International Courant
Astronomers have found greater than 5,000 planets outdoors of the photo voltaic system so far. The grand query is whether or not any of those planets are house to life. To search out the reply, astronomers will doubtless want extra highly effective telescopes than exist as we speak.
I’m an astronomer who research astrobiology and planets round distant stars. For the final seven years, I’ve been co-leading a staff that’s growing a brand new form of area telescope that might acquire 100 occasions extra mild than the James Webb House Telescope, the largest area telescope ever constructed.
Nearly all area telescopes, together with Hubble and Webb, acquire mild 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 supply than mirrored telescopes.
Due to these variations, it could be doable to launch many particular person items into orbit and create a strong community of telescopes.
Exoplanets, like TOI-700d proven on this artist’s conception, are planets past our photo voltaic system and are prime candidates within the seek for life. Picture: NASA’s Goddard House Flight Heart through The Dialog
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 area telescopes that acquire enormous quantities of sunshine to research these faint and faraway objects.
Present telescopes can detect exoplanets as small as Earth. Nonetheless, it takes much more sensitivity to start to be taught concerning the chemical composition of those planets. Even Webb is simply barely highly effective sufficient to go looking sure exoplanets for clues of life – specifically gases within the ambiance.
The James Webb House Telescope value greater than US$8 billion and took over 20 years to construct. The following flagship telescope is just not anticipated to fly earlier than 2045 and is estimated to value $11 billion. These bold telescope initiatives are all the time costly, laborious and produce a single highly effective – however very specialised – observatory.
A brand new form 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’s going to exoplanet area 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 constructing bigger mirrors and getting them into orbit. To bypass this bottleneck, just a few of us got here up with the concept of revisiting an outdated expertise referred to as diffractive lenses.
Diffractive lenses, left, are a lot thinner in comparison with equally highly effective refractive lenses, proper. Picture: Pko / Wikimedia Commons
Standard lenses use refraction to focus mild. Refraction is when mild modifications path 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 have been invented by the French scientist Augustin-Jean Fresnel in 1819 to supply light-weight lenses for lighthouses. Immediately, related diffractive lenses might be discovered in lots of small-sized client optics – from digicam lenses to digital actuality headsets.
Skinny, easy diffractive lenses are infamous for his or her blurry photographs, so that they have by no means been utilized in astronomical observatories. However in the event you may enhance their readability, utilizing diffractive lenses as an alternative of mirrors or refractive lenses would permit an area telescope to be less expensive, lighter and bigger.
One of many advantages of diffractive lenses is that they will stay skinny whereas growing in diameter. Picture: Daniel Apai/College of Arizona, CC BY-ND
A skinny, high-resolution lens
After the assembly, I returned to the College of Arizona and determined to discover whether or not trendy expertise may 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 staff and set to work.
Over the next two years, our staff invented a brand new kind of diffractive lens that required new manufacturing applied sciences to etch a posh sample of tiny grooves onto a bit of clear glass or plastic. The particular sample and form of the cuts focuses incoming mild to a single level behind the lens.
The brand new design produces a near-perfect high quality picture, much better than earlier diffractive lenses.
A diffractive lens bends mild utilizing etchings and patterns on its floor. Picture: Daniel Apai / College of Arizona, CC BY-ND
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 conserving it very skinny and light-weight. Larger lenses acquire extra mild, and low weight means cheaper launches to orbit – each nice traits for an area telescope.
In August 2018, our staff 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 shall be greater than 10 occasions lighter than a traditional refractive lens could be.
The ability of diffraction
This new lens design makes it doable to rethink how an area telescope may be constructed. In 2019, our staff revealed an idea referred to as the Nautilus House Observatory.
Utilizing the brand new expertise, our staff thinks it’s doable to construct a 29.5-foot (8.5-meter) diameter lens that will be solely about 0.2 inches (0.5 cm) thick. The lens and assist construction of our new telescope may weigh round 1,100 kilos (500 kilograms).
That is greater than 3 times lighter than a Webb-style mirror of an analogous dimension and could be greater than Webb’s 21-foot (6.5-meter) diameter mirror.
The skinny lens allowed the staff to design a lighter, cheaper telescope, which they named the Nautilus House Observatory. Picture: Daniel Apai / College of Arizona, CC BY-ND
The lenses produce other advantages, too.
First, they’re a lot simpler and faster to manufacture than mirrors and might be made en masse. Second, lens-based telescopes work effectively even when not aligned completely, making these telescopes simpler to assemble and fly in area than mirror-based telescopes, which require extraordinarily exact alignment.
Lastly, since a single Nautilus unit could be mild and comparatively low-cost to supply, it could be doable to place dozens of them into orbit. Our present design is in actual fact not a single telescope, however a constellation of 35 particular person telescope items.
Every particular person telescope could be an impartial, extremely delicate observatory in a position to acquire extra mild 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 items, Nautilus’ light-collecting energy would equal a telescope practically 10 occasions bigger than Webb. With this highly effective telescope, astronomers may search a whole bunch of exoplanets for atmospheric gases which will point out extraterrestrial life.
Though the Nautilus House Observatory remains to be a great distance from launch, our staff has made quite a lot of progress. Now we have proven that every one features 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 area on a high-altitude balloon. With that, we shall be able to suggest a revolutionary new area telescope to NASA and, hopefully, be on the best way to exploring a whole bunch of worlds for signatures of life.
Daniel Apai, Affiliate Dean for Analysis and Professor of Astronomy and Planetary Sciences, College of Arizona
Disclosure: Daniel Apai receives funding from NASA, NSF, and the Gordon and Betty Moore Basis. He works for The College of Arizona.
This text is republished from The Dialog beneath a Inventive Commons license. Learn the authentic article.
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