The Dragon spacecraft passed the underside of the space station and correctly calculated the distance between the two – two tests it cleared with flying colors on Thursday. The craft, owned by SpaceX, is set to dock on Friday.
With the relentless flash of a strobe light and some on-board number crunching, SpaceX's Dragon spacecraft cleared two more significant milestones Thursday in the company's effort to become the first commercial launch service to carry cargo to the International Space Station.
Appearing like a gnat silhouetted against the brilliance of Earth's cloud tops, Dragon passed within 1.5 miles of the station's underside in a test of its ability to receive data from the space station on the station's position – determined by Global Positioning System satellites – and accurately determine the distance and relative positions between the two craft.
In addition, space-station flight engineer André Kuipers activated a strobe light on Dragon, showing that the station crewmembers could command the cargo craft from their enviable perch in the multiwindowed cupola on the station – in essence the station's control tower for overseeing the arrival and departure of spacecraft from station partners.
SpaceX already is under a $1.6 billion contract with NASA for 12 cargo missions through 2015. But the company has its sights set on more than rations and experiment samples. A successful cargo service also paves the way for sending humans into space.
The company currently is one of four firms in which NASA is investing almost $270 million to develop human-spaceflight capabilities in the second phase of its commercial-crew development project. NASA is relying on commercial providers to ferry crews and cargo to and from the space station so that the agency can focus its human-spaceflight efforts on exploring space beyond low-Earth orbit, the space station's domain.