It is not surprising that the first flight of the spacecraft above Earth orbit was directed to the moon. This honor belongs to the Soviet spacecraft Luna-l, which was launched on January 2, 1958. In accordance with the flight program, after a few days it passed at a distance of 6,000 kilometers from the surface of the moon. Later that same year, in mid-September, a similar Moon series device reached the surface of the Earth’s natural satellite.
A year later, in October 1959, the Luna-3 automatic apparatus, equipped with apparatus for photographing, surveyed the far side of the Moon (about 70% of the surface) and transmitted its image to Earth. The device had an orientation system with sensors of the Sun and the Moon and jet engines running on compressed gas, a control and thermal control system. Its mass is 280 kilograms. The creation of “Moon-3” was a technical achievement for that time, it brought information about the far side of the moon: noticeable differences were found with the visible side, primarily the absence of long lunar seas.
In February 1966, the Luna-9 spacecraft delivered to the Moon an automatic lunar station, which made a soft landing and transmitted several panoramas of the nearby surface to the Earth – a gloomy rocky desert. The control system ensured the orientation of the apparatus, the inclusion of the brake stage on command from the radar at an altitude of 75 kilometers above the lunar surface and the separation of the station from it immediately before the fall. Depreciation was provided by an inflatable rubber balloon. The mass of the “Moon-9” is about 1800 kilograms, the mass of the station is about 100 kilograms.
The next step in the Soviet lunar program was the automatic stations “Luna-16, -20, -24”, designed to collect soil from the lunar surface and deliver its samples to Earth. Their mass was about 1900 kilograms. In addition to the braking propulsion system and four-legged landing gear, the stations included a soil intake device, a take-off rocket stage with a return vehicle for soil delivery. The flights took place in 1970, 1972 and 1976, small amounts of soil were delivered to the Earth.
In November 1970, the Luna-17 AMS delivered the lunar self-propelled lunar vehicle Lunokhod-1 to the Moon in the Sea of Rains, which, over 11 lunar days (or 10.5 months), covered a distance of 10 540 m and transmitted a large number of panoramas, individual photographs of the surface of the Moon and other scientific information. The French reflector mounted on it allowed using a laser beam to measure the distance to the moon with an accuracy of fractions of a meter. In February 1972, the Luna-20 AMS delivered lunar soil samples to Earth for the first time in the inaccessible region of the Moon. In January 1973, the Luna-21 AMS delivered the Lunokhod-2 to the Lemonier Crater (Sea of Clarity) for a comprehensive study of the transition zone between the sea and mainland plains. Lunokhod-2 worked for 5 lunar days (4 months), it covered a distance of about 37 kilometers. In addition to the panoramic chambers on the Lunokhods, the following devices were installed: a soil sampling device, a spectrometer for analyzing the chemical composition of the soil, and a track meter. The masses of moon rovers are 756 and 840 kg.
Ranger spacecraft were designed to take pictures during a fall, starting from an altitude of about 1,600 kilometers to several hundred meters above the lunar surface. They had a triaxial orientation system and were equipped with six television cameras. The devices crashed during landing, so the resulting images were transmitted immediately, without recording. During three successful flights, extensive materials were obtained to study the lunar surface morphology. Filming “Rangers” marked the beginning of the American program of photographing planets.
The design of the Ranger devices is similar to the design of the first Mariner devices, which were launched to Venus in 1962. However, the further construction of lunar spacecraft did not go this way. To obtain detailed information about the lunar surface, other spacecraft, the Lunar Orbiter, were used. These devices from the orbits of the artificial satellites of the moon photographed the surface with high resolution.
One of the goals of the flights was to obtain high-quality images with two resolutions, high and low, in order to select the possible landing sites for the Surveyor and Apollo using a special camera system. The images appeared on board, scanned by the photoelectric method and transmitted to the Earth. The number of shots was limited by the supply of film (210 frames). In 1966-1967, five launches of the Lunar Orbiter (all successful) were carried out. The first three Orbiters were launched into circular orbits with a slight inclination and low altitude; each of them was used for stereo recording of selected areas on the visible side of the moon with very high resolution and shooting of large areas of the reverse side with low resolution. The fourth satellite worked in a much higher polar orbit, it took pictures of the entire surface of the visible side, the fifth, the last Orbiter also made observations from the polar orbit.