The newly repaired Hubble telescope has been released into space by the shuttle Discovery.

Nasa called the mission, which included carrying out a series of repairs to the telescope, a total success.

French astronaut Jean-Francois Clervoy used the shuttle's mechanical arm to gently lift the 12-tonne telescope from Discovery's cargo bay and send it into orbit.

Discovery astronauts successfully completed the repairs on Christmas Eve during their third spacewalk of the flight.

US astronauts John Grunsfeld and Steven Smith installed a new radio transmitter, data recorder and steel shields to protect Hubble's exterior.

Nasa's main observatory on the universe has been out of commission since mid-November, when it shut itself down.

Two marathon spacewalks earlier this week replaced Hubble's central computer, and its navigational system which allows it to aim very precisely at distant stellar objects.

Hubble's new 'brain'

British-born Michael Foale and Swiss Claude Nicollier carried out the delicate operation of installing a new computer as they flew over Australia at an altitude of about 600km (360 miles) on Thursday.

Mr Foale, a software programming expert, directed the operation.

The Hubble's ageing "brain" was replaced with one with three linked Intel 486 microprocessors.

It will perform 20 times faster and has six times more memory than its predecessor - although it is less powerful than many home computers.

A quick electrical check showed that all the connections were good.

"The Hubble not only has new brains, it's thinking," Mission Control told the crew.

Nasa had spent several years developing a computer able to withstand the radiation in space which destroys normal electronics.

Foale and Nicollier also replaced one of the telescope's large guidance sensors which point the $3bn Hubble precisely toward phenomenon it is observing.



Their eight hours 15 minutes space walk was the third-longest recorded by Nasa. It was also a first walk for Mr Nicollier - a member of the European Space Agency.

US Discovery colleagues Steve Smith and John Grunsfeld completed their eight-hour marathon walkk to replace the telescope's navigational system late on Wednesday.

Nasa officials say Hubble could now aim at a coin more than 300km distant.

'Christmas gift'

A fourth scheduled space walk was cancelled after delays in Discovery's launch, because Nasa is determined to have the shuttle back on the ground before Millennium Eve to avoid the risk of any potential Y2K computer problems.