After fixing a check valve that caused an abort for the Falcon 9/Dragon launch on Saturday morning, SpaceX successfully launched the combination at 3:44 am Eastern Time today. SpaceX employees were heard cheering on the webcast as Dragon's solar panels deployed, and the spacecraft is now orbiting the Earth on its second mission. Should all go well, Dragon will attempt to become the first commercially developed spacecraft to berth with the International Space Station.

As the GNC door which covers the grapple fixture deployed, SpaceX's Elon Musk tweeted, "Dragon spaceship opens the navigation pod bay door without hesitation. So much nicer than HAL9000 #DragonLaunch."

The second flight of the Dragon spacecraft has been delayed a few times now, sometimes to fix teething pains and sometimes to accommodate range scheduling. Saturday's launch was aborted with a half second to go; as the engines came up, an overpressure sensor revealed the faulty check valve. This morning's launch went very smoothly.

Falcon 9 is significantly cheaper than its competition, allowing SpaceX to be the first American space launch company to go into mass production of launchers other than ICBMs. The reusable Dragon is also significantly cheaper than European, Russian or Chinese spacecraft. A projected loosening of export controls that adversely affect American launchers will soon help SpaceX go after more international payloads with the Falcon 9, while the Dragon will help SpaceX offer new kinds of services (and service to commercial space stations) at far lower prices than the normal cost for access to space.

The cargo version of the Dragon is very different from the manned version expected to begin launching humans to orbit in a few years, but it is similar enough to come up in every argument over NASA's efforts to turn the responsibility for Low-Earth Orbit over to commercial players.

We at Ars will be tracking this mission as it attempts to complete the demonstrations and prove that Dragon can berth with the ISS. You can watch a webcast of the launch here.