Sailing to the stars on the scale of human lifetimes could be a matter of choosing the right type of wind.
Researchers from McGill University in Canada and the Tau Zero Foundation in the United States have come up with a new way to traverse the extraordinary distances of interstellar space, using lots of nothing and a dash of seabird inspiration.
One of the most promising solutions for space travel so far uses the spectrum of starlight from the Sun. Although their impact is small, their numbers and high velocities make photons an intriguing source of energy for accumulating the high speed needed to cross light-years of vacuum in a short time.
Innovations in solar sail technology have advanced significantly over the years, with models even being tested in the harsh environments of our inner solar system.
Although functional, solar sails all have one thing in common: the sail itself. The solar sails must extend over several meters to capture the photons necessary for the propulsion of a machine.
They also need the right shape and material to turn the small momentum of each photon into motion. And they have to distribute the heat well enough not to warp and break.
It’s not just a material science puzzle; all of these requirements add bulk. Even using the lightest materials known, the fastest speeds we could achieve using radiation from our Sun would be just over 2% of the speed of light, which means that a trip to the nearest star would take another few centuries.
Needless to say, sailing to the stars would be much easier if we could ditch the sails part.
Fortunately, another type of gale blows from the solar surface, composed not of photons but of a plasma of ions whipped into a frenzy by the snapping and crackling of the Sun’s magnetic fields.
Although there are far fewer high-speed electrons and protons from the Sun than photons, their charged masses are more powerful.
Such particles would generally be a problem for typical sails, transmitting their charges to the surface of the material like static electricity on a wool sweater in winter, creating drag and changing the shape of the sail.
Yet, as anyone who has ever tried to bring the poles of magnets together knows, an electromagnetic field can provide resistance without requiring a large solid surface.
So goodbye to shiny materials, and hello to superconductors. A cable a few meters long could, in theory, produce a field large enough to deflect the charged wind from the Sun on the scale of tens to hundreds of kilometers.
The system would act more like a magnetic parachute, driven by a stream of particles moving at speeds close to 700 kilometers (about 430 miles) per second, or just under a quarter percent of the speed of light.
That’s not bad, but as birds like the albatross know, winds don’t set the speed limits when it comes to flying high.
By entering and exiting air masses moving at different speeds, seabirds can capture the energy of a headwind, using so-called dynamic flight to gain speed before return to their original path.
Using a similar trick in the termination shock “headwind” – a turbulent zone of contrasting stellar winds used by astronomers to define the edge of our solar system – a magnetic sail could exceed solar wind speeds, the potentially bringing it within range of the solar wind. sails based on radiation alone.
While the technology may not initially seem much faster than the “traditional” solar sail method, other forms of turbulence at the fringes of interstellar space could provide a bigger boost.
Even without a slight boost from dynamic surge, feasible plasma-based technology could place cube-sat satellites around Jupiter in months rather than years.
As in the days of sailing of yore, there are many ways to take advantage of the currents that flow through the vastness of space.
And yet, seabirds show us the way.
This research was published in Frontiers in space technologies.
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