The James Webb Space Telescope

The true successor to the Hubble space telescope. The James Webb Space Telescope (JWST) has been a mission long in the making but with the final golden mirror test almost completed it seems like it’s going to launch this October, after many push backs from its original launch date of 2007. With all types of scientists all around the world anticipating some of the biggest breakthroughs of the 21st century, what is JWST and what will it do? 

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In short, the Webb telescope will be an infrared telescope orbiting the sun at L2, looking further into the universe than ever before and seeing the universe just after the big bang. But let’s break this down. 

Firstly, the telescope has been specifically designed to cover wavelengths from 0.6 to 28.5 microns (the near-infrared).  This will allow it to see distant galaxies whose electromagnetic waves have been shifted longer and longer into the infrared due to the process of red-shift.

Secondly, JWST will be orbiting the sun at L2. L2 stands for Lagrange point 2. Simply put, the 5 Lagrange points are points in our solar system for one reason or another that have the same orbital period as Earth (365.25 days). L2 is positioned further out than the moon with a constant view of the Earth eclipsing the sun. This point is close enough to the Earth for the Earth to drag it along to make the orbital period shorter but far enough apart so that JWST won’t get pulled out of position by the Earth.

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Finally, JWST will look further into the universe and further into the past than ever before. Looking far into the past is something that the Hubble space telescope did with the Hubble deep field image. To this day that is as far back as we have ever looked:

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But how can these pieces of technology do this? The answer is light. Light is fast, relatively. Light has a speed of about 300,000,000 m/s in a vacuum. Although, this is minuscule compared to the vastness of space. Therefore, the further into the universe you look, the longer the light that you are looking at has taken to travel to you and therefore the image you see will be of that object when the light left it. Let’s use an example. A light-year is a unit of distance. It is how long light travels in an earth year (about 10 trillion km). Imagine now, you are looking at an object 1 light year away. The light you are seeing has taken 1 year to travel to you so you are viewing what that object looked like 1 year ago. The Hubble deep field image viewed a galaxy 13.4 billion light-years away and therefore saw it as it looked 13.4 billion years ago. 

JWST hopes to look almost 13.8 billion years into the past (just after the big bang). This could tell us about how the universe formed and help to answer many questions: is the universe infinite? is the big bang theory 100% correct? and how will the universe end?

How will JWST achieve this? With state of the art technology, including the new massive mirror that is just finishing its final tests. Hubble is 13.2 meters (43.5 ft.) long and its maximum diameter is 4.2 meters (14 ft.) It is about the size of a large tractor-trailer truck. James Webb’s sun shield is about 22 meters by 12 meters (69.5 ft x 46.5 ft). 

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With much larger light-gathering capabilities than Hubble, JWST will be able to revolutionise how we view the universe and cosmology itself.

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