Robotic Refueling Mission 3  -  Advancing Servicing Technologies and Driving Exploration RRM phase 1 and 2

Satellites use consumables like propellant and coolant to perform key functions such as maneuvering and maintaining optical equipment. Consumables, by their very nature, eventually run out. The technology to replenish these crucial supplies in space does not currently exist. NASA's Robotic Refueling Mission 3 (RRM3) will help change that paradigm, advancing satellite servicing capabilities and enabling long duration, deep space exploration.
RRM3 Fluid Transfer Module before launch

RRM3 Fluid Transfer Module before launch

Mission Overview

RRM3 builds on the first two phases of International Space Station technology demonstrations that tested tools, technologies, and techniques to refuel and repair satellites in orbit. RRM3 will demonstrate innovative methods to store, transfer and freeze standard cryogenic fluid in space.

The mission is scheduled to launch to the space station in 2018. It has a projected two-year life on station, though NASA intends to accomplish RRM3's objectives within the first year. RRM3 is developed and operated by the Satellite Servicing Projects Division at NASA's Goddard Space Flight Center in Greenbelt, Maryland, under direction of NASA's Space Technology Mission Directorate.

What Are Cryogenic Fluids?

Cryogen is an important consumable for long duration space travel, and for maintaining optical equipment and hardware cool.

A cryogenic fluid can be used to keep critical optical equipment cold and operational, or be used as a potent, high-thrust propellant. In its application as a coolant, cryogenic fluid is useful in satellite servicing in that it can be replenished to extend a satellite's lifespan.

As a propellant, cryogenic fluids such as liquid methane and liquid hydrogen are useful for long distance journeys because they produce enough thrust, or what is essentially acceleration, to successfully leave planetary bodies. Without a powerful enough propellant, a planetary body's gravitational pull would prevent a rocket from successfully escaping the body's orbit.

Liquid oxygen, another cryogenic fluid, is also used to maintain life support systems for astronauts, since it is a more efficient way to transport and store oxygen than in its gaseous form.

RRM3 will test and hone the ability to transfer and replenish cryogenic fluid so the technology is 'ready for primetime' when needed.


Artist's concept of Restore-L. Credit: NASA

Application to Satellite Servicing and the Restore-L Project

RRM3 demonstrations will also further develop twelve individual technology elements that are directly applicable to Restore-L, a project that aims to prove the combination of technologies needed to robotically service a satellite in orbit. These technologies range from robotic tools, to fluid transfer systems, to a high-speed processor called SpaceCube 2.0.

Enabling Human Exploration throughout the Solar System

The ability to resupply propellant and coolant enables longer journeys than a single tank of propellant would allow. The capabilities NASA will develop through RRM3 can thus be applied to future human exploration missions.

In the context of the Journey to Mars, RRM3's cryogen replenishment techniques could also be used to refuel spacecraft that arrive at Mars through In-Situ Resource Utilization (ISRU). Using this method, the carbon dioxide in Mars' atmosphere could be converted into liquid methane (a cryogenic propellant) and used to refuel a Mars departure rocket. Propellant saved using RRM3's established replenishment method would allow future manned missions to use that cargo mass for other necessary supplies.

Capabilities developed through RRM3 may also be applied to future lunar missions. When mining the moon for water, the hydrogen and oxygen can be separated, then used as fuel, meaning less fuel is required to be launched from Earth. Liquid hydrogen and oxygen are types of cryogens, so the ability to transfer and replenish them in space will be critical to this operation.

Finally, for long duration space travel, spacecraft transporting astronauts will need to store liquid oxygen to maintain life support systems. Having the ability to replenish these supplies frees up cargo mass for other supplies, making longer journeys possible. Additionally, any future habitats for humans will also require large and replenishable supplies of liquid oxygen.

RRM3 Primary Objectives

RRM3 Secondary Objectives

What's in and on the Module?

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Goddard Space Flight Center