A brand new, thin-lensed telescope design might far surpass James Webb—goodbye mirrors, hi there diffractive lenses

Astronomers have found greater than 5,000 planets exterior of the photo voltaic 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 possible want extra highly effective telescopes than exist at the moment.

I’m an astronomer who research astrobiology and planets round distant stars. For the final seven years, I’ve been co-leading a crew that’s growing a brand new sort of house telescope that might accumulate 100 occasions extra gentle than the James Webb House Telescope, the most important house telescope ever constructed.

Virtually all house telescopes, together with Hubble and Webb, accumulate gentle utilizing mirrors. Our proposed telescope, the Nautilus House Observatory, would change giant, heavy mirrors with a novel, skinny lens that’s a lot lighter, cheaper and simpler to provide than mirrored telescopes. Due to these variations, it might be doable to launch many particular person models into orbit and create a robust community of telescopes.

The necessity for bigger telescopes

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

Present telescopes can detect exoplanets as small as Earth. Nevertheless, it takes much more sensitivity to start to study concerning the chemical composition of those planets. Even Webb is simply barely highly effective sufficient to go looking sure exoplanets for clues of life—particularly gases within the ambiance.

The James Webb House Telescope value greater than US$8 billion and took over 20 years to construct. The subsequent flagship telescope isn’t anticipated to fly earlier than 2045 and is estimated to value $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 sort of telescope

In 2016, aerospace large Northrop Grumman invited me and 14 different professors and NASA scientists—all specialists on exoplanets and the seek for extraterrestrial life—to Los Angeles to reply one query: What is going to exoplanet house telescopes seem like 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, a number of of us got here up with the thought of revisiting an previous know-how referred to as diffractive lenses.

Typical lenses use refraction to focus gentle. Refraction is when gentle adjustments course because it passes from one medium to a different—it’s the motive gentle bends when it enters water. In distinction, diffraction is when gentle 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 supply light-weight lenses for lighthouses. At present, comparable diffractive lenses will be discovered in lots of small-sized shopper optics—from digicam lenses to digital actuality headsets.

Skinny, easy diffractive lenses are infamous for his or her blurry pictures, 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 a substitute of mirrors or refractive lenses would enable an area 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 trendy know-how might produce diffractive lenses with higher picture high quality. Fortunate for me, Thomas Milster—one of many world’s main specialists on diffractive lens design—works within the constructing subsequent to mine. We fashioned a crew and started working.

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 bit of clear glass or plastic. The particular sample and form of the cuts focuses incoming gentle to a single level behind the lens. The brand new design produces a near-perfect high quality picture, 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 possibly can simply make the lens larger whereas maintaining it very skinny and light-weight. Larger lenses accumulate extra gentle, and low weight means cheaper launches to orbit—each nice traits for an area telescope.

In August 2018, our crew produced the primary prototype, a 2-inch (5-centimeter) diameter lens. Over the following 5 years, we additional improved the picture high quality and elevated the scale. We are actually finishing a 10-inch (24-cm) diameter lens that can be greater than 10 occasions lighter than a traditional refractive lens could be.

Energy of a diffraction house telescope

This new lens design makes it doable to rethink how an area telescope is likely to be constructed. In 2019, our crew printed an idea referred to as the Nautilus House Observatory.

Utilizing the brand new know-how, our crew thinks it’s doable 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 assist construction of our new telescope might weigh round 1,100 kilos (500 kilograms). That is greater than thrice lighter than a Webb–model mirror of an analogous measurement and could be larger than Webb’s 21-foot (6.5-meter) diameter mirror.

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

Lastly, since a single Nautilus unit could be gentle and comparatively low-cost to provide, it might be doable 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 models.

Every particular person telescope could be an impartial, extremely delicate observatory in a position to accumulate extra gentle than Webb. However the true energy of Nautilus would come from turning all the person telescopes towards a single goal.

By combining knowledge from all of the models, Nautilus’ light-collecting energy would equal a telescope almost 10 occasions bigger than Webb. With this highly effective telescope, astronomers might search lots of of exoplanets for atmospheric gases that will point out extraterrestrial life.

Though the Nautilus House Observatory remains to be a good distance from launch, our crew has made lots of progress. We’ve got proven that every one features of the know-how work in small-scale prototypes and are actually 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 house on a high-altitude balloon.

With that, we can be able to suggest a revolutionary new house telescope to NASA and, hopefully, be on the best way to exploring lots of of worlds for signatures of life.

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