[Integza] was reading about a World War II-era rocket plane created near the end of the war by the Germans. The Heinkel He-176 wasn’t very practical, but he was intrigued when he read the rocket was cold and combustionless. He did a little research and found the engine was a monopropellent engine using hydrogen peroxide. This led to some interesting experiments and a 3D printed rocket engine, as you can see in the video below.
Usually, liquid-fueled rocket engines have a fuel and an oxidizer that mix and are either ignited or, in a hypergolic rocket, spontaneously combust on contact. With a monopropellent, the thrust comes from a chemical reaction between the propellant — hydrogen peroxide, in this case, and a catalyst.
Spaceflight is inherently dangerous. It takes a certain type of person to willingly strap into what’s essentially a refined bomb and hope for the best. But what might not be so obvious is that the risks involved aren’t limited to those who are personally making the trip. The construction and testing of space-bound vehicles poses just as much danger to engineers here on the ground as it does to the astronauts in orbit. Arguably, more so. Far more individuals have given their lives developing rocket technology than have ever died in the cockpit of one of them.
Reddish brown exhaust of hydrazine thrusters
Ultimately, this is because of the enormous amount of energy stored in the propellants required to make a rocket fly. Ground support personnel need to exercise great care even when dealing with “safe” propellants, such as the classic combination of kerosene and liquid oxygen. On the other end of the spectrum you have chemicals that are so unstable and toxic that they can’t be handled without special training and equipment.
One of the most dangerous chemicals ever used in rocket propulsion is hydrazine; and yet from the Second World War to the present day, it’s been considered something of an occupational hazard of spaceflight. While American launch vehicles largely moved away from using it as a primary propellant, hydrazine is still commonly used for smaller thrusters on spacecraft.
But soon, that might change. NASA has been working on a project they call the Green Propellant Infusion Mission (GPIM) which is specifically designed to reduce modern spacecraft’s dependency on hydrazine. In collaboration with the Air Force Research Laboratory at California’s Edwards Air Force Base, the space agency has spearheaded the development of a new propellant that promises to not just replace hydrazine, but in some scenarios even outperform it.
So what’s so good about this new wonder fuel, called AF-M315E? To really understand why NASA is so eager to power future craft with something new, we first have to look at the situation we’re in currently.
