Houston - With the end of the space shuttle programme, the US government intends to stimulate development of private space transportation and also to lay the foundation for an entire new industry to service satellites in orbit.
The Robotic Refuelling Mission flying aboard the space shuttle Atlantis will use the International Space Station's Dextre robot to test tools for refuelling and repairing existing satellites, none of which were designed with reuse in mind.
"I've likened it to a Fisher-Price play toy for a robot, and I don't mean that in a negative sense," Atlantis commander Chris Ferguson said in a pre-flight interview.
Ferguson and three crew arrived at the space station on Sunday to deliver a year's worth of food, clothing and other supplies. The mission is the 135th and final flight in the 30-year-old shuttle programme, which is ending due to high costs.
Nasa hired two firms, Space Exploration Technologies and Orbital Sciences Corp, to deliver cargo to the station beginning in 2012.
HardwareThe Obama administration wants Nasa to buy rides for its astronauts as well, though no commercial suppliers are expected to be available until around 2015. In the meantime, the US will pay Russia for space taxi flights, at a cost of more than $50m a seat.
The $22.6m Robotic Refuelling Mission equipment is scheduled to be installed to the outside of the space station during a 6.5-hour spacewalk on Tuesday.
The hardware consists of a box of tools, fittings and a tank of ethanol fuel that the station's Dextre robot can use to perform tasks that would be needed to refuel a satellite, such as cutting away thermal insulation and wires, removing protective caps, installing fuel valves and transferring fuel from one tank to another.
The test work, which won't start until after the shuttle leaves the station, is scheduled to run for two years. Nasa plans to hire an industry partner for a follow-on mission around 2015 to refuel a US government weather satellite and then nine other spacecraft in orbit.
"We want the commercial world to take over this service," said Benjamin Reed, deputy project manager for the Satellite Servicing Capabilities Office at Nasa's Goddard Space Flight Centre in Maryland.
There are currently about 360 operational commercial communications satellites and another 100 government-owned satellites orbiting Earth.
"Every single one of them one day is going to run out of fuel and be thrown away. That's the way it's always been done. If a robot can go up and refuel it, you wouldn't have to throw it away," Reed said.
Trial runBecause the satellites weren't designed with refuelling in mind - they have no navigational aids, no reflectors, nothing to help guide in an approaching spacecraft - the technical hurdles are steep.
Since the same technology also could be used to disable satellites, Reed said Nasa intends to be as open as possible about the project.
"We plan an international workshop next spring where we will lay out in more detail what our plans are to make the world aware of what we are doing so that we can minimise the anti-satellite weapon accusers," Reed said.
The spacewalk to install the project's trial run will be conducted by Nasa's two space station crew, Ron Garan and Mike Fossum.
The agency said on Monday that a piece of orbital debris that had been projected to pass near the station about the time of the spacewalk was not a threat. The debris, part of a defunct Soviet satellite, should pass about 18km from the station, said Nasa flight director Jerry Jason.
Nasa figures that over a six-month period, the space station has a 1-in-100 chance of being hit by a piece of debris and sustaining damage that might have to force the crew to evacuate part of the station, said spokesperson Kelly Humphries.
Overall, the chance of a debris strike to the shuttle during its 12-day flight is 1-in-314.
Atlantis, which blasted off on Friday from the Kennedy Space Centre, is due back on July 20.
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