The US Apollo programme sent astronauts into space on 17 occasions, all perfectly avoiding solar proton events.Are they lucky?"
This was the question posed by Wang Chi, director of the National Space Science Center of the Chinese Academy of Sciences, at a forum on lunar exploration on China Space Day 2021 held in Nanjing, capital of China, on April 24.
The obvious answer is, of course not."The US has been predicting solar proton events very early and has avoided solar eruptions."Wang Chi said space weather forecasting is also very important for our future manned lunar landing.
On December 17, 2020, Chang 'e-5 returned to Earth with 1,731 grams of lunar samples, announcing the completion of China's three-step strategy of orbiting, landing and returning to the moon.
So, is the lunar exploration project just to retrieve a pot of earth from the moon?Of course not.
On the same day, Prof. Wang Jing from the National Astronomical Observatories of the Chinese Academy of Sciences, Prof. Xiao Long from the China University of Geosciences (Wuhan) and Academician Wang Chi explained the three scientific achievements China has made on the basis of the lunar exploration program from three aspects: lunar astronomy observation, lunar geological evolution and space physics exploration.
What's the difference in looking at the stars from the moon
"It has always been an astronomer's dream to observe the universe from the moon!"Wang Jing explained that the moon has a high vacuum, so it can carry out ultraviolet observation and other observations that cannot be done on the ground.The second is the slow rotation of the moon, which can be used for long-term monitoring of astronomical targets;Third, the far side of the moon has very low electromagnetic noise, which is conducive to carrying out long-wave radio astronomical observation.
So far, only China and the United States have completed moon-based astronomical observations.The American Apollo 16 carried a far-ultraviolet camera;China's Chang 'e-3 and 4 missions carried moon-based optical telescopes and low-frequency radio antennas, respectively.
The difference is that the camera of Apollo 16 was hand-held and manually operated, while China is the first to rely on an extraterrestrial body to carry out independent astronomical observation.The advantages of this unmanned automatic observation, one is high accuracy, pointing to the calibration accuracy of 0.05 degrees, which to play which;The second is the long working time, 3 years of observation, 2 years of experiment.
Through the Chang 'e lunar exploration program, China has achieved three major astronomical scientific achievements, including material exchange on the evolution of binary stars, ultraviolet sky survey around the North Pole of the moon, and the revelation that the lunar atmosphere contains very little "water," Wang said.
The Chang 'e-4 mission, however, is a bit different in that it is the first to conduct very long wave astronomical observation experiments and is currently calibrating and analyzing the data.
How did the moon form? A few more drills to find out
Xiao Long said the early moon also had volcanic eruptions and magnetic fields, but when the moon became a dead place is mostly speculation, missing some key evidence.
"The Apollo rock samples were more than three billion years old, so the international scientific community believed that the moon was' dead 'three billion years ago, but the latest remote sensing observations conclude otherwise."Chinese scientists have found that volcanic activity on the moon lasted more than a billion years ago, rewriting our understanding of the formation of the moon, Xiao Long said.
According to Xiao, the lunar soil collected by Chang 'e-5 has five potential scientific values: first, to limit the time limit of lunar volcanic activity;The second is to correct the lunar impact crater age curve;The third is to reveal the nature of deep lunar mantle and the source depth of magma.The fourth is to restrict the end time of the lunar magnetic field;Fifth, optimizing the lunar magma ocean model is expected to solve major problems in lunar science.
Space weather research has a "lunar weather station"
Solar winds, particles, magnetic storms...Academician Wang Chi's research is "shirking the facts".
On the one hand, he is responsible for the space physics research. On the one hand, he is responsible for the lunar survey, carrying out near-lunar space and lunar surface exploration, and paying attention to the lunar space environment.The other is geodesy, which uses the moon as a natural satellite platform to observe the earth's space.These studies include the interaction between solar wind, earth wind and the moon, the microcosmic interaction between particles and the lunar surface, the characteristics of lunar surface radiation, the structure of earth plasma layer and its response to magnetic storms and substorms, etc.
Wang said that in the past, the study of the interaction between the solar wind and the earth and the earth's magnetosphere was like the blind men feeling an elephant. Now, when we stand 380,000 kilometers away, we will have a more comprehensive understanding of the whole picture.
From Chang 'e I to Chang 'e 4, China has made fruitful achievements in space physics research, some of which are the first in the world.In the future, it will focus on the large-scale multi-layer coupling research of the earth's space, and provide support for the space environment for the development and utilization of the moon.
In space, astronauts and scientific instruments are vulnerable to catastrophic space weather such as solar flares and coronal eruptions."The level of space forecasting is about the same as that of ground weather forecasting in the 1960s and 1970s, so there is still a long way to go," Wang said.In the future, it will be improved from three aspects: first, the understanding of physical laws;The second is to have independent and independent detection data;Third, there should be a model of numerical prediction.