Robot refuels satellite in space

Remote-controlled technology promises to extend the useful lives of satellites

A remote-controlled robot has refuelled a satellite experimentally in space for the first time.

The project, run by Nasa and the Canadian Space Agency (CSA), saw the Dextre robot use four tools with built-in cameras and LEDs that allowed remote control of the refuelling process over five separate days in January. 

The ability to refuel satellites in space could potentially save operators the significant costs of building and launching replacement satellites. There are more than 1,100 active satellites in the near-earth environment and a further 2,500 inactive satellites orbiting the planet. 

The refuelling valve of a satellite is triple-sealed and covered with a protective blanket, which is designed never to be accessed. On its mission, Dextre opened up a simulated fuel valve on a robotic refuelling module and transferred liquid ethanol through a fuelling hose. To do this, Dextre used a tool to cut wires on the safety cap and the actuation nut of the mock fuel valve, and a tool to remove the safety cap. Next, a nozzle tool threaded itself on to the fuel valve and a transfer of liquid ethanol took place. Once the transfer was complete, the tool disconnected from the valve, leaving behind a “quick disconnect” fitting to allow for a simpler and more efficient refuelling connection in the future. 

The CSA said that this was a “significant step in pioneering robotic technologies”. 

Dextre has two arms that are over 3m long. Each arm has seven joints that can move up and down, side to side, and rotate and roll. At the end of each arm is a gripper packed with features including a retractable motorised socket wrench to turn bolts and connect or detach hardware; a camera and lights for close-up viewing; and a retractable umbilical connector to provide electricity, data and video connections. 

The grippers also have sensors that provide the robot with a human-like sense of touch, which enables it to apply just the right amount of force in the precise direction, and is accurate to within millimetres of its target.

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