UA Team Proposes 'Lighthouse Lens' For Space Telescopes

By Nicholas Gerbis
Published: Monday, August 12, 2019 - 5:05am
Updated: Monday, August 12, 2019 - 8:20am

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Daniel Apai and the Nautilus Team
Rendering of the telescope launch containers (from left), a single unit telescope in the launch container (middle) and a single deployed unit. Compact and light, 15 such units can fly aboard a single SpaceX BFR.

Astronomers need stronger telescopes to study the cosmos and search for life on other worlds, but physics limits the size of telescope mirrors and lenses.

Now, a University of Arizona team is working on a way around those limits.

The research appears in the Astronomical Journal.

A large lens or mirror can deform under its own weight.

That fact limits ground-based mirrors to about 27 feet across and rocket-launched space telescope mirrors to one-third that size.

To get around this limitation, the James Webb Space Telescope will use segmented and actively controlled mirrors instead of a single mirror.

Historically, mirror-based reflecting telescopes came to dominate lens-based refractors because engineers could more effectively scale them up.

That could change in UA's lenses take off.

To drop their weight, the UA team took a cue from French physicist Augustin-Jean Fresnel, whose lighthouse lenses used a flat, lightweight array of prisms instead of a massive convex lens.

"Each of these telescopes would be replicated. The technology that we have developed enables this replicating lenses more readily than what's possible for mirrors," lead author Dániel Apai said.

The team estimates 35 of their lightweight space telescopes could gather as much light as a single, 160-foot lens.

The lightweight lenses could occupy inflatable telescopes, which would further reduce launch costs. Several could launch aboard a single rocket.

Moreover, lenses are also less sensitive than mirrors to misalignments or deformations.

"If your glasses are slightly misaligned, you can still see through them," Apai said.

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