Secret glimpse: space telescope-

202 1 12, the Webb space telescope originally scheduled to be launched in 2007 was finally successfully launched. This is a great event in the human space industry, and whoever did it deserves congratulations.

However, great events happen every day these days. How big is the Webb telescope?

What is the level of human understanding of the universe? This is a puzzling question. On the one hand, even the nine planets in the solar system can't be found, and it is impossible to launch orbital probes to Uranus and Neptune. On the other hand, Earth-like planets (Earth-like planets) dozens of light-years away are well-informed, and news of super-earth, twin-earth and livable planets is reported in newspapers from time to time. Which is the real level of human science and technology?

If we want to make this topic clear, we should start with the means of human exploration of the universe.

If the detector can be thrown to another planet, there are many detection methods, such as underground detection radar, X-ray spectrometer, magnetic field detector and so on. Regrettably, so far, human probes are far from flying out of the solar system. Even if they fly out of Saturn's orbit, they are really "inaccessible".

Therefore, this is the premise: human beings can only study the universe in the solar system, more precisely, human beings mainly study the universe near the earth.

How to study?

Can only passively receive information from the universe.

What information?

Electromagnetic waves, cosmic rays, gravitational waves, in which the big head is electromagnetic waves (including visible light). It can be said that most of human cognition of the universe is calculated by various electromagnetic waves collected on the earth.

Yes, the universe is calculated. For example, by observing the color of a star or collecting the visible light emitted by this star on the earth, we can calculate its surface temperature, add the brightness of the star, calculate its age, and add some parameters to calculate its distance.

Even weirder, kepler mission, this guy is looking for terrestrial planets. The principle is simple. Staring at a star, if the brightness of the star will decrease periodically, it means that a planet flies in front of the star regularly, blocking a small amount of light, just like a fly flying over a searchlight. This is called the transit phenomenon.

Based on this, we can calculate the period of revolution, orbit and size of the planet, and even analyze the composition of the planet's atmosphere through the characteristics of spectral changes. For example, if the fly is flaming red, it can detect a little red light when the detection light is blocked.

If these calculated parameters are similar to the earth, they are called terrestrial planets. The so-called earth-like planet is a shadow at best. As for what it looks like and whether it has life, scientists won't know much more than fortune tellers.

Is this reliable? Of course, it is not very reliable, but there is no better way. There are so many ways for human beings to perceive the universe. But it's not very unreliable. You can do a lot of work by doing these things to the extreme.

On the cosmic scale, time and space are actually the same thing.

If you want to know the universe 4.2 years ago, go to proxima centauri 4.2 light years away, because all the information we received about proxima centauri was sent 4.2 years ago. Similarly, if you want to understand the universe 65438+ billion years ago, you must observe the stars 65438+ billion light years away. For people on earth, the universe is a museum, and the stars at different distances represent the evolution of the universe in different periods. The farther a telescope looks, the older it looks. The farther it goes, the earlier the universe looks.

The so-called "look" here is to collect all kinds of electromagnetic signals from these stars. Long-wave signals can penetrate the atmosphere, so just put the antenna on the ground. The scientific name is "radio telescope". Short-wave signals are easily absorbed by atmospheric interference, such as infrared, visible light and X-ray. So it is necessary to put things in space, which is scientifically called "space telescope".

The visible part is the most intuitive, and it is also the most talked about by the people who eat melons. After all, this is what we can see with the naked eye. The most outstanding work is the famous Hubble Space Telescope.

Because of the disturbance of the atmosphere to light, ground-based telescopes look at space like myopia, which once led to the observation range of human beings being only several billion light years. 1990 The launch of the Hubble telescope is like a periscope put on the water by human beings, and finally we can get a glimpse of the whole universe.

Now many familiar knowledge: the age of the universe, the Big Bang, the size of the universe, all have Hubble's credit. This telescope, which mainly collects visible light, greatly expands human vision and is a milestone in astronomy.

Hubble not only has great scientific research value, but also its social value cannot be underestimated. A large number of exquisite deep space photos have inspired countless ordinary people to yearn for and think about the universe, which can be described as a great achievement in the future.

Hubble Space Telescope released the most detailed picture of the universe so far in 20 19. This picture contains 265,000 galaxies, and each bright spot can enlarge and see the whole galaxy (the original picture can be downloaded from official website, which is a thief).

However, it is inevitable that Hubble has been in the sky for more than 30 years because his successor has not arrived yet. Especially in recent years, faced with the same dilemma as the International Space Station, throw it away. Unfortunately, if you don't throw it away, tinkering and maintenance costs have already caught up with the cost. You know, working in the sky is very expensive, and the cost of one maintenance is enough to build a large telescope on the ground.

