Last year, 87 rockets went orbital. Each of these rockets was fueled by a propellant, and despite the wide variety of rocket propellants available, none of them are exactly what you’d call environmentally friendly. While the impact of astronautics might seem negligible when compared with other sources of emissions, NASA is nevertheless taking the environmental impact of space travel seriously.
To this end, the agency created the Green Propulsion Infusion Mission (GPIM), which will launch a small satellite into orbit in early 2017 to test out a new “green” alternative to the rocket propellants currently being used.
The propellant, known as AF-M315E, is a hydroxyl ammonium nitrate based fuel/oxidizer blend developed by the US Air Force at the Edwards Air Force Base in California. According to NASA, this new fuel offers a number of advantages over the hydrazine-based fuels currently in use.
Although the space industry’s impact on Earth’s environment is still negligible, by some estimates it isn’t likely to remain this way for long
In the first place, it is less toxic and safer to handle than hydrazine propellants, which will lower launch processing times and thereby decrease in mission costs. It is also more efficient than hydrazine. According to NASA, because AF-M315E is denser than hydrazine, it offers a 50 percent increase in a spacecraft’s maneuvering capability for the same volume of propellant. Moreover, it offers a higher thrust for a given amount of fuel and has a lower freezing point, meaning less of a spacecraft’s energy needs to be devoted to maintaining its temperature.
According to the agency, the GPIM mission just passed a crucial flight readiness test by successfully completing functional and environmental hardware and systems tests. When GPIM is ready for the real deal, it will fly to space aboard a small satellite developed by Ball Aerospace. The flight tests will seek to prove that AF-M351E is a viable alternative to current rocket propellants by using it for altitude control maneuvers and changing the satellite's orbital inclination.
Ultimately the agency hopes that the new greener propellant will provide “NASA and the commercial spaceflight industry…a viable, effective solution for future green propellant-based mission applications.”
GPIM concept art. Image: NASA
Although the space industry’s impact on Earth’s environment is still negligible, by some estimates it isn’t likely to remain this way for long—a 2011 study by the Aerospace Corporation estimated that there may be as many as 1000 annual suborbital launches by 2020, which would have a significant impact on Earth’s environment.
Now that we are approaching 2020 and are still launching under 100 rockets a year, the Aerospace Corporation’s predicted 1000 annual rocket launches seems unlikely. Yet with the advent of reusable rockets and other technological breakthroughs in space flight, it is unquestionable that the number of rocket launches is poised to explode in coming decades.