For more than a decade, aerospace experts had warned about the vulnerability of the aging, 100-ton space shuttles to the superheated gases that envelop the craft as they descend to Earth.

• 10几年来，航太专家不断提出警告：老旧、重达100公吨的太空梭重返地球时，梭身包裹在过热的气体中，是十分脆弱的。