The James Webb Space Telescope (JWST) is the largest and most powerful space telescope in existence. NASA’s infrared space observatory was launched on December 25, 2021, from ESA’s Kourou Spaceport in French Guiana at 7:20 a.m. ET (12:20 p.m. GMT; 9:20 a.m. local time in Kourou) aboard an Arianespace Ariane 5 launch vehicle. The $10 billion James Webb Telescope will explore the cosmos to uncover the history of the universe, from the Big Bang to the formation of exoplanets and beyond.
This is one of NASA’s observatories, giant space instruments like the Hubble Space Telescope that peer into the depths of the universe. JWST will orbit the Sun, at the second Lagrange point (L2), nearly 1 million miles (1.5 million kilometers) from Earth. Primary mirror: 21.3 feet (6.5 meters) across. Sunshield: 69.5 feet by 46.5 feet (22 meters by 12 meters). Mass: 14,300 pounds (6,500 kilograms). It was reported in Astrophysics in the Next Decade: The James Webb Space Telescope and Associated Facilities (Proceedings of the Astrophysics and Space Science Conference).
The James Webb Space Telescope’s primary mirror is 21.3 feet (6.5 meters) in diameter. NASA/C. Gunn
It took JWST 30 days to travel nearly a million miles (1.5 million kilometers) to its permanent point of gravity: Lagrange point 2, a gravitationally stable spot in space. On January 24, 2022, the telescope reached the L2 Lagrange point, the second Lagrange point between the Sun and Earth.
L2 is a point in space near the Earth opposite the Sun; this orbit allows the telescope to remain in line with the Earth as it orbits the Sun. This location has been used frequently by several other space telescopes, including the Herschel Space Telescope and the Planck Space Observatory.
According to NASA, the James Webb Space Telescope will focus on four main areas: the first light in the universe, the formation of galaxies in the early universe, the birth of stars and protoplanetary systems, and planets (including the origin of life).
NASA’s James Webb Space Telescope can now take clear images of celestial objects using multiple instruments, the agency announced April 28, 2022. NASA/STScI
On July 11, 2022, NASA announced that all 17 “modes” of the observatory’s science instruments had been fully tested and that the James Webb Space Telescope was ready to begin its epic science mission.
The powerful JWST, like its predecessor, the Hubble Space Telescope, takes stunning pictures of celestial objects. Fortunately for astronomers, the Hubble Space Telescope remains in good health, and the two telescopes will work together for the first few years of JWST’s operation. JWST will also study exoplanets previously discovered by the Kepler space telescope and continue to make real-time observations from ground-based space telescopes.
The “selfie” shows 18 segments of the James Webb Space Telescope’s primary mirror as seen by a special camera inside the NIRCam instrument. NASA
The James Webb Telescope is an international collaboration between NASA, the European Space Agency (ESA), and the Canadian Space Agency. According to NASA, more than 300 universities, organizations, and companies from 29 U.S. states and 14 countries participated in the JWST project.
JWST works like almost any telescope: its main job is to collect light and focus it so we can see further. However, there are a lot of differences: JWST sees in a different part of the electromagnetic spectrum than our eyes. We see visible light, but JWST sees infrared, or “thermal,” like a night vision camera. It’s also very big, so it can collect a lot more light and therefore see more distant, smaller, and colder objects. It also helps that it’s in space, since it doesn’t have to look through the atmosphere, which blocks out a lot of really useful and interesting information.
The first released image from the James Webb Space Telescope shows part of a mosaic created over a 25-hour period beginning on Feb. 2, 2022, as the James Webb Space Telescope began aligning its 18 mirror segments. NASA
Why does such a distant image allow JWST to see galaxies in the early Universe?
The further away an object is in the universe, the faster it moves away from us. Fast objects experience a phenomenon called redshift, which makes them appear redder. Eventually, when an object is very far away, it becomes even redder than red and becomes infrared. This is why JWST can see farther than any telescope we’ve ever had.
Light takes time to reach us, so the most distant objects are also the oldest. Telescopes like Hubble and the JWST peer into the past. The JWST can see further than Hubble because it operates in infrared light, allowing it to peer almost to the very beginning of the universe, 13.7 billion years ago.
The first published scientific image, taken by NASA’s James Webb Space Telescope on July 11, 2022, is the deepest infrared image of the Universe to date. NASA, ESA, CSA and STScI
JWST orbits a point in space called the L2 Lagrange point. It’s 1.5 million kilometers away from us so that Earth’s heat doesn’t interfere with its observations. L2 is a gravity well, so it can’t use less fuel to keep it going than if it were just floating at a random point in space. It’s also helpful that L2 follows the Earth around the Sun, so scientists can always communicate with the telescope and download images from it.
NASA’s JWST spacecraft was launched on December 25, 2021, from ESA’s Kourou Spaceport in French Guiana at 7:20 a.m. ET (12:20 p.m. GMT; 9:20 a.m. local time in Kourou) by an Arianespace Ariane 5 launch vehicle.
