Nasa has confirmed that computer problems on the Hubble orbital telescope have worsened, and that the mission planned to repair the situation is now even more complicated.

The telescope's main computer crashed three weeks ago but Nasa engineers managed to switch to a backup system, an antiquated model relying on 486 processors.

Now another computer for scientific analysis has failed, as has the power unit on one of the cameras.

"The soonest that we would be back doing full science would be late next week," Art Whipple, Hubble manager at Nasa's Goddard Space Flight Center in Greenbelt, Maryland, told reporters during a conference call on Friday.

"It is not known if these two events are related. At this point we are fairly certain it was not a configuration or a commanding error."

A Space Shuttle mission was scheduled for this week to repair the telescope, which has sent back images that have completely changed the prevailing understanding of how the universe works. The repair mission is now scheduled for February 2009.

"If we did not have the servicing mission we would have less options available to us for recovery, but we never take that for granted," Whipple said.