WASHINGTON — A latest NASA mission efficiently demonstrated the efficiency of a non-toxic “inexperienced” propellant, creating alternatives for its use in a variety of future spacecraft.
NASA flew the Inexperienced Propellant Infusion Mission (GPIM) spacecraft as one of many payloads on the Area Check Program 2 mission that launched on a SpaceX Falcon Heavy in June 2019. The spacecraft’s mission ended when it reentered in October 2020 after a collection of deorbiting maneuvers.
The aim of GPIM was to carry out an in-space demonstration of a inexperienced propellant developed by the Air Drive Analysis Laboratory (AFRL) referred to as AF-M315E. That propellant was designed to have efficiency just like hydrazine, generally used on spacecraft, however with out the toxicity and dealing with points related to hydrazine.
The spacecraft met its efficiency objectives, stated Trudy Kortes, program director of expertise demonstrations in NASA’s Area Know-how Mission Directorate (STMD), throughout a panel dialogue in regards to the mission throughout this month’s SciTech Discussion board by the American Institute of Aeronautics and Astronautics. That included a “stretch purpose” of pulsing the thrusters greater than 10,000 occasions.
The flight was the end result of a long time of labor on growing and in the end flight-testing this inexperienced propellant. “We had been considering that perhaps as early as 2002 we might do a demo of this propellant,” recalled Jeff Sheehy, chief engineer at STMD who beforehand labored on superior propellants like AF-M315E at AFRL. “On reflection, after all, we had been manner too optimistic about how lengthy it takes to get a brand new propellant to the purpose the place it’s able to exhibit.”
A part of that work concerned testing how the propellant interacted with varied supplies. “We had a long time of expertise with hydrazine with completely different supplies, however we had no concept how these items was going to behave,” stated Joe Cassady, government director of area applications for Aerojet Rocketdyne’s Washington workplace. Aerojet developed the propulsion system flown on GPIM that used AF-M315E. Some supplies, he stated, needed to be modified as a way to use the inexperienced propellant.
Engineers additionally needed to take a look at how the propulsion system would work together with different spacecraft techniques. Not like hydrazine, AF-M315E created a major quantity of water as a byproduct. That created considerations the water might deposit on optical surfaces on the spacecraft, like star trackers, stated Chris McLean, principal investigator for GPIM at Ball Aerospace, requiring modeling and testing on the bottom earlier than flight.
With the propellant efficiently examined, these concerned with the mission are optimistic in regards to the its potential for future missions. It additionally has a brand new, easier-to-remember title: Superior Spacecraft Energetic Non-Poisonous, or ASCENT.
Adam Model, superior propellant growth lead at AFRL, stated his group is variants of ASCENT. “We contemplate ASCENT a household of propellants,” he stated. “There are completely different blends for various functions, several types of missions.” Since ASCENT is a liquid salt, he stated one potential use of the propellant is in a sort of electrical propulsion system referred to as an electrospray thruster.
Cassady stated Aerojet is utilizing its GPIM to develop over thrusters that use variations of ASCENT, with a specific give attention to smallsats. One instance is a system that matches into one unit of a cubesat. “Should you had a 3U cubesat, you possibly can connect this to it, take up one of many three items, and have 2U out there for the payload,” he stated. A bigger model is designed for 12U cubesats.
He stated smallsats current a possibility for inexperienced propellants, since they’ll allow smallsats to fly propulsion techniques with out much less overhead than those who use propellants like hydrazine. “The decrease toxicity performs into this,” he stated, particularly for smallsats flying as secondary payloads. “By having a low-toxicity propellant, that permits lots smoother course of for getting approvals.”
It might additionally simplify spacecraft launch preparations. “It’s a possibility to gasoline the spacecraft on the producer’s facility and take it out to the launch pad and simply pressurize the tank,” McLean stated. ASCENT keep away from the problems related to transport a hydrazine-fueled spacecraft, and is earlier to take care of typically. “There’s all these intangibles related to dealing with the gasoline.”
Panelists stated there could also be extra unique makes use of of the gasoline, from ideas for Mars missions that profit from ASCENT’s tolerance to low temperatures to make use of in missiles. “Now we have no less than 5 completely different clients we’re within the means of constructing this sort of expertise for,” Cassady stated. “We’ll see it flying within the subsequent two to a few years on most of these missions.