Illustration of an external tank falling back to Earth after it has been discarded by a Space Shuttle. The Shuttle detached from the external tank nine minutes after launch, after the fuel was finished and the main engines were shut down. The tanks mostly burnt up in the atmosphere, with any remnants falling into the ocean approximately 40 minutes later. Over 100 external tanks were discarded over the course of the Space Shuttle program. Continuing design faults with the external tank led to an indefinite grounding of the Space Shuttles in 2005.