spacetoday.net: NASA reschedules STS-133 launch for February 24

Posted: Wed, Jan 12, 2011, 8:11 AM ET (1311 GMT)

NASA shuttle managers said Tuesday they have determined the root cause of the cracks found in the shuttle Discovery's external tank and believe they can have the shuttle ready to launch next month. Officials said a batch of aluminum-lithium brackets, or "stringers", have a mottled appearance and are weaker that expected, which would explain why several of them suffered cracks when the tank was loaded with propellant. NASA plans to install aluminum plates called radius blocks over the stringers to allow them to handle loads without cracking. That work will be done in time to permit a launch on February 24. That launch date also depends on an on-time launch of a European ATV cargo spacecraft, scheduled to dock with the station on February 23.