Scientists have spent years researching and discovering new worlds beyond our Solar System. In 2016, a new planet was discovered revolving around Proxima Centauri of the Centauri System – our nearest interstellar neighbor at four light years away. Labeled Proxima B, this rocky Earth-sized world lies within Proxima Centauri’s habitable zone, making it possible for the planet to contain liquid water and organic lifeforms.
Astrophysicists have spent years testing models and concepts with the potential of expediting interstellar travel, and the discovery of Proxima B has intensified that effort. While reaching another star system is one part of this convoluted equation, a challenge perhaps just as great for scientists is preventing their space probes from overshooting their targeted destination.
With over $100 million in funding, Breakthrough Starshot is an interstellar travel project started by billionaire Yuri Milner and renowned astrophysicist Stephen Hawking. The project is designing a space probe weighing just one gram that will be equipped with large, thin, solar sails. Generating thrust from any light source, this “nanocraft” would be propelled through space by powerful lasers from Earth striking their sails. Photons hitting the sail will transfer momentum (although a miniscule amount on an individual level), providing enough thrust to carry the probe through space where the probe will encounter virtually no resistance).
This method could hypothetically get a probe to reach speeds up to 20 percent the speed of light (37,282 miles per second) within minutes of launching. At this rate, the probe could complete one rotation around the Earth in six seconds and reach the Centauri System in as little as 20 years. It’s that high rate of speed, however, where the problem lies as the probe wouldn’t be able to stop in a timely manner upon reaching its destination.
Sending a probe faster than 8,574 miles per second would prevent the nanocraft from being slowed by gravity or radiation from other stars, which would take the journey to Proxima B up to 100 years. Two German physicists believe they’ve discovered some viable solutions to address this discrepancy. Colleagues Rene Heller and Michael Hippke from the Max Planck Institute for Solar System Research have proposed methods like repositioning the probe’s solar sails and utilizing counterthrust concepts as the nanocraft nears the Centauri System.
Redeployment of the craft’s solar sails could use the light coming from stars in the Centauri System to provide enough counter-resistance to decelerate the probe. The probe can also utilize the gravitational pull and radiation coming off Alpha Centauri A and B to adjust its speed accordingly, and direct it into an orbit around Proxima Centauri. However, for this to work the probe’s solar sails must be a few atoms thick, making them highly sensitive. The nanocraft also can be geared to enter a large elliptical orbit around one of the Centauri stars, allowing the probe to reorient and accelerate towards Proxima Centauri. These concepts would work best when all three stars are in the same plane from Earth’s perspective, an event that occurs roughly every 80 years and won’t happen again until 2035.
While exciting to think about, these propositions come with their series of drawbacks like the probe’s equipment malfunctioning from direct exposure to a star’s heat and radiation, along with intersecting high-energy particles, which could further damage equipment and a probe’s solar sails. The ultimate goal behind controlling speed is so the nanocrafts can travel at a stable enough rate to snap high-resolution images of Proxima B and gather other significant data, which it would beam back to Earth.
Filed Under: Aerospace + defense