Outer space, the dream of every child! The sun, the stars, the moon.
These skylights at night
How do we see them?
But how do they work?
Let’s find out!
What Are Space Telescopes?
Telescopes have been used by astronomers for hundreds of years to observe the night sky. The Dutch eyeglass maker, Hans Lippershey, invented the first telescope in 1608.
A device that could magnify things three times. His telescope had a convex objective lens and a concave eyepiece. According to a story, he was inspired to create his invention when he saw two kids in his shop holding up two lenses to make a faraway weather vane appear closer.
Modern telescopes must be in space to obtain the most accurate data!
A space telescope is extremely difficult to construct and operate. Additionally, it is very expensive. Only since the 1980s has it been feasible. The Hubble Space Telescope is a noteworthy space telescope. Over 1 million images have been captured since it started observing in 1990.
Numerous additional space telescopes have been launched since 1990. Some are like Chandra, which studies x-rays, and Fermi, which studies gamma rays. Microwaves or infrared can be seen by others. This has altered our perception of the universe. In December 2021, the James Webb Space Telescope (JWST)—the largest—was put into orbit.
The JWST is the space telescope that replaced the Hubble (HST). The JWST can see smaller details and fainter objects because its mirror is larger than the HST’s. It is also capable of observing light at longer wavelengths than the HST.
JWST captured its first picture of a star and a selfie in February 2022. The scientists completely aligned and focused the telescope on a star in March 2022. On July 12, 2022, the first batch of data from the fully calibrated telescope was made public. The information contained an image of one of the smallest infrared objects ever seen as well as proof of water in an exoplanet’s atmosphere!
JWST was built to conduct research into the early universe.
What were the initial stars and galaxies like?
How do galaxies and stars change over time?
Does Earth orbit any other stars besides our own?
Can we discover anything about dark energy and dark matter?
The JWST will gather data during its mission, which is expected to last between five and ten years, in order to assist scientists in resolving these issues. Plus a slew of others!
A total of 6,200 kg makes up the weight of the telescope, which is similar in size to an African bush elephant.
The enormous mirror on the JWST is 6.5 meters in diameter and collects light from space. 18 hexagonal segments make up its structure.
These spread out and positioned themselves appropriately in the air to create a single, enormous mirror.
Additionally, JWST has a sunshield the size of a tennis court. This prevents the Sun’s light (as well as light reflected off the Earth and Moon) from heating up the detectors. To function, the detectors need to be kept at a low 266 °C.
What Technologies Are Used In These Space Telescopes?
The enormous telescope is located 907,530 miles from Earth in the orbit of Lagrange Point 2 (L2). Due to a unique location at this distance, JWST can maintain alignment with the Earth as it revolves around the Sun. It is currently maintaining this orbit by moving at a speed of about 451 miles per hour.
The journey of the telescope, 1,500,000 kilometers from Earth, took about 29 days.
The telescope won’t move around too much because of the gravitational pull of the Sun and the Earth. It only requires tiny, infrequent rocket thrusts to keep its orbit at L2. The JWST will follow the Earth as it orbits the Sun because of this L2 location.
The James Webb Telescope’s near-infrared camera (NIRCam) is the primary imager being used.
For the purpose of detecting light with infrared wavelengths between 0.6 and 6 microns, a team from the University of Arizona created the NIRCam.
This imager’s mission is to search for stars in the far reaches of the Kuiper Belt as well as light coming from galaxies and stars that are still in the early stages of formation.
The NIRCam has a large number of coronagraphs to image challenging objects. These devices deflect light from brighter objects, enabling imaging of nearby fainter and dimmer objects.
On a more fundamental level, the NIRCam has ten mercury-cadmium-telluride (HgCdTe) detector arrays that function similarly to charge-coupled devices (CCDs) in traditional digital cameras in terms of image capture.
The NIRCam is made up of two nearly identical, completely redundant modules that each point to different fields of view in the sky. The two modules can be used concurrently and can simultaneously observe the short wavelength channel (0.6-2.3 m) and the long wavelength channel (2.4-5.0 m).
