The main engine of United Launch Alliance's Atlas V rocket shut down six seconds earlier than planned Tuesday night, but the glitch did not prevent the rocket from delivering an International Space Station resupply mission to its intended orbit, News 6 partner Florida Today reports.
ULA said the premature shutdown resulted from the kerosene-fueled RD-180 engine burning with a higher than normal ratio of liquid oxygen, for reasons now under review.
To make up for the booster's early cutoff, the rocket's Centaur upper stage RL10C engine, provided by Aerojet Rocketdyne, performed an extended burn before dropping off Orbital ATK's unmanned Cygnus cargo ship in an orbit about 150 miles above the planet.
The Atlas V blasted off from Cape Canaveral Air Force Station's Launch Complex 41 at 11:05 p.m. Tuesday, and the Centaur deployed the Cygnus 22 minutes later — about a minute later than planned due to the longer upper stage engine firing. The Cygnus and its nearly 7,500 pounds of cargo are on track to rendezvous with the ISS around 6:40 a.m. EDT Saturday.