3 August 2005 (RFE/RL) -- An astronaut will carry out repair work on the "Discovery" space shuttle today that has never been tried before.
The astronaut will make a space walk under the shuttle to fix two pieces of cloth sticking out between the shuttle's heat shield tiles.
NASA officials worry the ceramic cloth strips could overheat when the shuttle returns to the earth's atmosphere and lead to another disaster similar to the 2003 destruction of the "Columbia."
Wayne Hall, the deputy shuttle program manager, has said NASA engineers simply did not know enough about the problem to leave it unattended.
Astronauts have never ventured under an orbiting shuttle before, and have never attempted to fix their ship's thermal shielding in flight.
'Discovery' Astronauts Begin Second Spacewalk