Ares I Five-Segment SRB Lights Up For NASA, ATK

PROMONTORY, Utah — NASA and Alliant Techsystems (ATK) conducted the second test of the fully developed Ares five-segment solid rocket motor, known as Development Motor-2 (DM-2), on Aug. 31 at ATK’s test facility in Promontory, Utah.

With a roar that reverberated across the surrounding countryside and a blowtorch-bright light, the DM-2 came to life on schedule at 9:27 a.m. MDT. The 2-min. 5-sec. test checked out key design elements of the Ares rocket, which the Obama administration wants to cancel in favor of nurturing commercial means of carrying crew and cargo to low Earth orbit.

The firing of the motor was conducted to collect data on 53 different test objectives. Some of the elements tested include the new insulation, the redesigned rocket nozzle and the motor casing’s liner. When activated, the DM-2 produced about 3.6 million lb. of thrust, equaling 22 million hp. The motor was instrumented with 760 sensors to collect performance data.

At T-0, the engine was ignited and the propellant from the nozzle of the DM-2 sent out a jet of flame. The eruption that followed produced a visible shock wave.

“A lot of our objectives are to evaluate the motor’s performance,” says Kent Rominger, a five-time shuttle astronaut who is ATK’s vice president of test and research operations. “Many of these objectives center around this motor being chilled to gain data on performance at low temperatures.”

The horizontal ground test firing was a “cold motor” trial. To accomplish this, the DM-2 was chilled to 40F to measure how it performs at very low temperatures. The test also was held to validate new materials used in the motor joints. They are designed to eliminate the need for joint heaters (these heaters were required in the four-segment version of the motor’s design). It is hoped that the modifications will greatly reduce weight, simplify launch operations and make the overall system far less complex.

The 154-ft.-long DM-2 comprises solid rocket booster (SRB) segments that have flown on 59 shuttle missions. All SRB segments are recycled. Once jettisoned from the space shuttle, they are retrieved from the Atlantic Ocean via the Freedom Star and Liberty Star recovery ships and shipped back to ATK’s plant, where they are broken down into their individual segments and refurbished.

Aviation Week


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