Dragon To Make Near Approach, Possibly Rendezvous With ISS

December 8 2011, marked the one year anniversary of Dragon’s first Commercial Orbital Transportation Services (COTS) demonstration flight. The flight made history as SpaceX became the only commercial company to successfully return a spacecraft from orbit. This feat had previously been accomplished only by five nations and the European Space Agency. The company is now preparing the Dragon spacecraft for yet  another historic flight – becoming the first commercial vehicle in history to visit the ISS.

NASA recently announced February 7, 2012, as the new target launch date for the upcoming mission. In addition, NASA officially confirmed that SpaceX will be allowed to complete the objectives of COTS 2 and COTS 3 in a single mission. This means Dragon will perform all of the COTS 2 mission objectives which include numerous operations in the vicinity of the ISS, and will then perform the COTS 3 objectives. These include approach, berthing with the ISS, astronauts opening Dragon and unloading cargo, and finally, astronauts closing the spacecraft and sending it back to Earth for recovery from the Pacific Ocean off the coast of California.

This mission marks a major milestone in American spaceflight. While the first missions to the ISS will be to transport cargo, both Falcon 9 and Dragon were designed to ultimately transport astronauts. SpaceX says every trip to the ISS from this point forward is a step closer to that goal.

Just as Dragon’s first mission to orbit and back involved a level of effort equal to launching the first Falcon 9, preparing Dragon for two weeks of operation in space and for approach and berthing with the ISS poses new challenges. Meeting them requires a large amount of detailed planning and careful execution.
Each launch day will have just one narrow liftoff window—no more than a few minutes—in order to synchronize Dragon’s flight with the orbit of the ISS. Catching up to the ISS will take from one to three days. Once there, Dragon will begin the COTS 2 demonstrations to show proper performance and control in the vicinity of the ISS, while remaining outside the Station’s safe zone.

During the entire time Dragon is in the vicinity of the ISS, Station astronauts will be in direct communication with Dragon and will be able to monitor the spacecraft as well as issue spacecraft commands. After successfully completing the COTS 2 requirements, Dragon will receive approval to begin the COTS 3 activities, gradually approaching the ISS from the radial direction (toward the Earth), while under constant observation. Dragon will approach to within a few meters of the ISS, allowing astronauts to reach out and grapple Dragon with the Station’s robotic arm and then maneuver it carefully into place. The entire process will take a few hours. Once in place, Station astronauts will equalize the pressure between the ISS and Dragon, open the hatches, enter the vehicle and begin unloading Dragon’s cargo.

After Dragon spends about a week berthed at the ISS, astronauts will reverse the process, loading Dragon with cargo for return to Earth, sealing the hatches, and un-berthing Dragon using the robotic arm. Dragon will then depart from the ISS and return to Earth within a day or so, and the SpaceX recovery crew will meet it at splash down in the Pacific Ocean off the coast of California. (Images provided by SpaceX)

FMI: www.spacex.com