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One classical thermal escape mechanism is Jeans escape, [1] named after British astronomer Sir James Jeans, who first described this process of atmospheric loss. [2] In a quantity of gas, the average velocity of any one molecule is measured by the gas's temperature, but the velocities of individual molecules change as they collide with one another, gaining and losing kinetic energy.
If there is a strong thermally driven atmospheric escape of light atoms, heavier atoms can achieve the escape velocity through viscous drag by those escaping lighter atoms. [2] This is another way of thermal escape, called hydrodynamic escape. The heaviest species of atom that can be removed in this manner is called the cross-over mass. [3]
CubeSat UV Experiment (CUVE) is a space mission concept to study the atmospheric processes of the planet Venus with a small satellite. Specifically, the orbiter mission would study an enigmatic ultraviolet light absorber of unknown composition situated within the planet's uppermost cloud layer that absorbs about half the solar radiation downwelling in the planet's atmosphere.
In most situations it is impractical to achieve escape velocity almost instantly, because of the acceleration implied, and also because if there is an atmosphere, the hypersonic speeds involved (on Earth a speed of 11.2 km/s, or 40,320 km/h) would cause most objects to burn up due to aerodynamic heating or be torn apart by atmospheric drag. For ...
Atmosphere of Venus in UV, by Pioneer Venus Orbiter in 1979. Venus' atmosphere is mostly composed of carbon dioxide. It contains minor amounts of nitrogen and other trace elements, including compounds based on hydrogen, nitrogen, sulphur, carbon, and oxygen. The atmosphere of Venus is much hotter and denser than that of Earth, though shallower.
Venus Express was a mission by the European Space Agency to study the atmosphere and surface characteristics of Venus from orbit. The design was based on ESA's Mars Express and Rosetta missions. The probe's main objective was the long-term observation of the Venusian atmosphere, which it is hoped will also contribute to an understanding of ...
The escape of any atmospheric gas can be diffusion-limited, but only diffusion-limited escape of hydrogen has been observed in our solar system, on Earth, Mars, Venus and Titan. [1] Diffusion-limited hydrogen escape was likely important for the rise of oxygen in Earth's atmosphere ( the Great Oxidation Event ) and can be used to estimate the ...
The hydrogen can then escape from the atmosphere while the oxygen recombines or bonds to iron on the planet's surface. [2] The deficit of water on Venus due to the runaway greenhouse effect is thought to explain why Venus does not exhibit surface features consistent with plate tectonics, [ 25 ] meaning it would be a stagnant lid planet.