Probably you are interested in time traveling, yes, we all are. In reality, technically, we all are time travellers. Because as a matter of fact, time works at different speeds for different gravitational field. In other words, if a person is at sea level and another person is atop of a mountain, then for them time will pass at different speeds. But this difference will be so small ( probably billion billion times smaller than a second ) that you will never be able to figure it out that you are a time-traveller.

According to Einstein’s Theory of Relativity, you can travel in time to the future but you can not ever come back in the past. Of course you can not go back in time, but that doesn’t mean you can not look into the past. This is what James Webb Telescope is made for.

James Webb Space Telescope is named after James E. Webb, who ran the fledgling space agency in its early days from February 1961 to October 1968. He believed that NASA’s role should not be only to send humans into space but rather NASA should also contribute in space science.

What is James Webb Space Telescope ?

James Webb Space Telescope is going to be the most powerful telescope in space humans have ever built. It’s primary gold plated mirror is 2.75 times bigger than Hubble Space Telescope. When you set a big telescope on earth there are some problems that you have to face; such as, atmospheric disturbances, light pollution, local infrared radiation. Although technology is getting advanced everyday to deal with those problems, but it will never be like actually being in space.

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The Hubble Space Telescope which found so many galaxies, planets, stars can detect only visible light. But to look deeper into space, a telescope is needed which can detect infrared radiation. That’s where James Webb Space Telescope comes into the picture. The JWST is especially designed to detect infrared rays with a great precision. It will be one of its kinds when sent into space.

How come Webb can look into the past of our universe ?

Imagine light rays emitted by a galaxy 13 billion years ago. So, when we see any galaxy or star at a distance of 13 billion light-years, we basically looking into past, that is 13 billion years ago. But by the time this light reaches us, its color or wavelength has been shifted towards the red, something we call redshift.

Because when you leave the solar system and talking about something beyond that, Newtonian mechanics stops there, Einstein’s Theory of General Relativity comes into play. It tells that due to expansion of the universe as light rays travels into space its wavelength increases; it’s called ‘Redshift’.

Due to redshift the light rays from distant galaxies when comes to us, it becomes Infrared rays. JWST can detect those infrared rays and will be able to see the past, the first light rays, the formation of first galaxies and stars, What are the first galaxies ? When and how did reionization occur ? What sources caused reionization ? etc.

Primary Instruments of James Webb Space Telescope

To build such a huge kind of telescope is not so easy. Webb Telescope's scientists and engineers determined that a primary mirror 6.5 meters ( 21 feet 4 inches ) across is what was needed to measure the light from these distant galaxies.

Comparing with hubble which has a primary mirror of 2.4 meters diameter, it would be very heavy if its made of the same material the Hubble is made of. That’s why scientists choose Beryllium. Beryllium is light and strong material, perfect of such kind of operation. Because it is light and strong, beryllium is often used to build parts for supersonic ( faster-than-the-speed-of-sound ) airplanes and the Space Shuttle.

The primary mirror of webb can be divided in 3 different optical prescriptions for 18 segments, 6 of each. Finally, a roughly circular overall mirror shape is desired because that focuses the light into the most compact region on the detectors. Each of the beryllium segments is coated with a thin layer of gold, because gold is a good reflector of infrared rays.

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The Pillars of Creation in the Eagle Nebula captured in infrared light by Hubble. The light from young stars being formed pierce the clouds of dust and gas in the infrared. Credit: NASA, ESA, and the Hubble Heritage Team ( STScI/AURA )

Webb's instruments are contained within the Integrated Science Instrument Module ( ISIM ) which is one of three major elements that comprise the James Webb Space Telescope Observatory flight system. The others are the Optical Telescope Element ( OTE ) and the Spacecraft Element ( Spacecraft Bus and Sunshield ). The IISM is mainly include four instruments,

  • Near-Infrared Camera/NIRCam : (Provided by the University of Arizona) The Near Infrared Camera (NIRCam) is Webb's primary imager that will cover the infrared wavelength ranging from 0.6 to 5 microns. NIRCam will detect light from: the earliest stars and galaxies in the process of formation; the population of stars in nearby galaxies; as well as young stars in the Milky Way and Kuiper Belt objects.

    NIRCam is equipped with coronagraphs, instruments that allow astronomers to take pictures of very faint objects around a central bright object, like stellar systems.

  • Near-Infrared Spectrograph/NIRSpec : (Provided by ESA, with components provided by NASA/GSFC) The Near InfraRed Spectrograph (NIRSpec) will operate over a wavelength range of 0.6 to 5 microns. A spectrograph (also sometimes called a spectrometer) is used to disperse light from an object into a spectrum. Analyzing the spectrum of an object can tell us about its physical properties, including temperature, mass, and chemical composition.

    In order to study thousands of galaxies during its 5 year mission, the NIRSpec is designed to observe 100 objects simultaneously. The NIRSpec will be the first spectrograph in space that has this remarkable multi-object capability.

  • Mid-Infrared Instrument/MIRI : (Provided by the European Consortium with the European Space Agency (ESA), and by the NASA Jet Propulsion Laboratory/JPL) The Mid-Infrared Instrument (MIRI) has both a camera and a spectrograph that sees light in the mid-infrared region of the electromagnetic spectrum, with wavelengths that are longer than our eyes see.

    MIRI covers the wavelength range of 5 to 28 microns. Its sensitive detectors will allow it to see the redshifted light of distant galaxies, newly forming stars, and faintly visible comets as well as objects in the Kuiper Belt.

  • Fine Guidance Sensor/ Near InfraRed Imager and Slitless Spectrograph/FGS/NIRISS :(Provided by the Canadian Space Agency) The Fine Guidance Sensor (FGS) allows Webb to point precisely, so that it can obtain high-quality images. The Near Infrared Imager and Slitless Spectrograph part of the FGS/NIRISS will be used to investigate the following science objectives : first light detection, exoplanet detection and characterization, and exoplanet transit spectroscopy.

NASA’s James Webb Space Telescope ( JWST ) will reveal many mysteries about the formation of universe, the birth and death of stars, formation of first baby galaxies. Apart from that, Webb will also discover exoplanets, exoplanets' atmospheric and chemical composition, mass, density, Chemical composition of nearby stars, red dwarfs; we will get to know more about planets in our solar syatem, their chemical composition and more......

It is scheduled to be launched in 2021 to explore the cosmos.

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