An unmanned rocket carrying the Dragon cargo capsule blasted off Friday morning to deliver the second commercial shipment to the International Space Station (ISS). A Falcon 9 rocket with the Dragon capsule, built by the private spaceflight company SpaceX, lifted off from the Cape Canaveral Air Force Station in Florida at 10:10 a.m. EDT (1410 GMT), NASA TV shows. This is the second of 12 contracted flights by SpaceX to resupply the space station and marks the third trip by a Dragon to the station, following a successful demonstration mission in May and the first resupply mission in October. The capsule is packed with about 1,200 pounds of supplies for the ISS six-man crew, including frozen mouse stem cells, 640 seeds of mouse-ear cress, a small flowering weed used in research, and tasty treats for the station crew picked from the orchard of a SpaceX employee\'s father. The capsule is due to arrive at the space station early Saturday and be captured by astronauts using the outpost\'s robotic arm and parked at an open docking port. It will spend more than three weeks at the station before departing and parachuting into the Pacific with a full load of medical specimens, fish, plants and old equipment. Dragon is the only space station cargo craft designed to safely return to Earth, a critical capability that was lost when NASA\'s space shuttle fleet was retired in 2011. The Russian Soyuz spacecraft that ferry crews to and from the space station can only carry a few hundred pounds of small items back to Earth. All other station vehicles -- unmanned Russian Progress supply ships and European and Japanese cargo craft -- burn up during re-entry. Before Dragon\'s liftoff, flights to the space station have always been a government-only affair. Until their retirement, U.S. space shuttles carried most of the gear and many of the astronauts to the orbiting outpost. Since then, American astronauts have had to rely on Russian capsules for rides. European, Japanese and Russian supply ships have been delivering cargo. NASA is looking to the private sector, in this post-shuttle era, to get American astronauts launched again from the U.S. soil. It will be at least four to five years before SpaceX or any other private operator is capable of flying astronauts.