Gusting Mojave Desert crosswinds forced officials to delay the planned Sunday night landing of the space shuttle Discovery until this afternoon, when safer weather conditions are expected.
The decision to postpone the rare night landing, planned for 7:02 p.m. Sunday on the dry lake bed at this sprawling military base, came at 3:30 p.m., when officials announced that persistent crosswinds, gusting up to 25 knots, made a landing potentially dangerous.
"The maximum crosswind factor is 15 knots," explained National Aeronautics and Space Administration spokesman Don Haley.
He called the weather delay routine and said the shuttle and its five-member crew "are in good condition. There are no problems arising from the delay."
The new landing of the shuttle, which embarked on a secret military mission last Wednesday, was scheduled for 2:52 p.m. today, said NASA spokeswoman Kari Fluegel at the Johnson Space Center in Houston.
Flight controllers first planned a 4:32 p.m. landing this afternoon, then advanced the time, she said, presumably to give the shuttle astronauts better visibility and a daylight touchdown.
The change to the earlier landing time takes advantage of higher sun angle, reducing the sun glare on the spacecraft's windows during landing, Haley said.
Clear skies and a favorable tail wind of 9 to 15 knots were expected for the landing today, with weather reports indicating a storm condition that brought wind and wintry conditions to much of the state Sunday would dissipate.
The shuttle has alternative landing sites at an Army missile base in New Mexico and at the Kennedy Space Center in Florida, but officials said it did not appear that those sites would be needed.
Although there has been a news blackout on details of the mission for military security reasons, sources have said the crew completed their main task on Thanksgiving Day, when they released a spy satellite into orbit. The satellite is reportedly designed to monitor Soviet missile tests and military and diplomatic communications.
The postponement of Sunday's landing was the sixth time in the nation's 32 shuttle missions that weather has forced a change in plans, officials said. The shuttle carries two days of additional fuel and food for its crew in anticipation of such contingencies.
The Discovery's four-day mission is the seventh since the Challenger disaster of January, 1986.