NASA has put out the call for greener propellant fuel for use on the spacecraft of the future. Though it does not appear that NASA has stipulated that alternative propellants must match the performance of current mainstay hydrazine, it's clear that only high-performance substances need apply. Environmental credentials are where the new fuel must demonstrate an edge over hydrazine, which is a corrosive, toxic pollutant. As well as the environmental benefits, use of greener propellants should prove more economical, reducing the need for involved safety procedures that can lengthen launch times.
Though not generally used as a fuel to put rockets in orbit, hydrazine has seen wide use as a monopropellant to power in-flight thrusters and course correctors that maneuver spacecraft such as Space Shuttle's auxiliary power units and the Phoenix spacecraft.
An inorganic chemical compound, hydrazine molecules are composed of two nitrogen and four hydrogen atoms (nitrogen hydride is another of the liquid's many names). It first saw use as a rocket fuel during World War II when the fuel was mixed in relatively small proportions with with methanol and water to power Messerschmitt Me 163Bs. That it can be stored for long periods is one trait that makes it appealing to NASA for science and exploration missions to this day, as well as for use in commercial and defense satellites.
But it's nasty stuff. Even short-term exposure can hospitalize people, with the US Environmental Protection Agency publishing one of those almost comical lists of symptoms of ascending severity that begins with eye irritation and dizziness and ends in seizures and comas. It must be handled with extreme care, which entails significant expense, and so there's little wonder that NASA wants rid of it.
NASA has come up with the Technology Demonstration Missions Program to help technologies that have proven themselves in the laboratory navigate the long path to mission readiness. Its through this program that NASA is seeking to foster the development of at least one green propellant, with one or more awards of up to US$50 million available to the most viable proposals.
If you have an idea for a green propellant that may be of interest to NASA, you have until April 30 to submit.