This New Deep Space Propulsion System Rides Like A Leaf on the Solar Wind

Plasma Magnet Propulsion can revolutionize interplanetary travel, we just need to ride the wind.

In recent years, a surprisingly simple yet technologically viable option first proposed nearly twenty years ago has been steadily gaining momentum, and based on the tests and calculations already performed by its latest proponents, it may become the breakthrough propulsion system that opens up the greater parts of the Solar System to regular, affordable human exploration. Known as a Plasma Magnet, the present-day iteration gaining momentum is simply called Wind Rider.

Before We Learned to Ride The Solar Wind

Few if any individual achievement in human history is as impressive or as revolutionary as the chemical rocket. No other form of propulsion has ever launched a satellite into space, much less a human being, and pretty much every mission tasked with studying the various planets, moons, and other features of our solar system have been propelled to their destinations onboard chemical rockets.

Even the handful of experimental test flights of cutting-edge concepts like ion drives and solar sails performed by NASA have all hitched their initial ride to space on chemical rockets. Unsurprisingly, this method of propulsion is expected to dominate missions for NASA and the private sector alike, as well as pretty much every nation on Earth that has a space launch program for the foreseeable future.

Unfortunately, for all of the raw power these fiery behemoths can unleash when hurling a satellite or other space-bound payload into Low Earth Orbit and beyond, the need to carry enough fuel has severely limited their range. 

Sure, rockets have reached the moon and Mars, and will likely carry humans to both in the next decade or so, but human-crewed missions to tempting targets like the moons of Jupiter or Saturn are virtually impossible using this technology. Even robotic explorations of these faraway destinations take years to complete, costing millions and millions of dollars each and every year along the way. As a result, such “flagship” missions are few and far between, with efforts like the Cassini probe, which studied Saturn and a few of its moons up close, taking years to plan, prepare and execute.

This limitation to rocket technology has been known since the time of famed 20th-century rocketry pioneer and former Nazi scientist Werner von Braun, with untenable weight-to-payload ratios looming on the horizon like a huge barrier that seemed impossible to breach.

Now, a new wave of pioneering approaches to space travel have begun to emerge, offering humanity hope that missions to Jupiter’s moon Ganymede, a tempting target to search for life, Saturn’s moon Titan which offers some of the same tantalizing possibilities, or even the outer edges of the Solar System itself might one day become as routine and as inexpensive as launching a commercial satellite is today.

Some, like WARP drives, seem decades, if not centuries away, while things like Nuclear Fusion Propulsion or Directed Energy Propulsion still require more research and development to become practical options. 

Solar Sails are closer to reality, having been studied and even tested in space, but limitations on size and materials have limited those projects to only one potential NASA mission on the horizon.

Wind Rider Is Different

“The Plasma Magnet is a wind drag device invented almost twenty years ago by Dr. John Slough from the University of Washington,” said Dr. Brent Freeze, a Cornell-educated mechanical engineer and one of the two scientists championing Wind Rider in an interview with The Debrief. “Wind Rider is our updated version.”

In that same interview, Freeze explained the basics of the Wind Rider design and the basic science behind this revolutionary propulsion method.

“By definition, it is a drag device, meaning it’s not a rocket function,” said Freeze. This, he explained, means that, unlike a rocket that uses a propellant to create momentum, a plasma magnet like his Wind Rider uses the pressure of the solar wind to gather momentum.

“You can ride along with the wind currents and get to the destination efficiently,” said Freeze. “And it doesn’t require fuel.”

The enthusiastic engineer explained that this type of propulsion actually exists in nature, pointing to a dandelion coasting upon the wind to its ultimate destination. Riding the solar wind, Freeze explained, is what sets this type of technology apart from things like solar sails, which rely on the minute pressure of the photons and not the significantly more potent solar wind itself.

“The sun puts out two forms of energy that are propulsively useful,” explained Jeff Greason, a California Technical Institute educated aerospace and technology sector veteran and Freeze’s partner on the Wind Rider concept. “It puts out sunlight, the photon flux that we all see. And it puts out the solar wind, which is a stream of rapidly moving charged particles.”

This high-energy stream, says Greason, can vary in speeds from 450 kilometers per second up to 800 kilometers per second, depending on the angle. And, he says, Wind Rider is designed to capture the momentum of that stream of supercharged particles and ride its momentum to the edges of the solar system itself.

“The [solar wind] possesses tremendous amounts of concentrated kinetic energy that you can then grab onto,” Freeze told The Debrief, “and we have a Wind Rider structure system that can do that.”



wind rider
A rendering of Wind Rider, the Solar Wind Drag Device by PIP study member Michel Lamontagne. (Note: image is not to scale).

How Does Wind Rider Work?

“Plasma sail propulsion based on the plasma magnet is a unique system that taps the ambient energy of the solar wind with minimal energy and mass requirements,” the original 2005 research paper abstract states. “In this way, the mass of the sail is reduced by orders of magnitude for the same thrust power.”

