A test of a new rocket motor for NASA’s future moon missions went awry this week, with the full-size booster hurling a powerful blaze and scattering debris.
Northrop Grumman, lead contractor for the booster, conducted the two-minute ground test of the solid rocket motor, which was strapped down sideways. For the first 1.5 minutes, the motor — known as NASA's Booster Obsolescence and Life Extension, or BOLE — seemed to be working fine. Seconds later, debris blew out of the nozzle and flames rippled through the long exhaust plume.
The 156-foot booster kept firing through the remainder of the test, and no one was hurt. NASA's livestream, which you can watch below, caught the incident, starting at about 22 minutes and 17 seconds into the video.
Engineers didn't immediately acknowledge the issue during that broadcast, apart from one controller uttering "Whoa," followed by an audible gasp. The company later confirmed a problem occurred late in the burn, though representatives didn't elaborate on what went wrong.
The anomaly, which took place at a Northrop Grumman test facility in Promontory, Utah, raises questions about the hardware that could one day send astronauts into space — and potentially to Mars.
"As a new design, and the largest segmented solid rocket booster ever built, this test provides us with valuable data to iterate our design for future developments," said Jim Kalberer, Northrop Grumman's vice president of propulsion systems, in a statement.
The BOLE motor is a major redesign of the ones used on NASA’s Space Launch System, or SLS, the rocket built to carry astronauts to the moon under the Artemis program. It swaps out old parts with lightweight materials and new fuel, giving it more thrust and allowing the rocket to haul heavier loads.
The boosters for the first eight flights of Artemis repurpose the steel booster cases and other parts from the Space Shuttle program. Beginning with Artemis IX, the SLS rocket, sometimes dubbed the mega moon rocket, is supposed to use the BOLE. The plan is for two of them to flank either side of the rocket.
"In order to save cost and schedule, we implemented the Shuttle's proven heritage hardware into our design, but this is being depleted as the Artemis program progresses," said Julia Khodabandeh, NASA's deputy manager for the SLS booster element office. "It's just not practical to restart the manufacturing from that 1970s era."
This was the first demonstration test of the enhanced five-segment solid rocket motor. That single booster produced more than 4 million pounds of thrust, said Dave Reynolds, NASA's SLS booster subsystems manager.
"You can see from the side of the mountain up there," Reynolds said afterward, "it's still feeling the effects of that test."
The purpose of the demonstration was to test the limits of the motor's design, understand the stress and strain on different materials, and see if the motor's components could withstand extreme conditions. The two-minute test mimics the time a booster would fire during a real launch. Northrop Grumman officials said the data from the BOLE test will help improve the design.
The new boosters are not expected to fly until at least the late 2030s, and it’s unclear whether they ever will. Proposed budget cuts for NASA would mean SLS production ceases after Artemis III, the first human moon landing since Apollo 17. That mission has been postponed until 2027 at the earliest.
The White House has said it would like to see the space agency focus instead on using commercial systems. Lawmakers are still debating how many more SLS launches, about $4.1 billion each, to fund.
