Live coverage: Orion lands in Pacific

A United Launch Alliance Atlas 5 rocket lifted off from Cape Canaveral today at 7:42 p.m. EST (0042 GMT) to deploy the U.S. military’s SBIRS GEO Flight 3 observatory, equipped with advanced telescopic infrared vision to spot enemy missile launches, for early warning surveillance.

The U.S. military’s next GPS navigation satellite was ready for launch from Cape Canaveral at 9:43 p.m. EDT Friday (0143 GMT Saturday) aboard a SpaceX Falcon 9 rocket. But SpaceX aborted the countdown just two seconds prior to liftoff.

The first of up to seven United Launch Alliance missions lifted off Jan. 19 from Vandenberg Air Force Base in California, where a Delta 4-Heavy launcher fired into orbit with 2.1 million pounds of thrust from three hydrogen-fueled RS-68A main engines with a U.S. government spy satellite.