The Dragon Space X commercial cargo ship was lofted into orbit aboard a Falcon 9 rocket at 8:35 p.m. EDT, putting on a spectacular show of light and thunder from the rocket's nine engines.
"This was a critical event in spaceflight tonight," NASA Administrator Charles Bolden said shortly after launch.
"We're once again launching spacecraft from American soil with the supplies our astronauts need in space. NASA and the nation are embarking on an ambitious program of space exploration."
Dragon is slated to rendezvous with the International Space Station (ISS) on Wednesday, when astronaut and station commander Suni Williams will reach out with the station's robot arm and grapple the capsule.
The spacecraft will subsequently be joined to one of the station's ports where astronauts are scheduled to unload its 1,000 pounds of materials. They will also load about 2,000 pounds of used equipment and experiments inside the Dragon to be safely returned to Earth in about three weeks.
The supply flight is part of NASA's Commercial Resupply Services contract, which is paying SpaceX for 12 cargo runs to the orbiting laboratory. The station also is serviced by Russian Progress cargo capsules, European-made and launched Automated Transfer Vehicles, or ATVs, and Japanese-produced H-II Transfer Vehicles, or HTVs. All the cargo ships operate without astronauts or crew members aboard.
Once the spacecraft arrive at the station, the astronauts and cosmonauts onboard unload them and fill them with used materials or unneeded equipment before releasing them. Here, SpaceX again does something unique. The Dragons are designed with heat shields to survive a plunge through the atmosphere and splashdown safely in the ocean under billowing parachutes. The other cargo craft do not carry heat shields, so they simply burn up in the atmosphere.
As noted above, the Dragon capsule is slated to carry more than a ton of scientific samples collected during space station research on its return trip, along with the freezer the samples have been stored in. Astronauts will also load used station hardware into the capsule for return to Earth where engineers can get a firsthand look at it.