Every material used as a light sail is bound to very restrictive physical requirements. It must be extremely light, cannot melt from the energy used on it and does not have to bend from this pressure, but does not break. Various research groups around the world have worked on materials from which they believe that they will meet these requirements and a new paper from researchers from the University of Pennsylvania describes experimental tests of what they are for the most functional, previously developed light sailing material.
Modern designs of light sailing use lasers to push the sail along the sail instead of simply relying on photons from the next star to do this. This modern design is part of the design of the Breakthrough Starshot initiative to maintain a probe up to 20% of the speed of light and to get to Alpha Centauri. But to have a sail that is able to request the three properties mentioned above.
The researcher's solution is a three -layer material. His “core” consists of Molybdän -Disulfide, which is desirable for its high reflection capacity. In the past, it was difficult to produce large, smooth leaves of this material, but the researchers developed a two -stage process for this. First you spint molybdenum directly on a substrate. Then “Sulferize” the molybdenum by inserting it into a chemical vapor separation at high temperature and inserting hydrogen sulfide gas, which reacts with the molybdenum at an elevated temperature of 750 ° C to generate molybddenum -disulfide.
https://www.youtube.com/watch?v=udykxhq7x78
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There is an aluminum oxide layer on both sides of the molyb dancer, which is estimated for the thermal emission degree. It is designed in such a way that the laser light can pass directly to the molybdenum that it then reflects back, but the aluminum oxide is also designed so that it is strongly emitted in the infrared wavelength. In other words, it would enable the heat transmitted by the laser – so that the sail can cool down.
Another design is the shape of the sail itself. It is designed in such a way that it should be obtained with a hexagonal structure. This enables the structure itself to bend at intended points without causing too much stress to a certain point in the material itself, which can otherwise lead to breaking it.
According to the experimental results that the researchers presented, the new material was much better than any previous material that was presented as a potential light sail, at least in relation to two important metrics. It reflected 50% of the laser light, which was directed towards it, while only about 4% of the energy transmitted by the laser absorbed. This absorption number is much lower than earlier experimental results.
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While the corrugated design enables more flexibility in the structure, it also adds a certain weight. The general “surface density” of the material is about 0.7 g / m2 and a destination from a breakthrough of star shot of 0.1 g / m2 with an unsolved design of 0.7 g / m2. While it is still the same size, there is much more material science work before a material can get to this level of density.
Overall, this paper represents a further step towards the development of a fully functional light control, which one day could push a probe to our next star system. Admittedly, a lot of other development has to take place so that this mission is a success – sailing material is only a small part of it. Since more and more researchers are committed and tackled the technical challenges in connection with this extraordinary goal, closer humanity becomes an interstellar species.
Learn more:
MF Campbell et al. – Experimental demonstration of corrugated sheet nanolaminate films as reflective light sail
Ut – researchers continue to scale
UT – What should light sails be made from?
Ut – photonic lights are our best shot to reach another star
