"I can report that everything that we did has been checked out and this week, Hubble has started observing again," mission specialist John Grunsfeld said Friday at the meeting of the American Astronomical Society in Atlanta. Grunsfeld replaced several vital components aboard the satellite during two spacewalks on last months mission. He and shuttle crewmate Claude Nicollier -- who suited up for the second of the mission's three spacewalks -- appeared at the conference to talk about their latest trip to space.

All of the Hubbles instruments, including a piano-sized replacement fine-guidance sensor, are up and running, Grunsfeld reported. Six new gyroscopes, which replaced broken ones that had left the telescope crippled since early November are all working and now in the final phases of calibration. The telescopes imaging spectrograph is working well, and the Wide-Field Planetary Camera is in being returned to full observing status, he said.

"Once you got past the superficial blemishes and opened up the telescopeto look inside the bays, I mean, it looks absolutely pristine."

Although calibration and testing will continue into early March, science observations began last week, and will continue in concert with the check-out operations, said Cheryl Gundy, a spokeswoman for the Space Science Telescope Institute, which operates the Hubble.

Grunsfeld and Nicollier were two of the seven-member crew NASA sent to rendezvous with the ailing Hubble last month for both routine and emergency servicing.

The mission was so successful, Grunsfeld said, that "even some things that we didn't work on, that were broken, miraculously are now working." Several electronic relays in computer circuits had malfunctioned, but during the process of shutting down the telescopes electronics and turning them back on again after repairs, some of those relays came back to life.

Although Hubble has suffered more than its fair share of trouble since its launch 10 years ago, the telescope is in remarkably good shape, Grunsfeld said, and shouldnt be dismissed as aging or infirm. "Hubble is still a baby telescope," he said, pointing out that any ground-based telescope only a decade old would hardly have begun its useful life.

"The issues are that when something breaks on Hubble, somebody isn't there that night the night operator, or an engineer the next morning to go fix it. So it's still just remarkable to me that Hubble operates as well as it does with so few failures," he said.

During three spacewalks, shuttle astronauts examined the telescope for signs of wear and tear, and any other obvious signals of damage or degradation. The space environment is harsh on a telescope. Radiation, dramatic temperature changes between day and night, and pummeling by micrometeorites all pose hazards to the observatory.

Overall, though, "We found the telescope in better condition than we were expecting, than many people were expecting," Nicollier said. In some areas, the outer surfaces of insulation blankets are laced with tiny cracks, which appear to be the result of mechanical stresses from expansion and contraction between day and night, Nicollier said. In other places the edges of the blankets look singed, almost as if somebody had burned the edges with a blowtorch, Grunsfeld said. He guessed that some sort of ultraviolet radiation effect might be to blame.

"As far as the longevity, once you got past the superficial blemishes and opened up the telescope to look inside the [instrument] bays, I mean, it looks absolutely pristine," Grunsfeld said. Hubble should perform beautifully for at least 10 more years, the challenges for NASA will be to continue to develop and install better instruments in Hubble that will keep increasing its performance and sensitivity, he said. In this way the telescope will remain at the forefront of Earths great observatories for many years to come.