Dragon's capability to return cargo from the station is critical for supporting scientific research in the orbiting laboratory's unique microgravity environment, which enables important benefits for humanity and vastly increases understanding of how humans can safely work, live and thrive in space for long periods. The ability to return frozen samples is a first for this flight and will be tremendously beneficial to the station's research community. Not since the space shuttle have NASA and its international partners been able to return considerable amounts of research and samples for analysis.
Materials being launched on Dragon will support experiments in plant cell biology, human biotechnology and various materials technology demonstrations, among others. One experiment, called Micro 6, will examine the effects of microgravity on the opportunistic yeast Candida albicans, which is present on all humans. Another experiment, called Resist Tubule, will evaluate how microgravity affects the growth of cell walls in a plant called Arabidopsis. About 50 percent of the energy expended by terrestrial-bound plants is dedicated to structural support to overcome gravity. Understanding how the genes that control this energy expenditure operate in microgravity could have implications for future genetically modified plants and food supply. Both Micro 6 and Resist Tubule will return with the Dragon at the end of its mission.
SpaceX is one of two companies that built and tested new cargo spacecraft under NASA's Commercial Orbital Transportation Services (COTS) program. SpaceX completed its final demonstration test in May when it flew to the station and performed a series of checkout maneuvers, ultimately being grappled by the station crew and installed on the complex.
Orbital Sciences is the other company participating in COTS. Orbital's Antares launch vehicle is currently on the launch pad at Wallops Flight Facility in Virginia. The launch vehicle and pad will undergo a series of fueling tests that will take about three weeks. After tests are completed, a hot fire test will be conducted. Finally, a test flight of the Antares rocket with a simulated Cygnus spacecraft will be flown in late 2012. A demonstration flight of Cygnus to the station is planned in early 2013.