Case Study

NASA's Satellite Refueling Mission Bound for Space

Case Study: NASA's Satellite Refueling Mission Bound for Space


Since the initiation of the Robotic Refueling Mission (RRM) in 2009, NASA's team has been working hard developing the right set of tools and technologies that would extend satellites' lifespans, thus saving money while reducing orbital debris. Three RRM operational phases were executed to demonstrate a set of satellite servicing and refueling tasks. During phases one and three, specialized rotary unions were required to reliably transfer cryogenic fluid from a source tank through a sophisticated robotic fueling hose to a receiver tank.


DSTI's sales and engineering teams worked directly with NASA engineers to develop a custom-engineered rotary union solution for the RRM's first phase. During testing the union was subjected to the same vacuum and temperature extremes (as low as -310°F) that it encountered during its mission. In 2013, mission controllers successfully performed phase one - a first-of-its-kind demonstration of transferring a simulated fuel in space.

In preparation for the third and final RRM phase (scheduled to launch to the International Space Station in 2018), revisions to the rotary union design were required. DSTI engineers developed a revised, space-ready rotary union based off lessons-learned, equipment refinements, and test results from earlier prototypes.


DSTI provided NASA with two custom rotary union designs for RRM phase one and three. The first union performed very well in all tests and during the 2013 RRM mission. Under maximum pressure conditions, the rotary union operated with almost zero parasitic torque.

All of this work is leading up to the 2020 Restore-L mission, an endeavor to launch a robotic spacecraft to refuel a live satellite. Successful completion of the mission will demonstrate that servicing and refueling technologies are ready for incorporation into other NASA missions as well as allowing commercial entities to help jump-start a new domestic servicing industry.

Results Overview

  • Specialized sealing material and surface finishes suitable for transferring cryogenic fluid
  • Allows refueling hose to freely rotate during robotic positioning
  • Open communication and transparency throughout the process contributing to mission success
  • All required documentation delivered upon shipment
Shortly after investigating commercially available rotary unions, I soon realized this application would require a custom design. I began searching for suppliers who not only would be able to meet our strict application requirements but also be willing to provide supporting documentation, certifications, traceability paperwork and quality assurance.

In the end we choose DSTI because of their willingness to work with our unique design and budget and their transparency in providing technical information - which we value highly.

I have nothing but positive things to say about the team at DSTI. They have been incredibly accommodating and flexible in incorporating design revisions to meet the requirements needed by our engineering test division.
Matt Ashmore Satellite Servicing Projects Division at NASA

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