Nasas space shuttle fleet may be landing in museums, but the next step in space exploration is already underway as private concerns work to get into the ground floor of commercial flight to near-Earth orbit and possibly beyond. On Saturday, May 19, the company Space X plans to reach a major milestone by launching the first commercial craft bound for the International Space Station. Nasas ISS programme manager Mike Suffredini has dubbed it one of those historic launches. But there is much that could go wrong in what amounts to a test flight, and the launch has already been delayed repeatedly to make sure everything comes together correctly. Space takes longer and is more expensive than people expect, notes Scott Pace, director of the Space Policy Institute at the George Washington University in Washington. Space Xs Dragon spacecraft is to embark upon a three-day flight to the ISS and undertake a series of complicated docking manoeuvres in order to establish that it can safely attach to the orbiting station. This will be only the third flight for Dragon. The flight carries significant risk, but Space X has vowed that if any part of the mission does not succeed it will learn and try again. The unmanned Dragon capsule will blast off atop a Falcon 9 rocket from the Kennedy Space Centre in Florida and carry 521kg of cargo, mainly food for astronauts living on the station. If all goes as planned it will return to Earth with 660kg of discarded cargo. Nasa and Space X have said they were confident about the mission but stressed it was a test flight and that the docking to the station would be particularly difficult. The shift toward commercial spaceflight comes as part of an Obama administration review of space policy amid the retirement of the space shuttle fleet. Nasa will shift its focus to longer distance goals with the aim of eventually reaching an asteroid and later Mars while handing over routine space station flights to commercial providers. The US doesnt have its own government access to the space station, so it is reliant on private providers, and for cargo that is a reasonable bet, Pace said. But he expressed worries that the next step - commercial crew access - will be considerably more difficult. With the retirement of the shuttle, US astronauts can only reach the station via Russian Soyuz spacecraft, while cargo can be delivered on Russian, European and Japanese craft. The Space X advance would be good news not only for Nasa, but also for international partners. We wish Space X all the success in this matter because it is an important step to have access to space, Andreas Diekmann, who heads the European Space Agencys Washington office, said, noting the need for a US means to reach the station. Space X was awarded a possible $396mn contract, of which it has so-far received $381mn, to develop its capsule. It is under contract for 12 supply flights to the station. In 2010, Space X was the first private company to send a commercial craft into orbit. If all goes well, the company eventually plans to convert the Dragon capsule to allow it to also bring astronauts aloft - but it will likely be years before the first astronaut blasts off in a private rocket. The Dragon is to remain at the station for two weeks for the ISS crew to unload cargo, before the capsule re-enters the atmosphere and splashes down off the California coast. I think weve got a pretty good shot, but it is worth emphasizing that there is a lot that can go wrong in a mission like this, Space X chief Elon Musk said last month. The most complex part of the mission will be the docking to the station, and Nasa and Space X will take a series of steps to be sure the station and its resident astronauts are safe as the craft approaches. If any aspect of the approach looks to be compromised, the docking could be called off at the last minute. Finally, two astronauts aboard the ISS will use the stations robotic arm to grab the Dragon capsule and attach it to a port on the station. Nasa noted that the cargo aboard the craft is expendable, in case the Dragon fails to make it to the ISS or back home. Musk warned against placing too much value on the flight, saying that a failure should not be used as an argument to discredit commercial space flight. There should be doubt about our resolve, he said. We will get to the space station whether on this mission or a future one. Another company, Orbital Sciences Corporation, is set for its first flight to the ISS late this year.

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Space X set to launch first commercial flight to ISS