The Space Shuttle Discovery was set to begin its journey to the launch pad yesterday, but its departure was delayed when hairline crack was found in the foam insulation on the external fuel tanks. After a two hour delay, during which engineers examined the crack and judged it safe, the craft finally rolled out of the assembly building.

NASA said the crack was a "minor imperfection" that was no reason for concern. Engineers examined the fault and determined that no repairs were necessary, the BBC reports. A spokeswoman for the space agency, taking the art of understatement right to its limits, told reporters that "because the foam is a sensitive issue we want to make sure we're in a safe and right configuration."

In February 2003 the Shuttle Columbia disintegrated and burned up in the atmosphere on its return to Earth, a disaster that was caused by a chunk of foam falling off during take off.

Discovery will be the first shuttle to fly since the loss of the Columbia and all her crew. NASA is aiming to launch the craft during a launch window between 15 May and 3 June. She will dock with the International Space Station, bringing vital spare parts and supplies to the current residents.

Read more about Return to Flight here. ®

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