Vega missions

Other books of interest include Lewis and Prinn (1984), which emphasizes the use of observational data for understanding the origin, evolution, and present-day chemistry of planetary atmospheres. Krasnopolsky (1986) focuses on chemistry of the atmospheres of Mars and Venus. He also reviews the atmospheric composition, thermal structure, and cloud measurements by the Soviet Venera and Vega missions. Chamberlain and Hunten (1987) is the classic... 

Figure 16 Histograms of Fe/(Fe + Mg) for micron-sized Halley particles. Data from the PUMA mass spectrometer flown to Halley on the Soviet VEGA missions (source Lawler et al., 1989).

Holmes, B. J. D. K. Morris K. Razak "Data and analysis procedures for Improved aerial applications mission performance." Paper No. AA 79-001, Natl. Agricultural Aviation Meeting Las Vegas, NV, 1979. Am. Soc. Agri. 

Although information on the chemical composition and reactivity of interstellar ices can be obtained only from remote observations and laboratory simulations, cometary ices and dusts are subject to direct studies, eg within Vega and Giotto (comet Halley), Stardust (comet Wild 2) and Rosetta (comet Churyumov-Gerasimenko) missions (Figure 8.12). 

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. 

The most complete and reliable data about the chemical composition of the Venusian surface comes from three Soviet missions, the Venera 13, Venera 14, and Vega 2 probes. These spacecraft actually reached the planet s surface and conducted studies of elements and compounds present on the planet s surface. In atypical experiment, one of the lander s tools would drill a hole into the planet s surface about 1.2 inches (3 cm) deep and extract a sample about 1 cm3 in volume. The chart on page 110 summarizes data obtained from these three missions and gives the composition of Earth s continental crust for purposes of comparison. Notice that the major differences in crustal composition between the two planets appears to be in the relative abundance of Si02 (45.6 percent on Venus compared with 60.2 percent on Earth) and of MgO (about 11.5 percent on Venus compared with 3.1 percent on Earth). Otherwise, the two planets do indeed appear to be almost "sister planets," at least with regard to the composition of their outer crusts. 

Nearly all assured knowledge about the composition of comets comes from three sources (1) data collected from Comet Halley by the Soviet Union s two Vega spacecraft and the ESA s Giotto mission,... 

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