US space companies prepare for space station docking
Two US rocket companies are readying the first private space missions to the International Space Station (ISS).
SpaceX and Orbital both have multi-billion dollar Nasa contracts to supply cargo to the station, filling the void left by the retirement last year of the space shuttle.
California-based SpaceX has set the pace so far, having successfully launched its Falcon 9 rocket and Dragon capsule into orbit, and safely returning the capsule to Earth, in December 2010.
SpaceX is part of the new wave of commercial ventures that Nasa hopes can help reduce the cost of going into space.
The company says it could launch for the ISS as soon as 30 April.2012.
But the company is now looking to move quickly, with a static launch test and a first launch into orbit scheduled for the summer, and a possible rendezvous with the ISS in the autumn.
Frank Culbertson, a former astronaut and senior vice president at Orbital, admits it does feel a bit like a race.
"A little bit. They actually started the development of their system about a year-and-a-half before us, but we're almost neck-and-neck in terms of who's going to launch next, who's going to get to the station first.
"They're probably three or four months ahead of us on the schedule that we see, but who knows how things will work out?
"Nasa needs both companies to succeed on every single mission if at all possible."
The two companies have very different pasts, and have built very different spacecraft.
While Orbital has been in business since 1982, building satellites, small rockets and missile interceptors, SpaceX is just a decade old, even if its plans are big.
SpaceX designs and builds much of its Falcon 9 rocket system in-house, while its Dragon capsule can carry cargo or crew, say its makers.The Falcon 9-Heavy is a beefed up version of the vehicle the company will soon use to send a robotic cargo ship to the International Space Station.
The new rocket should be capable of putting more than 53 tonnes (117,000lb) of payload in a low-Earth orbit - more than twice that of the space shuttle.
Dragon could be used to ferry astronauts into space by 2015, and the company is one of four companies that Nasa has awarded seed funding to develop commercial crew vehicles.
Much of the the liquid-fuelled lower-stage rocket is designed and built in the Ukraine, while its engines are 40 years old and come from the Soviet Union's ill-fated N-1 lunar rocket.
Orbital's Cygnus capsule, meanwhile, is a purpose-built cargo vehicle that is designed to ferry supplies and not astronauts to the ISS. After being filled with waste from the station, it will burn up on its return to Earth.
SpaceX and NASA announced a new schedule for the private company’s planned rendezvous with the International Space Station. The launch of SpaceX’s Falcon 9 rocket was expected to take place earlier in the year, but as is often the case with space flights, it was postponed for more testing. Now the company is aiming for an April 30 launch from the Kennedy Space Center in Florida.
The mission will combine two tests for NASA’s Commercial Orbital Transportation Services (COTS) contract into a single flight. A few days after launching, the Dragon spacecraft will approach the space station for docking, getting very close, but not actually connecting in order to make sure everything works as planned on both the SpaceX and the station side. After retreating to some safe distance for a period of time, the Dragon will then repeat the approach. But on the second run engineers will go all the way, docking with the ISS.
The tests are to demonstrate SpaceX’s capabilities to deliver payloads to the ISS. Since the retirement of the space shuttle program last year, NASA has been relying on the Russian rockets to deliver a