Explorer 1, on January 31, 1958. For the next decade, both the Soviet Union and the U.S. would rack up a series of space firsts. But the U.S. did not nail down its final propaganda victory until Apollo 11 astronaut Neil Armstrong announced from the surface of the Moon on July 20, 1969, that he had taken "one small step for [a] man, one giant leap for mankind."

The triumph of the Apollo missions backfired on NASA. In an era of tight budgets, the space agency's plans for further manned missions were severely curtailed. Today, the dream of a long-term human presence in space hinges on the completion of a planned international space station, and, in the interim, a new era of cooperation between the U.S. and Russia. Despite the deteriorating condition of the Russian Mir space station, NASA seems to have--for now at least--decided to hang tough with its support.

Declassified records and contemorary accounts are now revealing that Eisenhower and Khrushchev may have both looked at the IGY programs as a way of diverting energy from the dangerous arms race. And there are indications that Khrushchev was on the verge of accepting an offer for a joint moon mission when President John F. Kennedy was assassinated.

Meanwhile, the skies are filled with Sputnik's descendents--nearly 2,500 of them--that carry communications signals, observe crops and weather, direct navigation, conduct scientific experiments--and, yes, some still sp

What began as an opening salvo in a battle between the superpowers when Sputnik beeped its way across the heavens in 1957 may have become the very thing the International Geophysical Year Committee envisioned 40 years ago--an international assault on the physical mysteries of Earth and space.