HOUSTON — Using a combination of U.S. commercial and multinational assets, NASA’s Mission Control issued commands to the International Space Station’s robot arm on March 6 that removed  two grapple bars from the recently berthed SpaceX Dragon resupply capsule, completing all de-stow activities planned for the Hawthorne, Calif.-based company’s second resupply mission to the six-person orbiting lab.

The grapple bars, weighing in at 602 lb., were the first payloads delivered to the station in the trunk, or unpressurized section, of a Dragon capsule.

Over several hours beginning at 2 p.m. EST, Mission Control operators commanded the Canadian-built robot arm to extract the grapple bars and reinstall them on equipment attach points aboard the station’s Mobile Base System (MBS). The MBS, a rail car, rides along the station’s solar power truss with the 58-ft.-long mechanical limb.

The grapple bars are scheduled for installation on the radiators that jut from the left and right side inboard space station truss segments during spacewalks currently planned for July. Once installed by future ISS crewmembers Chris Cassidy and Luca Parmitano, the grapple devices will provide a means of removing the inboard radiators that jut from the truss with the Canadian robot arm if the need arises.

Dragon was berthed to the station’s U.S. segment Harmony module early March 3, a day later than planned. The delay allowed SpaceX controllers to overcome March 1 post-launch difficulties with the vessel’s thruster pods. The station’s crew made up for the lost time by opening the cargo capsule within hours of its arrival.

The station crew unloaded all of the pressurized cargo — primarily U.S., European and Japanese research gear — on March 4, well ahead of schedule.

Dragon is currently being reloaded with just more than 3,000 lb. of cargo, including preserved medical and biomedical specimens, unneeded equipment and protective packaging, for return to Earth on March 25. SpaceX watercraft will be stationed in the Pacific Ocean about 300 mi. west of Baja, Calif., for the recovery after Dragon’s parachute descent.

The SpaceX mission is the second launched under a $1.6 billion, 12-flight NASA Commercial Resupply Services agreement awarded in late 2008.