The second redesigned Space Shuttle External Tank (ET) is in place at NASA’s Kennedy Space Center (KSC), Fla. It is designated for use on the Shuttle Atlantis Return to Flight mission (STS-121).

The ET incorporates several safety improvements, including an improved bipod fitting that connects the tank to the orbiter. In addition, the tank has temperature sensors and accelerometers, used to measure vibration and to collect data about its performance.

In the huge KSC Vehicle Assembly Building, the ET will be raised from a horizontal to a vertical position this week and lifted high into a checkout cell. It will undergo mechanical, electrical and thermal protection systems’ inspections. New processing activities, resulting from redesign of the tank, include inspection of the bipod heater and ET separation camera.

When tank preparations are complete, it will be attached to Atlantis’ Solid Rocket Boosters, on the Mobile Launch Platform. STS-121 is NASA’s second Return to Flight mission, a test flight carrying a seven-member crew to the International Space Station. The launch planning window is July 12 through July 31.

The ET traveled more than 900 miles by sea from NASA’s Michoud Assembly Facility, New Orleans on board the Solid Rocket Booster Retrieval Ship Freedom Star. Photos of the ET, from arrival to attachment, will be available at:

For information about NASA’s Return to Flight efforts visit: