NASA officials have again postponed the launch of the shuttle Atlantis on a final mission to repair and upgrade the Hubble Space Telescope.
The delay, from February to at least May, means astronomers will have to wait three months more before two of Hubble's key scientific instruments can be used again.
Engineers told Hubble managers they need more time to inspect and test the 18-year-old hardware that will replace a science data computer that failed on Sept. 27, and to train astronauts and build the tools they need to install it.
"Our plan is to try to have it ready to ship to Kennedy [Space Center] in the April-ish time frame, so that it would support a May-ish-type launch," said Preston Burch, the Hubble manager at the Goddard Space Flight Center in Greenbelt.
Despite what he described as "a little difficulty" getting the spare computer up and running after 18 1/2 years on the shelf, "we have a lot of confidence in it right now." But more work is needed. The delay is costing NASA $10 million a month
The failure last month of the on-board computer shut down most observations with Hubble's remaining instruments until engineers managed to diagnose the problem and switch the work to a backup system.
The backup began working this week, and the Wide Field Planetary Camera 2 sent back new images of a pair of interacting galaxies that are designated as Arp 147. But NASA wants to replace the entire science data computer so Hubble will again have both primary and backup capacity for as long as possible.
In the meantime, the telescope's Advanced Camera for Surveys and its Space Telescope Imaging Spectrograph remain idle after breakdowns in 2004 and 2007. Astronauts are scheduled to fix both.
They also expect to install two new instruments and replace batteries and gyroscopes in an effort to extend Hubble's useful life.
Hundreds of Marylanders work to support the observatory or use it for their astronomy and astrophysics research.
They manage Hubble science operations from the Space Telescope Science Institute in Baltimore, and control the spacecraft from the Goddard Space Flight Center in Greenbelt.
The institute's director, Matt Mountain, said the added delay was "a disappointment." There are two more shuttle flights scheduled before the Hubble mission can launch, and there is always a risk that an accident would dash hopes for Hubble repairs.
"On the other hand, we're pleased NASA is taking this so seriously," he said.
Astronauts have not visited Hubble since 2002. The fifth and final servicing mission to Hubble was scheduled for 2004, but was canceled after the loss of the shuttle Columbia and its crew in 2003.