To accomplish this feat of engineering, the drive itself consists of a pair of polyphase coils mounted at or near the center of a cylindrical craft that once energized produce a rotating magnetic field. In the original design, these magnetic coils were proposed as aluminum, but, Freeze pointed out, in 2021, it has been replaced with superconducting materials that weren’t available to Slough in 2005.

When properly engaged, this magnetic field powers currents that generate a huge shell of plasma to surround the spacecraft, potentially reaching tens of kilometers in size. This shell of magnetically driven plasma expands outward in a disc-like shape until its size is equalized by the pressure of the solar wind and then uses the principle of drag to essentially surf the solar wind like the dandelion on its summer breeze.

“In some sense, all sails are what I call drag devices,” Greason told The Debrief. “They’re like a parachute or a square-rigged sailing vessel, meaning they only fly before the wind.”

 “It is virtually propellantless as the intercepted solar wind replenishes the small amount of plasma required to carry the magnet currents, “the original paper abstract concludes. “Unlike a solid magnet or sail, the plasma magnet expands with falling solar wind pressure to provide constant thrust.”

Basically, as the craft moves farther and farther away from the Sun and the pressure of the solar wind continues to reduce, the size of the shell of plasma surrounding the spacecraft expands to compensate, offering the vehicle a constant thrust.

“There’s a magnetic pressure in that loop of current that makes it want to expand,” Greason explained. “And there’s a pressure from the wind and dynamic pressure that makes it want to contract. It grows until those forces are in equilibrium.”

He noted that this original design was even tested in 2006 by Slough, albeit on Earth and in laboratory conditions. Still, those results confirmed the method and thrust analysis of the original theory.

“We have not replicated the tests the previous people have done in the laboratory, but they’re based on published results in the literature,” Greason told The Debrief. “Subscale tests have been done on the ground in plasma wind tunnels, and it more or less matches the predictions made by the theory. They measured that they had thrust.”



How Fast is Wind Rider?

When NASA and the European Space Agency (ESA) launched the Cassini probe to study Saturn and its moons back in 1997, even the famed space administration noted the difficulty in reaching such a distant target.

“Unable to be launched directly to Saturn with the propulsion systems available at the time,” NASA’s mission archive site explains, “Cassini took a roundabout route to reach the ringed planet.” This route is known as a VVEJGA (Venus-Venus-Earth-Jupiter Gravity Assist) trajectory, and according to the same NASA mission archive site, “Cassini made two flybys of Venus (April 1998 and June 1999), one of the Earth (August 1999), and one of Jupiter (December 2000),” before gathering enough momentum to depart for its ultimate goal, Saturn.

It would be another four years before Cassini finally reached the ringed planet, and its companion, Huygens probe, wasn’t dropped toward Saturn’s moon Titan until 2005, nearly eight years after its launch.

“The missions to the outer solar system tend to be flagship missions, billion-dollar-plus missions that you don’t do very often,” Greason told The Debrief. “And that’s because of time and cost. You stand up this big team to design the mission, and then they have not to get laid off. They still have to be there when the mission arrives. So missions like that take a long time and cost a lot of money. By dramatically reducing the transit time, you dramatically increase the odds of the same team being on the project when the research is ready to be done on-site.”

So, if a probe like Cassini needed close to a decade to reach Saturn, how long would Wind Rider need to surf the solar wind to the ringed planet?

“Six weeks,” Freeze told The Debrief. 

In fact, he said, his team has calculated an entire array of potential targets within the solar system and has found that pretty much each of them is reachable in a year or less. 

Want to go to Jupiter? Wind Rider can have you racing by the gas giant within a paltry three or four weeks. Fancy a trip to Neptune, the planet farthest from the Sun (sorry Pluto)? Wind Rider can do it in about 18 weeks.

“It is possible to reach nearly all destinations within the solar system in a year,” Freeze said, “with at least one launch window opening per year for each of them.”

When asked about the possibility of using Wind Rider to venture to exoplanets that are light-years away, both team members pointed to the dramatic distances and hundreds if not thousands of years their vehicle would need to traverse those distances. However, both still noted that their proposed spacecraft is significantly faster for future interstellar robotic missions than the lone man-made vehicle to have actually left our solar system.

“Because it’s limited to solar power, you have to do all your acceleration in the inner solar system,” Greason explained. “So that limits us to quote-unquote, only about 300 kilometers per second of departure speed, which is still something like five times faster than Voyager.”

What is JOVE?

On October 6th, 2021, Freeze and Greason teamed up with ten other scientists and engineers to outline a technology demonstrator mission to Jupiter they call JOVE.

“The title of our talk is ‘Jupiter Observing Velocity Experiment (JOVE), Introduction to Wind Rider Solar Electric Propulsion Demonstrator and Science Objectives,'” Freeze explained in an email to The Debrief.

Presented at the 53rd Division of Planetary Sciences conference, which is an affiliated conference managed by the American Astronomical Society, the JOVE mission is a technology demonstrator that would serve as the first real-world test of a plasma magnet propelled craft in space, as well as a demonstration of a range of collaborative technologies designed to aid in the mission. 

For example, although Wind Rider can travel extremely fast, the lack of onboard fuel offers no way for the craft to slow down, much less maneuver once it has reached its target destination. The JOVE mission seeks to solve that challenge by combining a nuclear power source with the plasma magnet, offering separate propulsion systems for local and long-distance travel.

