How to measure the moon
The 1960s, the height of the Moon Race. It is still completely incomprehensible who first landed on the moon - we or the Americans.
Moreover, it is not very clear what the lunar ship will land on - on a hard surface or in a dust bog. After all, there are two theories about the surface of the moon: “dust”, according to which the moon is covered with a multimeter layer of dust, and “meteor-slag”, according to which dust just a few millimeters thick lies on a solid base.
To find out the properties of the surface, you need to lean on. And in order to lean on, you need to know the surface properties.
')
To solve the problem in the USSR, observations using the “artificial moon” method begin. In different regions of the Soviet Union, masts are placed on which disks with a diameter of several meters — artificial moons — are raised and lowered.
The disk was located on the mountain, the radio telescope was under the mountain.
Early 1960s (Zimenki radio astronomy station near Gorky):
Today (Crimea, near Sudak):
The disk had the same angular dimensions as the moon, and is at the same height above the horizon. The surface of the disk was a completely black body for radio waves:
Using a radio telescope, the team, under the leadership of Professor Vsevolod Sergeyevich Troitsky, measured the intensity of infrared and radio emission from the disk. The wavelength ranged from 0.87 mm to 70 cm.
Then the disk was lowered, the radio emission from the sky and the real Moon was measured, compared with a standard (radiation of a disk whose temperature is precisely known), and thus the temperature of the Earth satellite was determined.
The temperature was measured before. The breakthrough method was that the measurement accuracy has improved dramatically: from 20% to 1-2%. And from this it was already possible to draw far-reaching conclusions:
1) The density of the substance in the upper layer of the substance of the moon is close to the values ​​of 0.9-1.2 g / cc. The entire layer is in a highly porous (50-70%) state in the form of a frozen foamy material having a thermal conductivity in the range (3-5) * 10 -3 W / (m * K).
2) The angle of dielectric loss of the substance of the moon on the microwave is approximately equal to the loss in good dielectrics used in engineering.
3) Breed on the surface contains an average of 57% silica (quartz), 16.5% alumina (corundum), 7.5% iron oxide.
How can all these characteristics be determined by radio emission?
The sequence, apparently, was as follows:
a) Using a radar, we determined the coefficient of reflection of radio waves from the surface of the moon (2-4%). Knowing that the coefficient depends mainly on the density of the material and examining similar coefficients for terrestrial rocks (10%), they came to the conclusion that lunar rocks are 2-5 times lighter than terrestrial rocks.
b) With the help of a radio telescope, the Moon’s own radiation was investigated at different wavelengths and ground temperatures were obtained at different depths (the radio emission power is proportional to the temperature; the longer the wave, the more depth it comes from).
c) Following the dynamics of temperature changes over depth during lunar eclipses, we made conclusions about the value of the thermal conductivity coefficient of the soil: it turned out to be extremely small and did not change to a depth of several meters. So, firstly, this layer is homogeneous. And secondly, it is not dust (dust would self-compact under the action of gravity, and the coefficient of thermal conductivity would increase with depth). Consequently, the material is relatively durable, keeping the structure.
d) We studied the dependence of the thickness of the radio-emitting layer on the wavelength and compared it with similar indicators of terrestrial rocks. They came to the conclusion that there are no impurities of crushed (meteoric) iron on the Moon, since this would violate the linearity of the dependency. And it was established that earth granite, gabbro, diorite and volcanic tuffs are the closest in composition to the “lunite”. But, apparently, on the other (porous) structure, which explains the low thermal conductivity.
Here V.S. Troitsky and his colleagues themselves tell (Troitsky appears at 16:07):
To assess the accuracy of the findings of Troitsky, here are excerpts from laboratory studies of the regolith, conducted after taking samples on the Moon and delivering them to Earth:
1) Volumetric weight of 1.0-2.0 g / cc. Very large friability is characteristic: porosity is around 50%. Thermal conductivity is (8-13) * 10 -3 W / (m * K).
2) Regolith is a good dielectric, its dielectric constant is 3.36.
3) The chemical composition varies greatly depending on the place of sampling: silica 47-76%, aluminum oxide 12-19%, iron oxide 2-12%.
In February 1966, the 100-kilogram station Luna-9 made the first ever soft landing on another celestial body.
The photographs showed that there was no thick and loose dust cover in the landing site in which the lunar ship could sink, that the surface layer had a sufficiently high bearing capacity, and that the main danger during landing of the vehicles would be not the dust layer, but uneven terrain.
Actually, Trinity:
The same person on whose opinion S.P. Korolev, when he wrote his famous
"The landing of the lunar ship should be counted on a fairly hard soil like pumice."
