US NASA officials says there is a 60 percent chance the launch of the space shuttle Discovery may be delayed because of possible showers on Saturday.
The officials made the announcement Thursday during a press conference at the Kennedy Space Center in Florida.
NASA's weather officer, Kathy Winters, said any storms within 32 kilometers of the launch site would ground the shuttle.
Some NASA officials had previously asked that Saturday's Discovery launch be postponed, saying they fear the shuttle could be damaged during liftoff.
They say foam insulation could come off the external fuel tank, although they add that would not cause a threat to the crew.
The crew of six American astronauts and one German will resupply the International Space Station and test shuttle safety procedures during the nearly two-week mission.
This is the 18th U.S. flight to the space station and second since the Columbia tragedy.
Some information for this report was provided by AFP and AP.