The James Webb Telescope has played a unique and influential role in changing our understanding of astrophysics and the history of galaxies, stars and the universe. To fulfill its mission, many new and powerful new technologies have been developed, from optics to measuring instruments and thermal control systems.

Purpose of James Webb Space Telescope 

The James Webb Space Telescope (JWST) was developed by NASA in collaboration with European and Canadian agencies. It will build and expand the Hubble Space Telescope’s discoveries to help unravel the mysteries of the universe. Using the Webb telescope to compare the earliest galaxies with today’s galaxies, scientists hope to understand how they formed, how they were shaped, what chemical elements were dispersed in galaxies, how the black hole affected galaxies, and what collisions occurred when galaxies formed to change.

The working of the James Webb Space Telescope 

The Webb telescope has unique capabilities enabled by the way it views the universe, its size, and the new technologies aboard. Here’s how it works.

Peering Into the Infrared

For observing ancient, distant galaxies, the Webb Telescope is equipped with light-sensitive instruments in the near-infrared and mid-infrared wavelengths.

Light from galaxies can take thousands of years to reach Earth, so when we see them, we actually see them as normal. The further the object is from Earth, the sooner we look at it. In other words, when we look at the light left by an object 13.5 billion years ago, we see what happened in the early universe.

The universe continues to expand when light from distant objects reaches Earth, something that has been happening since the Big Bang. As the universe expands, the waves that cause light are stretched. You can see this effect by holding the pen on a rubber band and seeing how the mark flexes when you pull the rubber band.

Webb telescope’s infrared sensing equipment will give scientists the chance to study some of the earliest stars that exploded in supernova events, creating the elements necessary to build planets and form life.

Gathering Light

The first stars were so massive that their life cycles ended in a supernova explosion. The light from these bursts travels so far that it becomes very dark. This is because of the inverse square law. You have this effect where the room appears darker the further away you are from the light.

To see bright light, the Webb telescope must be very sensitive. The telescope’s sensitivity, or ability to detect weak signals, is related to the size of the mirror it uses to collect light. In the Webb telescope, 18 hexagonal mirrors combine to form a large mirror 21 feet (6.5 meters) wide.

Compared with the Hubble Space Telescope’s eight-foot (2.4 meter) diameter mirror, this gives the Webb telescope more than six times the surface area to collect those distant particles of light known as photons.

Keeping Cool

The Webb telescope collects scientific data in the form of infrared light. Camera equipment must be kept cool to detect weak signals from objects millions of light-years away, or the infrared signal may fall into the telescope’s vents. Mechanics has addressed this issue with various systems designed to keep the device cool.

Webb’s orbit around the Sun – Lagrangian point 2, about 1 million miles (1.5 million kilometers) from Earth – keeps the spacecraft away from Earth’s heat, but even that’s not enough.

To further reduce the temperature of the instrument, the aircraft will use the tennis court using five special layers to block light and heat from the sun, earth and moon. Each layer blocks the incoming heat, and the heat that passes through is sent to the side of the sun. In addition, the vacuum of each layer provides insulation.

To bring down the temperature of MIRI, the Webb telescope is equipped with a special cryocooler that pumps chilled helium to the instrument to reduce its operating temperature to about -448 F (-267 C, 6 K).

Spotting Exoplanets

Webb will search for exoplanets using two different methods. Using the transit method, it will look for dimming patterns that occur when exoplanets pass near the Sun or pass between a star and a telescope. The degree of dimming can tell scientists a lot about the exoplanet’s past, such as its size and distance from its star.

Webb’s second method of finding exoplanets is direct imaging – capturing real images of planets beyond our solar system. To view the outer planets directly, the Webb telescope is equipped with a coronagraph.

Just as you can block out bright light with your hand, a coronagraph can block a star from reaching its camera equipment, allowing faint exoplanets orbiting the star to be seen.

Webb can use spectroscopy to see more. The light from the star creates a spectrum that shows the intensity of light at different wavelengths. When Earth passes its star, some of the star’s light will pass through Earth’s atmosphere before reaching Webb. Because all elements and molecules, such as methane and water, absorb energy at certain wavelengths, the spectrum of light passing through Earth’s atmosphere may contain dark lines called water absorption lines, which can tell scientists whether certain elements are present.

All of this could lead scientists to the ultimate discovery of an exoplanet: a giant planet with an atmosphere like ours in the habitable zone of its star (where water might be).

Setting Up in Space

The Webb telescope will launch from French Guiana on the Ariane 5 rocket, a rocket large enough to carry the approximately 14,000-pound (6,200-kilogram) telescope to target.  It will fit into a 5.4 meter wide rocket launcher, protecting the aircraft during launch. To overcome this challenge, engineers designed the telescope’s lens and the sun to break apart to release it.

Both sides of the mirror assembly fold back for shooting, allowing them to fit into the fairing.

At 21 meters (5 feet) long and 14 meters (46.5 feet) wide, the paper was carefully folded 12 times like origami to make it narrow enough to be released. These are just two examples of the folding mechanisms required to assemble large telescopes for rocket launches. It took nearly a month for Webb to reach its destination and deliver its mirror and solar system. The scientists will need another five months to cool the device to operating temperature and make the glass properly.

The review should be completed about six months after launch, and the camera will begin its initial research and research work. 

Updates about the mission

Learn more and follow along with the mission from launch and unfolding to science observations and discovery announcements on the James Webb Space Telescope website.