In recent decades, the eternal and desolate surface of the moon has begun to become different. Both China and the United States have sent a number of probes to the moon and plan to send astronauts to the surface of the moon. At the same time, the moon is becoming a popular scientific research destination, and many scientific research teams around the world are drawing blueprints to try to build it into the most cutting-edge astrophysics laboratory in history. Is this possible?

　　The British website of "New Scientist" recently reported that large-scale scientific experimental devices and astronomical equipment that are being deployed on the moon are indeed expected to solve many mysteries of the universe. Some questions that have long troubled humanity may be answered in this silver wasteland.

The unique environment on the moon makes it possible to be an ideal place for astronomical observation and celestial body research (artistic imagination). Image source: British "New Scientist" website

Draw a panoramic view of the "Dark Age of the Universe"

　　Radio waves are the key key to exploring the mysteries of the distant universe. Although people can use various wavelengths of light to observe the "clues" of stars and galaxies, only through radio waves can we see the "dark age of the universe" before the birth of the first ray of dawn of the universe. This period laid the foundation for the subsequent formation of galaxies, and to unravel its secrets, it is necessary to capture the information carried by the photons released by the first hydrogen atoms about 380,000 years after the Big Bang.

　　However, these oldest photons exist only in the form of low-frequency radio waves. On Earth, they are either reflected by the atmosphere or flooded by noise generated by human activities and are almost impossible to capture. And the quiet place on the back of the moon, which is always facing the earth, may be the ideal window to observe them. By analyzing the distribution of these primitive photons, astronomers are expected to draw a panoramic view of the "Dark Age of the Universe".

　　Not only that, radio telescopes on the back of the moon can also capture the aurora and magnetic field signals of exoplanets, which are also difficult to distinguish on Earth. Such research will help scientists understand the environment of exoplanets and even explore the possibility of life.

　　The moon can also greatly improve the observation capabilities of the Event Horizon Telescope (EHT). EHT has taken the first photo of a black hole, and if the radio observatory on the surface of the moon is connected to the Earth's telescope, it will become a more powerful "eye of the universe." Higher precision black hole photos can not only reveal the nature of these mysterious celestial bodies, but also further verify the theory of gravity.

　　As the first lunar radio astronomy experiment, NASA's "Photoelectroshexa Lunar Surface Radio Wave Observer" (ROLSES-1) landed near the South Pole of the Moon last year. Despite its unexpected fall and limited data collection capabilities, radio signals from Earth and Jupiter were successfully captured, demonstrating the feasibility of lunar observations.

　　The "LuSEE Night" will be launched in 2026, with the goal of detecting the low-frequency light of the Milky Way and taking a step further to the ultimate answer to the "Dark Age of the Universe". NASA's "Moon Crater Radio Telescope" plans to erect a giant mesh antenna with a diameter of 350 meters to 1 km in the crater on the back of the moon. If successful, it will become one of the largest radio receivers in human history, with which it can hear the "whispers" of the ancient universe.

　　A scientific platform for studying "space-time ripples"

　　On the journey of exploring the mysteries of the universe, the moon is becoming an ideal platform for studying gravitational waves - "ripples of time and space".

　　At present, scientists on Earth have successfully captured gravitational waves generated by celestial events such as the merger of double black holes and the collision of double neutron stars. They hope to capture more gravitational waves in the future and further reveal the nature of black holes, neutron stars and gravity.

　　However, ground observation faces many challenges. The US Laser Interferometer Gravitational Wave Observatory (LIGO) must eliminate interference caused by earthquakes, water flows, tides and even human activities. In contrast, the moon is an ideal observation location. The earthquake activity here is weak, there is no atmospheric disturbance, and no man-made noise. More importantly, the air pressure on the moon's surface is only ten times higher than the vacuum tube carefully maintained by LIGO.

　　Astronomer Jane Hams, a Gran Sasso Institute in Science in Italy, believes that building and operating gravitational wave detectors on the moon will achieve twice the result with half the effort. Scientists are even expected to discover gravitational wave sources that cannot be detected by LIGO, such as mergers of supermassive black holes. Jasmin Gill of the Harvard-Smithsonian Center for Astrophysics in the United States said the lunar observatory will also help scientists study the core collapse process when supernova erupts, revealing the mystery of how stars transform into neutron stars or black holes.

　　At present, scientists have begun to develop the "Laser Interferometer Luna-LIGO". According to the plan, three landers carrying precision instruments will be deployed at the edge of the lunar crater, spaced several kilometers apart from each other. Each lander will be equipped with a laser system, mirror and advanced vibration isolation device to eliminate weak interference from moon shocks. This system is expected to be launched in the next decade.

　　The European Space Agency is also promoting the "LGWA" program. In the permanently shadowed areas of the moon's poles, the temperature can be as low as -246℃, which will greatly improve detection sensitivity. Deploying a set of vibration sensors at the bottom of the crater may detect gravitational waves generated by celestial bodies such as ancient black holes that cannot be captured on Earth. These breakthroughs will open new windows for scientists to observe the early universe.

　　The ideal home for the next generation of infrared observatory

　　In recent years, the James Webb Space Telescope has obtained breakthrough observation images with its advanced infrared observation technology, which is reshaping people's understanding of the evolution of the universe. And the deep craters on the moon may become the ideal home for the next generation of infrared observatories.

　　Jean-Pierre Maillard of the Institute of Astrophysics in Paris is leading a study to explore the possibility of building infrared telescopes in the permanent shadow area of ​​the moon. These concave structures that naturally form potholes are themselves perfect telescope bases. The moon's weak gravitational environment also allows for the construction of super-large-diameter lenses, a dream that cannot be achieved under the Earth's gravity field, because Earth's gravity can cause mirror glass to deform.

　　Maillard's research shows that the sensitivity of the lunar infrared telescope may be far greater than any existing ground-based or space-based observation equipment. Martin Elvis of the Harvard-Smithsonian Astrophysics Center said that on the moon, many technical problems are solved.

　　However, this grand plan faces a tricky challenge: lunar dust. Mihai Horai, a physicist at the University of Colorado Boulder, said that the reason why the moon's dust floats at sunrise and sunset is still unknown. This abnormal behavior may not only interfere with infrared observations, but also affect the operation of gravitational wave detectors and radio instruments. Before building any lunar observatory, scientists must thoroughly study the properties of lunar dust. In addition, future lunar observatorys will also need to deal with strong cosmic radiation and the huge temperature difference between day and night. (Reporter Liu Xia)

[Editor in charge: Zhu Jiaqi]