Light can make things fly

Light can make things flyRecently, American scientists were able to pick up a small object with … beam of light. It turned out he, like air, can give bodies heavier than him lift. The researchers believe that they discovered the principle can help to design perfect "solar sails" for space ships that fly to the planets of distant stars.

In fact, researchers at the Rochester Institute of Technology in New York did not open anything new, because physicists have long assumed that the light can lift objects heavier than him. However, it has been proved experimentally for the first time. True, the light in these experiments did not lift objects in the air and in the water.

First of all, scientists have created using a computer model of how light is refracted inside the bodies of various shapes, and the radiation leaves the body data. In the analysis of the resulting models of their attention was drawn to the situation with the refraction of light in transparent objects, a little reminiscent of the shape of its wing. Has been suggested that this "light wing" should work as usual: the irradiation of the object at a certain angle there skewed towards the light passing through the material, which creates a pressure difference, such a difference in air pressure above and below the aircraft wing.

Light can make things flyCould only test this hypothesis experimentally. And now researchers have designed a transparent polymer curved rods with a semicircular cross-section, the length and width of which does not exceed a few micrometers, and then put them in water and illuminated from below mW laser.

As predicted, the bar was raised not only up, but also, more importantly, to move in a direction perpendicular to the laser light. This confirmed the hypothesis that one of the researchers, Grover Shvartslendera that the angle at which the light hits the material in and out of it, should determine the direction of movement of the object.

After analyzing the results of the experiment, the scientists came to the conclusion that really Optical lift is created inside a transparent object created by the refraction of light pressure difference. It is noteworthy that during the experiments physicists received a record optical lifting angle — about 60 degrees. "If you take off under such circumstances, your stomach just to be in heels," — commented on these achievements Shvartslender. The study appears in the December issue of the journal Nature Photonics (http://www.nature.com/nphoton/journal/vaop/ncurrent/full/nphoton.2010.266.html).

Light can make things flyNow, researchers will test whether the light lift objects in the air. Subsequent experiments also expected to use materials with different coefficients of reflection and refraction, and see how different the lift created by light beams with different wavelengths. Based on them, physicists plan to construct the ideal "svetopodemnik."

Scientists believe that they discovered the principle can be applied in the drive micromachines, and implement targeted transport of microparticles in a fluid. However, their most cherished dream — to develop advanced solar sails for space vehicles. (Solar sail called device that uses the pressure of sunlight or laser on a mirror surface to propel the spacecraft.)

The idea of creating such sails belongs to one of the pioneers of the domestic space Friedrich Zander, was first suggested it in 1927. It came from the fact that the particles of the solar light — photons — have the momentum and deliver it to any of the illuminated surface, creating pressure.

It turns out that if you equip the ship such devices, he can drift into interstellar space, pushed the light just as the frigate glides over the surface of the sea by the wind.

However, it was already known that the pressure of sunlight is extremely small, on the Earth's orbit, it is about 5.10 -6 N/m2. In addition, it decreases with the square of the distance from the Sun. Therefore, high-velocity vehicle under solar sails are unlikely to reach (and in fact they are the deciding factor in interstellar expedition).

However, the solar sail does not require rocket fuel and can operate for an almost unlimited period of time, so in some cases, its use can be fully justified. For example, to display the aircraft to the orbit of the planet, while not polluting the atmosphere. Or to the ship could turn off the engine well before approaching the desired object and gently brake, using solar sails.

Perhaps that is why the effect of the solar sail has already been used several times for the small orbit correction of spacecraft. True, there is the role of the sails used solar panels or radiators thermoregulatory system. It was only May 21, 2010 the Japanese Space Agency (JAXA) launched into space launcher H-IIA, carrying the IKAROS spacecraft with a solar sail. So in the space left is the first device that has solar sails have been the main engine.

This solar sail was made of polyamide film thickness of 7.5 mm and was a four petals trapezoidal shape. Inside the petals were sewn solar cells and solar wheels. Disclosure of the sail was on June 3 this year, due to the rotation of a "space sail" around its axis at a speed of 20 revolutions per minute. Under the force of inertia of four weights pulled petals sails, and thus, IKAROS was like a square of side 14 meters.

However, the very first stages of flight "space sailing" showed that this schooner steering listen so good. Therefore Shvartslender and his colleagues propose to change the principle of the sails — to make them out of a material that will not reflect photons, and pass them through you. Then the angle at which the light hits the material in and out of it, will determine the direction of movement of "sailing" and it would be better to listen to their "rudder."

Light can make things flyShvartslender also argues that in this case the movement of the solar sail can be fully controlled in 3D-format if you use two sets of semicircular cross rods. The system appears to be most reliable. True, this idea has criticized Dean Alhorn, chief engineer recently launched a pilot sailboat NASA. He believes that the sunlight is too weak to implement the project in practice.

However, time and experimentation, as you know, put everything in its place and will show who was right and who was wrong. So far, scientists around the world believe that the Americans have made the discovery, which is comparable to the fact that in his day the Wright brothers to the development of aviation. I wish that these experiments have helped mankind to take the next step on the road to the stars …
Anton Evseev

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