The James Webb Space Telescope-Part 2

Introduction

In the last blog, I told you about the James Webb Space Telescope. I thought that was getting a bit lengthier so I shifted the other part into this blog. I will start this blog with the characteristics of Webb.

The Characteristics of Webb

So, what are the main features of Webb and how do they help? 

1. The ability to detect infrared ways

 First of all, Webb can detect infrared waves. In the large spectrum of waves the amount a wave takes to cover one up and down motion is known as its wavelength. In this, the only waves we can see are of visible light which extends from red to blue. These have a short wavelength and therefore, we can see them. But waves such as radiowaves have such a long wavelength that they can even jump around buildings and that is why you can hear your radio. Now infrared means ‘below the red’ and the wavelength is long enough to jump between dust clouds, stars, etc, And that is why none of our telescopes has been able to look at what the infrared waves might reveal. The James Webb Telescope has eyes that will help it see infrared waves too. Studying infrared waves will help because when anything that emits heat will also emit infrared waves and when the stars and planets will radiate heat they will also emit these types of waves and JWST will be able to study them taking more information. Another advantage is that as the universe expands, the wavelength of the light coming from far away planets also stretches. This phenomenon is known as red-shift meaning that the light shifts towards red a bit. As the wavelength stretches more and more it becomes infrared.

1. All-rounder mirror

Every telescope has a mirror on it, which reflects the light and passes it on so that it can be processed. The larger the mirror, the better will be the quality of the image. Now the Hubble Space telescope, the strongest telescope before Webb, has a mirror of a diameter of 2.4 m whereas the James Webb Space Telescope has a hexagonal mirror instead of a circular mirror. The hexagonal mirror in turn is made up of 18 hexagonal mirrors each 1.32 m long. So the overall diameter is 6.5 m. Now the best part is that the mirror is plated with 24 karat gold. Actually while making the mirror they thought to make it completely of gold but gold expands a lot on receiving temperature. They wanted a metal that shows zero thermal expansion on receiving huge amounts of heat. But gold was important as it was the metal that can reflect the most amount of infrared light. So they made the mirror out of beryllium and plated it with a little more than 48 grams of gold. The credit for the 98% reflectiveness of the mirror goes to this gold.

Image Source - Google | Image by - James Webb Space Telescope | The JWST mirror compared to that of Hubble

Problems and the figured-out solutions

There were many problems regarding the James Webb Space Telescope during its preparation. Firstly, when the JWST will get to work, it too will radiate heat which in turn will emit infrared waves of its own. If they merge with the waves of the galaxies then that will return an image with not much quality that’s why NASA has made arrangements to make the telescope work at -223°C. This temperature is not possible on earth but it is in the universe only if the sun does not interfere. So scientists have found 1-2 solutions to what should be done to avoid the sun. Firstly they have put five layers of Kapton sheet, an artificial metal that is best among all the metals in stopping the sun, which is as long as a tennis court and each thinner than a strand of hair, below the spacecraft. All of them are coated with aluminium and the 2 layers facing the sun are also coated with doped silicon. The next thing they did was that unlike Hubble, which revolves around the earth, Webb will be deployed 1.5 km far from the earth at a specific place called L2 meaning the second Langrangian point. The speciality of this point is that it keeps orbiting the sun and Webb will follow it. Not only that, the sun’s light never reaches there as the earth blocks it. NASA has reported more than 300 problems that may occur. The complicated procedure of making the Webb may also result in these problems becoming serious enough to fail the whole program.

Image Source - Google | Image by - NASA | The Earth, Hubble, Moon, L2 with Webb

How will the telescope see back in time?

I can guess that this is the part you were waiting for most. So let me reveal the secret recipe to watching back in time. First of all, you need to understand how you see things. In the first step, light hits something then it reflects and comes to our eyes but when it had hit the object it had captured its image onto itself and when it comes to your eyes the image gets stored there. The speed of light is so fast that we do not recognize when this process takes place. For example, the light from the sun takes around 8 minutes to come to earth. So if the sun shut down we would know that 8 minutes after the incident happens. Now suppose some stars are millions of light-years away. We would see them as they were millions of years ago. The same thing is what Webb is doing. It will go to L2 and wait for the light from distant galaxies and stars which are 13 billion lightyears away. The light that comes from there shows the galaxies as they were 8 billion years after the Big Bang. (64) this tells us that it will not exactly time travel but it will glimpse into the past. The Hubble space telescope can see 12.8 billion into the past whereas Webb will be able to see 13 billion years into the past(81)

Image Source - Google | Image by - The Washington Post | The range of Hubble as compared to that of Webb

The James Webb space telescope is one of its kind. No other space mission can match it. its importance can be justified by the fact that millions of dollars were diverted from different projects to make this seemingly impossible feat into a possible one