Besides summer, there is also the back of the moon.
"The universe is not silent ..."-The noisy electromagnetic environment of Journey to the Cosmic Soundtrack makes it a luxury to "monitor" the universe on the earth. Even if you listen to the FM signal of the universe with the "cauldron" of FAST, there are electromagnetic interferences of one kind or another. What should we do? Are you really so curious about the "song" of the universe? Why don't you put the "antenna" of the radio telescope in the universe and go to the moon 448~
and build a "pot" on the back of the moon
Recently, NASA's innovative advanced concept plan put forward a plan with a very scientific and futuristic sense, which is to build a huge lunar crater radio telescope on the back of the moon. The diameter of this telescope is 1 km, which is twice as large as that of Guizhou FAST. Once the project is completed, it will be the largest telescope in the solar system.
shocked! This "pot" is bigger than China's "cauldron"? !
compared with other radio telescopes, LCRT is 37 m from the Arecibo telescope in the United States, 5 m from the FAST telescope in China, and 1m in preparation. Source: Self-painting
At present, NASA has announced the first phase of funding for this project, which has been published on the official website, and the scientific pre-research of the project is also under way. Similar to FAST's selection of Dawodang in Guizhou for construction, NIAC plans to select a crater with a diameter of 3-5 km on the back of the moon as the basis for the construction of a 1 km telescope. Select a proportional crater with suitable width and depth to facilitate the laying of mirror surface. This will be the first time that human beings are engaged in the construction of outer space telescopes. Get rid of the shackles of the atmosphere, its achievements in science will be unprecedented. We will have a greater chance to find aliens, and at the same time, it will observe the whole universe at a longer wavelength, which will undoubtedly give people a new understanding of the universe.
The crater becomes a "cauldron". Although the idea is good, the universe is so big. Why is the "new cauldron" placed on the moon?
The LCRT effect map of the solar system's largest radio telescope. Source: NASA
The list of funded projects announced by NASA official website, in which only a part of LCRT is captured. Source: NASA
The back of the moon: "the land of geomantic omen"
Because of tidal locking, the moon always has its back to us. The back of the moon, which can't be directly witnessed by us, has always been an observation place that astronomers dream of. Since Apollo landed on the moon, several astronomical exploration plans based on the moon have been put forward back and forth. At present, there are two main factors to consider when the largest telescope in history is built on the moon:
Quiet electromagnetic radiation
For electromagnetic waves, the moon itself is a huge physical barrier, and electromagnetic waves cannot penetrate the moon with a diameter of more than 3,4 kilometers, which is why no spacecraft has landed on the back of the moon before except Chang 'e IV. Therefore, in order to meet the communication needs of Chang 'e-4, China specially launched the Queqiao relay star.
Moon Back-Compared with the front of the moon, the exploration of the moon back is much less. Source: wikipedia.org
The exploration of the moon back needs to face many obstacles, but it is good news for astronomers. The back of the moon, which is shielded from electromagnetic radiation, is a rare quiet place. The radio telescope built on the back of the moon can monitor the information from the depths of the universe without loss, without worrying about being confused with the surrounding electromagnetic environment, and there will be no such regrettable fallacy as taking microwave oven signals as cosmic signals.
With the development of communication, there are more and more radio noises in the air. In order to avoid interference, the location of radio telescopes on the earth is mostly in sparsely populated places, and radio silence zones need to be set around the telescopes. Astronomers are almost desperate to maintain the "tranquility" around the telescope in the face of the increasingly bad electromagnetic environment.
Take China's FAST as an example, its cost is 8 million RMB, and the relocation expenses of residents within 5 kilometers will cost 2.1 billion RMB. After the completion, in addition to the strict visiting regulations, a radio silent zone was set up within the surrounding 3 km, and different restrictions were set by zones to obtain a good electromagnetic environment.
electromagnetic interference will pollute the observation data, increase the difficulty of data processing, and the strong interference signal will even directly drown the data, which may cause us to lose some valuable information and mislead hard-working scientific researchers. So astronomers are eager to observe in space and the back of the moon to prevent these uncontrollable factors.
Ultra-long wave science in virgin land
In addition to isolating electromagnetic radiation, the moon back without atmosphere has many research advantages, such as the research of ultra-long wave science that we are most looking forward to.
in the electromagnetic spectrum, we call waves with a wavelength of more than 1 m ultra-long waves, and the corresponding frequency is lower than 3 MHz. This is the longest piece in the electromagnetic spectrum, and it is also a piece that human beings rarely contact.
when the earth's atmosphere absorbs different electromagnetic waves, the source with the longest wavelength on the far right is wikipedia.org
The earth's atmosphere absorbs different bands accordingly. While protecting us from cosmic rays, it also keeps two windows for us to observe the universe. One window is the visible light band, and the other window is the medium and long wave radio band. In the ultra-long wave range, due to the strong absorption of the earth's ionosphere, we can only look up at the sky and sigh. In addition, there are a large number of broadcast signals and communication signals in this ultra-long wave signal frequency band, which often directly drown out astronomical signals. Moreover, the interference signal will propagate repeatedly between the ionosphere and the ground, which will only make us more desperate.
