A new, thin-lensed telescope design could far surpass James Webb—goodbye mirrors, hello diffractive lenses

Astronomers have found greater than 5,000 planets outside of the solar system up to now. The grand query is whether or not any of those planets are residence to life. To search out the reply, astronomers will seemingly want more powerful telescopes than exist immediately.

I’m an astronomer who studies astrobiology and planets round distant stars. For the final seven years, I’ve been co-leading a crew that’s growing a brand new type of space telescope that would acquire 100 instances extra light than the James Webb Area Telescope, the largest space telescope ever constructed.

Virtually all space telescopes, together with Hubble and Webb, acquire mild utilizing mirrors. Our proposed telescope, the Nautilus Space Observatory, would exchange giant, heavy mirrors with a novel, skinny lens that’s a lot lighter, cheaper and simpler to supply than mirrored telescopes. Due to these variations, it could be attainable to launch many particular person items into orbit and create a robust community of telescopes.

The necessity for bigger telescopes

Exoplanets—planets that orbit stars apart from the Solar—are prime targets within the seek for life. Astronomers want to make use of large space telescopes that acquire large quantities of sunshine to study these faint and faraway objects.

Current telescopes can detect exoplanets as small as Earth. Nevertheless, it takes much more sensitivity to start to be taught in regards to the chemical composition of those planets. Even Webb is simply barely highly effective sufficient to go looking certain exoplanets for clues of life—specifically gases within the ambiance.

The James Webb Area Telescope value greater than US$8 billion and took over 20 years to build. The subsequent flagship telescope isn’t anticipated to fly earlier than 2045 and is estimated to cost $11 billion. These formidable telescope initiatives are at all times costly, laborious and produce a single highly effective—however very specialised—observatory.

A brand new type of telescope

In 2016, aerospace large Northrop Grumman invited me and 14 different professors and NASA scientists—all consultants on exoplanets and the seek for extraterrestrial life—to Los Angeles to reply one query: What is going to exoplanet space telescopes appear to be in 50 years?

In our discussions, we realized {that a} main bottleneck stopping the development of extra highly effective telescopes is the problem of creating bigger mirrors and getting them into orbit. To bypass this bottleneck, just a few of us got here up with the thought of revisiting an old technology known as diffractive lenses.

Standard lenses use refraction to focus mild. Refraction is when mild modifications route because it passes from one medium to a different—it’s the purpose mild bends when it enters water. In distinction, diffraction is when mild bends round corners and obstacles. A cleverly organized sample of steps and angles on a glass floor can type a diffractive lens.

The primary such lenses had been invented by the French scientist Augustin-Jean Fresnel in 1819 to offer light-weight lenses for lighthouses. Immediately, related diffractive lenses will be discovered in lots of small-sized shopper optics—from camera lenses to virtual reality headsets.

Skinny, easy diffractive lenses are notorious for their blurry images, in order that they have by no means been utilized in astronomical observatories. However in case you might enhance their readability, utilizing diffractive lenses as an alternative of mirrors or refractive lenses would enable a space telescope to be less expensive, lighter and bigger.

A skinny, high-resolution lens

After the assembly, I returned to the College of Arizona and determined to discover whether or not modern technology might produce diffractive lenses with higher picture high quality. Fortunate for me, Thomas Milster—one of many world’s main consultants on diffractive lens design—works within the constructing subsequent to mine. We fashioned a crew and set to work.

Over the next two years, our crew invented a brand new sort of diffractive lens that required new manufacturing applied sciences to etch a fancy sample of tiny grooves onto a chunk of clear glass or plastic. The precise sample and form of the cuts focuses incoming mild to a single point behind the lens. The brand new design produces a near-perfect quality image, much better than earlier diffractive lenses.

As a result of it’s the floor texture of the lens that does the focusing, not the thickness, you may simply make the lens greater whereas keeping it very thin and lightweight. Greater lenses acquire extra mild, and low weight means cheaper launches to orbit—each nice traits for a space telescope.

In August 2018, our crew produced the primary prototype, a 2-inch (5-centimeter) diameter lens. Over the subsequent 5 years, we additional improved the picture high quality and elevated the scale. We at the moment are finishing a 10-inch (24-cm) diameter lens that will likely be greater than 10 instances lighter than a standard refractive lens can be.

Energy of a diffraction space telescope

This new lens design makes it attainable to rethink how a space telescope is perhaps constructed. In 2019, our crew printed an idea known as the Nautilus Space Observatory.

Utilizing the brand new expertise, our crew thinks it’s attainable to construct a 29.5-foot (8.5-meter) diameter lens that may be solely about 0.2 inches (0.5 cm) thick. The lens and help construction of our new telescope might weigh round 1,100 kilos (500 kilograms). That is greater than 3 times lighter than a Webb–type mirror of an analogous dimension and can be greater than Webb’s 21-foot (6.5-meter) diameter mirror.

The lenses produce other advantages, too. First, they’re much easier and quicker to manufacture than mirrors and will be made en masse. Second, lens-based telescopes work properly even when not aligned completely, making these telescopes simpler to assemble and fly in space than mirror-based telescopes, which require extraordinarily exact alignment.

Lastly, since a single Nautilus unit can be mild and comparatively low cost to supply, it could be attainable to place dozens of them into orbit. Our present design is in reality not a single telescope, however a constellation of 35 particular person telescope items.

Every particular person telescope can be an unbiased, extremely delicate observatory capable of acquire extra mild than Webb. However the actual energy of Nautilus would come from turning all the person telescopes towards a single goal.

By combining information from all of the items, Nautilus’ light-collecting energy would equal a telescope practically 10 instances bigger than Webb. With this highly effective telescope, astronomers might search tons of of exoplanets for atmospheric gases which will point out extraterrestrial life.

Though the Nautilus Area Observatory continues to be a good distance from launch, our crew has made quite a lot of progress. Now we have proven that every one points of the expertise work in small-scale prototypes and at the moment are specializing in constructing a 3.3-foot (1-meter) diameter lens. Our subsequent steps are to ship a small model of the telescope to the sting of space on a high-altitude balloon.

With that, we will likely be able to suggest a revolutionary new space telescope to NASA and, hopefully, be on the way in which to exploring tons of of worlds for signatures of life.

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