SpaceX could make space history once again with this launch. This time, with a controlled descent of the Falcon 9’s first stage.  Approximately 161 seconds into flight, the first-stage engines will shut down, an event known as main-engine cutoff, or MECO.  At that point, Falcon 9 is 80 kilometers (50 miles) high, traveling at 10 times the speed of sound.  Three seconds after MECO, the first and second stages will separate.

After separation, landing legs will be extended into a 60-foot span from the first stage. SpaceX will then attempt a controlled descent (with the help of retro rockets) of the first stage into the Atlantic Ocean.   The ultimate goal of this test is to create a reusable first-stage booster rocket that would decrease the overall launch costs.

Once in orbit, the Dragon capsule will rendezvous with the space station where it will be grappled and berthed to the complex for an expected four-week visit.  

Dragon is later scheduled to return to Earth for a parachute-assisted splashdown in the Pacific Ocean off the coast of southern California. It will be bringing back more than 3,600 pounds of experiment samples and equipment.