One of the pressing problems hindering human spaceflight is the need for speed. Using chemical rockets available or in development, Mars is about the outer limit for human space exploration. Even so, Mars is a two to three year round trip with the hazards of microgravity and radiation waiting to threaten the lives of astronauts. A company called Princeton Satellite Systems aims to change all of that with something called small fusion propulsion.

How does small fusion propulsion work?

Unlike some of the immense fusion reactors being developed to deliver clean, limitless energy, Princeton Satellite Systems is building a version that will be just less than five feet in diameter and 13 to 26 feet long, weighing 11 tons.

The reaction would involve heating deuterium with helium 3 with low-frequency radio waves and then contain the resulting plasma with a magnetic field. According to, the plasma would be directed out the nozzle of the engine, creating an immense amount of thrust.

Two problems face this futuristic rocket engine concept. The fusion reaction creates a small amount of neutron radiation and X-rays, so shielding is going to be necessary. Also, Helium 3 does not exist in nature on Earth. The isotope will either have to be created in nuclear reactors on Earth or mined from the moon where it resides in abundance.

What could the new engine do?

The t that could be done in space if the 10-megawatt small fusion rocket engine becomes a reality is breathtaking. Mars becomes a 310-day round trip, cutting down on the exposure to radiation and microgravity the astronauts will be subjected to, not to mention a number of consumables required.

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A probe to Pluto, which took almost a decade to accomplish with the New Horizon mission, would take four years and would involve a lander and an orbiter to study the once and future ninth planet long term. Deflecting a killer asteroid would be just a matter of sending one of these engines to push it out of the way.

When will a fusion drive be ready?

Princeton Satellite Systems believes that it can execute a fusion reaction in about two to three years, using the funding it is getting from NASA. If the company is successful, the date of the first fusion ship from Earth is likely only a matter of financing. It might even be ready in time for the space agency’s Journey to Mars, whatever shape it takes after a couple of decades of technological development, not to mention political twists and turns that wave rolled space development in recent years.