Teams at NASA’s Marshall Space Flight Center tested a small solid rocket motor Dec. 5 that will help the agency build next-generation solid rocket boosters for future Space Launch System (SLS) flights.
The 20-second hot fire, conducted on a 24-inch-diameter, 20-foot-long subscale test motor at Marshall’s East Test area, produced 56,000 pounds of thrust and temperatures of more than 5,000 degrees Fahrenheit. The test will help NASA and prime contractor Northrop Grumman evaluate the effect a new propellant has on the performance of materials used in the motor’s insulation and nozzle. NASA is phasing out the current propellant, as the solid rocket motor industry has moved to a new propellant that provides better performance.
SLS flight boosters are 177 feet tall and 12 feet in diameter. Using a scaled-down rocket motor designed to mimic a full SLS booster provides an affordable and efficient way to evaluate new components and materials. For the insulation materials analysis, three types of insulation were placed into the motor’s aft dome, the last portion of the motor, which is dome-shaped and part of the aft assembly containing the nozzles: the insulation currently used in SLS boosters, and two variations of a new insulation, one with a variant that reduces the risk of static discharge and one without.
“All three insulation materials were tested at the same time,” said Sarah Howse, materials and processes lead for the solid rocket test motor. “The team will compare the effect of the new propellant on the material with the historical propellant.”
NASA is focusing its analysis on the insulation in the large acreage areas of the motor. “That part of the motor interfaces with the new propellant and historical materials are obsolete,” said Tim Lawrence, motor assembly system manager.
“In the forward end of the motor, engineers collected data to measure the thermal aspects of the motor during the test. This will help refine the accuracy of existing thermal models,” Lawrence said.
The SLS booster is the largest, most powerful solid propellant booster ever built for flight. Standing 177 feet tall, each booster generates a maximum thrust of 3.6 million pounds, providing more than 75 percent of the total thrust at launch.
NASA’s SLS booster is based on three decades of knowledge and experience gained with the space shuttle boosters and has been updated with the latest technology. The agency is working to design, develop and test next-generation boosters that will power SLS flights after all available shuttle-era hardware is expended. NASA has cast segments for the Artemis I and Artemis II lunar missions, the first two SLS flights, and has begun casting the third flight set of motor segments.
SLS and the Orion spacecraft, along with the Gateway in orbit around the Moon, are NASA’s backbone for deep space exploration and the Artemis program, which will send the first woman and next man to the lunar surface by 2024. SLS is the only rocket that can send Orion, astronauts and supplies to the Moon on a single mission.