BEIJING, Jan. 6 (Xinhua) — NASA’s James Webb telescope is currently scheduled for launch in March 2021, according tomedia reports. Before that, the project had been delayed year after year and billions of dollars in capital investment. Despite the waste of time and money, this telescope will become the unquestioned “king” of the infrared band, allowing us to reach for the first time in a remote corner of the universe that was once out of reach.
The assembled James Webb telescope, including its “parasol” and modular components, has been partially configured and will be further installed.
From the first galaxies formed after the birth of the universe to the possibility of extraterrestrial life, the about$9.7 billion James Webb telescope will be our only hope for a better understanding of everything in the universe.
Not afraid of the cold
Although the James Webb Space Telescope (JWST) has been hailed as NASA’s legendary Hubble “successor,” this is not the case. Hubble is primarily an optical telescope that captures a wavelength of light about the same as the human eye, extending only slightly to the infrared and ultraviolet bands. By its very nature, the Hubble telescope is like a giant eyeball in orbit, sending back shocking images. And if your light-sensitive nerve is as strong as it is, you can see these amazing sights yourself.
But the James Webb telescope is not. It will be fully observed in the infrared band, with little touching the most “red” band the human eye can see. In other words, it will study a universe that is almost invisible to humans.
One of the main reasons the James Webb telescope was designed was that infrared-band observations from the surface were difficult. Astronomers want to make accurate observations and measurements, they must ensure that the night sky is absolutely clear, but light pollution on the ground severely limits the observation almost.
Infrared light pollution is everywhere, because any object with temperature emits infrared light. The human body can produce 100 watts of infrared radiation. The Earth itself is also high in heat and appears bright and dazzling in the infrared band. Even the telescope itself emits infrared light radiation at room temperature.
In short, we are not completely unable to carry out infrared astronomical observations from the ground, but it is extremely difficult. So we chose to put the James Webb telescope in space.
Travel away from home
The James Webb telescope will operate 1.5 million kilometers from Earth to avoid the effects of Earth’s infrared light. Although far from the earth, the sun is also a problem. You must have felt the sun burning outside in the summer, and that’s infrared radiation. Even millions of kilometers from Earth, the sun’s heat is still not to be underestimated.
To do this, the designers of the infrared space telescope can take several options. One of the most common is the use of an active cooling system to lower the telescope’s temperature to a level suitable for observing infrared bands. This is a good method, which has been used in other infrared space telescopes. But it also limits the telescope’s useful life, as astronomical observations cannot continue once coolant is exhausted.
As a result, the James Webb telescope will have its own way, equipped with an expensive giant “space umbrella”. The umbrella is 22 meters long and 11 meters wide, and is made of five layers of material with a very high reflectivity, each of which is less than the diameter of human hair. This huge “parasol” will keep the telescope in the shadows, temperatures not exceeding minus 223 degrees Celsius, is suitable for observation in the target infrared band.
However, one of the instruments on the telescope will be cooled to minus 258 degrees Celsius with an active cooling system to receive infrared light with a longer wavelength.
The Power of Science
All in all, the James Webb telescope is too big to fit on a single rocket. With the exception of the huge parasol, its main mirror is 6.5 meters in diameter, far more than any rocket currently in service. Since the mirror could not be “glued” to the side of the rocket, smart NASA engineers decided to divide the mirror into 18 smaller hexagons so that it could be stuffed into the rocket with the folded “umbrella” and the rest of the telescope.
If all goes well, the James Webb telescope will fly toward the observation point a few days after liftoff, spread the mirror and parasol into place, and then begin the observation mission.
And its observations will be extremely striking. One of the telescope’s main observations will be the early universe, which was just a few hundred million years old. The first stars and planets to appear once glowed in the visible light band. But over the past 13 billion years, the universe has expanded, causing the wavelengths of these rays to grow longer and eventually leave visible light and fall into the infrared light band, just in the ideal range of the James Webb telescope.
Since the first stars and galaxies have not left any pictures, this will be the first time we have observed this important period in the history of the universe.
The James Webb telescope will study all “cold” objects in the universe, including the protoplanetary disk around the newborn star, molecular clouds, comets, the Kuiper Belt, and so on.
The telescope will also use a special device to block light from some distant stars, capturing any objectpassing from the front of those stars, such as exoplanets. These planets appear very bright in the infrared band, and by the light they emit, we can analyze the chemicals and elements in the planet’s atmosphere and perhaps find signs of life.
In short, from searching for extraterrestrial life to uncovering the truth about the dawn of the universe, the James Webb telescope must live up to our years of waiting.