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.

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 and xenon in space.

The mission is scheduled to launch to the space station in early 2018 aboard the SpaceX Commercial Resupply Services Mission 14 (CRS-14). It has a projected two-year life on the space 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 Cryogen and Xenon?

Cryogen and xenon are both important consumables for long duration space travel.

A cryogenic fluid can be used to keep critical optical equipment cold and operational, or be used as a potent, high-thrust propellant. Xenon produces a much lower thrust than cryogenic propellants such liquid as oxygen, methane, and hydrogen. Solar Electric Propulsion (SEP) utilizes xenon as its propellant, and this propulsion technique is low-thrust but tremendously efficient. For long journeys, an efficient propellant like xenon is useful because it means a spacecraft does not need to be burdened by transporting as much fuel, or having as large of a fuel tank. However, xenon does not produce a high enough thrust, or what is essentially acceleration, to successfully leave planetary bodies, because of gravitational pull.

To leave a planetary body like the Moon, or Mars, a chemical or cryogenic propellant is needed to produce a high thrust to allow a rocket to successfully escape the body's orbit. Tug spacecraft that will transport cargo to Mars will operate in a zero-gravity environment away from planetary bodies, so fueling them with an efficient propellant like xenon is ideal for that long journey.

RRM3 will test and hone the ability to transfer these two commodities so they are 'ready for primetime' when needed.


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, tugs powered by Solar Electric Propulsion (SEP) and used to transfer cargo to the Red Planet could be refueled with xenon, and sent on another round trip. Additionally, storing cryogens long-term is a prerequisite for getting to Mars. RRM3 will demonstrate both of these capabilities.

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. Hydrogen and oxygen are types of cryogens, so the ability to transfer and replenish them in space will be critical to this operation.

RRM3 Primary Objectives

RRM3 Secondary Objectives

What's in and on the Module?

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