March 22, 2016 at 08:19How to measure the moon
1960s, the height of the Lunar Race. It is still completely incomprehensible whether we or the Americans are the first to land on the moon.
Moreover, it is not very clear what the lunar ship will land on - on a hard surface or in a dust quagmire. Indeed, there are two theories regarding the surface of the Moon: “dusty”, according to which the Moon is covered with a many-meter layer of dust, and “meteor-slag”, according to which dust is only a few millimeters thick and lies on a solid basis.
To find out the properties of the surface, you need to take a break. And to lie down, you need to know the surface properties.
To solve the problem in the USSR, observations are begun using the “artificial moon” method. In different regions of the Soviet Union, masts are placed on which discs with a diameter of several meters, artificial moons, are raised and lowered.
The disk was located on the mountain, the radio telescope - under the mountain.
Early 1960s (Zimenki radio astronomy station near Gorky):
Today (Crimea, not far from 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 an absolutely black body for radio waves:
Using a radio telescope, a team led by Professor Vsevolod Sergeyevich Troitsky measured the intensity of infrared and radio radiation 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 the standard (radiation from the disk, the temperature of which is precisely known), and thus the temperature of the Earth satellite was determined.
We measured the temperature before. The breakthrough of the method was that the measurement accuracy improved sharply: from 20% to 1-2%. And from this it was already possible to draw far-reaching conclusions:
1) The density of matter in the upper layer of the Moon’s substance is close to 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 thermal conductivity in the range of (3-5) * 10 -3 W / (m * K).
2) The dielectric loss angle of the lunar matter on the microwave is approximately equal to the loss in good dielectrics used in technology.
3) The rock on the surface on average contains 57% silicon oxide (quartz), 16.5% alumina (corundum), 7.5% iron oxide.
How can one determine all these radio emission characteristics?
The sequence, apparently, was as follows:
a) Using the radar, we determined the reflection coefficient of radio waves from the surface of the moon (2-4%). Knowing that the coefficient depends mainly on the density of the material and having studied similar coefficients for terrestrial rocks (10%), we came to the conclusion that lunar rocks are 2-5 times lighter than terrestrial.
b) Using the radio telescope, we studied the proper radiation of the Moon at different wavelengths and obtained the temperature of the soil at different depths (the radio emission power is proportional to the temperature; the longer the wave, the greater the depth it comes from).
c) Following the dynamics of temperature changes in depth during lunar eclipses, we concluded about the value of the thermal conductivity 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 (the dust would self-compact under the influence of gravity, and the coefficient of thermal conductivity would increase with depth). Therefore, the material is relatively durable, retaining structure.
d) We studied the dependence of the thickness of the radiating layer on the wavelength and compared it with similar parameters of terrestrial rocks. We came to the conclusion that there are no impurities of fragmented (meteor) iron on the Moon, because this would violate the linearity of the dependency. And it was established that the closest in composition to the "Lunite" are terrestrial granite, gabbro, diorite and volcanic tuffs. But, apparently, with a different (porous) structure explaining the low thermal conductivity.
Here V.S.Troitsky and his colleagues themselves tell (Troitsky appears at 16:07):
To assess the accuracy of the conclusions of Troitsky, I will cite excerpts from laboratory studies of regolith, carried out after taking samples on the Moon and delivering them to Earth:
1) Bulk weight 1.0–2.0 g / cc. Very large friability is characteristic: porosity in the region of 50%. Thermal conductivity is (8-13) * 10 -3 W / (m * K).
2) Regolite 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%, alumina 12-19%, iron oxide 2-12%.
In February 1966, the 100-kilogram Luna-9 station made the first ever soft landing on another celestial body.
The photographs showed that at the landing site there was no thick and loose dusty cover in which the lunar ship could sink, that the surface layer had a sufficiently high bearing capacity, and that the main danger when landing the apparatus, apparently, would be not a dust layer, but uneven terrain.
Actually, Troitsky:
The same person on whose opinion S.P. was based Korolev, when he wrote his famous
“Landing of a lunar ship, one should count on fairly solid soil such as pumice”.
