MFT2 tool for Dextre operation (Figure from: NASA, via)New Atlas)
Up to now, any space mission must carry enough fuel to terminate its mission when it is launched. But that means the spacecraft must add extra weight, sometimes even as expensive as the boosters needed to put it into space.
On the one hand, NASA's Artemis mission will use a larger rocket than the classic Saturn 5, which will be extremely expensive. On the other hand, the duration of the satellite mission is severely limited by the fuel storage tanks it carries. Once exhausted, the satellite must be scrapped.
Considering the volume and cost, the on-orbit fuel injection scheme is very necessary. Depending on actual needs, agencies can launch rockets like a smaller one, or collect elements from the moon or even nearby asteroids, and then transport cryogenic propellants into space.
Since 2018, RRM3 has been installed alongside Canadian Dextre robots outside the International Space Station. Researchers have been working on how to transfer cryogenic liquids to satellite tanks and how to store them for months without boiling.
RRM3 Ground Operations Team at Goddard Space Flight Center (Fig.NASA)
According to NASA, when a failure occurs that requires fuel to be discharged, it has to abandon cryogenic tests using liquid methane. Since then, the project team has focused on the tools used in the transfer.
Specifically, they are coolant maintenance tools for connecting source and receiving tanks, multi-functional tools for operating cryogenic transfer adapters (MFT2), and visual inspection rotary robots (VIPIR2) for detecting proper transfer of refrigerants between tanks.
To this end, Dextre undertakes the task of taking out the refrigerant coupling adapter using MFT2 and putting it into the adapter port, and then RRM3 module takes over the remaining refueling tasks.