The maiden flight of the SpaceX Falcon 1 booster is being pushed to late October due to an engine failure at the company's Texas test facility.
Called the Merlin, this main stage engine was undergoing qualification testing at SpaceX test facilities, located in Central Texas.
"We did have an ablative chamber fail during the Merlin qualification program," explained Elon Musk, head of the entrepreneurial SpaceX, based in El Segundo, California.
Musk responded to a SPACE.com inquiry, noting that the Falcon 1 engine now being prepared for first flight at the firm's private rocket facilities at a Kwajalein Atoll launch area in the western Pacific Ocean has been acceptance tested. The Merlin passed with flying colors and is mounted in the first stage at Kwajalein, he said.
The Merlin engine problem, Musk said, occurred during a qualification program. That activity involves taking a series of engines and testing them in unusual circumstances, such as high and low mixture ratio, high and low thrust, hot and cold fuel temperatures, maximum suction speed on the turbopump, etc. It also tests for consistency of manufacturing, he added.
"To the best of my knowledge, every booster engine qualification program in history has had numerous failures of the kind that recently occurred with Merlin, so this is not unusual," Musk said.
Oddly, the chamber that failed was chamber 13, Musk said. "We believe it was due to a variance in manufacturing, given that the prior 12 worked fine. To address this issue, we are adding additional quality assurance tests and increasing film cooling flow as a failsafe."
Due to the engine qualification failure, Musk said the premier flight of Falcon 1 is to be pushed back a few weeks "to late versus early October as we verify the effectiveness of the above changes. We are taking no chances."
Merlin was developed internally at SpaceX, but draws upon a long heritage of space proven engines. For example, the fuel injector design at the heart of the engine was first used in the Apollo lunar module landing engine.
SpaceX was founded in June 2002 by Musk, co-founder of PayPal, the electronic payment system.