The SpaceX Dragon commercial cargo craft approaches the International Space Station on May 24, 2012 for a series of tests to clear it for its final rendezvous and grapple on May 25. At 3:58 a.m. (EDT), Dragon performed a height adjust burn to bring it to a path 2.4 kilometers below the station. During this “fly-under,” Dragon established UHF communication with the station using its Commercial Orbital Transportation Services (COTS) Ultra-high frequency Communication Unit (CUCU). Dragon performed a test of its Relative GPS system, which uses the relative positions of the spacecraft to the space station to determine its location.
On May 25, Expedition 31 Flight Engineers Don Pettit and Andre Kuipers will use the Canadarm2 robotic arm to grapple the supply ship about 8:06 a.m., with the berthing to the Earth-facing side of the station’s Harmony node following about 11:20 a.m. Dragon is scheduled to spend about a week docked with the station before returning to Earth on May 31 for retrieval.