by Larry Klaes
Tau Zero’s Larry Klaes returns with more details on a novel form of propulsion that just might, in the long term, have interstellar implications.
One of the most vital – and difficult – parts of a spacecraft is the type of propulsion it requires to move about in space. Most current forms of space propulsion, such as chemical fueled rockets, are both expensively heavy and explosively dangerous.
Dr. Mason Peck and his team at Cornell University may have found a
solution to this problem by utilizing the natural magnetic fields generated by our planet Earth and other worlds in space.
“If our research is successful, we will have devised a new way of propelling spacecraft,” declares Peck, who is an assistant professor of mechanical and aerospace engineering at Cornell, and the director of the Space Systems Design Studio. “We think of it as doing more with less. Instead of using rocket fuel, which is expensive, heavy, and often toxic, this technique allows spacecraft to change their orbits by pushing against Earth’s magnetic field. Such a spacecraft would have to carry little, if any propellant, saving that valuable mass for, say, a scientific payload bound for another planet. There are many other applications, too.”
The spacecraft envisioned by Peck would take advantage of the force exerted on charged particles in an electromagnetic field known as the Lorentz force, named after the Dutch physicist who first formulated the concept, Hendrick Antoon Lorentz.
Spacecraft orbiting Earth create a charge as they travel through the plasma that surrounds our planet. Since the effect is relatively small, a spacecraft wanting to take advantage of this force must either have a lightweight surface to contain large quantities of the charge or emit charged particles such as ions or electrons with a high-energy beam.
“One of our favorite ideas is use a thin wire mesh, like hurricane fence, that forms a large cylinder. Such a structure would resemble a long metal electrodynamic windsock that pulls the spacecraft along,” says Peck.
Peck notes that the concept might be ideal for small spacecraft. Cornell graduate student Justin Atchison is developing a satellite that is the size and heft of a single wafer of silicon.
“At this small scale, a spacecraft might be surprisingly susceptible to Lorentz force effects,” explains Peck. “But rather than launching just one of these ‘ChipSats’, NASA might launch millions of them that would act as a swarm of very small sensors to detect life on another planet, provide communications, or serve as a distributed-aperture telescope many kilometers in diameter.”
While an actual satellite that could sail on Earth’s magnetic field is a number of years away, Peck notes that his team may be able to launch Atchison’s ChipSat as an inexpensive demonstration.
“Within a university environment, it is possible to build small spacecraft. Professor Mark Campbell at Cornell has done so, having built two over the past eight years. I am also working with students to build two 20-kilogram spacecraft for the United States Air Force. In a program like that, we may be able to launch a demonstration of this technology for relatively little money, while at the same time giving students the chance to learn about building spacecraft in a hands-on, experiential environment.”
Peck has numerous visions for the Planetary Magnetic Fields Propulsion project. He sees spacecraft using celestial magnetic fields that could explore other planets like Jupiter, where the magnetic field is 18,000 times stronger than Earth’s. “A spacecraft orbiting Jupiter can use this powerful magnetic field to slow down, speed up, and even hover at high altitude,” says Peck.
The concept might even be the first to take our robot explorers to other star systems. Thousands of advanced versions of the ChipSat might be slung out of our Solar System to the nearest star, Proxima Centauri, 4.2 light years from Earth.
“If we’re capable of accelerating it to ten percent of the speed of light – and that would be no small feat – it would take about 43 years to Proxima Centauri. When these small craft arrive, they might send back a single, simple signal – one bit of information confirming or denying some scientific principle; is there a blue-green planet, for example. A one or a zero might not seem like much, but sent from a distant solar system, this single bit could be the most valuable information scientists will ever have received.”
For the technical details and updates, visit the Cornell Planetary Magnetic Fields Propulsion project online.