On December 24th one of the most expensive satellite was launched by NASA collaborations with Canada and Europe. The James Webb Telescope(JWST). Now what is special about this? Well it will help humanity to see through 13 billion years into the past and it is not a time machine. Webb will help us to see the universe as it was shortly after the Big Bang. Now this telescope is not which was built in the past few years but almost a quarter of a century. It's been nursed to life by experts from Canada and Europe. It was named after the second head of NASA - James Webb. This telescope was first planned to launch it into the orbit in 2007 but was delayed repeatedly. James Webb will join the Hubble(read my previous blog about Hubble for better understanding) to perform tasks including creation of 3-D model of our universe. We expect James Webb to show us the universe as it was 100 to 250 million years after it's birth. This will not only help scientists understand the processes that took place at that took place at that time but perhaps also transforms our current understanding of the structure of our universe.
Additionally the James Webb will be able to observe the planets and their satellites found outside of Solar System and learn a lot about Earth- like exoplanets. For example we will be able to determine their density and analyse their composition atmospheres in order understand what type of planet it is or whether there is life on it. Other previous telescopes have collected has collected data on the gas shells of about a hundred planets. According to experts the James Webb is capable of exploring the atmospheres of more than 300 planets. So it brings us to another question(Atleast that is what I thought) how does the James Webb work? The James Webb is an orbiting infrared observatory that will investigate the thermal radiations of space objects. Remember all solids and liquids when heated to certain temperature emit energy in the infrared spectrum. Here there is a relationship between wavelength and temperature. The higher the temperature the shorter the wavelength and higher the radiation intensity the better the Webb's sensitive equipment will be able to study cold exoplanets with surface temperatures of upto 27 degrees Celsius. An important quality of this new telescope is that will it will revolve around the Sun and not the Earth unlike the Hubble which is located at an altitude of about 570 kms in low-Earth orbits. With the James Webb orbiting the Sun it will be impossible for the Earth to interfere with it. However, the James Webb will move in sync with the Earth to maintain strong communication yet the the distance from the James Webb to the Earth will be between about 374,000 to 1500000 kms(lol just kidding it's just 1.5 million) in the direction opposite to the Sun so the potential of breakdowns needed to be eliminated. The new telescope weighs 6.2 tons compared to the Hubble's 11 tonnes. Nonetheless the James Webb exceeds it's predecessor in size. It's like is that of a tennis court with a height of a three-story house while Hubble is no larger than a bus. The first piece worth noting is the main mirror of the telescope with a diameter of 6.5 metres and a collecting area of 25m². It resembles a giant honeycomb consisting of 18 sections. On the Hubble, the diameter of the main mirror is 2.4 m almost 3 times smaller in size with approximately 7 times smaller surface area.
Due to it's impressive size, the main mirror has to be folded for start-up. This giant size will capture light from the most distant galaxies. The first segment of the mirror was installed on the telescope only at the end of 2015 and wasn't completely until February of 2016. A special type of Beryllium was used which retain it's shape at low cryogenic temperature. The front of the mirror is covered is covered with a layer of 48.2 grams of gold 100 nanometres thick. Such a coating best reflects infrared radiation.
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Written by: Sowmiya Narayanan
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Reference:
Riddle - https://www.youtube.com/watch?v=9dltpwxFKaA&t=356s
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