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Thursday, 28 February, 2002, 10:13 GMT
Hubble set for major upgrade
Hubble, Nasa
Hubble: Nasa's pride and joy
Seven astronauts are gearing up for a daring mission to service the Hubble Space Telescope (HST).

It is very ambitious. It's not easy. We'll worry all the way

Anne Kinney, Nasa
The orbiting observatory has proved to be one of the triumphs of modern astronomy - it has taken some astonishing pictures of deep space - but could do even better science if it received an upgrade.

The American space agency (Nasa) was intending to send up a shuttle crew on Thursday to add some new equipment and replace other degraded components, but a cold snap in Florida means the launch is now set for Friday.

The mission is a risky one. The upgrade will require Hubble to be completely powered down at one point and Nasa cannot guarantee that it will be able to switch the observatory back on again.

Dormant instrument

"That scares me a lot," Ed Weiler, the agency's head of space science said at a recent briefing. "It kind of violates a long standing policy in the space business that if something's working well, you don't turn it off and just hope it comes back on."

Hubble, Nasa/STSCI
Eagle Nebula: Hubble has produced so many great images
Blast off for the space shuttle Columbia is now scheduled for 0622 local time (1122 GMT) on Friday at the Kennedy Space Center, Florida.

At least five spacewalks are planned during the 11-day mission. The Columbia crew will fit Hubble with a new camera, solar wings, power-control unit, steering mechanism and a refrigerator system that should allow scientists to use an infrared camera that has lain dormant on the HST since 1999.

The most daunting part of the STS-109 shuttle mission will be the fitting of the new power unit, currently set for 5 March.

Hubble replacement

Astronauts John Grunsfeld and Richard Linnehan will first have to remove the degraded, old unit, "switching off" Hubble in the process.

It will then be a race against time to fit the new unit and power up the observatory again before the extreme cold of space does any damage to the telescope's instruments.

If the worst happens and Hubble cannot be turned back on, Nasa will have little choice but to abandon the observatory.

This would be a disaster, as the HST's replacement - the Next Generation Space Telescope - is still only in the design phase and is many years away from getting into orbit.

'Very ambitious'

"There're thermal clocks, if you will, that are counting against us as we power the [Hubble] down and then power it back up," said Bryan Austin, the mission's lead flight director.

"There's some confidence there that everything should come back up, but there's a large amount of equipment and relays and activity on the telescope that could throw us a curve."

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
Anne Kinney, Nasa's director of astronomy and physics, added: "Do we think we can do it all? Yes, we do. We wouldn't plan it if we didn't think that. But it is very ambitious. It's not easy. We'll worry all the way."

The mission is called the 3B servicing mission. It includes work not carried out when astronauts did an emergency repair on Hubble's gyroscopes in 1999.

If all goes well, Hubble will be back online to gather even more data about the Universe. Currently, it delivers daily between 10 and 15 gigabytes of data to astronomers all over the world.

This mission also marks Columbia's debut following the most extensive shuttle overhaul in years. The orbiter has not flown since July 1999, since which time it has undergone 133 modifications including the installation of a completely modernised cockpit.

See also:

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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