A last-minute glitch forced a NASA contractor to call off the first test firing Aug. 27 of the Ares 1 rocketโ€™s five-segment solid rocket booster.

The $75 million test by Alliant Techsystems (ATK) in Promotory, Utah, was scrubbed when a power unit required to point the boosterโ€™s engine nozzle properly failed with just 20 seconds remaining in the test countdown.

Engineers said it appeared a fuel valve in an auxiliary power unit that drives the rocketโ€™s booster nozzle hydraulics may have failed, but they are not sure why.

NASA and ATK are targeting no earlier than Sept. 1 to make another test attempt.

โ€œBy choosing to scrub today, we have not compromised any of the components and preserved the ability to execute a successful test and capture all of the data,โ€ ATK spokeswoman Trina Patterson said in an Aug. 27 statement.

โ€œ[Sept. 1] gives us enough to determine root cause and prepare the motor for test.โ€