NASA Developing Unique Robotic Satellite Refueling System

As reported by Network World: Refueling aging satellites that were never meant to be refueled is the goal with a emerging NASA system that could save millions.

NASA this week said since April 2011, engineers have been working to build robotic satellite servicing technologies necessary to bring in-orbit inspection, repair, refueling, component replacement and assembly capabilities to spacecraft needing aid. The project could also lead to life extension or re-purposing in Earth orbit or Earth-bound application like robotically fuel satellites before they launch, keeping humans at a safe distance during an extremely hazardous operation., NASA said.

Two of NASA's leading development groups -- Kennedy Space Center and the Goddard's Satellite Servicing Capabilities Office (SSCO) teamed on the most recent advancement.  Specifically SSCO demonstrated that a remotely operated robot - with supporting technologies - could transfer oxidizer into the tank of another orbiting spacecraft not originally designed to be refueled. Kennedy's propellant transfer system was an essential part of this Remote Robotic Oxidizer Transfer Test, or RROxiTT.

Satellite fuel, known as hypergolic propellants, includes fluids such as hydrazine and nitrogen tetroxide are the most frequently used fuel and oxidizers for maneuvering satellites in Earth orbit, NASA noted.

According to NASA, the team at Goddard shipped an industrial robotic arm to Kennedy for the test. From 800 miles away in Maryland, the team remotely controlled the robotic arm with its attached SSCO oxidizer nozzle tool to connect with a propellant fill and drain valve on the simulated satellite's servicing panel. 

Downstream, the Kennedy-provided propellant transfer system and hose delivery assembly flowed oxidizer through the tool into the client fill-drain valve, with all hardware located in the Kennedy facility in Florida.
Hypergolic propellant was controlled remotely at various flight, pressures and flow rates to prove the concept worked, NASA stated. 

"This is a unique test that's never been done, as far as we know, anywhere in the world," said Brian Nufer, a fluids engineer in the Fluids Engineering Branch of NASA Engineering and Technology.

The full contingent of operating spacecraft is right around 1,000 with more than 400 in the geosynchronous (GEO) Earth orbit belt some 22,000 miles above Earth. GEO is home to more than 400 satellites, many of which deliver such essential services as weather reports, cell phone communications, television broadcasts, government communications and air traffic management.


By developing robotic capabilities to repair and refuel GEO satellites, NASA said it hopes to add years of functional life to satellites and expand options for operators who face unexpected emergencies, tougher economic demands and aging fleets. NASA also hopes that remote refueling technologies will help boost the commercial satellite-servicing industry that is rapidly gaining momentum.