NASA's Replacement for Hydrazine?
NASA is developing a new type of fuel that would act as an environmentally friendly replacement for Hydrazine. This new fuel is safer to handle, easier to use, and lasts longer, allowing the spacecraft to remain operational for longer periods of time. This new fuel goes by the name AF-M315E.
Recently launched on SpaceX’s Falcon Heavy rocket, the Green Propellant Infusion Mission, or GPIM, will prove the real life applications of using this fuel as an alternative to other monopropellant fuels. This payload is being flown on a SmallSat manufactured by Ball Aerospace. During this flight, they will be conducting different orbital maneuvers to show the performance of the fuel in orbit.
Right now, the handling and storage of monopropellants such as Hydrazine, are very difficult and have strict procedures by NASA and their partners. Hydrazine has vapors that are toxic to humans and makes it an extremely dangerous environment to be in if you aren’t properly protected. This means that there’s a lot of prep time for large crews to get suited up and go through all the safety measures before handing and fueling Hydrazine into a spacecraft. With this new fuel, it has fewer handling restrictions and can be worked with in short sleeve shirts, instead of a full suit and mask like Hydrazine. This helps lower the amount of people needed to work with it and lowers processing times - ultimately lowering the cost of use.
` Having this green fuel instead of Hydrazine can also help reduce how much electricity you use on the spacecraft. You have to constantly warm Hydrazine so it doesn’t freeze, because it contracts and superpacks, so there is more than can fit through the plumbing when thawed and can cause damage. With this fuel, is doesn’t freeze into crystals, but turns into a glass. This substance can then be thawed and used again with no issues, meaning a heater doesn’t have to be run all the time to use the fuel, but only ran when needed. This drastically reduces the amount of electricity used and allows smaller batteries, or power to be allocated to more important instruments. The fuel stays usable for over 10 years if kept cold and still meets standards when unthawed for use.
The AF-M315E fuel is also nearly 50% more dense than Hydrazine, so you can fit more fluid into a larger tank or use smaller tanks that can hold the same a large tank of Hydrazine would. Think of it like having a smaller fuel tank in your car, but having the same range. It also offers a higher specific impulse, or “thrust delivered per given quantity of fuel”, which allows a 50% increase in maneuvering capabilities and helps save fuel for longer use.
While this fuel costs a little more than Hydrazine, the cost benefits are worth it in the long-term use of the fuel as it needs less people to hire and has lower processing times with spacecraft. All-in-all, this new fuel could become the replacement for Hydrazine and extend the use of satellites as well as make them more compact and efficient.