Still smarting over being 180 degrees out of position for a "Star Wars" laser test on Wednesday, the crew of the space shuttle Discovery today flawlessly launched a Spartan satellite whose x-ray telescopes will look for a black hole at the core of the Milky Way.

"We've got her out there and she's steady as a rock," Discovery Cmdr. Daniel C. Brandenstein said when the box-like satellite was set free in orbit about a thousand miles north of the Hawaiian Islands. "She's out there about 35,000 feet from us and we still have a visual on her."

The first of a new breed of inexpensive satellites built to be retrieved from orbit and returned to earth by a space shuttle crew, Spartan was built for a fraction ($3.5 million) of what most space observatories cost.

It has no radios, no television cameras, no air conditioning to cool electronic parts, no redundant parts in case of failure, only short-lived batteries for electricity and just enough fuel to swing its telescopes across the sky for two days.

Spartan must be retrieved by Discovery's crew and brought back to Earth so scientists can study videotapes of its observations. "If we don't get it back home," said scientist-astronaut Shannon W. Lucid, who worked the robot arm that set the satellite free today, "the scientists don't get any data. It's that simple."

Once the satellite was free, an onboard timer fired tiny coal gas jets that made it do a little pirouette so scientists could be sure it was working.

Discovery Cmdr. Brandenstein and Pilot John O. Creighton then backed the spaceliner away from the satellite, which looks like a space-borne refrigerator.

Spartan will scan two regions of the sky repeatedly in the next two days: the cluster of galaxies in the constellation Perseus and the center of the Milky Way galaxy itself.

The Perseus cluster and the galactic center are two of the strongest regions in the sky emitting x-rays, a sure sign that the gas in these regions is superheated to temperatures of 100 million degrees or more.

The superheated gas to be examined in the center of the Milky Way may be there because of the presence of a black hole.

A black hole is a stellar object so dense that it allows not even light to escape it. At the center of black holes are believed to be extremely small and extremely dense bits of matter which exert a huge gravitational pull. Long ago predicted by Einstein's Theory of Relativity, black holes are believed to be strewn all through the universe where they sit invisibly drawing interstellar gas and dust into them in such quantity that they superheat everything in their neighborhoods. It is believed that black holes may have played a role in the creation of galaxies.

Trying to forget the embarrassment they felt at being in the wrong position for a laser test over Hawaii, the crew was told today that the test is being rescheduled again for Friday morning to give Air Force engineers a second chance.

As they tried to do Wednesday, the crew of Discovery will position the spaceliner so a mirror positioned in the port side hatch window is pointed at the island of Maui, where Air Force technicians will fire a beam of laser light at the spacecraft. Flight directors said today there is a good chance that still another attempt will be made on Saturday, which had been designated as a backup day for the test that failed on Wednesday.