Heavy cloud cover and crosswinds forced the US space agency to put off the space shuttle Atlantis' return to Earth for at least another day, extending an otherwise successful mission to repair the Hubble telescope.
NASA had hoped to land the shuttle on Saturday at Kennedy Space Center in Florida, but the weather did not cooperate, waving off landing for a second straight day. The crew has enough fuel to fly until Monday at the latest.
The US space agency has prepared Edwards Air Force Base in California as a back-up landing point in case conditions do not clear up in Florida.
"There's a chance for a landing at Kennedy tomorrow, and we're going to keep that option open," said Greg Johnson, a NASA spokesman. "Edwards remains good for tomorrow and Monday, if needed."
The first chance to land at the Kennedy Space Center on Sunday is at 10:11 am EDT (1411 GMT), he said.
NASA would prefer to land the shuttle in Florida as it would cost the agency some two million dollars (1.4 million euros) extra to get the craft back home from California.
Atlantis blasted off on May 11 with a crew of seven astronauts on what was scheduled to be an 11-day mission to repair the Hubble space telescope and extend its range and life for another five years.
