Twenty-five years ago today, when the Soviet Union shocked the world by orbiting a satellite called Sputnik, President Eisenhower sought to soothe a bewildered American public by saying the United States would top the Soviet feat in the next year.

"After all," Eisenhower said consolingly, "the Russians have only put one small ball in the air."

Then Senate majority leader Lyndon B. Johnson saw things differently: "It is not very reassuring to be told that next year we'll put an even better satellite in orbit, maybe with chrome trim and automatic windshield wipers. I guess for the first time I've started to realize that this country of mine might not be ahead in everything."

Except for Pearl Harbor, no single event in history assaulted America's image of itself as did Sputnik. So rudely did the 184-pound sphere undermine the idea that the United States was the world's leader in military, economic and technological might that it changed the way Americans did research, supported universities and taught their children.

One historian placed the U.S. response to Sputnik "in the same category" as decisions leading to the Truman Doctrine, the North Atlantic Treaty, intervention in Korea, support for Taiwan and Vietnam and the confrontation with the Soviet Union over missile sites in Cuba.

Sputnik's orbit of Earth launched an American search for itself that did not end until two Americans stepped onto the moon in 1969, just as President Kennedy had promised eight years earlier.

Along the way, the United States went on a spending spree in education and technology, pouring as much as $50 billion into schools and laboratories from Long Island to Los Angeles and producing a generation of engineers and scientists who changed American lives and restored the nation's image of itself.

In the years immediately following Sputnik, U.S. space ventures did nothing but tarnish that image. One month after Sputnik, the Soviets orbited a dog named Laika, and three years later a virtual zoo of two dogs, rats, mice, flies and seeds was orbited and recovered alive. In 1959, the Soviets flew the unmanned Luna 3 around the moon and took the first photographs of the moon's hidden far side.

Meanwhile, the Navy and Army fought about which would orbit the first U.S. satellite.

The Navy had the first crack with Vanguard on Dec. 6, 1957, and literally blew it on the launch pad at Cape Canaveral. In January, 1958, the Army was given four days to launch its Explorer satellite from the cape. If the four days passed without a launch, the Air Force--which operated the cape test range and hoped the Army and Navy failed--would undertake "urgent" missile tests.

Two days passed while the jet stream unexpectedly moved south, raising winds 40,000 feet above Canaveral to unsafe levels. On the third day, winds died, and the Army fired away, but its feud with the Navy was not finished.

The Navy had given the Army permission to install tracking radios on Antigua in the Leeward islands but not to check them before the flight. Salty Caribbean air had so corroded the Army radios that Canaveral never received the signal that Explorer was on its way to orbit.

Explorer project scientist Alfred Hibbs remembers Army Gen. Bruce Medaris drumming his fingers on a desk in a Canaveral blockhouse about the time that the Antigua signal did not appear. "Hibbs, is it up?" Medaris asked.

Hibbs says he told Medaris "there is a 90 percent probability that the perigee [low point in the orbit] is higher than 200 miles, and Medaris said, 'Hibbs, is it up or not?' I said, 'Yessir, it's up, and it's going to stay up for 10 years.' It was a wild guess, but it turned out to be right."

In 1961, the roof fell in on America when Yuri Gagarin became the first man to orbit Earth and Gherman Titov later girdled the globe 17 times. The best U.S. orbital effort that year was that of Ham the chimpanzee, and Alan Shepard was flown 600 miles downrange in a "space" flight that never attained orbit.

Not until 1962 did John Glenn carry the Stars and Stripes into orbit, and that involved only three revolutions of Earth. By the end of that year, four Soviet cosmonauts had flown the hammer and sickle in space.

Just before Shepard's suborbital flight in May, 1961, some of the country's best brains told Kennedy to cancel the flight because it was not worth the risk. One White House science aide said, "Manned space flight will be man's most expensive funeral."

Kennedy gambled, won and then took the bigger gamble. On May 25, 1961, he stood before Congress and declared it a national goal to land men on the moon before the end of the decade and bring them back safely.

That decision changed the tide of the space race and altered the course of American lives. Ten years later, historian John M. Logsdon wrote: "The lunar landing decision started the largest single use of technological means to achieve a significant foreign policy goal in American history."

Along the way, the new civilian space agency, the National Aeronautics and Space Administration, squabbled with the Air Force, which had taken the role of the opposition. Failures ensued, and three astronauts died in a launch-pad fire. But by the time Apollo 8's three-man crew orbited the moon at Christmas in 1968, the space race was over.

Although the Soviets had started the race in 1957 with Sputnik, the United States ended it with Apollo 8 and then in 1969 with the moon landing of Apollo 11.

What happened to the Soviets? "They abandoned their moon program. We took the wind right out of their sails," former Johnson Space Center director Christopher Columbus Kraft said in a recent interview.

Sputnik and the space race produced far more than moon landings, and some critics argue that not all of the aftermath is beneficial.

Sputnik spurred U.S. determination to improve the quality of schools and students, but whether that succeeded is debatable. Critics say science and engineering schools were improved at the expense of reading and writing.

"Sputnik is one reason Johnny can't read today. He's far more interested in Pac-Man, which you might call an outgrowth of Sputnik," said one educator who asked not to be named.

If Sputnik led to Pac-Man, it also helped to produce the high technology of the computer revolution. The first pocket calculator was on the market in 1969 when Neil Armstrong became the first man on the moon in a feat made possible only by the speed and number-crunching power of navigational computers.

How far has America come since 1969? Now, there is a desk-top computer whose memory can store what 16,000 human brains can remember.

Today's state-of-the-art computer processes five million operations each second, and the supersecret National Security Agency has a classified computer whose speed is more than 100 million operations a second. By 1990, the average computer is expected to perform 200 million operations a second, and the machines expected 10 years after that will do eight billion operations a second.

Ironies abound in what Sputnik wrought. Kennedy never saw the flight of anything to which he gave the initial impetus, and President Johnson, who did more for the Apollo manned program than any president, suffered through the fatal Apollo fire. President Nixon inherited and basked in all of the Apollo triumphs only to answer for Watergate.

As one historian succinctly said: "History has a trajectory of its own."