Lunar migration prerequisites
Is there water on the moon?
The Moon is the closest celestial body to Earth. For a long time, the Moon was considered the ideal location for humanity to most likely achieve interstellar migration. Although humans have stepped on the lunar surface as early as the 1960s, there is still a very important resource problem to be solved if lunar migration and even the establishment of lunar bases - water. Is there water on the Moon?
In 1961, American scientist Kenneth Watson and others pioneered the idea that there might be water ice on the moon. For decades, scientists have been searching for evidence of the existence of lunar water and its possible sources. Recently, a research article published in Scientific Reports pointed out that hydrogen and oxygen ions escaping from the Earth's upper atmosphere, or combined on the moon, became one of the possible sources of known water ice on the moon. At present, lunar water has become a research hotspot in the field of planetary science at home and abroad. Lunar water not only has important scientific significance, but also contains potential application value, and studying it will not only help to understand the evolutionary history of the moon, but also help the construction of future lunar research stations and lunar bases, and provide key resources for the survival of animals and plants, rocket fuel, etc.
(The content of the article comes from the Internet)
Why can't I see water on the lunar surface?
Unlike Earth, the Moon itself has no global magnetic field and is not protected by a dense atmosphere, and its surface is directly exposed to extreme temperatures and harsh space vacuums. In addition, the average temperature on the lunar surface can drop from about 100 degrees Celsius during the day to about minus 150 degrees Celsius at night, such a large temperature difference makes it impossible for liquid water to exist stably. As a result, the moon was previously thought to be as dry and waterless as a desert. But with the deepening of observations, scientists have found that the lunar polar region has some permanent shadow areas at the bottom of the impact crater, which are not exposed to sunlight all year round, the temperature is extremely low, and under vacuum conditions, water ice may be stable. In the 1990s, scientists discovered anomalies in the echoes of the radar on the Clementine probe in the permanently shaded region of the moon's south pole; The neutron spectrometer on NASA's Lunar Explorer probe showed large amounts of hydrogen in the moon's permanent shadow zone.
In 2010, a U.S. satellite hit the moon's permanent shadow area, finding large amounts of water ice in the sputtering dust, confirming the existence of lunar water. In 2020, the National Aeronautics and Space Administration (NASA) confirmed the presence of water on the lunar surface for the first time through telescope observations; In January 2022, the mainland Chang'e-5 lunar lander obtained in-situ lunar surface exploration data for the first time, and the presence of water on the moon has since had "on-site evidence".
In August 2013, researchers at Johns Hopkins University in the United States used the lunar mineral mapper carried on India's Chandrayaan-1 probe to image and analyze the Blio Crater located near the moon's equator and found that the central peak of the Blio crater contained a large number of hydrogen and oxygen groups. The researchers believe this is direct evidence that the Blio Crater contains magmatic water deep in the moon, suggesting that water may have existed at the beginning of the moon's formation.
Major discoveries
Lunar soil samples are present in the lunar interior native water
On June 15, the international scientific journal Nature Communications released an important research result of chang'e 5 on the mainland online, and the research team led by Li Chunlai, Liu Jianjun, researchers of the National Astronomical Observatories of the Chinese Academy of Sciences, and Shu Rong, researchers of the Shanghai Institute of Technical Physics, cooperated with the Institute of Geology and Geophysics, the Institute of Physics, the Institute of Geochemistry and other units, for the first time in the world, combined the laboratory analysis results of lunar samples with the spectral data of the lunar surface in situ detection to test the presence or absence of water in lunar samples. The form and content answer the question of the distribution characteristics and source of water in the Chang'e-5 landing area, and provide the ground truth value for the interpretation and estimation of water signals in remote sensing data.
Whether the moon has water, how much water, what form of water it is, and where it comes from, these issues have always been very controversial, and they have always been a hot topic in lunar scientific research. At the beginning of the demonstration of the Chang'e-5 mission, the research team proposed to expand the spectral range of the lunar mineral spectroscopy analyzer on the lander to 3.2 microns, and realized the first in-situ detection of the spectral absorption characteristics of lunar surface water in the world (that is, in situ detection).
(The content of the article comes from the Internet)
After the lunar samples returned to Earth, the research team conducted a systematic analysis of the returned lunar samples in the laboratory, and the laboratory spectral analysis once again verified the existence of hydroxyl water, but the study of the form, content and source of the existence of "water" required detailed mineralogical analysis. Previously, after studying the Apollo lunar samples, the researchers believed that the (impact) cemented glass in the lunar soil contained hydroxyl material formed by the long-term injection of the solar wind, and the content of the cemented glass was an important factor affecting the "water" content in the lunar sample. Laboratory analysis of samples returned from the mainland showed that the Chang'e-5 lunar sample was a class of young basalt with very little cemented glass content (less than 16%), only 1/3 of the Apollo 11 lunar sample, thus estimating that the "water" formed by the cemented glass injected by the solar wind in the Chang'e-5 lunar soil sample was no more than 18 ppm. At the same time, the content of foreign impact sputter in the lunar soil samples in the Chang'e-5 landing area is also very low, and the contribution to the "water" in the lunar soil samples is basically negligible.
