We’ve been writing quite a bit about PayPal cofounder Elon Musk and his electric car company Tesla Motors, but Tesla isn’t Musk’s only current venture — his other company, SpaceX, hit an important milestone today by sending its Falcon 9 rocket into space.

SpaceX’s promise of commercialized space travel seems to be inching closer to reality. Back in 2008, it successfully launched the Falcon 1 after three unsuccessful tries, but that was more of a “proof of concept” vehicle, while SpaceX plans to use the Falcon 9 to power the Dragon, its craft that could transport cargo or even people to the International Space Station. This is also the Los Angeles company’s first orbital launch, according to Wired.

SpaceX is planning another launch later this year, with hopes of actually docking with the space station in 2011. It looks poised to take advantage of President Obama’s plan to rely on private companies to handle transport to the International Space Station while NASA focuses on developing new technologies.

The company’s investors include Draper Fisher Jurvetson, Founders Fund, and Musk himself.