Repairing and refueling satellites robotically may seem rather mundane, especially when compared with moon landings, Mars rovers and the Hubble space telescope, but NASA's two-year Robotic Refueling Mission (RRM) experiment, now underway on the International Space Station (ISS), turns out to be surprisingly complex. Designed to demonstrate that servicing working satellites with remotely-controlled robots is a feasible option, NASA, in conjunction with the Canadian Space Agency (CSA), initiated the first of several RRM test tasks just a few days ago and the results look very promising.
Prior to launch, a satellite not intended to be serviced again is fueled through a valve that is then triple sealed and covered with a shielding, insulating blanket. After deployment, once its fuel is spent, that's usually the end of the craft. Extending its life (and taking some heat off NASA's budget) presents several difficult challenges, especially if the work must be performed by robots.
The RRM development team first came up with a list of functions a robot would need to be capable of to service a working satellite. They then tasked the same team that designed the special gear to repair the Hubble telescope to come up with four special RRM tools to remove and replace caps, open and close valves, move fluid and handle wiring. The tools were then mounted on a carefully designed, 550-lb (250-kg), box-like RRM module roughly similar in size to a typical washing machine - 33 x 43 x 45 inches (83 x 109 x 114 cm).
The RRM module carries 0.45 gallon (1.7 L) of ethanol for fluid transfer tests along with extra protective thermal blankets, valves, caps and simulated fuel, and is organized such that each distinct servicing activity has access to parts and any of the four tools needed to practice them.
First up was the Gas Fittings Removal task, during which three of the four satellite-servicing devices deployed by Dextre, the two-armed ISS maintenance robot (remotely-controlled from the Johnson Space Center in Texas), successfully underwent comprehensive electrical and mechanical tests: the Wire Cutter and Blanket Manipulation Tool, the Multifunction Tool and the Safety Cap Tool. Several other functions will be tested over the next several months including Refueling, Thermal Blanket Manipulation, Bolt/Fastener Removal and Electrical Cap Removal.
RRM operations will continue through 2013.
Watch the NASA/CSA video below to see the RRM module being installed on the ISS by Mission STS-135 crew members using Canadarm2.