Therefore, there must be native water from the lunar interior in the Chang'e-5 lunar soil sample. Laboratory analysis of the Chang'e-5 lunar samples found that at least one aqueous mineral, hydroxyapatite, had an uneven content, and the content of hydroxyl water in the equivalent sample ranged from 0 ppm to 179 ppm (an average of about 17 ppm), which proved that there was "water" from the magma crystallization process in the Chang'e 5 lunar soil sample, indicating that "water" not only existed in the late magmatic activity of the moon, but may also play a very important role.
Not only water but also quartz
Recently, Du Wei's team, a member of the Center for Excellence in Comparative Planetology of the Chinese Academy of Sciences and a member of the Institute of Geochemistry of the Chinese Academy of Sciences, discovered the high-pressure phases of symbiotic silica in the Chang'e-5 lunar soil samples- race quartz and Squartz. It is understood that impact is an important geological process of the mixture of material on the lunar surface and an important factor controlling the formation and evolution of lunar soil. As an important recorder of impact events, high-pressure minerals are of great significance for limiting the temperature and pressure conditions of rock impact and the size of the inversion impact crater. However, both lunar return samples and lunar meteorites rarely find high-pressure mineral phases, limiting the study of the impact process of inverting the lunar surface through lunar samples.
By studying in detail the morphological characteristics and distribution of the silica phases of α-quartz and silica glass, the Chinese scientific research team deduced that the formation mechanism of quartz and quartz was solid-solid phase transformation. Controlled by the dynamics of the impact process, the semi-quartz appears as a metastable phase under lower pressure conditions, and as the temperature rises, some of the race quartz is converted to stony quartz, so the silica fragment records the boost of a lunar surface impact event and the subsequent rise and pressure reduction process. Based on the simulation calculation of the temperature and pressure conditions formed by the formation and the impact conditions, it is speculated that the silica debris is likely to come from the Arisstarchus impact crater south of the Chang'e-5 sampling area. This study is the first time that the discovery of Sai quartz has been confirmed in the lunar return sample, which provides important evidence for the previous view that there is a distant impact crater sputter in the Chang'e 5 sampling area through remote sensing data analysis.
For better research
The preservation environment of the lunar soil is very strict
Chang'e 5 successfully returned to Earth after completing the lunar soil collection mission, but for scientists of ground application systems, the scientific research work on lunar samples can be said to have just begun. So how will lunar samples be stored, managed, and studied?
According to the expert introduction: the lunar sample laboratory is mainly composed of extraterrestrial sample storage room, extraterrestrial sample preparation room, extraterrestrial sample processing and physical property analysis room and other laboratories, and samples from the moon will be stored, unsealed and processed here. In the newly built lunar sample laboratory, the first room is the scientific research equipment used for safe unsealing. Since the moon is in a state of almost vacuum, and there is a large pressure difference with the earth, safe unsealing has become the first problem facing the scientific research team.
The biggest problem is unsealing the device encapsulated in the vacuum environment of the lunar surface. In order to solve this problem, the researchers through technology and verification, and finally designed a set of schemes, under vacuum conditions to independently unseal the jar, after unsealing, the sample is transferred to the nitrogen environment for storage and processing. According to the scientific research team, because the lunar samples are produced in a high vacuum and high reduction environment, they are easily affected by the erosion, weathering and oxidation of oxygen and water on the earth, so in the process of storage in the nitrogen environment, it is also necessary to strictly control the indicators of water and oxygen. Zhang Guangliang said: "We know that the lunar soil sample is powdery and easily contaminated by the earth's material, so for the external environment to unseal it, we designed it as a clean room condition to minimize the pollution of the earth's particulate matter." ”
According to the sampling method and the use of samples, the samples collected this time will be divided into four categories: temporary storage of drill samples, temporary storage of samples taken from the table, permanent storage of drilled samples and permanent storage of samples taken from the table, experts introduced: "According to the characteristics of samples returned to samples, there are drill samples and table sampling, so we classify these two types of samples and design different storage devices for storage, so that we can more properly store samples." In the actual process, we must divide samples according to the actual needs of scientific research, and we must strictly comply with certain operating procedures to ensure that when the lunar samples are finally analyzed, the sample amount can be applied to scientific research and will not be wasted. "To this end, we can see the vacuum glove box many times during the sample opening process, providing a reliable and safe environmental protection for safe opening."
The role of the glove box is to fill the high-purity inert gas into the box body and circulate the laboratory equipment that filters out the water, oxygen, organic gases and other substances in it. Also known as vacuum glove box, inert gas protection box, etc. The main function is to remove O2, H2O, and organic gases. Widely used in anhydrous, oxygen-free, dust-free ultra-pure environment. Finally, the safe preservation of lunar soil is guaranteed.
If there really is water
Probably not far from lunar migration
More scientific and technical information
Keep an eye on the Itex glove box