Hubble Telescope upgrade on hold

CAPE CANAVERAL, Florida (Reuters) - A long-delayed and nearly canceled upgrade to the Hubble Space Telescope will have to wait until NASA completes delivery of three modules to the International Space Station, officials said on Tuesday.

The delay of shuttle Atlantis' mission to the space station, caused by fuel sensor failures in December, means Atlantis likely will not be ready for the Hubble mission planned for August. NASA has two other higher-priority flights for its space shuttles as well.

"Our watchword is safety," Alan Stern, NASA's associate administrator for science missions, told reporters in a conference call from the American Astronomical Society meeting in Austin, Texas.

Plans to deliver Europe's Columbus laboratory module to the space station in early December were put on hold when emergency engine cutoff sensors failed routine checks shortly before liftoff. NASA has reserved January 24 as the new launch date but does not expect the shuttle to be ready until February.

Two more missions to launch Japan's Kibo laboratory complex to the station must be finished before a shuttle crew can be dispatched to fix the Hubble Space Telescope, Stern said.

Though still operational, the Hubble telescope has limited steering capabilities due to gyroscope failures and two of its science instruments are broken. In addition to those repairs, NASA wants to replace Hubble's batteries, put on new insulation and extend its view of the universe with two new detectors, including a highly sensitive, wide-field camera.

The upgrades should extend Hubble's life five to 10 years. Without a servicing call by shuttle astronauts, the telescope likely would only last until 2010 or 2011, said project scientist David Leckrone of NASA's Goddard Space Flight Center in Greenbelt, Maryland.

"When the astronauts leave Hubble, it will be at the apex of its capability, better than it has been before," Leckrone said.

Astronomer Sandra Faber with the University of California, Santa Cruz, said once it is revamped, Hubble will be 90 times more powerful than its original versions.

"We can do more science," she said. "Instead of looking at 10 galaxies, we can look at 900 at the same time."

The Hubble has been in orbit since 1990 and its prime discoveries include evidence that the universe's expansion has been speeding up, not slowing down as originally predicted.

Hubble's new instruments include a high-resolution digital camera that can detect light radiating from the ultraviolet to the near-infrared wavelengths.

"When you look at new wavelengths, you often see very different objects even in the same parent galaxy," Faber said.

(Editing by Jim Loney and Bill Trott)