OUT OF TIME
NASA had until Thursday or Friday for launch attempts this year, but any analysis and repair of the problem would take longer than that to complete, officials said.
Disasters in 2003 and 1986, which killed the crews aboard the shuttles Columbia and Challenger, have made NASA especially cautious about launch safety.
After Thursday's scrubbed launch, managers met for two days and had decided to attempt the Atlantis launch again on Sunday despite the erratic sensors, which have a history of glitches.
Engineers had believed they had traced the problem to a subtle manufacturing issue and thought they had solved it by replacing all suspect devices.
NASA will start another round of investigations and engine upgrades to try to determine the cause of the problem. Atlantis will remain at the launch pad, positioning NASA for another launch try as early as on January 2.
NASA has 10 shuttle flights remaining to complete construction of the $100 billion space station. It also wants to make two resupply flights and a servicing call to the Hubble Space Telescope before the shuttle fleet is retired in 2010.
"It's not that big of an impact to us overall," Bill Gerstenmaier, NASA's associate administrator for space flight, said after Sunday's launch was cancelled. "There's enough margin that can accommodate this move into January."
The launch delay will keep station flight engineer Dan Tani in orbit for another month. He was to be replaced by France's Leopold Eyharts, one of Atlantis' crew members, who will oversee the setup of the Columbus laboratory.
Europe had planned to debut its science laboratory for the space station in 2002, but the launch was put on hold by delays largely caused by the grounding of the U.S. space shuttles after the 2003 Columbia disaster. With the delays, the laboratory's costs have climbed to more than $1.5 billion.