It is unrealistic to continue to burn money for the aging Hubble. Hubble's retirement is almost certain, which means that mankind is about to lose the only visible space telescope.

Will the days after that return to the era of myopia?

No, because of the emergence of adaptive optics technology. Simply put, this technology can correct the interference of atmospheric turbulence and other factors on light, and the idea is extremely simple and rude. If you see a distorted image in the mirror, then take a reverse mirror to restore the image. The atmosphere is a mirror, how to get a mirror?

For example, first send a laser to the sky to make sodium in the atmosphere glow. This light will also be disturbed when it passes through the atmosphere and returns to the ground. Calculating this disturbance is equivalent to measuring the concave-convex law of the mirror, so as to adjust the mirror shape of the telescope and get a mirror. Because the disturbance is irregular, the reverse mirror is a rugged flexible mirror, and because the air temperature, humidity and airflow change in real time, the flexible mirror also changes in real time, and even the mirror shape has to be adjusted thousands of times per second.

I wonder if this monk has made it clear. Anyway, this process is amazing. Just sigh with it.

After the telescope of the European Southern Observatory in Chile installed the adaptive optical system, the clarity of the photos taken has surpassed that of the Hubble telescope.

In that case, there is no need to put a visible telescope in space. Working on the ground is not only affordable, but also does not have to consider weight and volume at all. The lens can be hard, and life is beautiful.

The Gemini Observatory with a diameter of 8. 1 m in its early years is also considered as the first person. The two telescopes are located in Hawaii and Chile, one in the south and the other in the north. Coupled with the rotation of the earth, the observation range can cover the whole sky area. But soon, the threshold of 8 meters was stepped on. The very large telescope built by the European Southern Observatory in Chile consists of four telescopes with a diameter of 8.2 meters, and its focusing ability is equivalent to 16 meters. The Pleiades telescope of the National Astronomical Observatory of Japan dried the aperture of the monocular mirror to 8.3 meters. That's not all. The American Large Magellanic Telescope in Chile, which is about to be put into operation, consists of seven sub-mirrors with a diameter of 8.4 meters, with an equivalent aperture of about 25 meters, and the imaging clarity reaches 10 times that of Hubble.

The diameter of a single mirror is almost 8.4 meters, and then there is a more fierce way to play: make a big mirror with a bunch of small mirrors.

The 30-meter telescope, led by Canada and the United States, with the participation of many countries including China, is located in Hawaii, which is constantly blocked by environmental organizations. Its primary mirror is 30 meters in diameter, and its definition is one order of magnitude higher than that of Hubble.

The European telescope in Chile, which is expected to be completed in 2024, has a primary mirror aperture of 39 meters, and its resolution is 16 times higher than that of Hubble. ...

For telescopes, the caliber is king. If you have no idea about the caliber, you can compare it with the Hubble telescope, 2.4 meters.

Wait, it seems that Chile's appearance rate is a little high. Is this guy good at astronomy? When it comes to Chilean specialties, people may think of cherries, but this monk thinks of ... astronomical telescopes.

The climate and atmospheric environment in northern Chile are very suitable for watching the sky at night, where more than half of the world's top astronomical telescopes are concentrated. It is worth mentioning that China is also building its own observatory here. If we don't count the 0.68-meter-diameter sky survey telescope at the Antarctic scientific research station, it should be the first time that we have built a telescope in other countries.

By the way, these telescopes mentioned above, together, are not as expensive as Hubble.

So there's nothing to say. Compared with ground-based telescopes in full swing, visible space telescopes are almost ignored ... except China.

China Space Station has a supporting equipment called "Sky Survey Optical Module", which is a 2-meter visible telescope. It is planned to be launched in 2024, which may be the only visible space telescope left by humans. Then the question is, people do it on the ground, why do they have to do it in the sky?

First of all, of course, it is because space telescopes have advantages that ground telescopes don't have, such as being able to point in any direction freely, exposing in one direction for a long time, and not being interfered by satellites. Secondly, Hubble is too expensive in the final analysis. The telescope and the space station fly in the same orbit, next to each other and go out to work from the space station, and the cost is much lower.

The most interesting thing is that the sky survey can observe the earth. Isn't it a little unexpected? This astronomical telescope can actually turn around and observe the ground. As for the significance of doing so ... guess!

As the only visible space telescope for human beings, the survey of the sky will inevitably be compared with Hubble. In fact, this topic is the same as the space station, with a time difference of 35 years. What is the contrast? In addition to the technical level, the difference between the two is largely caused by design choices. In addition, people who eat melons should not expect to surpass the American imperialists in this field, and the gap is still as big as the naked eye.

Having said that, how big is Weber's heaven?

