Planet Venus – History of Research
Venus was known to people from ancient times. (See a brief description of this planet and interesting facts about it.) It received its modern name in honor of the Roman goddess of beauty, whom the Greeks called Aphrodite. The Babylonians called this planet Astarta, also named after the goddess of love. In ancient China, Venus was designated as the “golden star” and associated with the “element of gold.” In ancient India, Sura (Ushanas Kawya), the mentor of the asura demons, rivals of the Indian gods, was considered the lord of Venus.
Venus rises in the sky either in the evening or in the morning. The ancient Greeks long considered the “evening” and “morning” star two different bodies, calling the first Hesperus (“Evening”), and the second Phosphorus (“Lightbearer”). But the fallacy of this view was realized back in ancient times. The Roman Empire already understood that Phosphorus and Hesperus are one and the same planet.
In the space age, Venus was investigated by more than 20 artificial vehicles: Venus, Mariner, Pioneer Venus, Vega, and Magellan. Since 2006, the Venera Express probe has been operating in orbit around it. Initially, scientists did not know what atmospheric pressure the instruments should be designed for. For this reason, descent vehicles for the first time could not reach the surface in working condition: they were destroyed, because they were designed for low atmospheric pressure.
The Soviet probe “Venus-1” in February 1961 flew at a distance of about 100 thousand km from Venus and entered a near-solar orbit. In August 1962, Mariner-2 approached the planet and recorded a high atmospheric density and a high surface temperature. The Venus-3 descent vehicle first entered the atmosphere of Venus. In June 1967, Venus-4 (USSR) and Mariner-5 (USA) were launched almost simultaneously. The Venus-4 descent vehicle from high pressure collapsed at an altitude of 23 km above the surface of Venus. But it was he who first established the composition of the planet’s atmosphere. Scientists compared the data of measurements of Venus-4 with the results of measurements of Mariner-5 and determined that the pressure at the surface is about 100 bar. The deeper layers were reached by the Venus-5 and Venus-6 descent vehicles.
“Venus-7” became the first device to safely descend to the surface of Venus (1970). She worked on the surface for 23 minutes. In 1975, Venera-9 and Venera-10 made a soft landing on the lighted side of the planet at a distance of 2,200 km from each other, worked for about an hour and transmitted the first panoramas of the surface from the landing sites to the Earth. The panorama shows a lot of stones – from the smallest to a meter in size – and loose soil between them.
According to the radar sensing data of the American Pioneer-Venus-1 apparatus, in 1978 the first detailed map of the relief of the surface of Venus was compiled. Four probes were dropped from the Pioneer-Venus-2 apparatus for descent in the atmosphere on the day and night sides and for transmitting information before falling to the surface. But one of the devices withstood the shock and transmitted data from the surface for 67 minutes. In the same 1978, a soft landing on the surface was made by “Venus-11” and “Venus-12” at a distance of 800 km from each other. When descending in the atmosphere, they recorded radio pulses from electrical discharges – probably Venusian lightning.
Data on the chemical composition of the rocks were first obtained from the landing sites of the Venera-13 and Venera-14 devices in 1982, which worked on the surface for about 2 hours. Using soil sampling devices, samples were taken inside the apparatus and analyzed. It turned out that the substance of Venus is comparable to terrestrial basalts in the deep-sea troughs of the oceans.
Scientists were able to get acquainted with the global features of the relief of Venus in detail thanks to radar sensing from aboard the Pioneer-Venus orbital vehicles (1978), Venus-15 and Venus-16 (1983-1984) and Magellan ( 1990-1994). Ground-based radar allows you to “see” only 25% of the surface, and with a much lower resolution of parts than from orbit. The best images of the entire surface, with a resolution of up to 300 m, were received by Magellan.
Unique relief forms are visible on them: for example, seven large hills, about 25 km in size and up to 1 km in height each, located near the Alpha region, are very thick and slowly spreading lava flows; these are the so-called “pancake volcanoes”.
Unusual landforms representing the intersection of ridges and valleys, similar to parquet, were called tessers. These are the most ancient parts of the planet’s surface; their age is estimated at 1 billion years. And large depressions (depressions) of an oval shape with a raised central part, surrounded by ramparts, are called crowns; they also do not resemble landforms found on other planets. They were formed, apparently, as a result of active flows of matter in the mantle.