Discovery heat shield tiles with the shadow of the spacewalking astronaut Steve Robinson cast on them. Robinson performed a six-hour spacewalk to repair the heat shield after it was found that two ceramic strips were protruding. It was feared that the strips might have led to overheating of the shield during Discovery's re-entry. This was the first time that an astronaut had ever performed in-flight repairs to a shuttle. This mission, STS- 114 or Return to Flight, launched on 26th July 2005. It was the first shuttle mission since Columbia was lost on re-entry on 1st February 2003.