Space Observatory Launch Delayed--Again

Astronomers will have to cool their heels awhile longer for the debut of a long-anticipated space observatory. Newly discovered flaws in key circuit boards will hold up the space shuttle launch of the Advanced X-ray Astrophysics Facility (AXAF) at least until May, NASA officials announced today. The 5-week setback for the troubled $2 billion telescope also promises to complicate construction of the international space station and maintenance of the Hubble Space Telescope.

For 2 decades, scientists have been planning the giant orbiting AXAF telescope, which is designed to capture detailed images of galaxies, quasars, and other celestial objects. But costly delays have plagued the craft, originally slated for launch last summer, prompting NASA to appoint a special review panel to oversee the project. Those troubles appeared to be over last week when contractor TRW Inc. of Redondo Beach, California, prepared to ship AXAF, recently renamed the Chandra Observatory, to Kennedy Space Center in Florida for an April launch.

But on 15 January, TRW engineers testing an unrelated communications satellite discovered flaws in the copper plating on some circuit boards that were similar to 129 boards installed on the observatory. So far, NASA officials have inspected about a third of Chandra's suspect components and discovered two boards with defects that could block the flow of electric current and potentially disable the telescope. They won't know until next week how many more boards will have to be replaced but believe the total will not exceed 22. Recovering from that worst case scenario could take several months, NASA officials said.

In the meantime, researchers have little choice but to hope that the craft, whenever it is finally launched, is spaceworthy. Because its orbit will take it outside the shuttle's operating range, astronauts will not be able to fix the Chandra once it is in space, as they can the Hubble telescope. "Failure is not an option here," says NASA's Ken Ledbetter.

NASA officials must also sort out a shuttle schedule scrambled by the delay. Both the Chandra and an essential Hubble repair trip scheduled for August 2000 can fly only aboard the shuttle Columbia, which is outfitted for the missions. But Columbia will be grounded for a lengthy overhaul later this year. That means another shuttle may have to be reconfigured for Hubble repairs if Chandra delays make it impossible for Columbia to be spruced up in time for the Hubble mission. That switch, in turn, could disrupt shuttle flights needed to assemble the international space station, NASA officials say.