The U.S. space agency NASA says it has found a crack in the foam insulation on the fuel tank of shuttle Discovery, which was scheduled to launch Tuesday.
NASA managers said Monday, they were studying the crack on an external tank to determine whether or not to proceed with the launch at the Kennedy Space Center in Florida.
They said the problem was discovered late Sunday, after NASA managers were forced to scrub a planned launch earlier in the day because of stormy weather.
NASA officials have been struggling to address concerns about the foam insulation since the spacecraft Columbia broke apart in 2003, killing seven astronauts.
The agency says that foam had damaged Columbia's wing, which led to its disintegration during re-entry.
Some top NASA officials had sought to delay the latest Discovery mission, saying some of the problems that afflicted Columbia are not fully resolved.
But the space agency decided to go ahead with the flight, which is intended to deliver supplies and practice inspection and repair techniques on the International Space Station.
A German member of the Discovery crew will remain at the space station, expanding its crew to three for the first time since the Columbia tragedy.