Monday, December 07, 2009

Steering the Ares Rockets on a Straight Path

Ares I-X test rocket
The Ares I-X rocket stood more than 325 feet tall on the launch pad at NASA's Kennedy Space Center, Fla. Spectators watched in awe as its massive solid rocket motor blazed to life with a thunderous roar, and the spacecraft rose off the launch pad.

But what steered this rocket on its path as it climbed through Earth's atmosphere? The answer is a roll control system.

The roll control system used for the recently completed Ares I-X test flight is different from the system being developed for its sister vehicle the Ares I, but operates on the same premise.

For the Ares I-X test flight the roll control system performed two primary functions for the vehicle: It rolled the vehicle 90 degrees after liftoff to emulate the Ares I roll attitude at launch, and was used to maintain a constant roll attitude during ascent up to stage separation. The system began operating just after the rocket cleared the tower at launch and shut down just before first stage separation.

Ares I-X rocket looking back at the launch padUnlike the system being designed for Ares I, the Ares I-X roll control propulsion system components were harvested from decommissioned Peacekeeper missiles, which were to be dismantled by the U.S. Air Force as part of the second Strategic Arms Reduction Treaty, called START II. The use of Peacekeeper parts for the roll control system – and shuttle parts for the first stage of Ares I-X – was an effective means for NASA to reduce the cost and development time of this flight test.

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