Spacecraft Made from Ultra Thin Foam Could Reach Proxima Centauri in Just 185 Years

A hypothetical spacecraft made from an extremely thin layer of a synthetic foam could technically make it to our closest neighboring star Proxima Centauri in just 185 years, scientists have said. If Voyager were to make the same journey, it would take around 73,000 years, according to NASA.

In a study that is due to be published in the journal Astronomy & Astrophysics, René Heller from the Max Planck Institute for Solar System Research, Germany, and colleagues, propose the spacecraft as a precursor to interstellar travel—beyond our own solar system. They estimate a prototype would cost around $1 million, while the launch of an interplanetary mission would be around $10 million.

The spacecraft would be made from aerographite. This is a carbon-based foam that is around 15,000 times more lightweight than aluminium. It is versatile and light enough that it could be used to create solar sails—which harness energy from the sun for propulsion, a process called solar photon pressure.

Light consists of packages of energy that physicists call photons, Heller told Newsweek in an email. Photons do not have a mass, but carry energy and momentum. When a photon hits a target, this energy and momentum is delivered to it, giving it a tiny push. In most cases, photons would have little impact on an object. But if the target is an ultralight material, such as aerographite, then the target can actually be pushed to significant speed," he said.

"We found out that a thin layer of aerographite, with a thickness of about 1 millimeter (0.04 inches), can be pushed to speeds that are sufficiently high to let it escape the solar system. Once it has gained an initial push from the solar radiation pressure, it will simply float through space."

The team found if its shell was just 0.5 millimeters thick and the spacecraft was released from Earth, it could reach Mars in 60 days and Pluto in 4.3 years—less than half the time it took New Horizons. Heller said these spacecraft could travel far faster than any probe ever sent by humans before. "Voyager 1 currently recedes from the Sun with a speed of 17 km/s (10.5mp/s). Solar photon sails made of graphene could, in principle, go beyond 100 km/s (62mps) or even 1000 km/s (620mps).

Image showing aerographite, a carbon-based foam that scientists say could be used to create spacecraft for interstellar travel. René Heller

A spacecraft with a shell 1 micrometer thick that was released far closer to the sun—0.04 AU, or around 3.7 million miles—could pick up a speed of almost 6,900 kilometers per second (4,300 miles per second)," the team wrote. This would allow it to reach Proxima Centauri in around 185 years.

They said another possible use for such a spacecraft would be to look for Planet Nine, the hypothetical planet that some scientists believe exists at the edge of the solar system.

Heller said the biggest challenges of building an aerographite spacecraft would be to construct something thin enough while also maintaining its structural integrity—especially during the launch into space. They would also have to build tiny, gram-sized, on board electronics that could transmit information back to Earth.

He said the next step will be to look at the interaction of aerographite—which appears black to the human eye—and light in a laboratory to find out how much it absorbs at different wavelengths. how does its blackness—"absorptivity"—change with thickness? We don't know and that's what we need to find out in the lab."

Correction 07/30 9.23 a.m. ET: A previous version of this article contained an error relating to the launch distance from the sun which has now been rectified.