Live coverage of Delta 4 countdown and launch

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.

Lockheed Martin’s launch services team hopes to lure up to four commercial customers per year to fly on United Launch Alliance’s Atlas 5 booster as a stream of U.S. government missions is forecast to dry up starting in 2017, according to Lockheed Martin’s rocket sales chief.

An electrical problem on one of the Ariane 5 rocket’s two solid rocket boosters led to an on-pad launch abort Tuesday, likely delaying liftoff with two U.S.-built communications satellites until around the end of September, Arianespace officials said.