Researchers have proposed a new propulsion method that could make covering the vast distances required for interstellar missions feasible within a human lifetime.

The fundamental challenge in reaching a different star system lies in figuring out how to generate and transfer enough energy to a spacecraft both efficiently and affordably. The physical limitations of modern spacecraft pose significant challenges for reaching interstellar space in a human lifetime, especially with limited room onboard for carrying propellant or batteries. If we ever want to achieve the tremendous speeds necessary to cross interstellar distances in a human lifetime, we need to find outside-the-box solutions.

Enter relativistic electron beams made up of electrons moving close to the speed of light. "Beaming power to the ship has long been recognized as one way to get more energy […] than we can carry with us," Jeff Greason, Chief Technologist of Electric Sky, Inc, and chairman of the Tau Zero Foundation, told Space.com. "Energy is power [multiplied by] time — so to get a given amount of energy from a beam, you either need very high power or you need to stay in the beam a long time."

One such solution that was recently proposed uses electron beams accelerated to near the speed of light to propel spacecraft, something that could overcome the vast distances between Earth and the next closest star. "For interstellar flight, the primary challenge is that the distances are so great," Greason explained. "Alpha Centauri is 4.3 light-years away; about 2,000 times further away from the sun than the Voyager 1 spacecraft has reached — the furthest spacecraft we've ever sent into deep space so far. No one is likely to fund a scientific mission that takes much longer than 30 years to return the data — that means we need to fly fast."