From the time when Galileo used his first telescope to observe the moons of Jupiter to the time where we use telescopes to capture and observe the first lights just after the big bang. The advancements of telescopes took a huge boost in these recent years. There are various types of telescopes which use different mechanisms. These being mounted on spacecrafts and are sent into the space far away from earth to observe the distant lights of first stars in various frequencies in the frequency spectrum. There is a very special thing about telescopes. They are like time machines; observing the light from distant galaxies and stars . You may wonder why we are calling them as time machines; let me explain about that a bit to you. The group of Photons, light, takes some time to travel. We may not notice that happening here on earth where everything happens instantaneously (in terms of cause and effect). Although its speed is 299,792,458 m/s , which is the highest speed limit we know (for now), but,as we consider the grand scale of the cosmos, this speed is minuscule. The light takes 1.3 seconds from moon to reach earth . The light from sun takes nearly 8 mins and 20 seconds ( on a average) to reach earth. This means, when you look at the sun (not directly(don’t do it)) right now, you see the sun as it was 8 mins 20 seconds ago . Now lets increase the scale; the diameter of the milkyway galaxy is nearly 100,000 light years, i.e light takes 100,000 years to travel from one corner of the milky way to another corner.( point to note, the fastest thing in the universe we know of takes 100,000 years!!.). The fastest man made macroscopic unmanned object was the juno satellite which travelled 0.000134205 the speed of light . When we say an object in space is at so and so light years; consider alpha centura is 4 light years away, it means the light took 4 years to travel from alpha centauri and reach EARTH. We look at alpha centauri the way it was 4 years ago, indirectly, we are looking back in time.
Through telescopes, the farther we look in space, the backwards we look in time. As telescopes observe farther in space, they observed the fartherst light, the light which was travelling from 13.8 billion years . Due to various reasosn, we think that the age of the universe is 13.8 billion years. But those numbers may change soon. The amount of light collected by the telescopes is also depended upon the various factors of the telescope like size, coverage area and few others. the larger the telescope the larger the farther we can view.
Recently we have seen the image of the supermassive blackhole located at the center of M87 galaxy which is 55 million light years away. The event horizon telescope project made this dream come true. They built up a virtual telescope the size of the earth which helped them view through great distances. They captured an image of the shadow of a super massive blackhole which lies at the center of M87 galaxy. They captured the image which is 55 million years old. Which implies, they captured a moment(s) from the past.
We all might have heard about the Hubbles space telescope. One of the astronomers and science enthusistist favourite. As we might have heard by now, the hubbles life time is coming to an end. Soon, it will be replaced by advanced space telescope, and other amazing telescopes. Let us discuss about few of those telescopes.
The first stop on the pitch is the JAMES WEBB SPACE TELESCOPE.
JWST, is set to be the successor of hubbles space telescope. This telescope is set to launch on an Ariane 5 rocket from French Guiana in 2021. There was a news that JWST would be launched sooner, but technical errors were being encountered. It is for our own good for this telescope to take time and launch error free because this one is going to be a special one. Besides this being a billion dollar project, JWST is going to be the largest telescope to be sent into space by mankind. The JWST would be stationed at nearly 1.5 million km from (behind)earth , at a point known as Lagrange point 2 ( or L2). To imagine how far it is; the hubbles space telescope is situated 550km away from the earth ; the moon at nearly 400,000 km. Because of this reason , it makes repairs or manned deployment virtually impossible. Due to this exact reason, any small error is a crucial point to bring notice for the scientist, technicians , engineers to work upon. Unlike Hubble, JWST would observe the in low frequency part of the frequency spectrum. That particular spectrum is chosen because, the first galaxies and debris formed might be in cooling stage and would emit low frequency radiations. The instrumentations and the telescope itself is needed to be protected from the sun’s extreme temperature out there in the far points. For that, 5 layer sunshield is constructed which would allow the telescope to stay in temperature less than 50 Kelvin.
Now , coming to few technical Specifications of JWST, primary mirror is a 6.5-meter-diameter gold-coated beryllium reflector with a collecting area of 25 m2. This is too large for existing launch vehicles, so the mirror is composed of 18 hexagonal segments, which will unfold after the telescope is launched. The dimensions of the sunshield is listed as 21.197 m × 14.162 m , roughly speaking; it is near to the size of a tennis court. These 18 segmented mirrors are nearly 100 times more powerful than hubble’s and they are covered with gold as it is highly reflective in IR light. The scientific equipment’s loaded are NIRCam, NIRSpec, MIRI, FGS/NIRISS, which abbreviates as, Near IR camera, Near IR Spectograph, Mid-IR instruments, Fine Guided Sensor/Near IR imager and Slitless Spectograph respectively. These are powered and the computational work on board is done by a module known as Integrated Science Instruments Module or ISIM.
The primary mission of JWST is to gather lights from the very first galaxies which formed right after big bang. This is one of the 4 goals which JWST needs to fulfill. Following, it needs to observe how the galaxies form and how the Supermassive Black Holes and Stellar mass/ Intermediate Blackholes formed. It also needs to observe how the planetary systems were formed. We are concentrating here on the formation of the stuff because; the Hubble Space Telescope has seen back to about 500 million years after the big bang, revealing galaxies with much less defined and more compact structures, very different than those close to us in space and time. With the JWST, astronomers are looking back even farther, to the formation of the universe’s very first galaxies. By that point, gravity had already condensed gas into the first stars, which produced the first heavy elements, like carbon and oxygen. Within a few million years, the second generation of stars started forming from this enriched gas, and gravity began grouping them into the earliest galaxies. Webb will help us to understand the structure and composition of these first galaxies. And last but not the least, to observe the signs of life/formation of life in distant galaxies. JWST is going to act like a very powerful time machine by showing us the lights of very first galaxies. After the launch, The unfolding of the JWST in space would be prolonged for a period of time as at a distance of 1.5 million Km from earth, there would be no help. Everything needs to be planned and executed perfectly . The orbital path of The JWST and the deployment is shown in below images.
The operational period of the JWST is estimated to be around 5-10 years. Once the telescope is completely deployed, the data would be available world wide. Through the received data, simulations will be done through supercomputers and maybe Quantum computers for imaging and further processing of data which will be used in various fields of Infrared astronomy and cosmology.
This is just part 1 of series of future telescopes in the space industry. Stay Tuned.
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