NASA scientists and engineers amazed even themselves yesterday by getting the $150 million Astro-1 observatory aboard the spaceship Columbia back to work using a jury-rigged ground-to-space hookup to overcome a failed control system on the spacecraft.

Elated scientists said the system worked much better and faster than expected, producing a new view of a nearby exploding star, glimpses of a region where giant galaxies may be forming and evidence of the existence of a black hole, an object so dense that not even light can escape its gravitational pull.

After the loss of 22 hours of work time following what appeared Thursday to be a disastrous hardware breakdown, the observatory's efficiency beginning yesterday morning was about equal to what the astronomy teams had hoped to achieve with everything working perfectly, they said.

"It's working as well as it ever could possibly have worked," said Arthur Davidsen of the Johns Hopkins University team, which has one of three ultraviolet telescopes on board the shuttle.

While some crew members aimed the shuttle's telescopes yesterday, two astronauts transmitted the world's first "lesson from space" to students on Earth. {Details on Page B1.}

On Thursday, the mission had seemed in danger of losing much of its scientific purpose -- to make unprecedented observations of the universe through wavelengths of radiation that do not penetrate Earth's atmosphere -- when Columbia's seven-man crew lost its only working link with three of the four telescopes mounted in the shuttle's cargo bay.

This meant the astronauts could no longer send keyboard commands to computers that instruct the telescopes and equipment. Instead, the high-precision pointing and data collection had to be commanded from the ground, with the astronauts refining the pointing under the guidance of scientists on Earth.

A fourth telescope, which detects X-rays, is normally controlled from the ground and was not affected by the control system problem, although it has had periodic alignment problems of its own.

Late Thursday, the teams started the new operation slowly and cautiously, because of worries that the unrehearsed maneuvers could cause new harm to the mission, deputy mission scientist Eugene Urban said. But the system worked so well that by 6:30 a.m. yesterday, all three ultraviolet telescopes were back in operation, he said.

The mission, originally scheduled for launch in 1986, had already suffered repeated delays, including four unsuccessful launch attempts this year. It had also experienced a series of glitches since its launch early Sunday, including problems with the telescope-pointing system.

Under normal procedures, the pilot first maneuvers the orbiter to a desired attitude for viewing a target. Then, an astronaut uses a keyboard and video screen to talk to an on-board computer, which instructs instruments in the shuttle's cargo bay on how to set themselves and which filters to use. An automatic pointing-control system is supposed to fine-tune the telescopes' aim, but it has been broken off and on during the mission.

Under the impromptu system developed hurriedly Thursday, scientists at the National Aeronautics and Space Administration's Marshall and Goddard Space Flight centers continuously sent revised computer instructions for targeting and instrument settings, transmitting them to the orbiting telescopes through mission control in Houston.

Once the telescopes were pointed generally in the right direction, astronomer-astronauts on board fine-tuned the aim, which must be very precise, using a joystick control and guidance from the ground.

"Up, up, left, left, doing great," astronomer Ken Nordseick in Huntsville, Ala., radioed astronomer Samuel T. Durrance in orbit, as Durrance used the joystick to center an object being observed by the Ultraviolet Imaging Telescope.

The science teams, gathered at Marshall Space Flight Center in Huntsville, had planned 187 observations between late Sunday and Thursday morning, when the latest problem occurred, but had completed only 70, according to NASA.

The Astro scientists said the large number of observations had been planned "in case everything went perfectly," but emphasized that no one familiar with scientific endeavors had expected that to be the case. By mission's end, "every one of the high-priority targets will have been observed at least once," Davidsen said.

While news media have emphasized the percentage of targets missed, he said, quantity is not as important as quality. "We got an unbelievable spectrum" of a giant elliptical galaxy, he said. "I was ecstatic . . . . We're unraveling the mysteries of how galaxies form and evolve."

Chris Johnson, a member of the University of Wisconsin team, compared his experience on the Astro mission to a Chuck Norris movie, where one minute "he's a goner for sure," then he's "up kicking the bad guys." Thursday, he acknowledged, had been a "horrendous day." But yesterday, he pronounced the mission "a resounding success."

Observations reported by the scientists yesterday included the nucleus of the Andromeda galaxy; the largest nearby galaxy, known as M31; a quasar, or brilliant quasi-stellar object, one-third of the way to the end of the universe; the nearby supernova, or exploding star, discovered in 1987, and a variation in energy at the core of a bright galaxy that provides evidence that a black hole exists there.