New Delhi, June 12: The rip in space shuttle Atlantis’s heat shield system, where an insulation tile has peeled back, is not serious but needs to be fixed quickly, Indian space scientists said today.

Else, it could trigger a chain of events that could damage the shuttle to the point where re-entry into Earth’s atmosphere might prove fatal.

American space agency Nasa today announced that because of the tear, it was delaying the return of Atlantis, which is to bring Indian-American astronaut Sunita Williams back after six months at the International Space Station.

The announcement triggered fears of a repeat of the 2003 Columbia space shuttle disaster that had killed seven astronauts, including Kalpana Chawla, the first woman of Indian origin to become a space traveller.

Columbia’s outer insulation had peeled off during the shuttle’s re-entry, exposing it to searing temperatures above 2,000°C. Nasa scientists have tried to allay fears that the Atlantis rip might trigger a Columbia rerun.

“What is important is the tile’s location,” explained Indian Space Research Organisation (ISRO) scientist S. Krishnamurthy.

Unlike Columbia, which lost the insulation from it’s flanks — the cylindrical surface between the front and the rear — Atlantis has been “fortunate”, Krishnamurthy said. The flanks face the maximum friction with the air during both launch and re-entry.

“The Atlantis tear is in the rear — in a part where the temperature during re-entry generally does not cross 700 degrees. Of course, Nasa won’t take any chances after Columbia,” the scientist said.

Nor should it, a retired ISRO space expert explained.

“The truth is, when the shuttle re-enters, the aerodynamic pressure at the point where the tile has come off may cause adjoining tiles to peel off, and so on.... It could become a chain reaction. They need to fix the tile.”

It won’t take much to do that. Fortunately for the Atlantis, the four-by-six-inch tile hasn’t fallen off — it’s hanging from one edge into the inner graphite body of the shuttle.

A short spacewalk by an astronaut aboard the International Space Station, where the Atlantis is docked, followed by the application of a special adhesive that works at high temperatures ought to solve the problem, the scientists said.