For a very long time, satellites orbiting the Earth have had a very finite lifetime. Some satellites have lasted over ten years, and aside from anomalies and failing components, a satellite’s fuel tank has been key to how long a satellite can function. But that might change soon for geosynchronous (GEO) satellites, thanks to RROxITT (Remote Robotic Oxidizer Transfer Test).
RROxITT is a step in NASA’s and the Canadian Space Agency’s (CSA) remote servicing satellite program. Specifically, RROxITT is the result of the Satellite Servicing Capabilities Office (SSCO) Satellite Servicing Technology Develop Campaign’s Robotic Refueling Mission (RRM) experiment. The SSCO is developing a remote satellite refueling system, not just for future GEO satellites, but for GEO satellites currently in orbit.
This is hard, because the GEO satellites orbiting the Earth weren’t really designed to have a robotic “gas station attendant” refuel them. But RRM already proved in early 2013 that a robotic servicing system could service existing orbiting satellites. Another challenge is the matter of the satellite fuel, which in this case, it isn’t. The key is in RROxITT’s name: oxidizer. In this case, the oxidizer is nitrogen tetroxide. Nitrogen tetroxide is nasty, toxic, and corrosive. However, it’s also part of a hypergolic combination, that, when mixed with the other part of fuel, combusts. When the resulting combustion is directed, it becomes the satellite’s thrust.
RROxITT is only part of the story. Argon is the other part, according to the SSCO website. Argon is all about “Rendezvous and Proximity Operations.” Those fancy words describe what the servicing robot must do before it refuels another satellite.
For it to refuel another on-orbit satellite, the servicing satellite must be able to get in that satellite’s vicinity, and then dock with it. Autonomously. As in, no human hands will be guiding the servicing satellite to dock with the other satellite. Considering the oxidizer on board, it’s probably safer for everyone that way.
If you want to see a video about what all the fuss is about, then watch this.
The SSCO is currently in Phase 2 of the RRM tasks and projected to complete Phase 2 sometime in 2015. No one has clarified whether the person who named RROxITT is a Herbie Hancock fan.