May 24, 2012
SpaceX Dragon Spacecraft Catches Up With Space Station
After a two-day chase that began from the Cape Canaveral Air Force Station in Florida, the SpaceX Dragon commercial cargo craft has finally closed in on its destination, the International Space Station, for a series of tests Thursday to clear it for its final rendezvous and grapple Friday.
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 will establish UHF communication with the station using its COTS Ultra-high frequency Communication Unit (CUCU). Dragon will perform a test of its Relative GPS system, which uses the relative positions of the spacecraft to the space station to determine its location.
Using the crew command panel on board the station, the Expedition 31 crew will briefly interact with Dragon, monitoring the fly-under and sending a command to Dragon to turn on its strobe light. This ability for the crew to send commands to Dragon will be important for the Friday´s activity.
Once the fly-under is complete, Dragon will fire its engines beginning at 8:20 a.m. to begin a loop out in front, above and then behind the station in a racetrack pattern at a distance between 7-10 kilometers.
NASA Television will provide live coverage of the fly-under throughout the morning.
After Dragon successfully completes these tests, mission managers will clear the vehicle for Friday´s rendezvous and capture. Flight Engineers Don Pettit and Andre Kuipers will use the Canadarm2 robotic arm to grapple and berth the supply ship to Earth-facing side of the station´s Harmony node.
Dragon will spend about a week docked with the station before returning to Earth on May 31 for retrieval.