People's love to see the universe is eternal. Although solving the unknown mysteries of the universe began much earlier, the Galileo-Copernican period is considered the true beginning of space exploration. However, space exploration and the human race to conquer the universe began much later in the Cold War. After World War II, the competition between the United States and the Soviet Union to become the world's superpower created a Cold War atmosphere. Both countries also started competing in space research to prove themselves superior. However, in the later period, the United States moved ahead of the Soviet Union in this competition. The reason for this is the fall of the Soviet Union, civil war, communist regime, etc.
From the time of the great scientist Galileo, various astronomers have invented other improved telescopes to unravel the tangles of space over the centuries. But more powerful than any previous telescope, a high-tech telescope has been sent into space by the US space agency. The name of this advanced telescope is James Webb Space Telescope (JWST).
Scientists claim that a kind of time travel is possible through this James Webb Space Telescope. Although it sounds surprising, with the help of this modern telescope, it is possible to get images of all the past cosmic events that happened in the universe. Here we are not talking about cosmic event pictures of the past few years. Rather, with the help of the James Webb Space Telescope, it is possible to get images of cosmic evolution millions of years ago. For example, it is possible to trace the Big Bang or the beginning of the universe to about 13 billion years ago.
How and in what ways will the James Webb Space Telescope work?
The James Webb Space Telescope works by detecting infrared rays. It is good to know here that the wavelength of the visible ray is observed in ordinary telescopes. The light waves we see with the naked eye are visible rays. The wavelength range of visible rays ranges from blue to red, with red being the longest wavelength.
We know that the longer the wavelength of the electromagnetic wave, the more easily it can pass through an object. For example, radio waves from radio stations can easily pass through large buildings to reach radio devices. This is because radio waves have a range of several kilometers.
Infrared wavelengths are many times longer than radio wavelengths. Infrared wavelengths cannot be seen with the naked eye. However, the advantage of using infrared wavelengths in telescopes is that they can easily pass through clouds of space gas and dust to capture spot images. That is, telescope images taken by infrared rays are clearer and more detailed. The difference between the two can be easily understood by looking at the images captured between the infrared and visible light wavelengths below.
"Infrared" is a Latin word meaning "Below Red", i.e. the wavelength of infrared rays is below red. We know that infrared rays are produced by objects that radiate heat. For example, infrared rays are emitted from stars, humans, animals, etc.
This telescope will be used to observe the various stars, constellations, solar systems, etc. in the universe and all these objects radiate heat. Therefore, it is possible to capture accurate and advanced images of various places in the universe by using infrared rays.
In addition, because those stars and constellations are millions of light years away from the earth, the light waves emitted from them begin to grow in length. That is why telescopes require large mirrors to take high-quality images of stars and constellations. The bigger the mirror, the more light waves it can receive. The resulting image quality will be high quality. Therefore, the mirrors of modern telescopes are more significant than the mirrors used in earlier telescopes. For example, the difference between the mirrors of the James Webb telescope and the Hubble telescope can be mentioned.
The construction and history of the James Webb Space Telescope
On 25th December 2021, the United States space agency NASA sent the James Webb Space Telescope, the best invention of human civilization, into space to study the universe. In addition to NASA, the European Space Agency and the Canadian Space Agency jointly helped build the JWST telescope. According to NASA officials, the telescope has been under construction for more than 30 years. The James Webb Space Telescope cost a total of $10 billion to build.
The mirror of the James Webb Space Telescope is composed of 18 individual hexagonal mirrors. Each of the 21.3-foot-wide (6.5 m) composite mirrors is plated with 24-carat gold. Because gold can best reflect red light.
A sun shield is placed around the telescope mirror so that the infrared rays from the telescope's own body do not interfere with the infrared wavelengths reflected by distant stars and constellations, and to keep the temperature of the telescope low. The area of the sun shield is equal to that of a tennis court (21.197 m x 14.162 m). A sun shield made of 5 layers of a synthetic material called Kapton is used to cool the telescope. Each sun shield layer is lighter than human hair. Each layer is coated with aluminum. In addition, the two warmest layers (sunward layer 1 and layer 2) have a "doped-silicon" coating that reflects the sun's heat into space.
The James Webb Space Telescope, like the Hubble telescope, will be placed at the L2 point, 1.5 million km from Earth, rather than closer. The reason for this is that the earth's position between the sun and the L2 point at this place allows the temperature of the telescope to be kept normal from the earth's shadow solar radiation. Also, the L2 point continues parallel to the Earth's orbit.
Importance of James Webb Space Telescope in space exploration
With the James Webb Space Telescope, it is possible to capture images of many unknown parts of the universe. With the help of the aforementioned James Webb Space Telescope, it is possible to catch a glimpse of the creation of planets, stars, and galaxies and the growth of the universe from the gas clouds and dust of time during the Big Bang. Previously, the Hubble telescope was able to see images from 1 billion years ago, but the James Webb telescope was able to see images from 12.8 billion years ago. According to space scientists, a kind of time travel is possible with the help of this James Webb Space Telescope. That is, this telescope can be called a kind of "Time machine".
But many may wonder if time travel is possible. The answer to this question lies in the speed of light. For example, it takes about 5,333 seconds or 1.50 hours for light to reach Earth from Saturn. If Saturn were to be destroyed in any way, Earth would know about it after 5,333 seconds or 1.50 hours.
We know that distances in space are measured in light years. That is, the distance that light travels in 1 year is called 1 light year. Therefore, the distance between Earth and Saturn is 1.5 light years. The galaxy in which our solar system is located is called “The milky way”. It takes 1,25,000 light years to cross from one end of the “The milky way” galaxy. The surprising thing is that there are millions and billions of such galaxies in this universe and the light produced by the stars located in those universes is not possible to see with naked eyes but it is possible through a telescope.