Through the correction of atmospheric disturbance, the problem of visible light can at least be settled, but infrared, ultraviolet and X-rays are not so easy to get rid of, because these guys are not disturbed by the atmosphere, but absorbed by the atmosphere. No matter what you do on the ground, it is impossible to recover the signal that has disappeared.

Therefore, this job has to go to space.

According to the existing theory, the universe has been expanding, and the expansion speed exceeds the speed of light, which leads to the obvious red shift of the spectrum of distant celestial bodies. The visible light emitted there may turn into infrared light here.

In this way, if you want to see far, you have to count on infrared rays.

Hubble can only make do in the infrared band, and it will reach the sky after seeing 65.438+0.34 billion light years, that is, the situation of BIGBANG after 400 million years. However, according to the latest research, the first stars in the universe were born between 200 million and 300 million years after the Big Bang, which is the so-called "first ray of light in the universe".

Looking for this first ray of light is an infrared telescope.

That's why Webber came.

The official name we gave was "Webb Space Telescope", but everyone used to call it Webb.

It took 14 years to launch this guy, because it really took a lot of effort, which fully reflected the deep foundation of the American emperor in the field of precision industry and almost reached the limit of ergonomics.

For example, the surface roughness of the primary mirror with a diameter of 6.5 meters is lower than 10 nm. In addition, in order not to waste this machining accuracy, the accuracy of the support bracket and the control system can be imagined.

Such a complex and huge shelf, after being unfolded in space, has an error of no more than tens of nanometers.

The higher the temperature, the stronger the infrared ray, so as an infrared telescope, refrigeration has become a top priority, otherwise your own infrared ray is enough.

Give an irrelevant example.

The famous American javelin missile in the recent Russian-Ukrainian war needs continuous refrigeration of the infrared imaging device before using thermal imaging. The user manual of American Javelin Missile shows that it must wait 2.5 minutes to 3.5 minutes after starting. The small battery and refrigerator equipped with the missile can only last for 4 minutes, which means that the shooting window is only 1 min for 30 seconds at most. If the lock and launch are not completed within 1 minute and a half, the shooter must replace the refrigerator and battery. Therefore, javelin is not easy to deal with tanks as long as it is properly scouted and coordinated with each other.

That is beside the point. Whether in the sky or underground, if you want to deal with infrared rays, you must first be cold enough.

Many people think it's not easy to cool space so cold! In fact, on the contrary, because there is no air in space to dissipate heat, the sun will be hot as soon as it is exposed to the sun, so we must first isolate the sun. Webb brought five layers of big and thin sunshade sails. In order to reflect heat as much as possible, these five layers of thin sails, which are only a few tens of microns thick, are also trying their best to keep the temperature on the back below 50 K.

But this is not cold enough, so scientists have specially developed a pulse tube refrigerator, which can not only cool the infrared sensor to 7K, but also has almost no vibration. Think about it, if the cooler causes shaking of tens of nanometers, then the previous precision machining will be in vain.

If this is the case, Weber will not drag it to 14, and the most troublesome thing is yet to come.

The earth itself is a huge infrared emitter. In order to avoid the interference of the earth, Weber should stay away from the earth. How far is it? At the Lagrangian point, simply put, in this place, the gravity of the sun is equivalent to the gravity of the earth, and the aircraft can hover here, a bit like geosynchronous orbit. There are five such places, and Weber stops at L2, which is1.5000 kilometers away from the earth.

Comparatively speaking, Hubble is only 590 kilometers away from the earth. In fact, Hubble had problems immediately after the last day. The main mirror deviated by two thousandths of a millimeter, and the photos taken were terrible, so the astronauts were sent up for the first maintenance.

And Weber, 654.38+0.5 million kilometers away, it is absolutely impossible to send someone to repair it. Weber has as many as 344 failure points, and there is no redundant backup. As long as one of them goes wrong, $654.38+000 billion will be wasted. Sadly, during the ground test, these fault points often go wrong. For example, 20 18, the thin sunshade sail was torn when it was unfolded. Under this pressure, it is not so bizarre to drag it to 14 years.

In a word, Weber has many outrageous engineering details and impeccable scientific and technological content, which can be called the pinnacle of human precision industry and the title of "the strongest telescope in history".

Can it see the birth of the universe when it blows up the sky like this? No, infrared rays are not everything, and even electromagnetic waves are not enough to explain the origin of the universe. This kind of activity needs at least a group of backbones such as gravitational waves, dark matter and neutrinos to get a glimpse.

The Webb Space Telescope works in the near-infrared and mid-infrared bands to observe the formation of the first stars and galaxies in the early days of the Big Bang. According to the current theory, the age of the universe is 65.438+038 billion years, Hubble has seen 65.438+034 billion years, and Weber can have another 200 million years.

