Scientists recently published a study on what the space telescopes of the future will be like. Theoretically, they can be just mirror films deployed in vacuum. But there are a number of difficulties on the way to the realization of this idea.
Space telescopes of the future
Over the past few decades, the once fantastic idea of placing a telescope in orbit has not only become a reality, but has set a key trend in modern astronomy. Because these instruments are placed outside the Earth’s atmosphere, observations on them are more accurate than on telescopes with the same mirrors on the surface of our planet.
In a recently published paper, scientists try to figure out where space-based astronomical instruments should go next. And the real question is how to make them bigger. Because the mirror diameter of the Extremely Large Telescope, which is currently under construction in Chile, is 39 meters. The mirror of the most advanced James Webb Space Telescope is 6.5 meters, and it was difficult to place it inside the rocket, creating a bizarre structure.
Modern telescopes are really heavy structures because they have to resist gravity on Earth, which means the glass mirrors have to be very thick. But actually, if we were to place them in orbit directly, we wouldn’t have to do that. After all, there is no gravity there that tries to break or warp the mirror.
Mirror films
The authors of the study suggest making the mirrors of future space telescopes from mirror film. It can be easily rolled up on Earth and deployed in orbit so that it focuses starlight onto a light-sensitive matrix or a smaller secondary mirror. In this way, even larger telescopes can be built in orbit than on Earth.
However, this idea has challenges. Even in space, such a thin mirror will deform. The idea of a light frame on which to stretch the film is a good idea, but the reflective surface really needs to be perfect. When Hubble was launched, the deviation was no more than the thickness of a human hair. But a special correction device still had to be put on the telescope.
The solution to this is adaptive optics. It is a set of devices that “adjust” the shape of the mirror to the desired shape with high precision every time. But that brings us back to the need to launch heavy hard structures into space.
Is it possible to do this with film? The authors of the publication state that yes, we can. For this purpose, it is necessary to influence it with a laser beam, and it will get the desired shape. However, they note that there is a big difference between laboratory experiments and the application of the technology in deep space.
Provided by phys.org
