New thin-lens telescope design could outpace Ars Technica’s James Webb

Astronomers have discovered more than 5000 planets outside the solar system to go on a date. The big question is whether Which of these planets is home to life?. To find the answer, astronomers will likely need More powerful telescopes than what exists today.

I am Astronomer who studies astrobiology And planets around distant stars. For the past seven years, I’ve been co-leading a team developing a new type of space telescope that can gather 100 times more light than Earth. James Webb Space Telescopethe largest space telescope ever built.

Almost all space telescopes, including Hubble and Webb, collect light using mirrors. our proposed telescope, Nautilus Space ObservatoryIt will replace large, heavy mirrors with a new thin lens that is lighter, cheaper, and easier to produce than reflecting telescopes. Due to these differences, it will be possible to launch many individual modules into orbit and create a powerful network of telescopes.

The need for larger telescopes

Exoplanets — planets orbiting stars other than the Sun — are prime targets in the search for life. Astronomers need to use giant space telescopes that collect huge amounts of light Examine these dim and distant objects.

Current telescopes can detect small exoplanets like Earth. However, it takes a lot of sensitivity to begin to learn about the chemical composition of these planets. Even Webb is hardly powerful enough to search Some exoplanets for clues to life-he is called gases in the atmosphere.

The James Webb Space Telescope cost more than $8 billion and took more than 20 years to build. The next flagship telescope is not expected to fly before 2045 and is estimated to be cost 11 billion dollars. These ambitious telescope projects are always expensive and arduous and result in one powerful – but very specialized – observatory.

A new kind of telescope

In 2016, the space giant Northrop Grumman He invited me and 14 other professors and NASA scientists—all experts in exoplanets and the search for extraterrestrial life—to Los Angeles to answer one question: What will space telescopes look like for exoplanets in 50 years?

In our discussions, we realized that the main bottleneck preventing building more powerful telescopes was the challenge of making larger mirrors and getting them into orbit. To bypass this bottleneck, a few of us came up with the idea of ​​revisiting an old technology called refractive lenses.

Conventional lenses use refraction to focus light. Refraction is when light changes direction Because it passes from one medium to another – which is why light is bent when it enters water. In contrast, diffraction occurs when light bends around corners and obstacles. The pattern of steps and angles cleverly arranged on a glass surface can form a refractive lens.

The first lenses of this type were invented by French scientist Augustin-Jean Fresnel in 1819 to provide lightweight lenses lighthouses. Today, similar refractive lenses can be found in many compact consumer optics – from camera lenses to Virtual reality headsets.

Refractive lenses are thin and simple It is known for its lackluster images, so it has never been used in astronomical observatories. But if you can improve their sharpness, using refracting lenses instead of mirrors or refracting lenses will allow a space telescope to be much cheaper, lighter and larger.

Thin, high-resolution lens

After the meeting, I went back to the University of Arizona and decided to explore whether modern technology could produce better image quality refractive lenses. I’m lucky, Thomas Melster– one of the world’s leading experts in refractive lens design – works in the building next to mine. We formed a team and got to work.

Over the next two years, our team invented a new type of refractive lens that required new manufacturing techniques to etch an intricate pattern of tiny grooves onto a piece of clear glass or plastic. The specific pattern and shape of the cuts focuses the incoming light to a single point behind the lens. The new design produces a Almost perfect picture qualityMuch better than previous refractive lenses.

Since it’s the texture of the lens surface that does the focus, not the thickness, you can easily zoom in on the lens while you’re at it Keeping it slim and lightweight. Larger lenses gather more light, and mean lower weight Cheaper launches into orbit– both great attributes of a space telescope.

In August 2018, our team produced the first prototype, a lens with a diameter of 2 inches (5 cm). Over the next five years, we improved the image quality and increased the size. We are now completing a 10-inch (24 cm) diameter lens that will be 10 times lighter than a conventional refractive lens.

Space Diffraction Telescope Power

This new lens design enables a rethink of how a space telescope is built. In 2019, our team published a concept called Nautilus Space Observatory.

Using the new technology, our team believes it is possible to build a lens measuring 29.5 feet (8.5 meters) in diameter with a thickness of about 0.2 inches (0.5 cm). The lens and support structure for our new telescope can weigh about 1,100 pounds (500 kilograms). These are three times lighter than a Webb mirror of similar size and will be larger than a Webb mirror of 21 feet (6.5 m) in diameter.

Lenses have other benefits, too. First, they are Much easier and faster to be made of mirrors It can be made collectively. Second, eyepiece-based telescopes work well even when they are not perfectly aligned, which makes these telescopes easier to gathering And fly in space rather than mirror-based telescopes, which require very precise alignment.

Finally, since a single Nautilus would be light and relatively cheap to produce, it would be possible to put dozens of them into orbit. Our current design is not actually a single telescope, but a constellation of 35 individual telescope modules.

Each individual telescope will be an independent, highly sensitive observatory capable of collecting more light than Webb. But the real power of Nautilus will come from turning all of the individual telescopes toward a single target.

By integrating data from all modules, the light-gathering power of Nautilus would be equivalent to a telescope nearly 10 times larger than Webb’s. With this powerful telescope, astronomers can search hundreds of exoplanets for gases in their atmospheres Refers to extraterrestrial life.

Although the Nautilus Space Observatory is still a long way from launch, our team has made a lot of progress. We have shown all aspects of the technology to work in small scale prototypes and are now focused on building a lens with a diameter of 3.3 feet (1 meter). Our next steps are to send a small version of the telescope to the edge of space on a high balloon.

With that said, we’ll be ready to propose NASA’s revolutionary new space telescope and hopefully be on our way to exploring hundreds of worlds for signatures of life.

Daniel AbayAssociate dean for research and professor of astronomy and planetary sciences. University of Arizona. This article has been republished from Conversation Under Creative Commons Licence. Read the The original article.