The two projects, GRAIL and Rheform, form part of the EU Commission’s new framework programme Horizon 2020 in which European countries combine to transform scientific advances into innovative products. Two of the projects chosen have as their aim the development of more environmentally friendly fuel for rockets and spacecraft. FOI will be acting as coordinator for the GRAIL project which will be investigating the possibilities for development of a “green” solid rocket propellant.
“The solid propellant in use today is not good for the environment, not least because very large amounts of hydrochloric acid are produced when rockets are launched. This is harmful both in the atmosphere and on the ground since it gives rise to acid rain. There is also research that suggests that it can damage the ozone layer,” says Niklas Wingborg, an FOI research scientist and project leader for GRAIL at FOI.
The problem with today’s solid propellants is that they are based on ammonium perchlorate (AP). It is this that produces hydrochloric acid when it combusts. The GRAIL project will investigate whether, instead of using AP, it is possible to use the chlorine-free alternative ammonium dinitramide (ADN). The use of ADN as a component of rocket fuel is not new. It was discovered in Russia as long ago as the 1970s and it has been studied at FOI since the 1990s. But research takes time. There need to be methods for producing the substance, making it into particles and “baking” it in plastic to form a solid propellant. It is also necessary to arrive at a suitable mix of the various substances involved. That is the work that is now continuing within the framework of the GRAIL project.
The efforts to find alternative rocket propellants are being made on the initiative of the scientists involved; so far there is no concrete requirement to discontinue the use of today’s AP-based propellant. But many people are worried. Apart from the discharge of combustion products when rockets are launched, there are problems associated with manufacture. In the United States, for example, the local groundwater has suffered pollution in the area where the propellant is manufactured. Niklas Wingborg makes the point that it is by no means certain that in future it will continue to be thought acceptable to use AP as a rocket propellant.
It is true that some in the space industry voice the view that the number of rocket launches are so few in number that the discharge is relatively small when considered on a global basis. But Niklas Wingborg believes that this is a poor argument.
“If everyone maintained that their own impact was vanishingly small, there would be no cause to worry about the environment. All sectors of industry must take responsibility for their own actions. The space industry plays a pioneering role in technology as a whole, so perhaps it should take a similar lead in environmental technology in particular,” concludes Niklas Wingborg.