Thanks to the successful and precise launch, NASA announced that JWST should have enough fuel to more than double its minimum mission life of 10 years. Since launch, the James Webb Space Telescope’s accomplishments have continued to grow.
The James Webb Space Telescope after separating from the Ariane 5 rocket that carried it into space. This is one of the last images of this impressive telescope. ESA
The James Webb Space Telescope deployed and tested its key antenna on December 26, 2021. The process took about an hour, according to NASA. The antenna will be responsible for transmitting science data to Earth twice daily. Just one day later, on December 27, the observatory left the orbit of the Moon.
On December 31, 2021, the Webb telescope successfully deployed its massive sunshield. Tensioning of the sunshield’s five layers began on January 3, 2022, and was completed the following day. The telescope’s secondary mirror was successfully deployed and locked into place on January 5, 2022.
Then, on January 8, 2022, NASA announced that the James Webb Space Telescope had successfully deployed its giant primary mirror and was now fully operational. The next step for Webb was to align the 18 individual mirrors that make up the observatory’s primary mirror.
The first science images from NASA’s James Webb Space Telescope were officially released by NASA during a live broadcast on July 12, 2022, at 10:30 a.m. ET (14:30 GMT). The images included the Space Rocks in the Carina Nebula, the spectacular Southern Ring Nebula, Stephan’s Quintet, and an analysis of the atmospheric composition of the gas giant exoplanet WASP-96 b.
The James Webb Space Telescope will undergo a series of science and calibration tests, including sunshield deployment, telescope deployment, instrument activation, and telescope alignment. Future
“You know what excites me most?” said Thomas Zurbuchen, NASA’s associate administrator for science, at an event after the images were released. “Tens of thousands of scientists — and frankly, some of them were just born, some of them not even born yet — are benefiting from this amazing telescope because it’s going to be with us for decades to come.”
Before the first image and data were released, Webb had already delivered several impressive images during instrument checks.
On February 11, 2022, NASA announced that JWST had captured its first images of starlight. The first image, taken by Webb, was of the star HD 84406. The light from HD84406 was captured by 18 Webb mirror segments located on the primary mirror, resulting in a mosaic of 18 scattered bright points.
“As Webb aligns and focuses over the next few months, those 18 dots will gradually resolve into a single star,” Thomas Zurbuchen, NASA’s associate administrator for science mission management, wrote on Twitter.
On February 18, 2022, NASA released a new, improved image of HD84406, showing 18 out-of-focus copies of the star arranged in a hexagonal pattern. Once the observatory successfully aligns the individual segments of the primary mirror, it will begin the process of stacking the images. This will result in the 18 images being superimposed on each other to form a single, sharp image.
The James Webb Space Telescope is the largest and most powerful space telescope in existence today. dima_zel
Webb also took a spectacular “selfie” using a special camera installed inside the NIRCam instrument. The camera is intended for use in engineering and alignment. The “selfie” shows that one segment of the mirror is brighter than the others. This is due to the fact that at that time it was the only segment that was successfully aligned and pointed at the star. The remaining segments of the mirror were successfully aligned one by one.
On April 28, 2022, NASA announced in a statement that the James Webb Space Telescope had completed its alignment phase, demonstrating that it can produce “sharp, well-focused images” with all four of its science instruments.
The scientific goals of JWST are mainly divided into four areas:
First Light and Reionization
This refers to the early stages of the Universe after the Big Bang, which gave rise to the Universe as we know it today. In the early stages after the Big Bang, the Universe was a sea of particles (such as electrons, protons, and neutrons), and light was not visible until the Universe cooled enough for these particles to begin to coalesce. JWST will also study events after the first stars formed; this era is called the “epoch of reionization” because it refers to the period when neutral hydrogen was reionized (gaining an electric charge again) by radiation from these first stars.
Assembly of Galaxies
Observing galaxies is a useful way to understand how matter is organized on giant scales, which in turn gives us insight into the evolution of the universe. The spiral and elliptical galaxies we see today actually evolved from different shapes over billions of years, and one of the goals of the JWST is to study the oldest galaxies to better understand this evolution. Scientists are also trying to understand how the diversity of galaxies we see today came to be, and how they form and merge together today.
The birth of stars and protoplanetary systems
The Eagle Nebula’s “Pillars of Creation” are one of the most famous places where stars are born. Stars are born in gas clouds, and as they grow, the radiation pressure they create blows away the gas that envelops them (which could be used to make other stars if it weren’t so widely dispersed). But peering into that gas is difficult. JWST’s infrared “eyes” will be able to observe the heat sources, including the stars that are born in these cocoons.
Planets and the Origin of Life
A huge number of exoplanets have been discovered over the past decade, including by NASA’s planet-hunting Kepler space telescope. JWST’s powerful sensors will allow scientists to study these planets in greater detail, including (in some cases) imaging their atmospheres. Understanding the composition of planets’ atmospheres and how they formed could help scientists better predict whether planets are habitable.
JWST and Hubble. JWST is equipped with four scientific instruments that will allow observations in the visible, near infrared, and mid-infrared (0.6 to 28.5 micrometers) wavelength ranges.
