NASA’s Robotic Refueling Mission 3 (RRM3) completed an initial set of tool operations designed by the Satellite Servicing Projects Division, making the idea of using water ice, oxygen or methane from other worlds as fuel for spacecraft seem plausible. The ability to store and transfer cryogenic fuels will help enable interstellar voyages in the far future.

Currently, any spacecraft to far away destinations such as the Moon and Mars must carry all of its propellants with it from launch to termination. This requires the spacecraft to carry more weight and the boosters needed to put them in space must be just as proportionally large.

refuel spacecraft in space

Robotic Refueling Mission 3’s Multi-Function Tool 2, operated by Dextre, demonstrates robotic refueling operations on the outside of space station.
Credits: NASA

Ability to Refuel Spacecraft in Space

Keeping cryogenic fuels at extremely low temperatures is vital. If the tank heats up, the fuel could boil off and be lost. NASA had to learn about this the hard way in April when a hardware issue during a Refueling Mission caused the cryogenic tanks to heat up unexpectedly and the gas had to be released.

fuel spacecraft in space

The RRM3 team manages operations from the Goddard Satellite Servicing Control Center at NASA’s Goddard Space Flight Center in Greenbelt, MD.
Credits: NASA/Taylor Mickal

“NASA’s proven experience and unique facilities are helping commercial companies mature their technologies at a competitive pace,” Jim Reuter, associate administrator of NASA’s Space Technology Mission Directorate (STMD) said in a NASA statement. “We’ve identified technology areas NASA needs for future missions, and these public-private partnerships will accelerate their development so we can implement them faster.”

RRM3 launched into the International Space Station in December 2018. It demonstrated the longest storage of fuel without loss due to the process called boil off. Special coolers within RRM3 kept the liquid cold for four months.

Green Fuel in Space

NASA spacecraft may even use ‘green fuel’ one day. Unlike hydrazine, which is toxic to people and extremely difficult to handle, NASA’s Green Propellant Infusion Mission (GPIM) is a less toxic alternative. The ‘green fuel’ was developed by the Air Force Research Laboratory.

“Spacecraft could be fueled during manufacturing, simplifying processing at the launch facility, resulting in cost savings,” explained Christopher McLean, principal investigator for GPIM at Ball Aerospace of Boulder, Colorado. The company leads this NASA technology demonstration mission.