The first private company to resupply the space station overcame a stuck thruster valve and completed docking with the ISS on Sunday.
A SpaceX Dragon cargo capsule overcame a potentially mission-ending technical problem to make a belated but welcome arrival at the International Space Station on Sunday.
Astronauts aboard the outpost used the station's robotic arm to pluck the capsule from orbit at 5:31 a.m. EST as the ships sailed 250 miles over northern Ukraine.
Flight controllers at NASA's Mission Control in Houston then stepped in to drive the capsule to its berthing port on the station's Harmony connecting node. Docking occurred at 8:44 a.m. EST.
The Dragon capsule, loaded with more than 2,300 pounds (1,043 kg) of science equipment, spare parts, food and supplies, blasted off from Cape Canaveral Air Force Station in Florida on Friday aboard a SpaceX Falcon 9 rocket for the second of 12 planned supply runs for NASA.
SpaceX is the first private company to fly to the station, a $100 billion project of 15 nations.
Dragon was to have arrived at the station on Saturday but a problem with its thruster rocket pods developed soon after reaching orbit. Engineers sent commands for Dragon to flip valves and clear any blockage in a pressurization line in an attempt to salvage the mission.
By Friday evening, Dragon had fired its thruster rockets to raise its altitude and begin steering itself to rendezvous with the station.
The orbital ballet ended when station commander Kevin Ford, working from a robotics station inside the outpost, grabbed the capsule with the station's robot arm.
"As they say, it's not where you start but where you finish that counts. You guys really finished this one on the mark," Ford radioed to Dragon's flight control team in Hawthorne, California, and NASA's Mission Control in Houston.
"What a fantastic day," Ford said.
Indeed, it wasn't so fantastic that the thruster valve wouldn't work. What is truly great news is that they were able to fix the problem and complete their mission.
Whether it's NASA or a private company, space flight is still in the experiemental stages. And especially when dealing with new hardware, the potential for disaster is never far from the minds of controllers. Over the next several years, other private companies will be launching rockets of their own design -- some of which will carry humans into space. And they will do it far cheaper and more efficiently than NASA could ever do.
The ability of Space X to overcome the thruster glitch is an important milestone for the private exploration and exploitation of space.