Volume: 03, Issue: 05 03/09/2005 
The External Tank is lowered between the Solid Rocket Boosters to be mated to for launch. Image courtesy NASA.
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Suspended high inside the Vehicle Assembly Building, the External Tank is being lowered toward the Mobile Launcher Platform and twin Solid Rocket Boosters. Image courtesy NASA.
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Other Articles in This Issue:
Virgin Atlantic Global Flyer Lands in Record Books
Mars Exploration Rovers Shatter Expectations
Lunar Reflectors Help Test Einstein Theory
Chat about Cassini-Huygens Mission to Saturn and its Moons

Discovery Solid Rocket Boosters Mate with External Tank

Space Shuttle Discovery is continuing to be re-outfitted for its Return to Flight mission. Workers have successfully attached the shuttle’s redesigned External Tank to the twin Solid Rocket Boosters (SRBs). Mating the tank with the boosters is another major step in readying the Space Shuttle system for flight.

The fuel tank and booster rockets will help launch Discovery on its mission to the International Space Station, currently targeted for May 15 - June 3, 2005. The External Tank was lifted by a giant crane and joined to the already assembled, or "stacked," boosters in the 52-story Vehicle Assembly Building at NASA's Kennedy Space Center.

Following integration and final checkout of the External Tank with the SRBs, orbiter Discovery will join its propulsion components in the Vehicle Assembly Building. Discovery will roll over from its hangar, the Orbiter Processing Facility, later this month to mark the completion of Return to Flight processing. The orbiter then will be attached to the stack.

The External Tank will fly with several modifications, including two new forward bipod heaters at the forward attach fittings that connect the tank to the orbiter. NASA and Lockheed Martin Space Systems Co. spent nearly two years modifying the tank to make it safer. It is the largest element of the Space Shuttle system, measuring 27.6 feet wide and 154 feet tall. The aluminum skin covering it is only an eighth of an inch thick in most areas, yet it still withstands more than 6.5 million pounds of thrust during liftoff and ascent. The tank is the only Shuttle component that cannot be reused.

During mating of the tank and the SRBs, the left and right boosters are bolted to the tank at both the forward (top) and aft (tail) ends. At the forward end, a vertical bolt mechanism attaches each booster to the tank. On launch day, approximately two minutes after liftoff, the SRBs will separate from the tank when pyrotechnic devices fire to break the 25-inch, 62-pound steel bolts. One half of the bolt is caught in canister-like "bolt catchers" located on the tank; the other half remains with the boosters. Discovery will boast a modified bolt catcher, upgraded from a two-piece welded design to a one-piece, machine-made design.

Photos and additional information are available at the following websites:

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