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Wednesday, 6 March, 2002, 15:03 GMT
Hubble 'heart transplant' success
Nasa astronauts fixing the Hubble telescope, AFP
"Some tough work with those gloves on"
The Hubble Space Telescope appears to have survived a tricky spacewalk operation to fit a new power control unit.

"Hubble has a heartbeat," Nasa spokesman Rob Navias said after astronauts from the Columbia space shuttle fitted the new component and mission controllers turned the power back on.

The spacewalkers had to work quickly so that Hubble's power could be turned back on before it was damaged by the extreme cold of space.

Signs of weakness had been detected in the existing power unit. The new one is to last until the telescope is taken out of service in 2010.

Element of risk

There was no guarantee that the power would come back on once the unit was installed - although Nasa was always confident it would.

Astronauts John Grunsfeld and Richard Linnehan took about four hours to remove the old power unit and fit the new one.

It was a tricky job, delayed by a leak in Grunsfeld's spacesuit and involving 36 connections in cramped conditions.

"What I need," said Grunsfeld via his intercom while working on the orbiting telescope, "is to have talked about this in 1975 and laid out this bay."

Hubble history
1977 - Project begins
1985 - Hubble built
1990, 24 April - Hubble launched
1990, 18 May - First light
1993, December - Flawed mirror corrected
1997, February - Second servicing mission
1999, December - Emergency service to repair gyroscopes
2002, March - Repairs not done in 1999
2010 - End of Hubble mission

A loose screw in the old power unit was posing a risk to Hubble's future operations and Nasa decided to gamble that the astronauts could do the job in the time they had.

The gamble appears to have paid off.

The HST is 12 years into a 20-year mission and has already established itself as one of history's finest scientific instruments, having proven the existence of super-massive black holes, witnessed the formative stages of solar systems and given scientists their best estimate yet for the age of the Universe.

But the current servicing mission, being undertaken by a seven-member crew on the Columbia shuttle, should substantially improve Hubble's abilities.

The new Advanced Camera System (ACS) to be fitted later this week will be able to see finer detail and will have a much wider field of view than the Wide Field Camera that it replaces.

Columbia launched from the Kennedy Space Center on Friday and is set to land there on 12 March after releasing Hubble back into orbit.

Hubble SlideShow
See also:

02 Mar 02 | Sci/Tech
Nasa gives Hubble mission go-ahead
02 Mar 02 | Sci/Tech
Hitch threatens Hubble mission
28 Feb 02 | Sci/Tech
High hopes for new Hubble camera
14 Apr 00 | Sci/Tech
Ten years of Hubble science
14 Apr 00 | Sci/Tech
Hubble's vision is blurred
14 Apr 00 | Sci/Tech
Building the first space telescope
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