The “dynamic levitation” trick can accelerate spacecraft through interstellar space

Sailing to the stars on a human scale can be a matter of choosing the right kind of wind.

Researchers from McGill University in Canada and the Tau Zero Foundation in the US have proposed a new way to cross the extraordinary distances of interstellar space, using lots of nothing and a touch of inspiration from seabirds.

To date, one of the most promising solutions for space travel uses the spectrum of starlight streaming from the Sun. Although their effect is small, their sheer numbers and high speeds make photons an intriguing source of energy to build the high speed needed to cross light-years of space in a short time.

Innovations in solar sail technology have evolved dramatically over the years, as models have been tested in the hostile environments of our inner solar system.

Although functional, sun sails have a common downside: the sail itself. The solar sails must extend to meters to capture the photons needed to propel the craft.

They also need the right shape and material to convert a small part of the photon’s momentum into motion. And they need to conduct heat well enough so that they don’t deform and break.

This isn’t just a materials science headache; All of these requirements add up to mass. Even using the lightest materials known, the fastest speeds we might achieve using our sun’s radiation would be just over 2% of the speed of light, which means the journey to the nearest star would take a few centuries.

It goes without saying that sailing to the stars would be a lot easier if we could get rid of the sails part.

Fortunately, another type of storm is blowing from the sun’s surface, one made not of photons but of a plasma of ions being driven mad by the crackling of the sun’s magnetic fields.

Although there are far fewer high-speed electrons and protons shooting off the Sun than photons, their charged masses contain more power.

These particles are usually a problem for typical sails, as they transfer their charge over the surface of the material as if it were fixed to a pullover in winter, causing it to drag and change the shape of the sail.

However, as anyone who has tried to push the poles of a magnet together knows well, an electromagnetic field can provide resistance without the need for a large solid surface.

Goodbye shiny material, hello superconductor. Theoretically, a cable a few meters long could produce a field wide enough to deflect the charged winds of the Sun on a scale of tens to hundreds of kilometres.

The system will act more like a magnetic parachute, pulled in by a stream of particles moving at nearly 700 kilometers (about 430 miles) per second, or just under a quarter of a percent of the speed of light.

That’s not bad, but as birds like the albatross know, the wind doesn’t set speed limits when it comes to flying high.

By entering and exiting air masses moving at different speeds, seabirds can capture the energy of headwinds, using what is known as dynamic hovering to gain speed before returning to their original trajectory.

Using a similar trick in the terminator’s “headwinds”—a turbulent region of contrasting stellar winds that astronomers use to mark the edge of our solar system—the magnetic sail could exceed the velocities of the solar wind, potentially making it accessible to solar sails that rely on radiation alone.

Although this technique may not initially seem much faster than the method of “traditional” solar sails, other forms of disturbance at the fringes of interstellar space may provide an even bigger boost.

Even without a slight nudge from dynamic altitude, feasible plasma-based technology could put cubic satellites around Jupiter in a matter of months rather than years.

Like the ancient age of sail, there are plenty of ways we might be able to take advantage of the currents that wash across the vastness of space.

However, seabirds show us the way.

This research has been published in Frontiers in space technologies.

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