Project Breakthrough Starshot: Will the probe from Earth come to the Alpha Centauri system at a speed of 20% light?

In science fiction, spacecraft have long been moving throughout the universe with the help of wormholes, hyperdrives, and other systems, phenomena, and devices. Wormholes or hyperdrives, according to some scientists, are not at all a fairy tale, and it is theoretically possible to create them. True, not now and not in the near future - we simply do not have the necessary knowledge and technology.

Well, what about flying to another star at a speed of 15-20% of the light? It is quite real. So say scientists, popularizers of science, so do the authors of the project Breakthrough Initiatives, working on the project Breakthrough Starshot. The objective of the project is to create spaceships with a light sail that can fly to the Alpha Centauri system in 20-30 years. In order to get to this system in such a time, the spacecraft must move at a speed of 15% to 20% of the speed of light.

What is the plan?

The main idea of ​​the project was announced on April 12 of this year at a press conference in New York. The founders of Breakthrough Starshot are Yuri Milner and Stephen Hawking. The initiative council of the project includes Mark Zuckerberg, the head of Facebook. According to Milner, the cost of the project is not so high - 5-10 billion US dollars. The first ship, he believes, can go to the star after 20 years.
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As part of the Breakthrough Starshot, it is planned to launch the base ship, which will launch into orbit a multitude of small spacecraft. From the ground, the solar sails of these devices will be affected by a laser beam. The lasers are quite powerful, it is planned to send several laser beams with an energy of 1 terajoule (according to some sources - 100 gigajoules) to the solar sails of 4 * 4 m.



Using a laser, miniature spacecraft will target the Alpha Centauri system, while the laser will accelerate the probes to the required speed. When (and if) earthly devices reach there, they will be able to take pictures of the entire system. In total, about 1,000 miniature starships will be sent to Alpha Centauri. The devices will transmit data to earth using a miniature laser system - the solar sail will serve as an antenna. Each probe will consist of a camera, a solar sail, a laser data transmission system, a plutonium energy source.

And now - about the problems.

The project itself looks quite realistic - you can probably launch mini-starships. And it is also possible to reach a speed of 15-20% of the light. But there is one problem. The fact is that at such a high speed the probe will be a problem not only a meteorite or dust, collisions even with individual atoms become dangerous. Now scientists are trying to understand how dangerous such collisions will be and how often they will occur (there will be no doubt that they will). Actually, that's why it is planned to send 1000 devices - according to the authors of the project, a certain part of the probes will remain intact.

The main problem is that interstellar space is not empty. There is dust here, and there is quite a lot of it, there are individual atoms, of which there are even more. All these objects are a real danger to the probes.

Atoms . In itself, a collision with an atom is not so dangerous, but the energy released during a collision is already a significant problem. When energy is released, the body or individual elements of the probe will heat up. The temperature will be so high that the probe material will simply evaporate at the point of impact. Or simply melt, which will cause changes in the properties of the material.

Using known data on the concentration of interstellar gas, the authors performed some calculations to obtain more or less real information about the consequences of such collisions. As it turned out, the most common hydrogen and helium in the universe do not pose a significant problem. Worst of all will have probes in collisions with heavier atoms of such elements as oxygen, magnesium, and iron.

According to experts, heavy atoms can evaporate or melt the material of the probe body in the range of 0.1 mm. Not so much, but if atoms occur frequently, the probe will be in great danger.

Dust . This is a slightly different problem. Dust is formed from atoms and molecules of elements heavier than hydrogen or helium. Dust, even the smallest, is much larger than a single atom. And the consequences of a collision with dust particles for a probe will be more severe than a collision with atoms. A relatively large dust particle — a single particle — can disable the entire apparatus. The size of such a particle is estimated at 15 micrometers. Fortunately, in the interstellar space, dust of this size is rather rare, so probably not all probes will encounter this danger on the way. In fact, the probability of a probe meeting a 15 μm particle or a larger particle is vanishingly small.

Smaller dust particles will cause the destruction of the apparatus body on a much larger scale than atoms. Each particle will evaporate the material within 1.5 mm of the surface of the apparatus. But the material will melt to a depth of up to 1 cm. Considering the miniature of the probes, this is very significant.

How can you avoid the danger of destruction of the probe?

There are several ways to avoid destruction of the probes on the way to the goal. One of them is to place the solar sail behind a special shield. The probe body will be shaped like a bullet in order to minimize the chance of a vehicle colliding with dangerous dust particles or atoms.



To absorb heat, the probe body is proposed to be covered with a layer of graphite. This material will dissipate heat, ensuring a minimal impact of collisions with particles and atoms on the probe.

And one more problem, not so obvious. When a substance evaporates at the moment of collision, the direction of movement of the vehicle and its speed will change. 1-2 meetings with dust particles will not change much, but if such meetings happen all the time, the device can deviate greatly from the initial trajectory, the speed will also change significantly. In this case, the probe either does not reach the target at all, or it reaches, but the travel time will increase. What to do with this problem, experts have not yet come up with. According to project experts , each frontal square centimeter will collide at high speed with about a thousand particles of 0.1 microns and above.

In addition to all the above, there are also purely technical difficulties. The fact is that the probe must be very miniature in order to meet the mass limit. All probe elements must withstand extreme space conditions and acceleration. And focusing the most powerful lasers on solar sails of probes is a task that people cannot cope with right now due to a number of technical problems . According to The Economist, the project will be possible only after the improvement of a number of modern technologies by several orders of magnitude .

Anyway, the project itself is much more realistic than all the others, where either nuclear engines, or antimatter, or warp drive and other technologies are needed, which so far belong to the category of very, very distant future projects.