A little over six months since the failure of Blue Origin's NS-23 New Shepard mission, the company has released the detailed failure analysis of what failed and caused the mission abort.
The direct cause of the NS-23 mishap was a thermo-structural failure of the engine nozzle. The resulting thrust misalignment properly triggered the Crew Capsule escape system, which functioned as designed throughout the flight. The Crew Capsule and all payloads onboard landed safely and will be flown again. All systems designed to protect public safety functioned as planned. There were no injuries. There was no damage to ground-based systems, and all debris was recovered in the designated hazard area. Blue Origin expects to return to flight soon, with a re-flight of the NS-23 payloads.
The emergency escape system performed as intended, rapidly pulling the spacecraft away from the disintegrating rocket. Had a crew been on board this flight, they would have experienced a significant jolt and some high gravitational forces before landing safely in the West Texas desert.
Blue Origin led the investigation, with assistance from the Federal Aviation Administration and the National Transportation Safety Board. There was plenty of data available from both telemetry during the flight and post mortem on the remains that fell into the Texas "designated hazard area." On the engine nozzle, investigators found "hot streaks," indicating that the engine was running hotter than it was designed to. I'm not sure where he gets this but Eric Berger at Ars Technica notes:
Although the summary does not explicitly say so, it appears that at some point in the flight campaign of this booster, design changes were made that allowed for these hotter temperatures to be present.
In their report, Blue notes:
Aided by onboard video and telemetry, flight hardware recovered from the field, and the work of Blue Origin’s materials labs and test facilities, the MIT [Mission Investigation Team - SiG] determined the direct cause of the mishap to be a structural fatigue failure of the BE-3PM engine nozzle during powered flight. The structural fatigue was caused by operational temperatures that exceeded the expected and analyzed values of the nozzle material. Testing of the BE-3PM engine began immediately following the mishap and established that the flight configuration of the nozzle operated at hotter temperatures than previous design configurations. Forensic evaluation of the recovered nozzle fragments also showed clear evidence of thermal damage and hot streaks resulting from increased operating temperatures. The fatigue location on the flight nozzle is aligned with a persistent hot streak identified during the investigation.
The emergency escape system is seen firing on the New Shepard spacecraft Monday morning after its rocket was lost. - Blue Origin photo
Their report concludes by saying they expect to return to flight soon, but doesn't say much else. Insiders who track this sort of thing (in this case Eric Berger at Ars), report they only know of one operational booster left.
The company has used its newest rocket, Booster 4, exclusively for human launches. It has some modifications from Booster 3 to qualify it as a human-rated rocket. The company has also built a fifth booster that may be ready for its debut flight.
The capsule from NS-23 survived with no known issues, and Blue has said they plan to re-fly the same payloads as on the NS-23 mission on a similar, uncrewed mission.