NASA's Robotic Refueling Mission (RRM) experiment aboard the International Space Station (ISS) has demonstrated remotely controlled robots and specialized tools can perform precise satellite-servicing tasks in space. The project marks a milestone in the use of the space station as a technology test bed. The Canadian Space Agency's (CSA) robotic handyman, Dextre, successfully completed the tasks last month on the ISS external RRM module, designed to demonstrate the tools, technologies, and techniques needed to robotically refuel and repair satellites.
"The Hubble servicing missions taught us the importance and value of getting innovative, cutting-edge technologies to orbit quickly to deliver great results," said Frank Cepollina, associate director of the Satellite Servicing Capabilities Office (SSCO) at NASA's Goddard Space Flight Center in Greenbelt, MD. "The impact of the space station as a useful technology testbed cannot be overstated."
Before a satellite leaves the ground, technicians fill its fuel tank through a valve that is sealed, covered, and designed never to be accessed again. The RRM experiment demonstrates a remote-controlled robot can remove these barriers and refuel such satellites in space. Dextre successfully retrieved and inspected RRM tools, released safety launch locks on tool adapters, and used an RRM tool to cut extremely thin satellite lock wire. These operations represent the first use of RRM tools in orbit, and Dextre's first participation in a research and development project.
During the next two years, RRM and Dextre will conduct several servicing tasks using RRM tools on satellite parts and interfaces inside and covering the cube-shaped RRM module. NASA expects the RRM results to reduce the risks associated with satellite servicing. It will encourage future robotic servicing missions by laying the foundation for them. Such future missions could include the repair, refueling, and repositioning of orbiting satellites.
During the three-day RRM Gas Fittings Removal task, the 12-foot Dextre performed the most intricate task ever attempted by a space robot: cutting two separate "lock wires" 20-thousandths of an inch (0.5 millimeters) in diameter using the RRM Wire Cutter Tool (WCT). Deftly maneuvered by ground-based mission operators and Dextre, the WCT smoothly slid its hook under the individual wires and severed them with only a few millimeters of clearance. This wire-cutting activity is a prerequisite to removing and servicing various satellite parts during any future in-orbit missions.
RRM operations are scheduled to resume next month with the completion of the gas fittings removal task. The RRM Refueling task is scheduled for later this summer.