NASA has extended to May 2007 its six-and-a-half-year
$2.4 billion contract with ATK Thiokol Propulsion in Brigham
City, Utah, for the production and refurbishment of 70
Reusable Solid Rocket Motors for the Space Shuttle Program.

Under the modified contract, Thiokol will produce and
refurbish 35 Reusable Solid Rocket Motor flight sets (70
motors) and three flight support motors. The modification
adds $429 million to the contract.

The contract, issued in October 1998, is the sixth in a
series of contracts for the design, development, production
and refurbishment of Solid Rocket Motors for the Space
Shuttle Program and represents a continuing relationship
between NASA’s Marshall Space Flight Center in Huntsville,
Ala., and Thiokol. Marshall is home to the Space Shuttle’s
Reusable Solid Rocket Motor Project Office.

At launch, the three Space Shuttle Main Engines and the two
Reusable Solid Rocket Motors provide enough thrust to lift
the 4.5-million-pound shuttle vehicle — the propellant
weighs 3.5 million pounds — into orbit.

The Shuttle’s Reusable Solid Rocket Motor (RSRM) is the
largest solid motor ever flown and the first designed for
reuse. Each motor consists of four segments lined with 1.1
million pounds of solid fuel propellant. The forward segment
holds an igniter.

Two motors, each producing an average thrust of 2.6 million
pounds during their 124-second burn, are used on each space
shuttle flight. At burnout the shuttle has reached an
altitude of 24 nautical miles and a velocity of more than
3,000 mph. After the propellant is depleted, the Solid Rocket
Boosters, which house the motors, separate from the shuttle’s
orbiter and land in the ocean.

The Solid Rocket Boosters are recovered and disassembled and
the motors are returned to Thiokol. At Thiokol, the cases are
cleaned, inspected and reassembled for propellant casting,
and a new nozzle and igniter are installed. The motor’s steel
case components can be used as many as 20 times.

Marshall is NASA’s key leader for development of space
transportation and propulsion systems.