A premature engine shutdown was the reason behind the failure of Firefly Aerospace's debut rocket launch last week, company representatives have determined.
Texas-based Firefly conducted its first-ever orbital test flight on September 2, sending its 29 metre Alpha rocket skyward from Vandenberg Space Force Base in California.
About 2.5 minutes after liftoff, the two-stage launcher began to tumble, and shortly thereafter, exploded in a dramatic fireball.
Initial investigations revealed that one of Alpha's four first-stage Reaver engines shut down unexpectedly about 15 seconds after liftoff, Space.com reported.
"The vehicle continued to climb and maintain control for a total of about 145 seconds, whereas nominal first-stage burn duration is about 165 seconds. However, due to missing the thrust of 1 of 4 engines, the climb rate was slow, and the vehicle was challenged to maintain control without the thrust vectoring of engine 2," Alpha representatives said on Twitter.
"Alpha was able to compensate at subsonic speeds, but as it moved through transonic and into supersonic flight, where control is most challenging, the three-engine thrust vector control was insufficient and the vehicle tumbled out of control. The range terminated the flight using the explosive Flight Termination System (FTS). The rocket did not explode on its own," they added.
Engine 2 shut down because its main propellant valves closed, Firefly added in the Twitter thread.
The company will continue to work to understand what caused the valves to close, and to determine if anything else anomalous happened during the flight, the report said.
Alpha is an expendable rocket designed to deliver up to 1,000 kg to low Earth orbit on each $15 million mission, according to the company.
During the failed launch, Alpha carried about 92 kg of payload on the flight, which Firefly called DREAM (short for "Dedicated Research and Education Accelerator Mission"). The plan was to carry this gear to an orbit 300 kilometres above Earth.
In February this year, the company was also awarded approximately $93.3 million by NASA to deliver a suite of 10 science investigations and technology demonstrations to the Moon in 2023.