Washington: A videotape released by National Aeronautics and Space Administration (NASA) shows final moments of Kalpana Chawla and six other astronauts chatting casually, blissfully unaware of the tragedy that awaited them as the space shuttle Columbia made its fiery re-entry before disintegrating into pieces in February.

The tape shows four astronauts – Kalpana Chawla, Laurel Clark, Rick Husband and William McCool – preparing themselves for the landing.

"We have 10 minutes to get the gloves on. Laurel, do you need help?" Chawla is seen asking co-astronaut Laurel Clark.

The 13-minute tape that ends minutes before the shuttle showed first signs of trouble was found in Texas on February 6 and was shown to the family members of the crew before making it public.

The tape holds no investigative value, NASA said.

"It's bright orange-yellow out over the nose, all around the nose," pilot William McCool says referring to the superheated air or plasma that engulfs a spacecraft as it enters the atmosphere.

Three astronauts seated on the lower deck – Michael Anderson, David Brown and Israeli Ilan Ramon – are not seen on the tape.

"Wait till you start seeing the swirl patterns out on your left or right windows," Commander Rick Husband says.

"Looks like a blast furnace."

"We are getting some Gs. Let go of the card and it falls," McCool said, apparently referring to some gravitational force as the spacecraft approached the Earth.

"All right, we are at 100th of a G," confirms Husband.

The tape shows all four astronauts clad in orange flight suits, with their helmet visors up, and seen going through routine checklist activities in the cockpit.

Husband is seen sipping from a drink pouch and, along with McCool, putting on gloves. The two women, Chawla and Clark take turns smiling for the camera.

NASA broadcast the tape on its television service on February 18 with an introduction by astronaut Scott Altman, who commanded a Columbia mission in 2002.

The very ordinariness of the tape moved NASA administrator Sean O'Keefe.

"It's like a lot of the footage you see for every other flight and that's the part that's most emotional about it," he said.

"There is not even a hint of concern, anxiety nothing… It's a very emotional piece because of what you already know, and they don't," he said.

Altman said of the more than 250 tapes flown during the doomed flight, this was the only one recovered that had any recording left on it.

Because of heat damage, the tape ends four minutes before the first sign of trouble.

Columbia was 61 kilometres above, travelling Mach 18 on 18 times the speed of sound, when it disintegrated.

PTI