* Experiment to be installed during spacewalk Tuesday
* Shuttle Atlantis on 135th and final flight
* Orbital debris no threat to space station (Adds mission extension, no inspection needed)
By Irene Klotz
HOUSTON, July 11 (Reuters) - With the end of the space shuttle program in sight, the U.S. 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 Refueling Mission flying aboard the space shuttle Atlantis will use the International Space Station's Dextre robot to test tools for refueling 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 preflight interview.
Ferguson and three crewmates 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 program, which is ending due to high costs.
NASA hired two firms, Space Exploration Technologies and Orbital Sciences Corp ORB.N, to deliver cargo to the station beginning next year. The 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 United States will pay Russia for space taxi flights, at a cost of more than $50 million a seat.
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The $22.6 million Robotic Refueling 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 U.S. 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 Center 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.
Because the satellites weren't designed with refueling 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 minimize 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 crewmembers, Ron Garan and Mike Fossum.
Atlantis, which blasted off on Friday from the Kennedy Space Center, is due back on July 21. NASA managers gave the crew an extra day at the space station to complete more unpacking tasks. The extension sets Atlantis up for a night landing at 5:56 a.m. EDT, about 40 minutes before sunrise.
"That's awesome news, thanks so much," shuttle commander Ferguson said after getting the word from Mission Control.
Ground controllers also told Ferguson that they would not require Atlantis' crew to conduct an extra inspection of the shuttle's heat shield after a prior survey found "extremely minor" damage at one tile site, deputy space shuttle manager LeRoy Cain said.
The inspections have been required on every mission since 2003, when shuttle Columbia broke apart as it returned to Earth, killing all seven crewmembers.
In another positive development, NASA on Monday said a piece of orbital debris that had been projected to pass near the station about the time of Tuesday's spacewalk was not a threat. The debris, part of a defunct Soviet satellite, should pass about 11 miles (18 km) from the station.
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 spokesman Kelly Humphries.