Last Christmas, NASA gave us a new telescope. Now, it’s working on seeing some of the earliest stars and galaxies of the universe.
The James Webb Space Telescope launched from Earth on December 25th, 2021. Meant to replace Hubble as our primary telescope, the main goal of Webb is to help us understand the earliest time in the universe, about 100 million years after the Big Bang.
Earth’s atmosphere makes it notoriously difficult to observe the sky, posing a challenge for scientists and astronomers for centuries. This problem was addressed first by Hubble, which gave us our best images of the universe by orbiting the Earth. Webb will go even further, 1 million miles away from Earth. It is orbiting the sun at what is called the L2 point, or the Lagrange point. This point is one of five positions around the sun in which the gravitational pull of the Earth and the Sun is equal to the centripetal force of a small object, keeping it in place. Therefore, Webb will require very few course adjustments in order to remain in its orbit. It reached the L2 point on January 24th, about a month after launch. However, the cost of this position is that Webb will be completely unserviceable, unlike Hubble, making it extremely difficult to fix if something goes wrong.
During its travels, Webb has also successfully completed all of its other set-up steps meant to take place during its flight: the deployment of its solar array, the assembly of its antenna, the deployment of its sun shield, the addition of the momentum flap, and the extension of all of Webb’s individual mirrors, as well as some course corrections, to name a few.
Webb’s mirrors are definitely the most crucial, and delicate, part of the mission. Made up of eighteen large segments of beryllium and coated with gold, the mirror has the ability to fold into pieces, making it smaller for launch. Since a telescope’s sensitivity is strongly related to the size of its mirror, the entire configuration is huge: about six meters, several times the size of Hubble’s primary mirror.
In addition to the mirrors, the other major part of the telescope is its sun shield. Since the telescope must operate at extremely low temperatures while orbiting the sun, engineers developed the sun shield to keep temperatures stable, and therefore reduce any harm to the delicate instruments. About the size of a tennis court, the shield’s five layers keep the telescope cool even when it changes its orientation to the sun.
The most recent development is that Webb has detected its first photons with its infrared camera. By pointing the telescope at a distant and isolated star, scientists plan to calibrate the eighteen segments in order to get an image. This marks the beginning of what will be a long period of tuning the telescope, focusing it so it is able to see the universe clearly.
This is a major step forward, not only for the technology used to make this possible but for its ability to expand our understanding of the universe itself. Its predicted lifetime, according to NASA, is going to be 10 years, during which it will provide priceless information and images.
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