The Direct Fusion Drive That Could Get Us to Saturn in Just 2 Years

Caroline Delbert

From Popular Mechanics

Experts say the right kind of propulsion system could carry spacecraft to Saturn in just two years. The direct fusion drive (DFD), a concept being developed by Princeton Plasma Physics Laboratory, would make extremely fast work of the nearly billion miles between Earth and Saturn.

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Researchers there say the Princeton field reversed configuration-2 (PFRC-2) drive could be the secret to feasible travel within our solar system.

The research team chose Saturn’s moon Titan as an ideal, well, moonshot. The #1 moon in our solar system has a great deal of scientific interest because of its surface liquids, and the fact that they’re hydrocarbons means Titan could even become a refueling waystation in some far future space highway system.

Universe Today reports:

“[T]he engine itself exploits many of the advantages of aneutronic fusion, most notably an extremely high power-to-weight ratio,” a press release reads. “The fuel for a DFD drive can vary slightly in mass and contains deuterium and a helium-3 isotope. Essentially, the DFD takes the excellent specific impulse of electric propulsion systems and combines it with the excellent thrust of chemical rockets, for a combination that melds the best of both flight systems.”

In a way, this is a lot like how hybrid consumer vehicles are designed. There are times when electric provides the best, most efficient push, and there are times when fossil fuels are still the most logical choice. The PPPL direct fusion drive is being studied in two modes: one where it thrusts the entire time, and another where, like a Prius, it thrusts to get up to speed at the beginning only. The trip to Titan changes from about 2 years to about 2.5 depending on the mode.

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The reactor itself is relatively small, because even a larger spacecraft for our current imagination is far smaller than family homes or businesses on the ground. “DFD employs a unique plasma heating system to produce nuclear fusion engines in the range of 1 to 10 MW, ideal for human solar-system exploration, robotic solar-system missions, and interstellar missions,” PPPL researchers wrote in 2019.

The plasma inside is heated to performance temperatures by radio waves, and like other rocket engines broadly, the design is open on one end in order to generate thrust as energy pushes out extremely rapidly.

For now, this design, as Universe Today jokes about all of nuclear fusion, is about 30 years away. That’s because the next good window to travel to Saturn’s satellites is in 2046, giving scientists at PPPL a concrete timeframe as well as a specific goal to work toward. And their DFD design has another major advantage: it can also power the ship’s internal systems.

That means propulsion and steering as well as life support and research aboard the ship will all run on the same energy efficient drive.

It will still be decades before anyone travels to the moons of Saturn. But when they do, the achievement will be . . . Titanic.

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