If the SpaceX Dragon does link up with the International Space Station, it will represent a milestone for commercial space craft.
On Saturday, SpaceX will send its Dragon capsule spiraling all the way up to the International Space Station, approximately 230 miles above the surface of the earth – the first time a commercially-built, private spacecraft has linked up with the orbiter. In a press release, representatives for SpaceX called the mission a "milestone," which could help yield "rapid advances" in space transport.
"This is a demonstration mission, a test flight primarily designed to provide NASA and SpaceX with valuable insight to ensure successful future missions," the SpaceX team wrote.
The Dragon was originally slated to blast off in late April, but unspecified problems with the docking software hampered the launch, and the event was rescheduled for 4:55 am on Saturday morning.
According to a schedule provided by SpaceX, three days after launch, the Dragon, which is unmanned, will draw close to the International Space Station. On the fourth day, NASA will decide if the Dragon "is allowed to attempt to berth with the station. If so, [the capsule] approaches; it is captured by station’s robotic arm and attached to the station. This requires extreme precision even as both Dragon and station orbit the earth every 90 minutes."
In other words, these things are going to be moving very fast indeed. And SpaceX is prepared for the possibility of failure: "If any aspect of the mission is not successful, SpaceX will learn from the experience and try again," the company said. But if the Dragon is successful, SpaceX will move forward on a NASA contract to ferry supplies, over a series of 12 flights, to and from the ISS.