Breakthrough Starshot members have compiled a list of the challenges they will have to solve in order to create a solar sail of the right size to fly to Alpha Centauri in 20 years. Their findings were published in the journal Nature Materials.
“The first results of our analysis were unexpectedly optimistic - the materials already existing today, in combination with new methods of manufacturing and measuring their properties, in principle allow us to create a prototype sail suitable for accelerating an interstellar ship,” wrote Harry Atwater and colleagues. from the California Institute of Technology in Pasadena (USA).
In April 2016, the late British cosmologist Stephen Hawking and Russian billionaire Yuri Milner spoke about their next "space" initiative within the Breakthrough Initiatives series - Breakthrough Starshot. Within its framework, the businessman allocated $ 100 million to create a spacecraft based on an idea outlined by California physicists under the leadership of Philip Lubin two years ago.
Its essence is to send not classic spaceships to distant planets, but extremely light and flat structures made of reflective material, which will be accelerated to near-light speeds using a powerful orbital laser.
Such an interstellar "sailing ship", according to the calculations of American physicists, will be able to reach Alpha Centauri in 20 years, and will fly between Mars and Earth in just three days without a payload, and in a month with a load of 10 tons.
The main problem in both cases will be the deceleration of the probe - while the team that came up with it has no ideas on how to make the stop of the laser "sailboat" safe. Similar problems will arise, as other physicists later suggested, during its acceleration - the sail will either be burned by a laser, or it will collapse when it collides with dust particles.
Atwater and his colleagues at the institute, directly involved in Breakthrough Starshot, for the first time studied in detail how such a sail would behave when interacting with a laser and the interstellar medium, and formulated a set of minimum requirements for its manufacture.
As the scientists found out, despite the almost "impossible" set of characteristics - an area of 10 square meters, a mass in grams and a reflectivity of 99.999999% - the main problem in the manufacture of a sail will not be the selection of material, but a number of other things. It turned out that a number of materials already exist on Earth, including films made of molybdenum disulfide, amorphous silicon and a number of other semiconductors that have similar properties.
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If this film is thin enough, then, paradoxically, collisions with helium and hydrogen atoms present in the interstellar medium will have almost no effect on the life of the sail. Most of the atoms will pass through it without causing harm, and collisions with dust particles, as physicists' calculations show, will damage no more than 10% of the total sail area.
The problem, in turn, is that today there are no technologies that would allow growing very homogeneous and thin films of these substances of the required size. Scientists will have to find a way to glue relatively small fragments of these films, 10-20 centimeters in diameter, and this operation must be carried out with virtually atomic precision.
On the other hand, Atwater and his colleagues are confident that such techniques for "gluing" pieces of sail can be quickly developed, relying on the technologies that are used in the IT industry today for soldering individual elements of microcircuits. Their creation will allow Breakthrough Starshot to solve one of the main problems and start creating a laser system capable of accelerating this sail to the required speed.