New Delhi: NASA on Tuesday decided to delay the return of Atlantis amid concerns over some damage on the body of the space shuttle, which has caused apprehension among experts over the safe return of Indian-American astronaut Sunita Williams.
Atlantis suffered a four-inch tear in its thermal blanket during the liftoff on Friday. While its managers said it was not of great concern, experts voiced apprehension about possible problems during its re-entry in the light of the disaster that claimed the lives of Kalpana Chawla and six other astronauts aboard Columbia in 2003.
Nasa has played down the concerns over the damage to Atlantis. Engineers who studied the earlier episodes are, however, reported to be uncomfortable with the safety margins of the tears during re-entry.
The loosened blanket was discovered Saturday during an inspection of the shuttle. Atlantis is scheduled to bring back Indian-American astronaut Sunita Williams home after her six month space sojourn.
Nasa says the two-day delay will now help the astronauts fix the problem. The announcement of delay came even as two Atlantis astronauts ventured out for the first space walk of the mission on Monday.
The decision to add a fourth spacewalk to the Atlantis crew's schedule to fix the thermal blanket on the shuttle's exterior will mean a mission of 13 days in space rather than the originally planned 11 days. The shuttle, which blasted off last Friday, was originally scheduled to return to earth on Tuesday next.
No decision has been made on whether the loosened blanket, covering a 4-inch by-6-inch area over a pod for engines, will be repaired during a previously planned third spacewalk or a fourth, extra one, officials said.
Engineers think the blanket was loosened by aerodynamic forces during launch, not by being hit by a piece of debris during liftoff. The rest of the vehicle appeared to be in fine shape, Nasa said.
The shuttle — on its first mission of the year — docked with the ISS on Sunday, after performing a dramatic backward somersault in space.
Lift-off damage has become a major concern after the February 2003 shuttle disaster. The Columbia craft disintegrated as it returned to Earth due to breaks in its heat shield caused by foam insulation peeling off its fuel tank and striking a wing during the launch.
All seven astronauts aboard including Indian-born astronaut Kalpana Chawla perished and the shuttle programme was put on hold for nearly two-and-a-half years while the space agency sought to overcome the problem, modifying the external fuel tank and setting procedures to check the heat shield while in orbit.
(With PTI inputs)