“It’s like in Star Trek with the WARP drive and Impulse,” Freeze said, “only the Wind Rider is the WARP, and the nuclear gives you the local, the impulse drive capabilities.”

In JOVE, that metaphorical “impulse” drive is actually a pulsed nuclear fusion concept in development by researchers from the University of Huntsville, Alabama, which will be covered in an upcoming article on The Debrief. Regardless of the specific system used once the craft is at its destination (Greason noted that there are even some proposed nuclear-based power systems using the same readily available isotope found in a common smoke detector), combining that secondary drive system with the Wind Rider plasma magnet system offers up a whole range of untapped targets for researchers to explore.

“The combination of those two (plasma magnet and nuclear) would be really interesting,” Greason told The Debrief. “Now you can start thinking about doing, you know, 100, 200 million dollar missions to the outer solar system. And there are so many places to go. We haven’t been to any of the moons of Uranus and Titan, except for the Voyager flyby once. We have never been to any of the trans-Neptunian objects other than Pluto. There are all kinds of incredibly interesting moons of even Jupiter and Saturn that we would love to do a dedicated mission to that we simply haven’t done.”

When Will Wind Rider Fly?

There are currently no officially planned missions to test Wind Rider or any other plasma magnet style propulsion system on the books at NASA. Still, when asked by The Debrief how quickly such a system could be put into place with appropriate funding, both members of the Wind Rider team gave similar estimates.

“I think that if it were fully funded in the next 90 days, with NASA approval and all regulatory approval, you could launch in late 2023,” said Freeze. 

“Two or three years,” echoed Greason. “Maybe a bit more.”

Of course, to even be considered for funding in the next ten years, the team pointed out that a project like Wind Rider would have to show up on NASA’s Decadal Survey, a document that essentially guides the administration’s missions over the ensuing ten years, and whose next iteration is not expected to be released until later this year.

“The way that actually works is you have various outer solar system bodies that people think might be good candidates for life,” Greason told The Debrief. “And then it becomes a fight in order to even get your mission under consideration.”

Fortunately, after presenting their concept at the AIAA annual conference in August and the JOVE presentation in October, it appears that the Wind Rider concept is gaining even more momentum, with yet another presentation planned at the American Geophysical Unions (AGU) Fall 2021 Meeting, that the researchers say is even more aggressive than JOVE.

“There is a follow-on presentation for a different destination (much farther out than Jupiter) that also involves the use of a Wind Rider,” Freeze stated. “It was accepted last week for a poster session at the AGU Fall Meeting in New Orleans on Monday, December 13th.”

According to its written summary, that mission proposes sending a Wind Rider out to the mind-numbing distance of 542 AU (one AU, or Astronomical Unit, is the distance between Earth and the Sun, or just shy of 150 million kilometers), a point at which Freeze told The Debrief, “you can use the Sun as a magnifying lens to image things.” Their particular target in that upcoming conference presentation is the star system Trappist-1, which is of particular interest to astronomers and astrobiologists alike for its Earthlike planets that may have a high potential for harboring extraterrestrial life.

As far as what, if any more experiments can be conducted before putting an actual test vehicle like Wind Rider in space, both Freeze and Greason indicated that the testable concepts have all more or less been done and proven successful, and for any further progress to be made it will take the will and funding to put such a vehicle in space and see if it works.

“The next step is to actually go fly,” Freeze told The Debrief. “There’s only so many tests you can do on the ground.”

When asked if any technological barriers exist or if any custom materials will have to be created to perform such a real-world flight, the Wind Rider team said no.

“Everything is commercially available,” said Freeze. “We’ve been very careful to make sure that all of the coatings, all the materials that are available, all of the systems have really been demonstrated on the ground for years.”

“What we need now is funding,” added Greason. “Exactly how much I’ll defer to Brent, but it’s tens of millions, not hundreds of millions of dollars.”

Regardless of cost, both researchers are convinced of the present-day viability of their solution and confident that if successful, it would represent the fastest spacecraft around.

“There’s no rocket I’m aware of, chemical, electric, or otherwise, to keep up with a Wind Rider,” said Freeze.

Greason echoed the system’s advantages, telling The Debrief, “this technology, or this suite of technologies, has the potential to break that paradigm and say, ‘Okay, well, if you can do a $200 million mission, we could fly one every year. And in 10 years, we could have done a mission to every single one of these interesting targets.'”

Time will tell if the Wind Rider system or one like it makes it onto the next Decadal Survey, but given the enthusiasm and reputations of the researchers involved, not to mention the impressive teams joining the efforts on the JOVE and Trappist-1 mission concepts, the overall viability of the technology itself makes it feel like it may finally be time to put one of the suckers in space and watch it sail like a leaf on the wind.


Correction: In the original version of this article, it was mistakingly stated that the Wind Rider project would cost hundreds of millions of dollars. This was a misquote and has been corrected to acuretly reflect the statements provided by the project leads.


Follow and connect with author Christopher Plain on Twitter: @plain_fiction