Spacewalkers pull off toughest Hubble repairs

Spacewalking astronauts gave the Hubble Space Telescope a more commanding view of the cosmos by installing a new hi-tech instrument, then pulled off their toughest job yet: fixing a broken camera.

It was the third spacewalk in as many days for the shuttle Atlantis crew and the most intricate ever performed because of the unprecedented camera repairs.

Astronauts had never before tried to take apart a science instrument at the 19-year-old observatory.

Hubble’s chief mechanic John Grunsfeld deftly opened up the burned-out camera and plucked out all four electronic cards that needed to be replaced.

“Somehow I don’t think brain surgeons go ’woo-hoo’ when they pull something out,” one of the astronauts observed from inside Atlantis.

To everyone’s surprise, the new cards and power supply pack went in just as smoothly. In fact, the astronauts found themselves running ahead of schedule for a change, their spacewalk lasting the allotted six and a half hours. The first two spacewalks ended up running long because of unexpected difficulties encountered with Hubble, last visited seven years ago.

The astronauts cheered when Mission Control radioed the news that the repaired camera had passed the first round of testing.

“That’s unbelievable,” Grunsfeld said.

Even with two spacewalks remaining, including the repair of a major instrument today, Nasa managers were handing out accolades and talking about how improved the telescope already is.

“At this point in time, Hubble has reached a new high in terms of its capability,” Hubble programme manager Preston Burch said. “We’re enjoying the moment and savouring it.”

In a video sent to Earth taken before the spacewalk, Mike Massimino, who spacewalked on Friday and will do so again today, compared dealing with Hubble to a heavyweight boxing match.

The high-stakes job unfolded 350 miles above Earth. Orbiting so high put Atlantis and its astronauts at an increased risk of being hit by space junk. Nasa had another shuttle on launch standby in case a rescue was needed.

Earlier, Grunsfeld and his spacewalking partner Andrew Feustel accomplished their first task, hooking up the Cosmic Origins Spectrograph.

They made room for the new supersensitive spectrograph – designed to detect faint light from faraway quasars – by removing the corrective lenses that restored Hubble’s vision in 1993.

“This is really pretty historic,” Grunsfeld said as he and Feustel hoisted out the phone booth-size box containing Hubble’s old contacts.

Hubble was launched in 1990 with a flawed mirror that left it nearsighted. But the newer science instruments have corrective lenses built in, making the 1993 contacts unnecessary.

The latest addition, the cosmic spectrograph, is expected to provide greater insight into how planets, stars and galaxies formed.

Nasa hopes to keep Hubble working for another five to 10 years. Already, the astronauts have given Hubble two top-of-the-line science instruments, fresh batteries and gyroscopes, and a new science data unit.

If all goes well, the final spacewalk is set for tomorrow and the telescope will be released on Tuesday from Atlantis.