On March 1 1, 2022, the Weber telescope completed the last round of fine-tuning of the lens and returned the first clear photo taken during calibration, which has gradually entered the working state. It is expected that scientific observation will officially begin in summer, adding another 200 million light years to human vision.

Another digression is that Weber is not only a model of science and technology, but also a model of cheating money, which fully reflects not only the scientific and technological strength of the American emperor, but also the fishing methods of the American emperor.

Weber's initial budget was $500 million, but it was soon found that it was not enough to burn. In the second year, it increased by 500 million dollars. Otherwise, the previous 500 million dollars will be wasted. After two years, I found that the money was still not enough to burn. I added 800 million yuan, but I can't live without it, otherwise the previous 654.38+0 billion will be in vain. In two years, there will be 700 million people. I can't do it without it. Three years later, add another 500 million. A year later, it was another 500 million. Two years later, 600 million ... bite by bite, has eaten as much as 9.7 billion, worse than Hubble.

When we talk about visible light, we can still see our country, but in the infrared band, it seems a little shabby?

This is not surprising. China is a developing country. Most of the satellites launched are used for specific purposes, such as agricultural satellites used to monitor whether cultivated land is occupied or not, infrared satellites used to monitor whether forests are on fire, and so on. They are rarely used for pure basic scientific research. The monk counted with his finger, and it seems that there are only two and a half: one is Wukong, looking for dark matter, the other is an eye for studying X-rays, and the other is Mozi, which is used to verify quantum communication technology (not pure basic science in the strict sense).

Among them, goggles are a space telescope, full name: hard X-ray modulation space telescope.

If infrared ray is essential to study the origin of stars, then X ray is essential to study the death of stars. X-ray is a kind of electromagnetic wave with high energy, which usually comes from violent celestial activities, such as star explosion. The study of high-energy celestial bodies is definitely indispensable, so it is also a research hotspot.

Compared with the invisible visible space telescope, X-ray telescopes are endless. No way, after X-rays pass through the atmosphere, there is nothing, and everyone can only work in the sky. XMM- Newton satellite in Europe, Rossi X-ray time-varying detector in the United States, Chandra X-ray Observatory, Suzaku satellite in Japan and eROSITA X-ray telescope in Germany. ...

Among many X-ray telescopes in various countries, Yan Hui is the best. It is the hard X-ray telescope with the highest sensitivity and resolution in the world. It's nothing. As the successor of "Goggles Eye", the large-scale international cooperative space project "Enhanced X-ray Time-varying and Polarized Space Observatory" led by China is expected to be launched in 2025, and it will be the international leading flagship space X-ray observatory.

Up to now, the most detailed cosmic X-ray map contains 654.38+00,000 X-ray sources, and the data comes from the first survey mission of the German eROSITA X-ray telescope.

Finally, let's find a hard-core reason to burn money.

1974, to celebrate the completion of arecibo radio telescope's reconstruction, the telescope sent a series of messages containing human civilization to the M 13 globular cluster 25,000 light years away, which is the famous "Arecibo message".

Now this message has been running for about 50 light years. If the technology of aliens is a little higher, they can detect tiny radio signals, then Marconi's transatlantic telegraph experiment in 190 1 was the first radio signal sent by human beings, and now this signal has passed 120 light years.

This is the farthest distance that human traces can reach in the universe.

With any luck, consider it 50 light years. At present, about 50 terrestrial planets have been found in this range. It is very unlikely that intelligent creatures will be born on these 50 planets, and creatures have the ability and intention to attack the solar system, so people on earth don't have to worry.

So, the news continued to run forward. Five or six thousand Earth-like planets have been discovered within the scope of the destination M 13 globular cluster. Counting undiscovered planets, let alone tens of thousands, I can't guarantee this time.

Expanding the base, according to astronomers' conservative estimation, there are at least 6 billion Earth-like planets in the Milky Way. Do you think, how can the earth become one in six billion? It is almost certain that there must be other intelligent creatures in the galaxy.

Then, in the next 654.38 million+years, there may be intelligent creatures receiving information from people on earth. This guess is well-founded. With the current level of human science and technology, ordinary radar signals 50 light years away can already be detected. If aliens develop two or three thousand years longer than us, wouldn't it be a piece of cake to receive an electromagnetic wave thousands of light years away?

In this matter, we should plan ahead!

Do you want the alien uncle to help the earth people selflessly? Or do you want to have friendly exchanges and exchange needed goods with equal scientific and technological level? For example, if you want to see the picture of Qin Shihuang's accession to the throne, you should find aliens more than 2,200 light-years away, take photos of them now (for them, it was more than 2,000 years ago), and then communicate with them through wormholes.

Arecibo information is on its way, earthlings, and there is not much time left for you.