The nervously anticipated landing of the space shuttle Discoveryhas been delayed until tomorrow.
The landing was initially to have been at 9.46am (Irish time) but due to low cloud, it was put back to around 11.21am at Cape Canaveral.
But Nasa has now decided the weather means the crew will have to orbit the Earth for another day and are expected to return tomorrow.
Nasa officials have also said they would consider two alternative landing sites in addition to Florida's Kennedy Space Center.
The return to the Earth's atmosphere has not been attempted since the Columbiadisintegrated minutes from landing in early 2003, killing all seven astronauts on board.
Nasa insists it is not deeply concerned about the dangerous re-entry, even though Discovery's13-day mission has been fraught with problems.
Tensions have run high ever since lift-off, when a piece of insulating foam broke off the external fuel tank. Unlike Columbia, which was doomed by a similar problem, Discoverynarrowly missed being hit by the large chunk of foam.