Relativistic Electron Beams Could Revolutionize Interstellar Travel

Space.com reports that a new idea might solve the biggest problem in interstellar travel: how to go fast enough to reach other stars within a human lifetime. Modern spacecraft rely on limited onboard fuel and energy, making them too slow to cross the massive distances between stars. To make this possible, we need faster and more efficient methods to power a spacecraft.

Jeff Greason, Chief Technologist at Electric Sky, Inc., and Gerrit Bruhaug, a physicist at Los Alamos National Laboratory, have introduced a unique approach.

Their study, published in Acta Astronautica, focuses on using relativistic electron beams—streams of electrons moving near the speed of light—to accelerate spacecraft. This idea is based on ‘beaming power to the ship,’ which means sending energy from a distant source rather than carrying it onboard.

One challenge with interstellar travel is the immense distance. Alpha Centauri, the closest star system, is 4.3 light-years away, which is over 2,000 times farther than the Voyager 1 spacecraft has traveled. Greason says a mission taking longer than 30 years to send back data isn’t realistic.

To meet this timeline, the spacecraft must reach at least 10% of the speed of light.

In the past, scientists explored other ‘beam rider’ methods like laser-powered sails and interstellar ramjets. Lasers push the spacecraft with photons, while ramjets collect hydrogen gas in space to fuel fusion reactions.

However, both have major issues. Laser beams are hard to aim over long distances, and ramjets can’t work efficiently in the sparse interstellar medium.

Electron beams offer some big advantages. Accelerating electrons to nearly the speed of light is easier than working with photons or hydrogen, and they can travel vast distances while staying focused.

When electrons move through space, they interact with the plasma (thin ionized gas) that fills the universe. This creates a magnetic effect called a ‘relativistic pinch,’ which holds the beam together.

Greason and Bruhaug calculated that such a beam could power a spacecraft weighing about 2,200 pounds (similar to Voyager 1) up to 10% of light speed. This could reach Alpha Centauri in just 40 years, compared to the current 70,000 years it would take. The system would involve placing a beam-generating spacecraft near the sun, where sunlight could supply the required energy.

While promising, this concept still has many challenges. The spacecraft would need to convert the energy from the beam into propulsion without overheating or wasting power. Computer models and space experiments, like testing beams aimed at the Moon, will help refine these ideas.

Greason argues that electron beams could be more affordable and effective than lasers, offering 10,000 times the range and enough power to push larger spacecraft. These larger designs could carry more instruments, power supplies, and better communication systems to send back data from distant stars.

Though still in the early stages, this concept could one day make interstellar travel faster and cheaper, opening new doors for exploring the universe.

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