Masten Space Systems' Xaero reusable testbed was destroyed during an 11 September test flight, the Mojave, California-based company has announced.
"Our test objectives were met and initial results show the vehicle performed better than expected at altitude," says Masten. "However, the vehicle was lost during final approach to landing, and the initial cause appears to be a throttle valve failure."
The reusable suborbital testbed crashed during its landing from its highest altitude yet reached, 1km above ground. The rocket has successfully flown more than 100 times.
Masten has previously disclosed the production of a second Xaero to add to its flight-test fleet. It is not immediately clear when the second rocket will be ready for flight.
Masten did not immediately respond to questions.