'Everything we know about space travel is going to change within a decade': The fusion breakthrough that could unlock a path to the stars

Fusion-powered space travel has long held the promise of rapid trips across the solar system : Mars in weeks, Saturn in months, Pluto in years.

For decades, such possibilities have remained theoretical, like something plucked out of a science fiction novel. But several companies are now working to build practical nuclear fusion propulsion engines, with significant milestones being hit.

Pulsar Fusion, a U.K.-based startup, hopes to launch a demonstration mission to space in 2027, while Princeton University and Helicity Space in the U.S. are continuing their own work on fusion drives.

If any of these efforts prove successful, missions across the solar system for robots and humans could be unlocked like never before, turning us into a true spacefaring species.

"If we continue on the current trajectory, everything we know about space travel is going to change within a decade," Stephane Lintner , CEO and co-founder of Helicity Space, told Live Science.

But is it too good to be true? Can the dream of nuclear fusion propulsion ever be fully realized, or will it remain a sketchbook fantasy? After decades of dreaming, we might be on the cusp of finding out.

Nuclear fusion is a process whereby two atoms combine, or fuse, to form a heavier one, releasing excess energy in the form of light and heat. The best-known type of fusion is the process that occurs inside the sun at up to 27 million degrees Fahrenheit (15 million degrees Celsius), where atoms of hydrogen fuse to form helium.

If this process could be replicated on Earth, it would provide us with huge amounts of energy. "The holy grail is free energy for everyone," Lintner said. Entire cities and countries would be transformed, bringing about a new age of clean and abundant power.