For the first time, the ISS will conduct an experiment to create an optical component in space. With the help of the new technology, it will theoretically be possible to create huge lenses for space telescopes.
One of the main characteristics of any telescope is the diameter of the main mirror or collecting lens. The larger the mirror or lens, the more light the telescope "catches. Consequently, it sees fainter objects and can peer deeper into space.
The diameter of the Hubble's main mirror is 2.4 meters, the James Webb's is 6.5 meters. This is enough for their tasks, but larger mirrors will expand the observational possibilities. A space telescope with a mirror or lens of several tens or even hundreds of meters will see exoplanets directly.
Making a lens is a laborious and lengthy process. First, a mold is cast into the desired shape. The glass is then heated and slowly cooled, making it stronger and more resistant to temperature changes. The lens is then ground, polished and tested. This process is suitable for creating small lenses, but a new method is needed for huge lenses.
An international team of scientists from NASA Ames Research Center, Goddard Space Flight Center and Technion (Israel University of Technology) offers to take advantage of microgravity and use liquids to cast huge lenses on the space station. According to the inventors, it will take much less time to create such lenses, but their quality and optical characteristics will not be inferior to those of the Earth.
At first, the method was tested in laboratory conditions. Liquids are suitable not only for creating lenses, but also for compensating gravity. The main thing here - to achieve the same density of water and material. In the experiments, the scientists used ordinary polymers, of which make acrylic nails or superglue.
"We filled a round frame submerged in water with a solidifying liquid. We created the lenses in a bucket we borrowed from a local janitor," says Valeri Frumkin, author of the method. Frumkin is a member of the research group of Moran Bercovici, a professor of mechanical engineering at the Technion. The surface quality of the resulting lenses was no worse than that of the traditional method, and production was much faster.
In December 2021, scientists repeated the experiments during two ZeroG parabolic flights. Each flight allows 25 times for 15-20 seconds to experience weightlessness. This time, instead of polymers, scientists used synthetic oils of varying viscosity. The lenses were made small, the size of a coin, and the quality was measured with lasers. Of course, the "lens" lost its shape as soon as the plane began to gain altitude again, but for those few seconds it was perfect. The experiment proved the effectiveness of the method.
The next stage will take place on the ISS. This Saturday, April 9, as part of the commercial Axiom-1 mission, Eytan Stibbe arrives at the station to conduct the "Liquid Telescope Experiment" (FLUTE). This time, as in the laboratory, polymers will be used. The solidified lenses will return to Earth for further analysis.
Space telescopes are the future of astronomical observations. If we are able to move the production of components into space, the cost of such devices will decrease significantly, and their capabilities will expand. By the way, according to the inventors, in some cases lenses can be left in a liquid state. This will allow them to quickly change their optical properties during operation.