1. Advances in physical sciences, 1963
2. Troitsky VS, "Radio surveillance 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 quagmire. Indeed, there are two theories regarding the surface of the Moon: “dusty”, according to which the Moon is covered with a many-meter layer of dust, and “meteor-slag”, according to which dust is only a few millimeters thick and lies on a solid basis.
To find out the properties of the surface, you need to take a break. And to lie down, you need to know the surface properties.
To solve the problem in the USSR, observations are begun using the “artificial moon” method. In different regions of the Soviet Union, masts are placed on which discs with a diameter of several meters, artificial moons, are raised and lowered.
The disk was located on the mountain, the radio telescope - under the mountain.
Early 1960s (Zimenki radio astronomy station near Gorky):
Today (Crimea, not far from 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 an absolutely black body for radio waves:
Using a radio telescope, a team led by Professor Vsevolod Sergeyevich Troitsky measured the intensity of infrared and radio radiation 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 the standard (radiation from the disk, the temperature of which is precisely known), and thus the temperature of the Earth satellite was determined.
We measured the temperature before. The breakthrough of the method was that the measurement accuracy improved sharply: from 20% to 1-2%. And from this it was already possible to draw far-reaching conclusions:
1) The density of matter in the upper layer of the Moon’s substance is close to 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 thermal conductivity in the range of (3-5) * 10 -3 W / (m * K).
2) The dielectric loss angle of the lunar matter on the microwave is approximately equal to the loss in good dielectrics used in technology.
3) The rock on the surface on average contains 57% silicon oxide (quartz), 16.5% alumina (corundum), 7.5% iron oxide.
How can one determine all these radio emission characteristics?
The sequence, apparently, was as follows:
a) Using the radar, we determined the reflection coefficient of radio waves from the surface of the moon (2-4%). Knowing that the coefficient depends mainly on the density of the material and having studied similar coefficients for terrestrial rocks (10%), we came to the conclusion that lunar rocks are 2-5 times lighter than terrestrial.
b) Using the radio telescope, we studied the proper radiation of the Moon at different wavelengths and obtained the temperature of the soil at different depths (the radio emission power is proportional to the temperature; the longer the wave, the greater the depth it comes from).
c) Following the dynamics of temperature changes in depth during lunar eclipses, we concluded about the value of the thermal conductivity 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 (the dust would self-compact under the influence of gravity, and the coefficient of thermal conductivity would increase with depth). Therefore, the material is relatively durable, retaining structure.
d) We studied the dependence of the thickness of the radiating layer on the wavelength and compared it with similar parameters of terrestrial rocks. We came to the conclusion that there are no impurities of fragmented (meteor) iron on the Moon, because this would violate the linearity of the dependency. And it was established that the closest in composition to the "Lunite" are terrestrial granite, gabbro, diorite and volcanic tuffs. But, apparently, with a different (porous) structure explaining the low thermal conductivity.
Here V.S.Troitsky and his colleagues themselves tell (Troitsky appears at 16:07):
To assess the accuracy of the conclusions of Troitsky, I will cite excerpts from laboratory studies of regolith, carried out after taking samples on the Moon and delivering them to Earth:
1) Bulk weight 1.0–2.0 g / cc. Very large friability is characteristic: porosity in the region of 50%. Thermal conductivity is (8-13) * 10 -3 W / (m * K).
2) Regolite 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%, alumina 12-19%, iron oxide 2-12%.
In February 1966, the 100-kilogram Luna-9 station made the first ever soft landing on another celestial body.
The photographs showed that at the landing site there was no thick and loose dusty cover in which the lunar ship could sink, that the surface layer had a sufficiently high bearing capacity, and that the main danger when landing the apparatus, apparently, would be not a dust layer, but uneven terrain.
Actually, Troitsky:
The same person on whose opinion S.P. was based Korolev, when he wrote his famous
“Landing of a lunar ship, one should count on fairly solid soil such as pumice”.
1. Advances in physical sciences, 1963
2. Troitsky VS, "Radio surveillance of planets and satellites", 1983
3. Photos of the current state of the installation from here .