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Astronauts Repair Hubble with Ease

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Spacewalking astronauts outfitted the Hubble Space Telescope with a new cosmic time machine Saturday while pulling off planetary camera repairs unprecedented in complexity.

Anchored at the end of a 50-foot robotic arm, shuttle mission specialist John Grunsfeld surgically cut into a near-comatose camera, transplanting new computer circuit boards and a new low-voltage power supply.

Grunsfeld and partner Drew Feustel were understandably elated when Mission Control told them they had successfully resuscitated the scientific instrument.

"Woo-hoo!" Feustel called out.

"Oh, that's unbelievable," Grunsfeld said.

"Nice work, guys," Atlantis mission commander Scott Altman said. "Congratulations to you, John and Drew, for the great effort."

With the four-story telescope looming in the shuttle's cargo bay, Grunsfeld and Feustel carried out the third of five back-to-back spacewalks planned during the final Hubble servicing mission.

Crewmates Mike Massimino and Mike Good have an equally challenging job Sunday: repairing a spectrograph that broke down in 2004.

Hubble project scientists warn that the job — which involves working with 117 tiny screws that could float into the telescope and damage sensitive optics and electronics — might not go as planned.

"We've warned from the very beginning that this is a very ambitious mission. We've set the bar very high, and please don't get mad at us if we don't get absolutely everything done," said Dave Leckrone, senior Hubble scientist at NASA's Goddard Space Flight Center in Greenbelt, Md.

But he predicted that Massimino and Good would rise to the occasion.

"I think Mike Massimino and Mike Good are probably feeling pretty competitive," Leckrone said. "They saw how things went (Saturday), and they don't want to be shown up. So I think it's going to go extremely smoothly."

After two opening spacewalks fraught with trouble, Grunsfeld and Feustel breezed through what was expected to be the toughest excursion of a highly demanding mission.

They encountered no major problems removing Hubble's 16-year-old set of "contact lenses" — the Corrective Optics Space Telescope Axial Replacement, or COSTAR.

At the size and shape of a phone booth, the instrument was devised to correct for a debilitating flaw discovered in the telescope's 94 1/2-inch primary mirror two months after its April 1990 launch.

The mirror was ground to the wrong prescription, so it didn't focus light properly.

COSTAR contains small mirrors that sharpen the focus of light before it enters Hubble spectrographs — instruments that help scientists deduce the chemical makeup of stars and galaxies.

Now all Hubble instruments have built-in corrective optics, so Grunsfeld and Feustel removed COSTAR to make way for a new state-of-the-art spectrograph.

The $88 million Cosmic Origins Spectrograph, or COS, will shed new light on mysterious dark matter that makes up 90 percent of the universe's mass. It also will detect faint light from faraway quasars, providing insight into the birth and evolution of the universe.

"We haven't said a lot about COS, and it's sort of the quiet instrument back in the background waiting to come out and be a superstar," Leckrone said.

The instrument's installation paved the way to the unparalleled repairs on the Advanced Camera for Surveys.

The planetary camera was inserted in the Hubble in 2002. A critical power supply for the camera failed in 2007, shutting down two of its three channels.

In what amounted to orbital surgery, Grunsfeld sliced through camera shielding, then unscrewed 32 bolts to remove a plate that covered four failed circuit boards.

Then, he transplanted a new set of circuit boards and a new electrical power supply, waltzing through a job that originally was spread over two separate spacewalks.

"John Grunsfeld went into this being challenged by the clock. He was playing a big game of beat-the-clock," Leckrone said. "Adversity somehow led to a superhuman effort to get the job done."

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