NASA Scientists, along with the collaboration of astrophysicists and engineers worldwide have worked for over 2 decades to design, engineer, and build the James Webb telescope, the largest, most powerful space telescope in history. It will, hopefully, allow scientists to peer into the very cloudy (literally) history of the universe and capture images of the first galaxies ever formed. Here is how it works.

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In the beginning of the universe, there was simply nothing. Well, except a tiny, super-dense, very bright dot. And the dot expanded into the universe as we know it, over the course of billions of years. At least, this is what the space scientists think was the beginning of our world and they have built the super-powered time machine to find out.

The Webb Telescope will show us the universe 13 billion years ago

You see, the first rays of light emitted by the rapidly expanding bubble that is our universe, although a lot of it disturbed and absorbed by the objects before them, namely the stars and dust just forming, many of the light is still traveling. Unhindered, straight to us. This is where the time-machine part comes true. You see, light is not simply spontaneous. It too, takes time to travel, albeit a very short one relative to other objects we know of. Yet, this incredible speed of light (>300,000m/s) takes it billions of years to travel enormous distances. The Webb telescope is hoping to capture this light, which, even though is very, very late, is from the universe billions of years ago.

The telescope

To capture this ancient light, the telescope itself is very advanced, evident from the whopping 10 billion spent on it. Anyways, let's start with its size.

Slightly larger than a full-size tennis court and almost as tall as a three-story building, the Webb telescope is …huge, to say the least. The iconic Hubble telescope, which still roams the universe and rains down astonishing images to Earth, is just over a third of the size of the new one. This extra size is due to the significantly larger light-collecting area possible, making it more accurate and effective in capturing images of early galaxies. Simply put, the bigger the mirror, the more details the telescope can see. It’s very difficult to launch a giant, heavy mirror into space. So, engineers gave the Webb telescope 18 smaller mirrors that fit together like a really oversized puzzle. The mirrors fold up inside the rocket, then unfold to form one large mirror in orbit.

The Mirror

And you might have also noticed the striking gold shine of the hexagonal mirrors. Although the sleek finish makes it look like a sci-fi art piece, it is purely a functional feature. The Webb Space telescope has been plated with gold due to the element’s properties—a high reflection of infrared light and extreme unreactivity. Furthermore, the color optimizes them for reflecting infrared light – the primary wavelength of light this telescope’s camera will observe.

The Camera

The James Webb Space Telescope sees the universe in light that is invisible to human eyes. This light is called infrared radiation, not part of the visible spectrum of colors, and we can feel it as heat. Firefighters use similar cameras to see through the smoke in a fire. The Webb Space Telescope will use its infrared cameras to see through dust in our universe. Stars and planets form inside those dust clouds, so peeking inside could lead to revolutionary discoveries, things never before accessible to humans! It will also be able to see objects (like the first galaxies) that are so far away that the expansion of the universe has made their light shift from visible to infrared! But, you might wonder, very rightly, how the camera will capture the extremely faint and slight rays of early stars when a giant star, the Sun is shining bright in its eyes.

The Sunshield

The Webb telescope’s cameras are very sensitive to heat from the Sun. So, just like you might wear a hat to block the sun from your eyes, the telescope has a massive reflective sun shield to protect its instruments and mirrors. The telescope’s sunshield is about the size of a tennis court when folded out completely. The temperature difference between the sun-facing and shaded sides of the telescope is more than 600 degrees Fahrenheit! To achieve this level of heat insulation, the sunshield is made up of 5 layers of very thin, lightweight fabric coated with a reflective layer. These layers are arranged with a small gap between each other in spaced tiers. This arrangement is necessary, as it ensures the majority of sunlight is deflected away from the camera. This is because sunlight can not be fully reflected by just one layer, and making it pass through 5 layers, it makes it very hard for the light the come through, near the camera.

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So, this is a brief (I tried) description of how the James Webb telescope was designed and built to capture the most accurate snapshots of the early universe. Hopefully, we will see some revolutionary images picked up by the telescope that changes and sharpen our knowledge of the expansive universe.