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Venera 3 to 6 edit
Main articles: Venera 3, Venera 4, Venera 5, and Venera 6
Venera station liquid based engine.
The Venera 3 to 6 probes were similar. Weighing approximately one ton, and launched by the Molniya-type booster rocket, they included a cruise "bus" and a spherical atmospheric entry probe. The probes were optimised for atmospheric measurements, but not equipped with any special landing apparatus. Although it was hoped they would reach the surface still functioning, the first probes failed almost immediately, thereby disabling data transmission to Earth.
Venera 3 became the first human-made object to impact another planet's surface as it crash-landed on 1 March 1966. However, as the spacecraft's data probes had failed upon atmospheric penetration, no data from within the Venusian atmosphere were retrieved from the mission.
On 18 October 1967, Venera 4 became the first spacecraft to measure the atmosphere of another planet. This spacecraft first showed that the major gas of Venus' atmosphere to be CO2[1][2]. While the Soviet Union initially claimed the craft reached the surface intact, re-analysis, including atmospheric occultation data from the American Mariner 5 spacecraft that flew by Venus the day after its arrival, demonstrated that Venus's surface pressure was 75–100 atmospheres, much higher than Venera 4's 25 atm hull strength, and the claim was retracted.
Realizing the ships would be crushed before reaching the surface, the Soviets launched Venera 5 and Venera 6 as atmospheric probes. Designed to jettison nearly half their payload prior to entering the planet's atmosphere, these craft recorded 53 and 51 minutes of data, respectively, while slowly descending by parachute before their batteries failed.
Venera 7 edit
Main article: Venera 7
The Venera 7 probe, launched in August 1970, was the first one designed to survive Venus's surface conditions and to make a soft landing. Massively overbuilt to ensure survival, it had few experiments on board, and scientific output from the mission was further limited due to an internal switchboard failure that stuck in the "transmit temperature" position. Still, the control scientists succeeded in extrapolating the pressure (90 atm) from the temperature data with 465 °C (869 °F), which resulted from the first direct surface measurements. The Doppler measurements of the Venera 4 to 7 probes were the first evidence of the existence of high-speed zonal winds (up to 100 metres per second (330 ft/s) or 362 kilometres per hour (225 mph)) in the Venusian atmosphere (super rotation). Along with the pressure and temperature data acquired Venera 7 also measured atmospheric composition[3][1].
Venera 7's parachute failed shortly before landing very close to the surface. It impacted at 17 metres per second (56 ft/s) and toppled over, but survived. Due to the resultant antenna misalignment, the radio signal was very weak but was detected (with temperature telemetry) for 23 more minutes before its batteries expired. Thus, it became, on 15 December 1970, the first human-made probe to transmit data from the surface of Venus.
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Scientific findings edit
There were many scientific findings about Venus from the data retrieved by the Venera probes making them pivotal in our understanding of Venus. The Venera probes provided direct data regarding Venus' surface and atmosphere. Venera 4 was the first successful probe and showed that CO2 is the main component in Venus' atmosphere[2][1]. Venera 7 found the temperature and pressure data as well as the atmospheric composition[1][3]. Venera 8 measured the K, U, Th on the surface through gamma-ray analysis[1]. Venera 9 provided the first images of the surface of Venus as well as more gamma-ray analysis[4]. By sending the first images of Venus' surface back to Earth the Venera missions provided scientists with the ability to relay the achievements with the public. Venera 13 provided the first color images and X-ray flourescence data of the surface of the planet. After analyzing the radar images returned from Venera 15 and 16, it was concluded that the ridges and grooves on the surface of Venus were the result of tectonic deformations. This was found by radar imaging while in orbit. Even with their short lifetimes, the Venera missions each added significant understanding of our sister planet.
References edit
- ^ a b c d e Fegley, B. (2014), "Venus", Treatise on Geochemistry, Elsevier, pp. 127–148, doi:10.1016/b978-0-08-095975-7.00122-4, ISBN 978-0-08-098300-4, retrieved 2022-05-04
- ^ a b Jastrow, R. and S.I. Rasool (Eds.), 1969: . Gordon and Breach.
- ^ a b Marov, M.Ya. (1972). "Venus: A perspective at the beginning of planetary exploration". Icarus. 16 (3): 415–461. doi:10.1016/0019-1035(72)90094-2.
- ^ Hunten, Donald M.; Colin, Lawrence; Donahue, Thomas M.; Moroz, Vassily I. (2022-01-04), "PREFACE", Venus, University of Arizona Press, pp. vii–viii, retrieved 2022-05-04