Cone-shaped sails are so last year. If we really want to send probes outside our solar system, spherical sails may be the way to go.
Earlier this year, billionaire Yuri Milner announced Breakthrough Starshot, an ambitious plan to accelerate tiny probes through space at a fifth of the speed of light. At that speed, an interstellar probe could reach our closest neighbouring star system in just 20 years, sending back pictures of anything interesting once it arrived.
The LightSail spacecraft successfully showed last year that it is possible for solar sails to propel spacecraft using rays of sunlight. But to achieve the mind-melting speeds required for interstellar travel, it might be better to push the spacecraft with high-powered lasers shot from Earth. The principle is the same, but the sail’s design will look completely different.
One challenge for the Breakthrough Starshot project will be keeping the orientation of the sail just right in relation to the laser beam that propels it. “An obvious solution is to have an on-board adjustment system that would constantly keep the sail facing the right way,” says Zachary Manchester at Harvard University, a member of the advisory committee behind the project. “But that would add significant complexity and mass to the spacecraft.”
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