Can We Get To Mars Using a Spacecraft Powered With Ordinary Water?

The demand for a more sustainable and accessible fuel for spacecraft has prompted a research team, led coordinated by the University of Bologna, to adapt a fuel that is at once readily abundant, not only on Earth but throughout the cosmos, while at the same time being non-toxic to the point that generations of children have already been using the fuel for toy rockets for generations: ordinary, everyday water.

The team, led by Fabrizio Ponti, a professor with the University of Bologna’s Department of Industrial Engineering, is looking to adapt ordinary H2O as a fuel source for plasma rockets in what they call a Water-based Electric Thruster (WET). Unlike chemical rockets, plasma thrusterscan operate for long periods of time, potentially allowing them to build up a great amount of speed through a long period of acceleration. They differ from ion engines in that they don’t require high-voltage grids to accelerate the ionized fuel, instead using the magnetic energy within the plasma itself to generate thrust.

In a WET engine, the water fuel is subjected to extreme heat, typically generated by radio-frequency or microwaves, that converts the fluid into plasma, a highly-conductive blob of free hydrogen and oxygen atoms. Since the process causes each atom to lose at least one electron, the entire mass becomes ionized. From there, the plasma, highly magnetized from its ionized state, is accelerated out of the engine via a magnetic nozzle to produce thrust.

“Thanks to water, an eco-friendly and versatile propellant, unprecedented possibilities for deep-space exploration could open up, with particular attention to economic and environmental sustainability,” Ponti remarked in a press release.

Although the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) isn’t being developed by Ponti’s team and doesn’t run on water, the experimental engine produces thrust that could potentially cut the travel time for a trip to Mars from two-and-a-half years down to five months, according to a claim made in 2010 by NASA Administrator Charles Bolden. Replacing such an engine’s typical diet of hydrogen with water means that a spaceship powered by these thrusters could be refueled from water deposits on the Moon, Mars, or Enceladus—needless to say, water is extremely abundant throughout the Solar System.

Although they offer advantages over both chemical rockets and ion thrusters, plasma engines still have a number of engineering challenges, most notably the megawatt-level power that would be required for a manned expedition to Mars. However, more modest thrusters mounted on small satellites could be scaled down to run on just a few hundred watts, and prevent the release of toxic propellants such as hydrazine into the atmosphere if the spacecraft were to suffer reentry.

“The WET project is not just about developing an innovative technology but also about creating a new vision for the future of space exploration,” Ponti added. “Thanks to collaboration between world-class institutions, we can imagine a future where access to space becomes increasingly sustainable and democratic, opening new opportunities for research and industry.”