Scientists from the Starshot Project claim to have discovered the fundamental bases to build a ship that will reach another solar system within our lifetimes.
The dream of traveling to another star system for the first time in history is closer than ever: researchers from the Breakthrough Starshot Initiative have found a way to build a spacecraft capable of traveling at one-fifth the speed of light to reach Alpha Centauri in just 20 years.
This discovery means that many of us who are reading these lines now could see how humanity reaches another solar system before the end of our lives. That is precisely the objective of this initiative: to allow humanity to explore a star in a reasonable time instead of wasting thousands of years that would be needed with the current engines and the gravity assistance of the planets of our solar system.
How does it work
To achieve this, Starshot must achieve star travel at relativistic speeds. That is, at a reasonable percentage of the speed of light. And doing it with current technology, not with ion engines or theoretical 'warp drives', is impossible at the moment.
Starshot's goal is to travel at one-fifth that speed using an array of lasers — located at a ground station — to power a solar sail microscopically thick and just three meters in diameter. Like a space sail ship, this sail would drag microscopic-sized sensors to Alpha Centauri, the closest star system to Earth, located "only" 4.37 light-years away. At a fifth of the speed of light, the Starshot spacecraft would reach its destination in about 20 years. Once there, its signal would reach our planet in just under four and a half years.
The project — well-known among the former director of the legendary NASA Ames Research Center Pete Worden, the director of the Institute for Theory and Computing at the Harvard-Smithsonian Center for Astrophysics Avi Loeb, and several luminaries from CalTech and other North American universities— is progressing well but it is only now that they have found the solution to make this technique work. A team of researchers from the initiative — led by Igor Bargatin, from the University of Pennsylvania — has just published the results of their research in two papers published in the scientific journal Nano Letters. The two studies solve two fundamental problems.
The Two Fundamental Problems
The first study describes what shape these solar sails actually have to be. Contrary to the ideas that we had until recently, the sails would not be flat but quite the opposite. They should be puffed out like the sails of a sailboat in order to prevent them from breaking, with a curve as deep as their width. Only then, says the study, could it resist the hyper-acceleration to which it will be subjected. According to another of the study's authors — Matthew Campbell of the University of Pennsylvania — “laser photons will fill the sail just like air fills a beach ball.”
It's an idea that, as Bargatin says, hadn't been considered but, after simulations, seems like it can actually work." The idea of a light [solar] sail has been around for some time, but we just figured out how to make sure that that design survives the voyage," says Bargatin. The intuition, he continues, is that a flat, taut sail would break just like on a sailing ship.
"It's a relatively easy concept to grasp, but we had to do some very complex math to show really how these materials would behave at this scale." The second key is the dissipation of heat from the laser beams that will push the sail to accelerate the ship. The sail materials — which will be made of sheets of aluminum oxide and molybdenum disulfide — would not withstand the energy buildup caused by the lasers alone.
According to Dr. Aaswath Raman — a co-author of the study and a researcher at the University of California, Los Angeles — "if candles absorb even a small fraction of the incident laser light, they will heat up to very high temperatures." disintegrate so it is necessary to "maximize their ability to radiate heat, which is the only mode of heat transfer available in space".
The solution lies in nanoscopic technology. Only by increasing the effective surface area of the sail using nanoscopic texture etching will it be possible to effectively cool the sail, allowing it to travel at relativistic speed without being torn to shreds. Hopefully, after these discoveries, the prototypes will arrive soon and we will indeed see such a project in space in less than five years.