Moving from conventional materials to building space telescopes, scientists are now moving on to building observatories by harnessing liquid in microgravity. It may sound weird, but it was the behavior of liquid in space that gave rise to the idea of using liquid to create lenses in microgravity. The same idea will be used to conduct an experiment aboard the International Space Station (ISS) that will be carried by astronauts on Axiom Space’s private Ax-1 mission on April 8.
Are liquid lenses the future of space telescopes?
To explain how lenses made of liquid have potential as a component of future space telescopes, NASA highlighted the behavior of water in space. On Earth, all liquids have an elastic force called surface tension, which gives water droplets their shape and even allows some insects to glide through water without sinking. If these droplets are small enough (2 mm or less), surface tension overcomes gravity and they remain perfectly spherical, however, a droplet would be crushed under its own weight if it grew larger.
(Free-floating water bubble inside the ISS; Image: NASA)
But in space, this is not the case because drops of water and other liquids eventually take on a perfectly spherical shape, regardless of their size. “We thought, why not take advantage of the way liquids naturally behave in microgravity and apply that to building large-scale telescopes or fabricated optical components in space that can have all kinds of uses. “, Edward Balaban, principal investigator of the Fluidic Telescope Experiment, said. “In microgravity, liquids take on shapes useful for making lenses and mirrors, so if we make them in space, they could be used to build telescopes that are considerably larger than previously thought,” added Balaban.
Dr Valeri Frumkin, part of the Liquid Lenses Project on Earth, said scientists were able to create lenses in a janitor bucket by injecting a liquid, solidifying it and submerging it in water in circular frames. “The trick is to make sure the water has the exact same density as the polymer we’re injecting so that the buoyancy forces precisely oppose the gravitational forces to simulate zero gravity conditions,” Frumkin said.
The idea was first tested in December 2021, under two parabolic ZeroG flights that offered 50 opportunities to achieve microgravity periods of 15 to 20 seconds. NASA says that if the idea succeeds, scientists could create a telescope 10 times or even 100 times larger than existing ones.