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Hubble getting new view on universe

Advanced Camera for Surveys is about phone-booth size

A view of the Hubble Space Telescope after it got its new power unit on Wednesday.  

Editor's note: The fourth of five planned Hubble spacewalks is to begin at roughly 2:30 a.m. EST Thursday.

JOHNSON SPACE CENTER, Texas (CNN) -- A day after undergoing what scientists likened to heart transplant surgery, the Hubble Space Telescope is close to giving astronomers a better perspective on the universe.

Spacewalkers Jim Newman and Mike Massimino are making a return trip to the shuttle's cargo bay where the 12-ton telescope is berthed. The astronauts, who started the series of upgrades on Hubble on Monday, are to change out a camera on Hubble and install an electronics support module.

The new camera, called the Advanced Camera for Surveys, or ACS, is expected to greatly improve Hubble's ability to create images of the cosmos.

"It covers twice as much sky with twice the clarity in one-fifth the time," said Hubble project scientist Dave Leckrone.

The new camera -- about the size of a telephone booth -- is to replace Hubble's Faint Object Camera, the last of Hubble's original instruments.

The ACS should become what NASA describes as the workhouse for Hubble. It will search for extra-solar planets, scour regions deep in space and observe weather here on Earth.

'Houston ... we have a heartbeat'

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The Hubble Space Telescope on Wednesday got what scientists likened to a new heart.

Spacewalkers John Grunsfeld and Richard Linnehan changed out the 12-year-old telescope's power control unit, or PCU. The mission required powering down Hubble for the first time since it was deployed from space shuttle Discovery on April 25, 1990.

The tense part for astronauts and Hubble scientists came when it was time to turn Hubble back on.

"Columbia, Houston, with a post-operative report," said astronaut Mario Runco at Mission Control after power started flowing to the telescope again. "We have a heartbeat."

Leckrone, who earlier had likened the power-unit change to a heart transplant, said afterward that the patient was recovering nicely.

"The patient has revived and is talking to us," he said, referring to the good telemetry that Hubble was relaying down to Earth.

The surgery went quickly. Power to Hubble was turned off at 4:37 a.m. EST. Grunsfeld and Linnehan quickly unplugged the power unit's 36 connectors and by 8:20 a.m. EST they had changed out the PCU and connected the new unit. By 9:02 a.m. EST, Hubble had been revived and systems on the telescope were being restarted.

Leaky suit

Wednesday's spacewalk lasted 6 hours and 48 minutes. It started about two hours late because of a leak in Grunsfeld's spacesuit. He was wearing the suit when the leak was detected, but he was still inside the shuttle at the time and was not in any danger, according to NASA spokesman Ray Villard at the Johnson Space Center in Houston, Texas.

The leak was "water from the coolant system," Villard said.

The spacewalkers plugged in dozens of connectors like this one as they installed Hubble's new power unit.
The spacewalkers plugged in dozens of connectors like this one as they installed Hubble's new power unit.  

Grunsfeld changed into one of four other suits on the shuttle and the pair got to work.

The suit will be not be used again on this mission, said spacewalk coordinator Dana Weigel. She said work is under way to determine what caused the leak, but that it involved a solenoid valve located in the shoulder of the suit. Weigel said it's possible a power surge in the airlock power supply tripped the valve and caused it to open prematurely.

New solar wings

On Tuesday, Newman and Massimino added a second solar wing to Hubble. Grunsfeld and Linnehan added the first wing on Monday. The new array is smaller, but 20 percent more powerful than the old solar wings. Newman and Massimino also installed a new reaction wheel assembly, a device that helps aim Hubble. One of the four devices had a brief outage in November and engineers were worried it might fail again.

The last spacewalk, scheduled for Friday, involves installation of another camera and a cooling system.

In all, Columbia carried up $172 million in new equipment for Hubble. The 11-day mission is scheduled to end March 12 with a landing at Kennedy Space Center in Florida.


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