SpaceX Dragon completes first leg of mission

With the opening of the hatch to the Dragon spacecraft by International Space Station (ISS) Commander Suni Williams and Flight Engineer Aki Hoshide, SpaceX officially becomes the first commercial cargo delivery to the ISS.  This cargo includes the much talked about ice cream.  This mission continues their record-setting streak.  In their May ISS cargo supply demonstration flight SpaceX became the first commercial company to dock with the ISS, and this new first is a continuation of that ground-breaking effort.

In addition to these firsts, the Dragon spacecraft is providing another new capability: the ability to return significant amounts of cargo to earth.  Other resupply spacecraft are filled with trash and allowed to burn up on re-entry, as shown here.  The only other spacecraft that returns to earth after its mission is the manned Soyuz spacecraft, whose primary purpose is returning crew from the ISS and has very limited cargo capacity.

During Dragon's May demo mission, it demonstrated its ability to return cargo safely to earth by bringing back 660 kilograms of cargo.  One of the most significant aspects of the current mission is the scheduled to return 1,384 lb. (about 628 kg) to earth, including scientific experiments and samples.  This capability fills a large gap left by the retirement of the Space Shuttle - which left the severely limited Soyuz spacecraft as the only means to return cargo to earth.

So, while the SpaceX mission is historical in that it is the first commercial resupply mission, it's upcoming return to earth - laden with cargo - is actually the bigger accomplishment.