Problems Prompt NASA to Wait on Restarting Hubble

NASA yesterday suspended a plan to restart the Hubble Space Telescope by using long-dormant backup equipment onboard after the effort ran into problems.

Agency scientists said they remain optimistic that they will overcome the difficulties, but they said they do not yet know why the computer that controls all the science instruments shut down as the backup equipment was powering up.

If an Earth-based fix cannot be found, virtually all of the science instruments on the orbiting observatory will be shut down until astronauts arrive for a repair and replacement mission planned for next year.

NASA had initially planned to launch the Hubble mission earlier this month until one of the two science data formatters onboard failed in late September. NASA has an additional data collector at the Goddard Space Flight Center, and it is now being readied for installation by the astronaut team tentatively scheduled to arrive in February.

Arthur Whipple, manager of Hubble operations at Goddard, said that Hubble experienced two problems as efforts progressed to power up the 18-year-old backup data formatter. First, scientists received a low-voltage signal, and then the main computer that controls most of the science instruments shut down, apparently to protect the equipment.

Whipple said agency scientists do not know if there is a problem with the hardware. He said it is also possible that sensors monitoring the computer gave a false signal or that the software being used to test the switchover from the failed data collector to the onboard backup was flawed.

Although the failure was a disappointment, Whipple said, NASA will continue efforts to restore Hubble from the ground.

The longest the telescope has been out of service is six weeks, in 1999, and it looks as if the current problems will keep it from operating longer than that. Although the loss of Hubble's stream of scientific data is a blow, Whipple said, the observatory itself remains in good working order, and the current problems should not have any effect on the upcoming repair and upgrade mission.

Thursday's failures occurred well into the complex process of switching a number of systems from the dead data formatter to the backup. Whipple said the team's ability to get as far as it did was a promising sign that they will eventually be able to start the backup before the astronauts arrive.

Every Hubble operating part has a backup onboard, but most were installed in the observatory before it was launched in 1990. (Four earlier repair and resupply missions have added new equipment, as well.) NASA engineers have worked for several weeks shifting functions to the backup system and rebooting the computers that control it.

The Hubble observatory, which orbits 380 miles above Earth, has revolutionized astronomy and provided dramatic and revealing images and data about the solar system and faraway galaxies. It also has won a loyal following on Earth: After a previous NASA administrator decided against sending a repair mission in 2006, public protests grew until his successor overturned the decision.

The scheduled final repair mission is expected to keep the Hubble operating until at least 2013, and NASA says the repairs and upgrades will make the telescope more powerful than ever.