A beam of laser light fired from a mountaintop in Hawaii bounced off a reflecting mirror on the space shuttle Discovery today as it flew 230 miles overhead at a speed of 17,500 mph.

The event was the first "Star Wars" test between the Air Force on the ground and the National Aeronautics and Space Administration shuttle in orbit. After seeing the test botched two days earlier, the Air Force declared today's attempt a success. But it was not intended to solve any of the most difficult problems of setting up a "Star Wars" defense system. It also was not the first laser tracking test, but it probably was the most media-tracked of the tests in the Strategic Defense Initiative program, as it is formally known.

The "Star Wars" plan envisions knocking down enemy missiles with lasers or other weapons before they reach the United States.

Air Force Lt. Col. Thomas Meyer, manager of the laser test program, said today's experiment was more a test to see how the atmosphere distorted the laser beam than a test of the beam's ability to track the space shuttle. Atmospheric distortion could limit the usefulness of ground-based lasers against targets in space.

Today, the laser beam "painted" a blue-green light on the nose of Discovery for at least 2 1/2 minutes, three times longer than the minimum time the Air Force hoped for. So tight and steady was the beam that it never wavered from the nose of the DC9-sized Discovery, which measures 110 feet from nose to tail. So well was the test run that an identical test planned for Saturday morning was canceled.

"We were able to pulse the beam and change the size of the beam from a fine point a quarter of an inch across to a beam 30 feet across at the point where it tracked the shuttle. We did everything we wanted to do," Meyer said at the Johnson Space Center in Houston.

With a tape recorder playing Tchaikovsky's "1812 Overture" in the shuttle cockpit, the seven crew members stayed glued at the port side windows to watch the spectacle of laser light shining on them. Discovery pilot John O. Creighton said he was able to follow the beam from a 10,000-foot mountain on the Hawaiian island of Maui without any danger to his eyes because of the low power output of the four-watt beacon.

"We can see a steady stream of light that looks blue-green from here," Creighton said. "Now it's pulsating and it looks more blue than green."

"I would definitely say today's test was made a lot more demanding by those winds," Meyer said, referring to gusts up to 55 mph on the peak near the dome holding the laser equipment. "The winds were a lot higher than we expected but they did nothing to dampen our test."

Meyer said that today's laser test was one step by the Pentagon's Strategic Defense Initiative Organization to develop lasers that can track and destroy hostile satellites and ballistic missiles. The "Star Wars" program is a composite of countless small research projects like the one demonstrated today that draws on a budget of $1.4 billion.

"We demonstrated today that we can track a fast-moving target with a laser on the ground," Meyer said. "Our next step is to perform the same kind of test with rockets fired to an altitude of 360 miles to see if ground-based lasers can stay with them all the way to altitude."

Today's feat was not a technical advance, but one of a series of laser tests in the sky and space. Lasers were first observed from space by American astronauts 20 years ago and have been used by the Pentagon in various applications for the last 15 years. Laser telescopes on the island of Maui, where today's test was conducted, routinely reflect beams off Soviet spy satellites to determine what kinds of optical sensors they carry.

The Air Force used a powerful laser as long ago as 1973 to hit a winged drone at Kirtland Air Force Base in New Mexico. The Army has used lasers to shoot down drone helicopters, the Navy has used lasers to destroy surface-to-air missiles and the Air Force now has a 400,000-watt laser aboard a KC135 aircraft that has shot down Sidewinder air-to-air missiles by overloading their electronics guidance systems with heat.

A far more difficult and important goal than tracking objects with lasers is the Pentagon's plan to develop more powerful lasers that can be used as weapons. A 2 million-watt laser will soon be tested at White Sands Missile Range in New Mexico and a 5 million-watt laser is being built