Pioneer Venus mission

The Pioneer Venus mission provided the first radar imaging and altimetry of Venus surface from synthetic aperture radar on an orbiting spacecraft. Subsequently, the Venera 15 and 16 orbiters also carried out radar imaging and altimetry of part of Venus northern hemisphere. Orbital spacecraft radar observations of Venus culminated with the very successful Magellan mission in the early 1990s. 

The Pioneer Venus mission (1978) explored the atmosphere of Venus. One of the payloads was a GC system equipped with two gas columns and a TCD detector. Tlie system was used to analyze samples of the atmosphere during the probe s descent to determine the composition of Venus lower atmosphere. From these measurements, deductions were made of the gaseous sources of infrared opacity, the degree of differentiation of Venus interior, the degree of similarity between the solid bodies of Earth and Venus, and the evolution of Venus atmosphere to determine the composition atmospheric composition measurements [50]. 

At present the 7-ray detectors in operation are those aboard the Solar Maximum Mission (SMM) and Pioneer Venus Orbiter (PVO). We estimate the typical detection limit of the counter of SMM to be 0.1 2 2... 

In the early 1970s, Earth-based measurements of the polarization and refractive index of the cloud particles led to their identification as droplets of concentrated (—75% by mass) sulfuric acid (Esposito et al., 1983). Several years later. Barker (1979) discovered SO2 at Venus cloud tops. Almost simultaneously, instmments on the Pioneer Venus and Venera 11-12 missions also observed SO2. 

Venus. Venus is characterized only by the immensely valuable but still incomplete and relatively imprecise reconnaissance data from the Pioneer Venus and Venera spacecraft missions of the late 1970s. Additional in situ measurements, at precisions within the capabilities of current spacecraft instrumentation, are now necessary to refine atmospheric evolution models. Unfortunately, the possibilities of documenting the volatile inventories of the interior of the planet are more remote. A significant question that must be addressed is whether nonradiogenic xenon on Venus is compositionally closer to SW-Xe (as seen on Mars) or to the U-Xe that is seen on the Earth and so is expected to have been present within the inner solar system. Also, the extent of xenon fractionation will be an important parameter for hydrodynamic escape models if intense solar EUV radiation drove hydrodynamic escape on the Earth, it would also impact Venus, while losses from the Earth driven by a giant impact would not be recorded there. 

The United States has launched nine spacecraft in the direction of Venus. Three of these were part of the Mariner series (2, 5, and 10) and two were part of the Pioneer Venus program in 1978. Two more were part of the Vega series, in which balloons were dropped into the planet s atmosphere. Another was the Magellan spacecraft of 1989-90, and the last one was part of the Galileo mission of the same period. 

Other applications of inorganic mass spectrometry in planetary sciences were reviewed by de Laeter, including the analysis of the planets Mars (Viking spacecraft mission), Venus (Pioneer mission) and Jupiter (Galileo mission), where small molecules were discovered on the planets, and extraterrestrial materials from comets, Moon and meteorites.32... 

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