How green is your ROCKET FUEL?

NASA is plotting the end of the hydrazine era, and has announced some successful tests of “green” propellants to replace it.

Hydrazine, which has burned beneath bloody big rockets since World War Two, produces decent thrust, but it's toxic and difficult to handle.

So, as the space-boffins explain here, a “green” alternative wouldn't just be kinder to the environment, it would also be easier to handle and cheaper to store.

In that ongoing project, the space agency's Tracy McMahan of the Marshall Space Flight Center writes that NASA has conducted “hot-fire tests” of AF-M315E (based on hydroxylammonium nitrate), and LMP-103S (based on the oxidizer ammonium dinitramide).

McMahan writes that AF-M315E is slated to get flight-tested in the Green Propellant Infusion Mission (GPIM).

While that mission will use conventional rockets to hoist a small satellite, but AF-M315E will be used to provide manoeuvring thrust. That mission is set down for a 2016 launch, and as is noted on the mission page, while the new propellant is more dense than hydrazine (meaning the satellite can carry more and manoeuvre for longer), it burns hotter, which means new metal components have to be developed for the thrusters.

The GPIM propellant tests used 1 Newton and 22 Newton thrusters, with five of the 1 Newton versions to be installed on the satellite.

NASA infrared image of a 22-Newton hot-fire test

The other propellant, LMP-103S, got tested on 5 Newton and 22 Newton thrusters, but there's no word on how far that propellant has progressed towards deployment.

AF-M315E was developed by the Air Force Research Laboratory, while LMP-103S came from work at Swedish chemical company Eurenco Bofors. ®