NASA’s huge new James Webb Space Telescope is the most powerful telescope ever launched into space, but the agency is already looking to the future. He is currently exploring the possibility of creating liquid lenses to make a giant telescope perhaps 100 times larger than Webb.
In a new article on its website, NASA writes that it is exploring new ways and flowing materials to create giant telescopes.
“When it comes to telescopes, the bigger the better,” the agency writes. “Larger telescopes collect more light and allow astronomers to look farther into space and see distant objects in more detail.
“What if there was a way to make a telescope 10 times – or even 100 times – bigger than before? What began as a theoretical question is a series of experiments to find out whether it is possible to use liquids to create lenses under microgravity.
Experiments to create liquid lenses in space
The experiments are currently being held on the ISS National Labin, the United States Orbital Segment (USOS) of the International Space Station (ISS), pending the arrival of astronauts aboard Axiom Mission 1, a private crew mission scheduled to send four people to the ISS for departure.
Private Israeli astronaut Eitan Stibbe, a specialist on Mission 2 in the crew, will conduct experiments as part of his research portfolio.
While liquids may be less useful as optical lenses in terrestrial gravity, they perfectly focus light in microgravity.
“All liquids have a resilient force that holds them together on the surface,” says NASA. “This force is called surface tension. This is what allows some insects to glide on the water without sinking, and gives the water droplets a shape. On Earth, when water droplets are small enough (2 mm or less), surface tension overcomes gravity and they remain perfectly spherical. When the droplet becomes much larger, it is compressed under its own weight.
“But in space, drops of water and other liquids (after oscillations) eventually take on a perfect spherical shape.”
Stibb’s experiments investigate whether high-precision lenses and mirrors can be produced in space using liquids.
“We thought, why not take advantage of how liquids naturally behave in microgravity, and not apply this to build large-scale telescopes or space optical components that can have all kinds of uses,” says Edward Balaban, principal investigator of the Experiment with liquid telescope (FLUTE) at NASA’s Ames Research Center. “In microgravity, liquids take on shapes useful for creating lenses and mirrors, so if we make them in space, they can be used to make telescopes much larger than previously thought.”
Previous successful trials on Earth
Earlier, researchers tested the idea of liquid lenses on Earth by modeling a weightless medium with water.
“By injecting a solidifiable liquid into round frames submerged in water, we were able to create lenses literally in a janitor’s bucket,” says NASA’s Dr. Valery Frumkin of Technion, Israel Institute of Technology. “Polymers, which are also used in nail salons to make acrylic nails or in adhesives such as superglue, are a natural choice of material for lenses.
“The trick is to make sure the water has the same density as the polymer we inject, so that the buoyancy forces accurately counter the gravitational forces to mimic weightlessness conditions.”
It has been found that solid lenses created in this way with liquid have an “excellent” surface quality that competes with or even surpasses what can be created with the best polishing techniques that exist in the production of optical lenses. Moreover, their creation took only a fraction of the time compared to traditional lenses.
“This method allows us to completely skip any mechanical processes, such as grinding or polishing,” – says Professor of Mechanical Engineering Technion Moran Berkovichi. “Natural fluid physics just does all the work for us.”
After successful experiments on the ground, the researchers also tested their experiment in a simulated microgravity on the flights of the ZeroG parabolic aircraft. They successfully but instantly created liquid lenses of the desired shape before the plane stopped diving and gravity ruined the lenses.
Opening the door to giant space telescopes
If the experiment is conducted in constant microgravity aboard the International Space Station, Stebbe will add an extra step to cure the fluid in the lens that holds its shape. Once the lenses are made of liquid polymers and cured under ultraviolet light or temperature, they will be sent back to Earth for analysis by NASA researchers from Ames.
“We expect that this approach will create smooth surfaces of perfect shape: the best surfaces that can be turned into mirrors,” said FLUTE scientist Vivek Dwivedi of NASA’s Goddard Space Flight Center.
“If our experiment at the station is successful, it will be the first time that an optical component has been made in space,” says Balaban. “It’s like making history.”
If all goes well, the liquid transported during several missions into space could be combined to create colossal space telescopes that might otherwise be too large to launch from Earth.
The James Webb Space Telescope is set to produce the highest quality images of space people humans have ever seen, but one day it could be replaced by telescopes with “liquid lenses” 100 times larger that make the space photos we can only dream of today.