Project Icarus is an ambitious five-year study into launching an unmanned spacecraft to an interstellar destination. Headed by the Tau Zero Foundation and British Interplanetary Society, a non-profit group of scientists dedicated to interstellar spaceflight, Icarus is working to develop a spacecraft that can travel to a nearby star.

Adam Crowl, Module Lead for Fuel and Fuel Acquisition for Project Icarus, investigates the pros and cons of various fusion fuels required to accelerate an interstellar vehicle to a nearby star.

One might think that fusion propulsion requires some exotic fuel to propel a rocket a million-or-so-times more energetically than standard chemical fuels. However, one fusion fuel option isn't so exotic.

In fact, by drinking the recommended 8 glasses of water per day you've ingested about half a pound of the stuff: hydrogen. One-ninth of all water on Earth is hydrogen. But there's a snag in its widespread adoption as a fusion fuel.

Regular hydrogen fuses very, very slowly even in a place as unimaginably hot as the center of the sun. That's fortunate for all life on Earth -- because that's what allows stars to shine for billions of years -- but it does make it a very difficult fusion fuel to utilize.

But there's an answer: Add a neutron to the single proton in the heart of every hydrogen atom and you have deuterium, also known as "heavy hydrogen."

Good luck with that one.  To read the rest of the article, click here.