Dragon C2, also known as COTS Demo Flight 2, is a planned second test-flight for SpaceX

SpaceX

Space Exploration Technologies Corporation, or more popularly and informally known as SpaceX, is an American space transport company that operates out of Hawthorne, California...

's unpiloted Dragon cargo spacecraft, and the third overall flight for the company's two-stage Falcon 9

Falcon 9

Falcon 9 is a rocket-powered spaceflight launch system designed and manufactured by SpaceX. Both stages of its two-stage-to-orbit vehicle use liquid oxygen and rocket-grade kerosene propellants...

 launch vehicle.
The flight is under contract to NASA

NASA

The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

, as the second Dragon mission in the Commercial Orbital Transportation Services

Commercial Orbital Transportation Services

Commercial Orbital Transportation Services is a NASA program to coordinate the delivery of crew and cargo to the International Space Station by private companies. The program was announced on January 18, 2006...

 (COTS) phase 1 program.
The purpose of the COTS program is to develop and demonstrate commercial sources for cargo re-supply of the International Space Station

International Space Station

The International Space Station is a habitable, artificial satellite in low Earth orbit. The ISS follows the Salyut, Almaz, Cosmos, Skylab, and Mir space stations, as the 11th space station launched, not including the Genesis I and II prototypes...

 (ISS).

The Falcon 9 launch vehicle arrived at SpaceX's Cape Canaveral facilities at Launch Complex 40 (LC 40) in July 2011. The mission's
Dragon spacecraft arrived at the launch site on 25 October 2011. Further mission delays were caused by the failure of the Russian Progress 44

Progress M-12M

Progress M-12M , identified by NASA as Progress 44 or 44P, was an unmanned Progress spacecraft that was lost in a launch failure in August 2011, at the start of a mission to resupply the International Space Station. It was the twelfth modernised Progress-M spacecraft to be launched...

 cargo resupply vessel in August, that might have forced the ISS to be temporarily abandoned in mid-November. With the successful launch and docking of the Progress 45

Progress M-13M

Progress M-13M , identified by NASA as Progress 45 or 45P, is a Progress spacecraft which reached the International Space Station on 2 November 2011. The Progress M-13M spacecraft lifted off from the Baikonur Cosmodrome in Kazakhstan at 10:11 GMT on 30 October, starting off the 45th unmanned...

 mission, SpaceX began working towards a 19 December 2011 projected launch date. In November 2011 the launch was postponed to 7 January 2012, but that seems optimistic according to NASA officials involved with the program, and they suggest the launch will occur in late January or early February.

History

NASA and SpaceX signed a contract for COTS cargo resupply services on 18 August 2006. The agreement called for three test-flights, under the COTS phase 1 demonstration program. The first COTS mission was completed successfully on 8 December 2010, when the Falcon 9/Dragon C1 mission became the first private-sector flight to orbit and then return a spacecraft from low-Earth orbit. Due to the mission's success, SpaceX lobbied NASA to combine the COTS 2 ISS flyby flight, which would have seen a Dragon spacecraft approach the station but stay about 10 km away from it, and the COTS 3 flight that would actually dock with the ISS.
At a 15 July 2011 meeting, NASA tentatively approved combining the two COTS missions to accelerate the program into the operational supply mission phase in early 2012.

Mission plan

The proposed mission plan, which combines the objectives of the previously planned COTS 2 and COTS 3 flights into a single mission, has the Dragon spacecraft performing a space rendezvous

Space rendezvous

A space rendezvous is an orbital maneuver during which two spacecraft, one of which is often a space station, arrive at the same orbit and approach to a very close distance . Rendezvous requires a precise match of the orbital velocities of the two spacecraft, allowing them to remain at a constant...

 with the International Space Station, test its communication systems with the space station, and then berth with the ISS by utilizing the station's Mobile Servicing System (Canadarm2) to capture and then position it. The Dragon spacecraft will then return to Earth with cargo from the ISS, with the expected splashdown and recovery zone in the Pacific ocean, off the California coast.
NASA will make the final determination whether or not to allow the Dragon spacecraft to berth with the ISS after it is launched, because SpaceX intends to launch two secondary payload satellites from the Dragon sometime in the first 72 hours after launch. If allowed to berth, the mission is projected to last 22-days.