1. Achievements of physical sciences, 1963
2. Troitsky VS, “Radio-observation of planets and satellites”, 1983
3. Photos of the current state of the installation from here .
Moreover, it is not very clear what the lunar ship will land on - on a hard surface or in a dust bog. After all, there are two theories about the surface of the moon: “dust”, according to which the moon is covered with a multimeter layer of dust, and “meteor-slag”, according to which dust just a few millimeters thick lies on a solid base.
To find out the properties of the surface, you need to lean on. And in order to lean on, you need to know the surface properties.
')
To solve the problem in the USSR, observations using the “artificial moon” method begin. In different regions of the Soviet Union, masts are placed on which disks with a diameter of several meters — artificial moons — are raised and lowered.
The disk was located on the mountain, the radio telescope was under the mountain.
Early 1960s (Zimenki radio astronomy station near Gorky):
Today (Crimea, near Sudak):
The disk had the same angular dimensions as the moon, and is at the same height above the horizon. The surface of the disk was a completely black body for radio waves:
Using a radio telescope, the team, under the leadership of Professor Vsevolod Sergeyevich Troitsky, measured the intensity of infrared and radio emission from the disk. The wavelength ranged from 0.87 mm to 70 cm.
Then the disk was lowered, the radio emission from the sky and the real Moon was measured, compared with a standard (radiation of a disk whose temperature is precisely known), and thus the temperature of the Earth satellite was determined.
The temperature was measured before. The breakthrough method was that the measurement accuracy has improved dramatically: from 20% to 1-2%. And from this it was already possible to draw far-reaching conclusions:
1) The density of the substance in the upper layer of the substance of the moon is close to the values ​​of 0.9-1.2 g / cc. The entire layer is in a highly porous (50-70%) state in the form of a frozen foamy material having a thermal conductivity in the range (3-5) * 10 -3 W / (m * K).
2) The angle of dielectric loss of the substance of the moon on the microwave is approximately equal to the loss in good dielectrics used in engineering.
3) Breed on the surface contains an average of 57% silica (quartz), 16.5% alumina (corundum), 7.5% iron oxide.
How can all these characteristics be determined by radio emission?
The sequence, apparently, was as follows:
a) Using a radar, we determined the coefficient of reflection of radio waves from the surface of the moon (2-4%). Knowing that the coefficient depends mainly on the density of the material and examining similar coefficients for terrestrial rocks (10%), they came to the conclusion that lunar rocks are 2-5 times lighter than terrestrial rocks.
b) With the help of a radio telescope, the Moon’s own radiation was investigated at different wavelengths and ground temperatures were obtained at different depths (the radio emission power is proportional to the temperature; the longer the wave, the more depth it comes from).
c) Following the dynamics of temperature changes over depth during lunar eclipses, we made conclusions about the value of the thermal conductivity coefficient of the soil: it turned out to be extremely small and did not change to a depth of several meters. So, firstly, this layer is homogeneous. And secondly, it is not dust (dust would self-compact under the action of gravity, and the coefficient of thermal conductivity would increase with depth). Consequently, the material is relatively durable, keeping the structure.
d) We studied the dependence of the thickness of the radio-emitting layer on the wavelength and compared it with similar indicators of terrestrial rocks. They came to the conclusion that there are no impurities of crushed (meteoric) iron on the Moon, since this would violate the linearity of the dependency. And it was established that earth granite, gabbro, diorite and volcanic tuffs are the closest in composition to the “lunite”. But, apparently, on the other (porous) structure, which explains the low thermal conductivity.
Here V.S. Troitsky and his colleagues themselves tell (Troitsky appears at 16:07):
To assess the accuracy of the findings of Troitsky, here are excerpts from laboratory studies of the regolith, conducted after taking samples on the Moon and delivering them to Earth:
1) Volumetric weight of 1.0-2.0 g / cc. Very large friability is characteristic: porosity is around 50%. Thermal conductivity is (8-13) * 10 -3 W / (m * K).
2) Regolith is a good dielectric, its dielectric constant is 3.36.
3) The chemical composition varies greatly depending on the place of sampling: silica 47-76%, aluminum oxide 12-19%, iron oxide 2-12%.
In February 1966, the 100-kilogram station Luna-9 made the first ever soft landing on another celestial body.
The photographs showed that there was no thick and loose dust cover in the landing site in which the lunar ship could sink, that the surface layer had a sufficiently high bearing capacity, and that the main danger during landing of the vehicles would be not the dust layer, but uneven terrain.
Actually, Trinity:
The same person on whose opinion S.P. Korolev, when he wrote his famous
"The landing of the lunar ship should be counted on a fairly hard soil like pumice."
1. Achievements of physical sciences, 1963
2. Troitsky VS, “Radio-observation of planets and satellites”, 1983
3. Photos of the current state of the installation from here .
Source: https://habr.com/ru/post/391505/
All Articles