The most expensive human eye

 　　On Christmas Day 2021, the Webb Telescope will be launched. This is an exciting journey.

　　In the early 1990s, the Hubble Telescope was launched. In the past 30 years, it has completed nearly 1.5 million scientific observations of space, showing scenes such as quasar environments and distant nebulae that humans have never seen before. . The Webb telescope is expected to be the "successor" of the Hubble telescope.

　　However, it is very different from the Hubble telescope.

　　On January 9, 2022, astronomers have fully opened the Webb Space Telescope's primary mirror consisting of 18 hexagonal mirrors after 50 major deployments through a controlled release mechanism. It was like an eye that was slowly opening. It will stare at the vast sky and look at the boundless universe that has attracted mankind's reverie for thousands of years.

"Senior" Hubble

　　The biggest difference between the Webb telescope and the Hubble telescope is that it can observe radio wavelengths.

　　The Hubble telescope is "mixed and complete", observable in the spectrum, from ultraviolet, visible light, all the way to the infrared and above. The Webb telescope is "specialized" and can only observe radio in the infrared band.

　　This is not a flaw, but an improvement.

　　The Webb telescope was first planned to be launched around 2010. However, the related progress has been delayed by a full 10 years. Its predecessor, the Hubble Telescope, took more than 40 years from project to launch.

　　But it's all worth it. In 1990, the Hubble Telescope was launched, about 540 kilometers above the ground. Above the atmosphere, Hubble uses its 2.4-meter-diameter lens to "gaze deeply" into the distant universe, revealing the secrets of many distant galaxies.

　　Many of the cosmological wonders we now know were brought about by the Hubble Telescope.

　　For example, the "Eye of God", from the picture data, it is a blue pupil and a transparent eyelid around the white eyeball, which is very similar to the eye. In fact, this is the planetary nebula numbered NGC 7293 in the constellation Aquarius.

　　For another example, through the Hubble telescope, human beings saw the "dying" planet for the first time. In August 2019, a hot 'rugby'-shaped exoplanet was photographed. The planet is being torn apart and heated by being too close to the star, the atmosphere is escaping at an accelerated rate, and the entire planet is on the verge of being swallowed. This spectacle is also known as "Death Embrace".

　　More importantly, the Hubble telescope has expanded our view of "time", allowing us to see what the universe looks like in its oldest form.

　　In January 2020, an international team of astronomers used the US Hubble Space Telescope to discover the most distant and oldest group of galaxies known to date. This triple group of galaxies is called EGS77. Observations suggest that this triple group of galaxies was involved in a transformation process known as "reionization" in the early days of the universe. EGS77 was born about 680 million years after the Big Bang, when the universe was less than 5% of its present age of 13.8 billion years.

　　The Hubble Telescope has made great achievements, and the above-mentioned are just a few of the most well-known wonders.

　　However, it has to be accepted that the spacecraft will eventually be reimbursed for retirement one day.

　　In 2010, Hubble underwent maintenance for the last time, and since then, due to the retirement of U.S. spacecraft and safety concerns for maintainers, it can no longer be repaired.

　　Now 11 years later, according to NASA, 3 of the 6 gyroscopes used to maintain stability on the Hubble telescope have broken down, and the entire fuselage is "old and old", and it may return to the atmosphere at any time. retired.

　　Fortunately, as its successor, the Webb telescope was finally launched.

another "eye"

　　The Webb telescope, the successor to Hubble, is undoubtedly an enhanced version of it.

　　According to the traditional performance parameters, the most basic one is that the diameter of the mirror surface of the Webb telescope reaches 6.5 meters, and a larger area can collect more light. This also means that it can see farther and dimmer starlight.

　　The Webb telescope only picks up in the infrared band, which, based on what we know about electromagnetic waves, means it will see a more sophisticated, older picture of the universe.

　　Looking at it all the way, technology has advanced by leaps and bounds since the 20th century. The technology on the ground is "invoked" endlessly. Fortunately, aerospace technology "has not changed its original intention", and has not forgotten the journey to find the sea of ​​stars.

　　The destination of this journey is to build a complete modern cosmology. So, before we get into the Webb telescope in detail, let's go back to the 20th century again.

　　The field of astronomical observation has been associated with cosmology from the very beginning. In Galileo's time, through a small telescope in his hand, Galileo overthrew the concept of the universe that had been "round the sky and the earth" for thousands of years. In the 20th century, there was a growing realization that the real universe seemed boundless.

　　In 1912, American astronomer Sleifer was studying extragalactic galaxies and found that their spectral lines generally shifted to the red end. With the accumulation of research materials, he concluded that almost all extragalactic galaxies have a "redshift effect". According to the Doppler effect explanation, these galaxies are moving away from the earth.

　　In 1929, the American astronomer Hubble proposed "Hubble's Law": the redshift of galaxies is proportional to their distance from the earth. To put it figuratively, the universe is an expanding balloon, and the more it is in the outer layer, the faster it expands. Yes, the Hubble telescope commemorates the scientist who proposed the model of the universe.

　　Because of the "balloon" model, the universe has become lively from the "eternal night" that people thought. Since the universe is getting bigger and bigger, then, moving forward in time, it should be getting smaller and smaller. But where is the evidence?

　　The evidence is on the radio. According to the "Big Bang" theory, the universe continues to expand, the temperature continues to drop, and various elements begin to form. However, the blackbody spectrum remains after the primary radiation is decoupled from the matter element. That is to say, the original explosion of the universe left behind debris that pervaded the universe, and they appeared as "cosmic microwave background radiation".

　　The study of the "cosmic microwave background radiation" is the most important task of the Webb telescope.

　　According to NASA, it will investigate the residual infrared evidence (the cosmic microwave background radiation) of the Big Bang theory, observing the early state of the universe visible today. It can pick up infrared light emitted by early galaxies and observe the first stars and galaxies that formed a few hundred million years after the Big Bang 13.5 billion years ago.

　　Because of the delay, Webb's configuration for capturing faint radio waves has been enhanced. Compared with the Hubble telescope's orbit of only 540 kilometers, this time, the Webb telescope directly landed in the satellite orbit of 1.5 million kilometers, in order to reduce the thermal radiation interference of the moon and the earth.

　　It is the most expensive pair of human eyes in history. At the end of April this year, after seven rounds of calibration, the Webb telescope entered the trial phase of scientific research equipment, which takes about two months. After that, it will fully open and start officially.

　　What kind of photos will it send back then? It is worth looking forward to.