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| James Webb Telescope |
In the beginning our universe was very dense and very hot with temperatures of up to billions of degrees. As the universe cooled, electrons interacted with nuclei to form the first atoms. A few hundred million years later the first start and eventually galaxies appeared. But how did they form this thing will help us understand? A $10 billion time machine that has been in development for over 20 years.
Chapters
Imagine you are 65 million light years away from Earth. Somewhere in the Virgo cluster and you have a very powerful telescope that you can use to study Earth. Take a look through the telescope and you'll be able to see what dinosaurs look like on our planet. Of course, we will face many obstacles along the way. But we are talking about an incredibly powerful telescope, right? Just look at their primary mirror size comparison. And yet James Webb's mirror is only 113 kilograms 249 pounds lighter, which is very light for a telescope mirror. The telescope works in the infrared Spectrum. The infrared radiation can penetrate the dust cloud and allow us to see the stars forming within. Additionally Einstein's theory of relativity states that the space between objects in our universe expands and so does light. It's waves lengthen and the light becomes infrared. Also known as redshift. Every time you look up at the night sky just know that there are many stars and galaxies the light of which stretched and became invisible or too faint for you to see.
The Mirror
So here's a question, how is the James Webb Space Telescope supposed to detect that light?? It will be assisted by a huge mirror which will increase the amount of collected light. The mirror is made with 18 hexagonal segments each one 1.32 meters 4.3 feet in diameter. This shape will enable the crew to fold the mirror on Earth and unfold it in space. Then the focus of the mirror will be calibrated by Shifting the various segments with an accuracy of one to ten thousand. Only one ten thousandth of the density of a human hair which is really tiny. The light is collected on secondary mirrors, then reflected and sent to scientific instruments. After it is filtered it is then focused on the hypersensitive infrared detectors at which point the photons are converted into electrical voltage.
Tools of James Webb Telescope
The actual telescope is equipped with four tools. Nercam is the telescope's primary imager in the near infrared range. 10 sensitive detectors allow it to detect the light of the first stars and galaxies. In addition nercam is equipped with chronographs. And what are they imagine that you're blocking the sun with your hand.
Coronagraph
By blocking the bright light you can see the road ahead of you a coronagraph follows a similar principle. This function will allow our researchers to see more faintly lit starts, galaxies and even take photos of exoplanet. But near cam cannot show us everything we need to know about the physical properties of the planet. Is there water, air? Impossible to say therefore another tool called near spec will be working with the same range. By studying the spectrum of light emitted by an object we can tell its mass, temperature and chemical composition. The atoms and molecules of an object leave their mark on the Spectrum in the form of black lines.
Superpower
But to analyze the faintest light the telescope has to stare at the object for over a hundred hours. Which is ages but surely the scientists did not spend 10 years working in vain. To avoid wasting the telescope resources on a single object. The near spec is equipped with a superpower to provide spectroscopy of hundreds of objects at once. Which was achieved by developing a new technology called Micro Shutter System.
Micro Shutter System
This system is made of 250,000 shutters that open and close. If you ever observed the night sky in a town or city and compared it to what you can see at night in the countryside you could probably tell the difference. It happens due to the high volume of light in the city. Therefore the micro shutter system will block the irrelevant light allowing us to see the most faintly lit object. The light is then dispersed into the Spectrum and sent to the detectors. How much light is there in space?? A huge amount and in order to capture only the relevant light the telescope has to be constantly directed at different targets. This will be possible with the help of the fine guidance sensor FGS. Additionally scientists from the Canadian space agency developed the near infrared imager and stilt the spectrograph. Which also takes pictures and captures spectroscopies in near infrared light.
Miri
But how do we deal with thick dust clouds that obstruct the View? Near infrared light might not be able to penetrate them. Miri is also equipped with a camera and a spectrograph but it works in a different range of infrared light. One with longer waves which can penetrate the thick dust cloud. It's sensitive detectors will allow us to observe the red-shifted light of distant galaxies newly forming stars and Comet. The issue with Miri is that unless this tool is cooled to 6.7 Kelvin or negative 266.5 Celsius. It starts capturing its own heat. So scientists developed an additional cooling system called Cryo Cooler. In essence it's a sophisticated refrigerator in which helium will travel along pipes, cooling Miri to the right temperature as a result.
Sun Shield
But now we have a different problem the Sun, the Moon and Earth radiating heat. And as a solution for this problem the engineers developed an incredible passive cooling system for the telescope. The size of this sun shield is only 21 meters long and 14 meters wide. The Shield is made up of five layers with space in between each layer of material so they can cool efficiently. Each layer is made from a special film that can withstand very high temperatures. This material is called Captain. In addition each layer is coated in aluminum and the first two have an additional coat of doped silicone. In order to be able to withstand even higher temperatures. For the sun shield to be able to hide the telescope from the Sun, the Moon and Earth simultaneously the JWST has to be 1.5 million kilometers away from Earth. As a reference, a Hubble Space Telescope was only 547 kilometers. The James Webb Space Telescope will travel to a special location known as laraji point 2. It is one of the five places in the solar system where gravitational forces allow the objects to remain in a fixed position relative to Earth.
What's Next?
Remember how we talked about a folding mirror?? Similarly the sun shield and many other components will be foldable. This way the scientists can fold the telescope and pack it into the rocket Ariane 5 which is the most reliable rocket capable of delivering the telescope into space. And now let's talk about the most exciting thing. We already mentioned its ability to capture faint infrared light emitted by the first stars and galaxies. So what's next well for example you could spot the heat signature of a bumblebee at a distance of the Moon with the JWST. But why should you care about a bumblebee?? Saturn is not the only planet in this solar system that has rings, there are many other planets in this solar system that have rings. Uranus, Neptune and Jupiter have them too. It's just that in the visible spectrum their rings are dark and indistinct. Using the transit method in the infrared range. The telescope will be able to help us understand how the rings around these four planets formed. Well, what about a detailed analysis of an exoplanet atmosphere? The researchers are interested in the planet located in the habitable zone. Which means they might contain Water. By using the telescope we can learn the chemical composition of those planets atmospheres. Scientists Machio Kaku thinks that the chances of encountering an alien civilization are quite strong. The telescope will be able to tell us more about the birth of planets, galaxies and stars. The universe keeps many Secrets. But the James Webb Space Telescope should help us uncover these Mysteries. And in the meantime we will continue to Delight you with new content.