The essence of scientific progress is to “stand on the shoulders of giants,” and JWST does just that, with its scientific goals driven by results obtained by the Hubble Space Telescope.
The James Webb Space Telescope and the Hubble Space Telescope have very different capabilities. drmakkoy via Getty Images
The two space telescopes have different capabilities: Hubble has observed the cosmos primarily in optical and ultraviolet light (with some infrared capabilities). JWST studies the universe primarily in infrared light. As the universe expands, light from distant objects is shifted toward longer wavelengths at the redder end of the spectrum, known as a redshift, according to ESA. JWST will observe this infrared light in exquisite detail, shedding light on some of the oldest stars and galaxies in the universe.
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Another important difference between the James Webb Space Telescope and the Hubble Space Telescope is that the JWST orbits the Sun, while Hubble orbits the Earth. The JWST would be too far away to be serviced, unlike Hubble, which was accessed by the space shuttle.
JWST is named after former NASA Administrator James Webb. Webb led the space agency from 1961 to 1968, stepping down just months before NASA put the first man on the moon. Under Webb’s leadership, NASA launched more than 75 space science missions. These included missions to study the Sun, stars and galaxies, and the space just beyond Earth’s atmosphere.
Comparison of the corresponding mirrors of the Hubble Space Telescope (NASA/ESA) and the James Webb Space Telescope (NASA/ESA/CSA). Future/Adrian Mann
When Webb takes a picture of a distant galaxy, astronomers are essentially seeing what that galaxy looked like billions of years ago. The light from that galaxy takes billions of years to travel through space to reach the telescope’s mirror. It’s like a time machine, taking snapshots of the early universe, The Conversation reports.
Using a giant mirror to collect ancient light, Webb unlocks new secrets of the universe.
Before the light can reach the cameras, it must first be collected by the Webb telescope’s enormous gold mirror. The mirror is more than 6.5 meters wide and is made up of 18 smaller mirror elements, all connected together like a honeycomb. It is coated in a thin layer of real gold — not just for looks, but because gold is very good at reflecting infrared light.
A man works on the James Webb Space Telescope’s science module, which contains numerous instruments. Gunn/NASA
The mirror collects light from deep space and reflects it back to the telescope’s instruments. The larger the mirror, the more light it can collect and the farther it can see. Webb’s mirror is the largest ever launched into space.
The most important “eyes” of the telescope are two scientific instruments that act as cameras: NIRCam and MIRI.
NIRCam stands for Near Infrared Camera. It is the main camera on the Webb telescope, which takes stunning pictures of galaxies and stars. It also has a coronagraph, a device that blocks out starlight, allowing it to photograph very dim objects near bright sources, such as planets orbiting bright stars.
NIRCam works by imaging near-infrared light, the closest to what the human eye can see, and separating it into different wavelengths. This helps scientists not only learn what an object looks like, but also what it’s made of. Different materials in space absorb and emit infrared light at specific wavelengths, creating a kind of unique chemical “fingerprint.” By studying these “fingerprints,” scientists can uncover the properties of distant stars and galaxies.
MIRI, or the Mid-Infrared Instrument, detects longer infrared wavelengths, which are particularly useful for detecting cooler, dustier objects, such as stars that are still forming inside gas clouds. MIRI may even help find clues about the types of molecules in planetary atmospheres that could support life.
A comparison of a thermal image of a garden plot (left) and a real image, showing the temperature difference between the warm asphalt and the relatively cooler plants. Peter Bruce-Eary
Both cameras are far more sensitive than standard cameras used on Earth. NIRCam and MIRI can detect tiny amounts of heat coming from billions of light years away. If Webb’s NIRCam were your eyes, you could see the heat coming from a bumblebee on the Moon. That’s how sensitive it is.
Because Webb is trying to capture the faint heat from distant objects, it needs to keep its temperature as low as possible. That’s why it’s equipped with a giant sunshield the size of a tennis court. This five-layer sunshield blocks heat from the Sun, Earth, and even the Moon, helping Webb stay incredibly cold: about -223 °C (-370 °F).
MIRI needs to be even colder. It has its own special refrigerator, called a cryocooler, that keeps temperatures down to nearly -447 degrees Fahrenheit (-266 degrees Celsius). If Webb were even slightly warm, its own heat would drown out the distant signals it’s trying to pick up.
Once the light reaches the Webb telescope’s cameras, it hits sensors called detectors. These detectors don’t take regular photos like a phone camera. Instead, they convert the incoming infrared light into digital data. That data is then sent back to Earth, where scientists convert it into full-color images.
The James Webb Space Telescope’s mirrors are assembled. NASA/MSFC/David Higginbotham/Emmett
The colors we see in Webb’s images don’t match what the camera “sees” directly. Because infrared light is invisible, scientists assign colors to different wavelengths to help us understand what’s in the image. These processed images help us see the structure, age, and composition of galaxies, stars, and more.
By using a giant mirror to collect invisible infrared light and send it to ultra-cold cameras, Webb allows us to see galaxies that formed just after the birth of the universe.
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