VI.

Columbia Disaster and Return to Space

The space shuttle Columbia broke apart and burned up while reentering Earth’s atmosphere over Texas on February 1, 2003. The entire seven-member crew was killed as they returned to Earth after completing a series of scientific experiments. Investigation of the disaster pointed to structural failure of the heat-shielding system for the shuttle’s left wing. Sensors inside the wing recorded unusually high temperatures just before NASA lost contact with the shuttle. The investigation determined that the wing was damaged during liftoff when it was struck by a piece of insulation foam from the external fuel tank, opening a hole in the left wing. On reentry, superheated gases in the atmosphere penetrated the left wing, dooming the craft and the crew.

The space shuttle fleet was grounded until July 2005, when the shuttle Discovery returned to space. However, during the launch of Discovery a chunk of insulation foam broke off again from the external fuel tank, despite a more than two-year and nearly $1-billion effort to prevent a recurrence of the problem. Although the Discovery appeared to be undamaged, NASA suspended further shuttle flights until the foam problem could be studied further. Discovery returned to orbit in July 2006, when it docked with the International Space Station.

Shuttle missions have concentrated on adding modules and equipment to the International Space Station, aiming for completion in 2010 when the shuttle is scheduled to be retired. A planned service mission to the Hubble Space Telescope (HST) calls for shuttle astronauts to upgrade, repair, or replace a number of working parts and scientific instruments, and to give the HST a boost to a higher orbit. The efforts should help extend the HST’s scientific working life until the new James Webb Space Telescope is operational.