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The 21st Century Space Shuttle

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IMAGE: Inside the external tankA Lighter Fuel Tank

April 1983, STS-6
A redesigned Lightweight External Tank — 4,536 kilograms (10,000 pounds) lighter than the original design — flew on STS-6 in 1983, increasing the shuttle’s cargo capacity by the same amount. In 1998, a Super Lightweight External Tank flew on STS-91, further reducing the tank’s weight by 3,402 kilograms (7,500 pounds) and again increasing the shuttle’s cargo capacity by the same amount. The new super lightweight tank is manufactured from a Lockheed-Martin-developed aluminum-lithium alloy that is not only lighter, but also is 30 percent stronger than the previous tank design.

The Return to Flight

September 1988, STS-26
When Discovery returned the shuttle fleet to space following the Challenger accident, more than 200 safety improvements and modifications were ushered in. The improvements included a major redesign of the solid rockets, the addition of a crew escape and bailout system, stronger landing gear, more powerful flight control computers, updated inertial navigation equipment and several updated avionics units.

Endeavour's Maiden Voyage

May 1992, STS-49
Endeavour’s first flight in 1992 marked the debut of many shuttle improvements, including a drag chute to assist braking during landing, improved nosewheel steering, lighter and more reliable hydraulic power units and updates to a variety of avionics equipment.

Extended Duration Flights

June 1992, STS-50
Columbia was the first shuttle to be modified to allow long-duration flights, and flew the first such mission in 1992. The modifications included an improved toilet, a regenerative system to remove carbon dioxide from the air, connections for a pallet of additional hydrogen and oxygen tanks to be mounted in the cargo bay and extra stowage room in the crew cabin.

IMAGE: Main engine start upSpace Shuttle Main Engines

July 1995, STS-70
The shuttle main engines have had three major redesigns that have more than tripled estimates of their safety. With its first flight in 1995, the first redesign, called the Block I engine, included design changes to strengthen the oxygen turbopump and engine powerhead. The second overhaul, called the Block IIA engine, included a larger throat to the main combustion chamber and first flew on STS-89 in January 1998. The third redesign, called the Block II engine, includes a stronger fuel turbopump and will fly for the first time in 2000. A fourth major overhaul is now planned to fly by 2005. Called the Block III engine, it will include further improvements to the combustion chamber and a simplified nozzle design.

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Slow motion video of the main engines starting up. (no audio)

International Space Station Assembly

IMAGE: Shuttle docked to Mir space station
June 1995, STS-71
The first docking of a shuttle with the Russian Mir space station debuted changes made to the shuttle that allowed it to dock with Mir and prepare for assembly of the International Space Station. To allow docking with Mir and with the International Space Station, the shuttle’s airlock was relocated from inside the cabin to the cargo bay on all orbiters except Columbia. Reductions in weight also were developed, including lightweight lockers, seats and other cabin equipment. Those changes, coupled with the super lightweight external tank and performance improvements, increased the cargo capacity for the shuttle by 7,257.5 kilograms (16,000 pounds) since 1992.

Curator: Kim Dismukes | Responsible NASA Official: Amiko Kauderer | Updated: 04/06/2009
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