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The propulsion system for the descent stage of the lunar module was designed to transfer the vehicle, containing two crewmen, from a 60-nautical-mile (110 km) circular lunar parking orbit to an elliptical descent orbit with a pericynthion of 50,000 feet (15,000 m), then provide a powered descent to the lunar surface, with hover time above the lunar surface to select the exact landing site.
The shortest-lived heavy helium isotope is the unbound helium-10 with a half-life of 2.6(4) × 10 −22 s. [7] Helium-6 decays by emitting a beta particle and has a half-life of 0.8 second. Helium-7 and helium-8 are created in certain nuclear reactions. [30] Helium-6 and helium-8 are known to exhibit a nuclear halo. [30]
Each atom of helium-4 is a boson particle, by virtue of its integer spin. A helium-3 atom is a fermion particle; it can form bosons only by pairing with another particle like itself, which occurs at much lower temperatures. The discovery of superfluidity in helium-3 was the basis for the award of the 1996 Nobel Prize in Physics. [1]
Aestus is a hypergolic liquid rocket engine used on an upper stage of Ariane 5 family rockets for the orbital insertion.It features unique design of 132 coaxial injection elements causing swirl mixing of the MMH propellants with nitrogen tetroxide oxidizer.
Gas tungsten arc welding (GTAW, also known as tungsten inert gas welding or TIG, and heliarc welding when helium is used) is an arc welding process that uses a non-consumable tungsten electrode to produce the weld. The weld area and electrode are protected from oxidation or other atmospheric contamination by an inert shielding gas (argon or ...
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Buckingham proposed this as a simplification of the Lennard-Jones potential, in a theoretical study of the equation of state for gaseous helium, neon and argon. [1] As explained in Buckingham's original paper and, e.g., in section 2.2.5 of Jensen's text, [2] the repulsion is due to the interpenetration of the closed electron shells.
Airlander 10 in Hangar One at Cardington Airfield, January 2016. The HAV 304 / Airlander 10 is a hybrid airship, achieving lift, and thereby flight, via both aerostatic and aerodynamic forces. Unlike most airship designs, it does not have a circular cross-section, having adopted an elliptical shape with a contoured and flattened hull.