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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.
Escape speed at a distance d from the center of a spherically symmetric primary body (such as a star or a planet) with mass M is given by the formula [2] [3] = = where: G is the universal gravitational constant (G ≈ 6.67 × 10 −11 m 3 ⋅kg −1 ⋅s −2 [4])
Air-launched hypersonic scramjet; fastest free-flying air-breathing vehicle [73] 22 April 2010: Uncrewed: 13,201: 21,245: HTV-2 Falcon: Air-launched hypersonic glider; fastest uncrewed aerial vehicle [74] 14 November 1981: Joe H. Engle: 17,500: 28,000: Space Shuttle Columbia: Fastest manually controlled flight in atmosphere during atmospheric ...
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]
Terminal velocity is the maximum speed attainable by an object as it falls through a fluid (air is the most common example). It is reached when the sum of the drag force ( F d ) and the buoyancy is equal to the downward force of gravity ( F G ) acting on the object.
Atmospheric entry speed of the Galileo atmospheric probe—Fastest controlled atmospheric entry for a human-made object. 66,000: 240,000: 150,000 0.00022: Lower speed bound of the steel plate cap from the Pascal-B nuclear test of Operation Plumbbob. [26] [circular reference] 70,220: 252,800: 157,100 0.00023: Speed of the Helios 2 solar probe ...
Fastest non-tornadic winds: 408 km/h (254 mph) (3-second gust); recorded by anemometer in Severe Tropical Cyclone Olivia passing over Barrow Island, Western Australia, 10 April 1996. [ 315 ] [ 316 ] Fastest non- cyclonic winds: 372 km/h (231 mph) (1-minute average); recorded by anemometer on Mount Washington , New Hampshire , USA, 12 April 1934.
Rather than air, the solar wind is a stream of charged particles—a plasma—ejected from the upper atmosphere of the Sun at a rate of 400 kilometers per second (890,000 mph). [154] It consists mostly of electrons and protons with energies of about 1 keV .