Astronauts orbiting the earth have succeeded in an unprecedented repair operation designed to remove two ceramic strips that endangered the heat shield on the Discovery shuttle. Broadcast live on television, Steve Robinson had no difficulty in plucking out the fibre strips, each little more than an inch long, that stuck out from the heat resistant tiles on the shuttle’s underbelly.Robinson was accompanied on his spacewalk by fellow astronaut Soichi Noguchi of Japan and manoeuvred into place at the end of a 20-metre robot arm by Discovery co-pilot James Kelly. The strips could have caused dangerous heat damage. Two and a half years ago the Columbia shuttle burnt up on reentry as a result of damage to its heat shield, with the loss of all seven astronauts on board. The shuttle spaceflights were then grounded. This time NASA is taking no risks.