Robotic Refueling Mission leaves ISS
After a six-year stay attached to the International Space Station (ISS), NASA’s Robotic Refueling Mission (RRM) payload made its way back to Earth on March 19, 2017, to burn up in the atmosphere inside the trunk of SpaceX’s CRS-10 Dragon spacecraft.
Launched in 2011 on the final Space Shuttle flight, Atlantis’ STS-135 mission, RRM was a multi-phased demonstration mission that developed technologies and techniques to remotely refuel and service satellites in space.
RRM was washing machine-sized box covered with activity boards and had four tools stowed inside that could be “grabbed” and used by the station’s Special Purpose Dexterous Manipulator, also known as Dextre.
The technologies, tools, and techniques studied on this mission could eventually give satellite owners the resources to diagnose problems on orbit, fix anomalies, and keep certain spacecraft instruments performing longer in space.
“Our team worked very hard to develop the suite of RRM tools and experiments and are extremely pleased to see what they accomplished,” said Ben Reed, the deputy division director for the Satellite Servicing Projects Division (SSPD), which operates out of NASA’s Goddard Space Flight Center.
RRM had to be removed to make way for Raven, an experiment that will test autopilot technologies for future spacecraft. It was launched on Feb. 19, 2017, aboard CRS-10. Both were developed by the SSPD, the same division that developed astronaut tools for the Hubble servicing missions.
The mission was created by a group of engineers at Goddard who were concerned about how future spacecraft would be serviced after the absence of the Space Shuttle. Led by Frank Cepollina, the “father of servicing” and previous director of the SSPD, the team determined the future of servicing would rely on robotics. They decided to use the ISS as a test bed.
“The space station is on-orbit and already has a robot,” said Cepollina. “Space station was tailor-made for RRM and worked beautifully as a test bed for servicing.”
It took the team 18 months to design and build RRM, just in time for Atlantis’ final launch on July 8, 2011.
Once Atlantis was docked to the ISS a couple days later, RRM was transferred to a temporary platform during a spacewalk by NASA astronauts Mike Fossum and Ron Garan. It was the last payload to be removed from a Space Shuttle payload bay by an astronaut.
In September 2011, the station’s robotic Canadarm2, with Dextre attached, transferred RRM to its permanent location on the space station: ExPRESS (Expedite the Processing of Experiments of the Space Station) Logistics Carrier 4, located on the Earth-facing side of the S3 truss segment.
During the operations of phase 1 of the mission, flight controllers on the ground at Goddard remotely commanded Dextre to reach into the RRM module and pick up tools to use on the experiments activity boards.
The mission’s tasks included cutting and peeling back thermal blankets, unscrewing multiple caps, and accessing valves to transfer a simulated satellite fuel.
In January 2013, RRM confirmed that current robotic technology could refuel a triple-sealed satellite valve by transferring 1.7 liters of ethanol.
For Phase 2, hardware delivery was split into two batches, which occurred in August 2013 and August 2014. Two new task boards and a new tool were sent to the space station.
These task boards demonstrated activities that would occur during the servicing of a free-flying satellite. The tool that was sent up, the Visual Inspection Poseable Invertebrate Robot or VIPIR, was a state-of-the-art near and mid-range inspection tool using an articulable, “snake-like” borescope.
The team is currently designing and developing equipment for a third phase of the mission that will be launched sometime in the future. It will focus on servicing cryogenic fluid and xenon gas interfaces, which will support future scientific missions into the Solar System.
According to NASA, the RRM was an “essential bridge” between the crewed Hubble servicing missions and future robotic servicing that will be demonstrated on the Restore-L mission, a free-flying spacecraft designed to rendezvous and repair satellites.
“Space station was a wonderful facility to test our technologies, and we know that RRM’s departure will make room for another great experiment,” said Jill McGuire, RRM project manager. “We are proud of what we accomplished with RRM, and are excited to contribute to the next stages of enabling robotic satellite servicing.”
Video courtesy of NASA
Heather Smith's fascination for space exploration – started at the tender age of twelve while she was on a sixth-grade field trip in Kenner, Louisiana, walking through a mock-up of the International Space Station and seeing the “space potty” (her terminology has progressed considerably since that time) – she realized at this point that her future lay in the stars. Smith has come to realize that very few people have noticed how much spaceflight technology has improved their lives. She has since dedicated herself to correcting this problem. Inspired by such classic literature as Anne Frank’s Diary, she has honed her writing skills and has signed on as The Spaceflight Group’s coordinator for the organization’s social media efforts.