Launch of the Air Force’s first Space Based Space Surveillance (SBSS) satellite has been delayed again by new problems with the service’s Minotaur 4 launch vehicle, according to a July 1 Air Force press release.

The SBSS spacecraft is intended to orbit the Earth at a low altitude and use its optical telescope to keep tabs on satellites and other space objects in higher orbits. The satellite was ready for launch last fall but problems with its Minotaur rocket, which is built by Dulles, Va.-based Orbital Sciences, kept it grounded. The rocket’s third-stage motor was producing unwanted thrust after shutdown, which required new hardware to be engineered and built to correct.

The Minotaur 4, which is based on repurposed U.S. strategic missile motors, made its debut in April with a suborbital launch for the Defense Advanced Research Projects Agency.

The planned July 8 launch of SBSS was put on hold after a software anomaly was discovered in a Minotaur 4 being built for another mission, the press release said. The government-industry team is working to solve  the problem and expects to announce a revised launch date in a matter of days, the release said.