The Crazy Plan to Get to Alpha Centauri

Humans are attempting to achieve interstellar travel. Here’s why some of the world’s greatest minds believe a nanocraft is the best way to journey into deep space.

About 4.3 light-years from Earth lies our closest stellar neighborhood. The Alpha Centauri system consists of three known stars. Alpha Centauri A and Alpha Centauri B are a binary pair, which means they have about the same mass and thus orbit a common center of mass. The third star, Proxima Centauri, is the closest to Earth at about 4.22 light-years away. In 2016, astronomers detected an Earth-sized planet orbiting Proxima Centauri within the star’s habitable zone - the right distance to potentially support liquid water on its surface. Which is why eyes are on Alpha Centauri as our first destination once we master interstellar travel.

Outer space is bigger than we can comprehend and sending a spacecraft into its depths takes a lot of time. NASA’s Voyager 1 is Earth’s farthest spacecraft to date. It was launched in 1977, and in 2012, it was the first craft to enter interstellar space. If Voyager 1 was pointed in the direction of Alpha Centauri, it would still take tens of thousands of years to reach the system. And that’s because its propulsion system is not ideal for deep space travel.

Some scientists agree that our best attempt at interstellar travel are light sails. These sails would be made of ultra-thin sheets that will be propelled using light instead of wind. One of the major initiatives researching their potential is Breakthrough Starshot. The program, backed by the late cosmologist Stephen Hawking, aims to create a nanocraft comprised of a lightsail and a gram-scale wafer that hosts a number of instruments - called a StarChip. The nanocraft has a mirror-like sail design and is measured at 10 square meters with a mass of less than 1 gram.

The lightsail will purportedly be accelerated by laser radiation pressure from Earth at about 20 percent the speed of light. The planned laser array, called a Light Beamer, will fire beams as powerful as 100 gigawatts of specific wavelengths of near-infrared light. The nanocraft sail will need to reflect a huge majority of the laser light to avoid instantly burning up on contact. The idea is to launch thousands of nanocraft at once to increase the chances that at least a few will conquer the elements and reach Alpha Centauri. And if they do make it, it’s estimated, the journey will only take around 20 years.