Gallery: Antares rocket explodes

A commercial Northrop Grumman Cygnus supply ship berthed at the International Space Station fired its main engine for 50 seconds Tuesday in a test of the spacecraft’s ability to reboost, and possibly eventually deorbit, the massive research outpost.

The Atlas 5 rocket emerges from the Vertical Integration Facility for rollout to Complex 41 at Cape Canaveral in preparation to launch the Orbital ATK Cygnus resupply ship to the International Space Station. Liftoff is set for Thursday at 5:55 p.m. EST.

A Northrop Grumman Cygnus cargo ship arrive at the International Space Station Monday carrying around 4.1 tons of supplies, experiments and small research CubeSats. The automated spacecraft was captured by the station’s robotic arm at 4:10 a.m. EST (0910 GMT) Monday to close out a two-day flight from a launch pad in Virginia.