However, the near-infrared spectrograph is more impressive (NIRSpec). A multi-object near-infrared spectrograph, or NIRSpec, is a tool that dissects incident light into its individual color components for more in-depth analysis. The James Webb Telescope uses NIRSpec, a near-infrared wavelength detector, to examine distant galaxies’ chemical composition and star formation processes.
The device’s intelligent microshutter assembly, a feature that enables NIRSpec to observe over 100 objects simultaneously, is one of the technology’s most impressive achievements.
The four 1.5-inch squares that make up the microshutter assembly each contain a separate array of 62,000 microscopic shutters. The shutters are 100 x 200 mm rectangles that selectively open and close, only catching light coming from an object that the NIRSPec’s detector has been trained on. From this point, the light is concentrated into a single, bright point that produces the sharpest image.
The shutter doors of the arrays are lined with magnetic strips that are contained within an electrically charged metal box, and the arrays themselves are made of silicon nitride wafers. Applying an electric charge and corresponding magnetic polarization to each shutter causes them to physically open and close.
When the doors are all open, a magnet sweeps over the shutters, repelling the magnetic strips on the doors. The desired shutters are then given voltage by electronic controllers, which causes them to change their magnetic polarization and close the doors when the magnet passes by again.
The microshutter system can make sure that the only doors left open are those that are in alignment with the object that is intended to be observed in this way.
In its brief time of operation, the James Webb Telescope has already generated some extraordinary images, entirely as a result of the cutting-edge imaging technology installed.
The imaging technology developed by the telescope team ranks among the best that humanity has ever created.
The James Webb Space Telescope’s first science images were officially released by NASA during a live event on July 12, 2022. They included the Cosmic Cliffs in the Carina Nebula, the striking Southern Ring Nebula, Stephan’s Quintet, and an analysis of the atmospheric composition of the hot gas giant exoplanet WASP-96 b.
According to a NASA press release, the breathtaking image was produced with just 12.5 hours of observing time on one of the telescope’s four instruments. It shows the deepest infrared view of the universe to date.
One of the mirror segments is shining brighter than the others in the “selfie” because it was the only one that had been successfully aligned and was pointing at a star at the time. One by one, the remaining mirror segments were successfully aligned.
What Can We Expect From JWST?
The four main areas of the JWST’s science mandate are:
First Light and Reionization
This refers to the period of time immediately following the Big Bang, which created the universe as we know it today.
The universe was initially a sea of particles after the Big Bang, and light was not visible until the universe cooled enough for these particles to start combining. The “epoch of reionization” refers to the period after the first stars formed, when neutral hydrogen was reionized by radiation from these first stars.
The Assembly Of Galaxies
By observing how matter is arranged on enormous scales, such as in galaxies, we can learn more about how the universe came into being. One of the objectives of JWST is to look back at the earliest galaxies to better understand how the spiral and elliptical galaxies we see today evolved from various shapes over billions of years.
Additionally, researchers are attempting to understand how galaxies formed and assembled in the past, as well as how we came to have the variety of galaxies that are visible today.
Birth Of Stars And Protoplanetary Systems
One of the most famous places for star formation is the “Pillars of Creation” of the Eagle Nebula. Stars form in gas clouds, and as they get bigger, their radiation pressure blows the gas away that was surrounding them.
However, looking inside the gas is challenging. JWST’s infrared eyes will be able to observe heat sources, such as stars developing in these star-forming cocoons.
Numerous exoplanets have been found in the last ten years, including ones using NASA’s planet-hunting Kepler Space Telescope.
Planets And The Origins Of Life
JWST’s powerful sensors will be able to take a closer look at these planets, possibly even imaging their atmospheres in some cases.
Scientists may be better able to predict whether or not a particular planet is habitable if they have a better understanding of the atmospheres and conditions under which planets form.
The James Webb Space Telescope is another milestone in the path of exploring the universe. We do not fully know what the future holds, but we are pretty sure it’s going to be bright and exciting.