The Columbia Space Shuttle disaster

Twenty years on, Amy Arthur looks back at fateful flight STS-107

NASA's Space Shuttle programme ran from 1972 to 2011, its successes including the launch of the Hubble Space Telescope, Spacelab and the construction of the International N Space Station.

But the programme had its problems. Schedule pressures and tight budgets had been blamed for the loss of one of its five orbiters, Challenger, and its seven-person crew in 1986. Organizational changes were made, but by the launch of Columbia's flight STS-107 on 16 January 2003, problems had returned. Initial reports after launch were positive, and the crew looked forward to the 16 days of scientific research ahead of them. On the ground, a team reviewing launch footage noticed that something had fallen from Columbia's fuel tank and struck the underside of its left wing, where reinforced carbon-carbon panels would act as a heat shield against the 1,600°C endured during re-entry to Earth.

The object was a piece of insulating foam, roughly 60cm by 38cm, with an impact speed of 877km/h. Smaller foam strikes were common on Shuttle missions, but to assess whether the damage posed a real threat, the team requested high-resolution images from the US Department of Defense. This request, and the two more submitted in the week following, were denied.

"Absolutely no concern"