of course, it's not that we haven't made efforts on the ground. In high magnetic latitudes, there are observation opportunities when the ionosphere becomes thinner at night in winter. In the 196s and 197s, some scientists made observations, but the amount of data was very small, and the resolution of observation was poor, so it was difficult to distinguish a single celestial body, and there was no complete number of all-day observations. Although the observation frequency of some radio arrays is lower than 1 MHz, it is mainly used to observe a few particularly bright celestial bodies such as solar bursts and Jupiter radio, which is far from reaching the scale of cosmological research.
at present, only the ultra-long wave remains a huge blank in the whole electromagnetic spectrum. According to the relationship between wavelength and frequency of electromagnetic waves, wavelength × frequency = the speed of light, and the long wave of electromagnetic waves corresponds to the low frequency. At present, we know that many celestial bodies can produce low-frequency radio emission, but there is still a lack of observation means. In order to carry out scientific exploration in one frequency band, it is not realistic to sit on the earth and watch the sky. We can only hope to observe in the open space or on the quiet back of the moon. NIAC's proposal to build a 1 km LCRT project on the back of the moon undoubtedly excited the whole astronomical community. The ionosphere of the moon is very thin, and we can observe the ultra-low frequency as low as 5 kHz on the surface, which is completely enough for the exploration of cosmology.
Therefore, in the ultra-long wave band, LCRT is bound to show its talents and help to complete the last electromagnetic puzzle in astronomical observation. LCRT with ultra-long wave vision will discover many unknown new phenomena. It can help us further reveal the structure of the Milky Way and galaxy clusters, the acceleration and spread of cosmic rays, understand the formation of large-scale structure of the universe, spy on the origin of the universe, and even help us receive signals of extraterrestrial life. It's like a cookbook, full of secret recipes of delicious food waiting for people to discover. Plus the attribute bonus of 1 km caliber, it can not only make people see farther, but also make us see more clearly.
Move the "pot" to the moon
When you hear this news, you may see a scene of hundreds of astronauts working hard on the lunar surface with geotechnical equipment.
stop for a moment! It is true that the scene of hundreds of astronauts building on the moon is spectacular, but we should also see that the US plan to return to the moon has been pushed back and forth, not to mention sending so many astronauts and equipment there. Judging from the data currently displayed, only a few robots need to be launched from the earth during the whole construction process. Although it doesn't look so spectacular, it is extremely economical compared with launching dozens of manned spacecraft to the moon.
Construction Imagination Map Source: NASA
The whole construction process is divided into four steps: 1. Investigate the crater with complex construction conditions and prepare to launch the working robot; 2. Using robots to "shape" craters; 3. Laying an antenna network for receiving celestial radiation; 4. Place the feed and receiver for receiving antenna signals. On the whole, it is similar to the process we prepared to build FAST.
According to the site selection, there are about 3, craters with a diameter of 1-5 km on the back of the moon to choose from, and the "pits" with appropriate width and depth ratio should be selected. When FAST was first built, Mr. Nan Rendong left and visited many karst landforms in order to finalize the appropriate construction site. However, the construction of LCRT cannot be surveyed by sending astronauts on the spot, which is uneconomical in terms of economy and efficiency. However, fortunately, with the high-precision terrain information mapped by the lunar probe, it is not difficult to finalize the construction site.
after the site is selected, it will be the most exciting construction work. First of all, we should launch the corresponding digging and road pressing robots to "facelift" the crater and erase its various defects. The second step is to lay the reflective antenna. If you want to build a 1 km telescope, materials are indispensable. This step requires launching about 2 tons of metal antenna from the earth, which contains 1, antenna elements weighing 2 kg. In order to receive the signal reflected by the antenna, a receiver with good performance is also needed. After being manufactured on the earth, the receiver will be hung above the crater by robots. In this way, after some calibration work, the telescope will be completed.
Quality estimation required in the process of building LCRT
Expected schematic diagram of construction Source: NASA
Written at the end
The construction of LCRT is really a bold idea. This will be the first time that human beings have built a telescope outside the earth, and it will also be the largest in the solar system.
We will complete the last puzzle of electromagnetic waves-ultra-long waves, and there will be one scientific problem after another waiting for it to be solved, which can extend human vision to the dark age of chaos before the cosmic microwave background radiation. Or maybe you can really realize close encounters of the third kind-hearing the signals from aliens.
Of course, there are many scientific problems behind countless expectations. For example, robots working on the moon are easily blocked by moon dust, how to ensure communication with the earth during the period, how to arrange the construction under low gravity, and so on ...... There are great challenges behind each step, but it is these challenges that make human beings go further and further on the road of exploration. Finally, I would like to take President Kennedy's speech on the moon as the end of this article.
"We decided to go to the moon and realize more dreams in this decade, not because they are easy, but because they are full of difficulties." —Kennedy Source: efancy.com
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this article source: deep space game editor: anonymous heart of the king 2 click on the demo.