What is a "solar sail" and how does it work?

About 5 thousand years ago in ancient Egyptsomething happened that radically changed the world. Judging by archaeological finds, around this time the Egyptians invented sails, which began to be used to control ships using wind power. It's hard to believe, but at the moment, humanity is again on the verge of a discovery that will affect the whole world. Scientists are trying to use the so-called "solar sails" to control space satellites. There is very little time left until the spacecraft can operate without fuel engines.

At the moment, most of the artificialsatellites that circle around our planet are powered by the energy of ion engines. These engines are heavy, they are quite expensive and only work for about three years, so scientists have long been trying to find an alternative to them. Back in 1920, the Soviet inventor Friedrich Zander realized that for flights in space, you can use the semblance of sails used in ships. But how, in his opinion, can sails set in motion space objects? Indeed, in space there is no wind.


  • 1 How do satellites fly?
  • 2 The first working solar sail
  • 3 Solar sail LightSail 2
  • 4 What is the speed of the solar sail?
  • 5 Benefits of Solar Sails

How do satellites fly?

The fact is that in space there is a wonderfulAn alternative to wind is sunlight, which consists of an unimaginable amount of particles called photons. Each of them can hit hard surfaces and create pressure that can push objects forward. Imagine how a billiard ball collides with other balls on the table - something like this photons of light and affect the surface of the sail. So why not make this solid surface a huge sail, and a tiny satellite a movable object?

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Scientists have tried many times to bring spacesatellites set in motion with the help of solar sails, but they did not succeed for a long time. The fact is that the force of particles of sunlight is very small and not enough to push large satellites forward. It took scientists decades to reduce satellites to the size of tiny smartphones. One of such compact devices are cubsats, which are manufactured in sizes of 10 x 10 x 11 centimeters. Despite their small size, they have everything necessary for observing the Earth.

The first working solar sail

The first space satellite to operatethe Japanese sail IKAROS became the solar sail. Its launch took place on May 21, 2010, when a thin sail with a 20-meter diagonal was folded. After entering orbit, the sail began to unfold and completed this process only a week after the start. With the help of this sail and sunlight, the device was able to regulate the direction of its movement. However, then the apparatus fell into the shade and fell into hibernation, because of which the experiment had to be stopped.

IKAROS - the first spacecraft with a working solar sail

Solar sail LightSail 2

But scientists did not give up and test the solarthe sails are coming right now. If you look at the night sky, there you can quite notice the LightSail 2 spacecraft from the Planetary community. It was launched into orbit on our planet in June 2019 with the help of the Falcon Heavy booster rocket. A few weeks later he opened his solar sail - its area is 32 square meters and that is why people have the opportunity to see it from the Earth. Just think - the sail has almost the same area as the average apartment!

The LightSail 2 device is now in Earth orbit

The sail is not without reason such a huge size. The fact is that in order to set in motion even a small apparatus the size of a loaf of bread, particles of sunlight need to act on the maximum possible sail area. Perhaps in the future, scientists will be able to create smaller satellites, for example, from matchboxes. Then the sails will really become small, and it will be impossible to make them out from the Earth.

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By the way, the LightSail-2 device had a prototype forcalled LightSail-1. It was launched into orbit on May 20, 2015 and deployed the sail on June 7. After another 7 days, he conducted his test flight, which lasted no more than a day. Unlike the prototype, the LightSail-2 will fly in the orbit of the Earth until at least mid-August.

What is the speed of the solar sail?

You probably wonder what speed you canto develop with the help of a solar sail? The speed and intensity of acceleration depends on the size of the sail and satellite. The LightSail 2 device is currently making a complete revolution around our planet in 90 minutes. The speed of the satellite, by the way, is constantly increasing - for one month of being under the influence of sunlight it accelerates by 549 kilometers per hour. While the speed of the device is quite small, but over time, if left in working condition, it can reach the speed of the International Space Station, which is about 27,000 kilometers per hour.

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LightSail 2 needs to spin constantly to catch the sun.

Since the performance of satellites with solarsails are directly dependent on particles of light, they cannot be used outside the solar system. Although, in the rest of the Universe, there are probably other sources of light, so in the very distant future, solar sails can also come in handy.

Benefits of Solar Sails

Solar sails really work and quitesatellites may soon lose their ion engines. This will significantly reduce their cost, because solar sails are clearly cheaper than engines, because in fact it is a mirror canvas stretched around the satellite. In addition, aerospace companies will not have to spend money on expensive fuel - it simply is not needed in “sailing” satellites.

The ion engine really looks more expensive than solar sails, right?

Unfortunately, having the opportunity to createcheap satellites, companies can often put them in low Earth orbit. And there are so many objects around our planet, and in the next ten years there will be even more of them - after all, no one forgot that Elon Musk wants to create the world’s Starlink Internet using 12,000 satellites? We humans have almost created working solar sails - now we need to think about how to get rid of space debris.

Wait, maybe space benefits can be of some use?

Finally, I want to recommend a storyEnglish science fiction writer Arthur Clarke "Solar Wind". It talks about the regatta of spaceships that move with the help of solar wind pressure. In his work, the writer talked about different types of solar sails (they do not exist yet!) And how to control them.

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