It is a known fact that all bodies strive for a perfect shape in which they have the smallest outer surface for their volume – in ideal conditions, this shape is spherical, and it is easiest to achieve it in conditions of zero gravity. The more massive a body is, its own gravity will shape it into a sphere.
In the case of liquid, surface tension will also help, and the best illustration of this is the round droplets of water that are created in, for example, experiments on the International Space Station.
These effects will be tested by NASA scientists, in collaboration with the crew of the first private mission on the ISS, which has just arrived there, for one very useful application.
Their idea is to create round drops of special transparent polymers in microgravity conditions, which would independently form into perfect spheres, and then harden them with the help of ultraviolet light. In this way, they will get perfect lenses, significantly more precise than could be made of glass, first by casting and then by polishing the surface.
Liquid polymer to a solid lens
The goal of this experiment is to examine how feasible the idea scientists have for a new generation of space telescopes is. According to them, in the future, large telescope lenses could be made in this way – thanks to the conditions of zero gravity, the liquid in space could create perfect shapes, which would then be solidified. Even ten or a hundred times bigger and more precise telescope lenses would, of course, enable significantly better characteristics of the telescope that would be used with it.
NASA has already conducted an experiment with spheres of liquid polymers on Earth, in a liquid of the same density as the polymer, which simulated a weightless state. Then they tested the same thing on parabolic ZeroG flights, and now the experiment has been moved to space, ie to the International Space Station. It will be conducted there by crew members from the private AX-1 mission.
If their experiment succeeds, it will be the first time in history that an optical component has been produced in space. In addition, it will be another step toward huge and powerful space telescopes that NASA could build in the future.