A New Recipe for Rocket Fuel

Researchers are using aluminum and frozen water to make a propellant that could allow rockets to refuel on the moon or even Mars.

Last week researchers from Purdue University and Pennsylvania State University launched a rocket that uses an unconventional propellant: aluminum-ice. The fuel mix, dubbed ALICE, is made of nano-aluminum powder and frozen water, and gets its thrust from the chemical reaction between the ingredients. The propellant is environmentally friendly, and it could perhaps allow spacecraft to refuel at locations like the moon, where water has been discovered.

Using aluminum for fuel is not completely new–the space shuttle’s solid rocket boosters use a small amount of the metal, as will the National Aeronautics and Space Administration‘s Ares rocket. But the new work involves making aluminum one of the key ingredients by using nanoscale particles. These tiny particles, when ignited, combust more rapidly than larger particles, forcing more exhaust gases out of the metal and giving the rocket the necessary kick.

The oxygen and hydrogen in water molecules enhance the combustion of the aluminum. Freezing the propellant keeps it intact, avoiding any premature reactions.

The propellant was able to lift a rocket 396 meters during an August flight test, which was funded by NASA and the Air Force Office of Scientific Research. Now, for even better performance, the researchers are working on adjusting the ratios of different ingredients and possibly mixing the nano-aluminum with larger aluminum particles.

A water-based propellant might one day mean that spacecraft could carry less fuel when traveling to distant locations like the moon or even mars. But it would also be nice to have a “greener” fuel for rocket launches back on Earth.

One Response

  1. Here’s a couple of comments from that article’s page:

    396 meters = 1299 feet 2.5 inches. Methinks the rocket rose more or less 1300 feet and some PR flack did the metric conversion, adding false accuracy in the process. A round number like 400 meters might have been more truthful. Some verbiage on energy density versus standard fuels would have been nice, but the real issue is that any monopropellant that can’t be safely stored at room temperature is a (non)ticking time bomb. Even cryogenic fuels have the advantage of boiling off without spontaneous ignition. This stuff might be of interest to the Pentagon for time delay bombs, but as rocket fuel I consider it a curiosity.

    there are other options based on metals like magnesium and (it seems) salt water:

    http://www.ghostnasa.com/posts/007saltrocket.html

    however, I did not agree that an aluminum-water rocket is better and simpler for Moon or Mars ISRU refuel than a (much simpler) LOX/LH2 engine

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