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"How a rotating and non-rotating skyhook would appear in orbit A skyhook is a proposed momentum exchange tether that aims to reduce the cost of placing payloads into low Earth orbit. A heavy orbiting station is connected to a cable which extends down towards the upper atmosphere. Payloads, which are much lighter than the station, are hooked to the end of the cable as it passes, and are then flung into orbit by rotation of the cable around the centre of mass. The station can then be reboosted to its original altitude by electromagnetic propulsion, rocket propulsion, or by deorbiting another object with the same kinetic energy as transferred to the payload. A skyhook differs from a geostationary orbit space elevator in that a skyhook would be much shorter and would not come in contact with the surface of the Earth. A skyhook would require a suborbital launch vehicle to reach its lower end, while a space elevator would not. History Different synchronous non-rotating orbiting skyhook concepts and versions have been proposed, starting with Isaacs in 1966,See also: letter in Science 152:800, May 6, 1966. Artsutanov in 1967,Artsutanov, Y. V Kosmos na Elektrovoze (Into Space by Funicular Railway). Komsomolskaya Pravda (Young Communist Pravda), July 31, 1960. Contents described in Lvov, Science 158:946, November 17, 1967.Arsutanov, Y. V Kosmos Bez Raket (Into Space Without Rockets). Znanije-Sile (Knowledge is Power) 1969(7):25, July, 1969. Pearson and Colombo in 1975,Colombo, G., Gaposchkin, E. M., Grossi, M. D., and Weiffenbach, G. C., "The 'Skyhook': A Shuttle-Borne Tool for Low Orbital Altitude Research," Meccanica, Vol. 10, No. 1, Mar. 1975. Kalaghan in 1978,Kalaghan, P., Arnold, D. A., Colombo, G., Grossi, M., Kirschner, L. R., and Orringer, O., "Study of the Dynamics of a Tethered Satellite System (Skyhook)," NASA Contract NAS8-32199, SAO Final Report, Mar. 1978. and Braginski in 1985.V.B. Braginski and K.S. Thorne, "Skyhook Gravitational Wave Detector," Moscow State University, Moscow, USSR, and Caltech, 1985. The versions with best potential involve a much shorter tether in low Earth orbit which rotates in its orbital plane and whose ends brush the upper Earth atmosphere, with the rotational motion cancelling the orbital motion at ground level. These "rotating" skyhook versions were proposed by Moravec in 1976, Presented at 23rd AIAA Meeting, The Industrialization of Space, San Francisco, CA,. October 18–20, 1977. and Sarmont in 1994. When the Italian scientist Giuseppe Colombo proposed in the early 1970s the idea of using a tidally stabilized tether for downward-looking Earth observation satellites, NASA officially began to assess in 1979 the possible scientific applications for long tethers in space and whether the development of a tethered system was justified. This resulted in a Shuttle-based tether system: the TSS-1R mission, launched 22 February 1996 on STS-75 that focused in characterizing basic space tether behavior and space plasma physics. The Italian satellite was deployed to a distance of from the Space Shuttle. An engineer speculated in 1994 that the skyhook could be cost competitive with what is realistically thought to be achievable using a space elevator. In 2000 and 2001, Boeing Phantom Works, with a grant from NASA Institute for Advanced Concepts, performed a detailed study of the engineering and commercial feasibility of various skyhook designs. They studied in detail a specific variant of this concept, called "Hypersonic Airplane Space Tether Orbital Launch System" or HASTOL. This design called for a hypersonic ramjet or scramjet aircraft to intercept a rotating hook while flying at Mach 10. While no skyhook has yet been built, there have been a number of flight experiments exploring various aspects of the space tether concept in general. Types of skyhooks=Non-rotating skyhook= 200 km long non-rotating skyhook, as proposed by E. Sarmont in 1990 A non-rotating skyhook is a vertical gravity- gradient stabilized tether whose lower endpoint appears to hang from the sky. It was this appearance that led to the adoption of the name skyhook for the construct. =Rotating skyhook= The rotating concept. If the orbital velocity and the tether rotation rate are synchronized, the tether tip moves in a cycloid curve. At the lowest point it is momentarily stationary with respect to the ground, where it can 'hook' a payload and swing it into orbit. By rotating the tether around the orbiting center of mass in a direction opposite to the orbital motion, the speed of the hook relative to the ground can be reduced. This reduces the required strength of the tether, and makes coupling easier. The rotation of the tether can be made to exactly match the orbital speed (around 7–8 km/s). In this configuration, the hook would trace out a path similar to a cardioid. From the point of view of the ground, the hook would appear to descend almost vertically, come to a halt, and then ascend again. This configuration minimises aerodynamic drag, and thus allows the hook to descend deep into the atmosphere. However, according to the HASTOL study, a skyhook of this kind in Earth orbit would require a very large counterweight, on the order of 1000–2000 times the mass of the payload, and the tether would need to be mechanically reeled in after collecting each payload in order to maintain synchronization between the tether rotation and its orbit. Phase I of Boeing's Hypersonic Airplane Space Tether Orbital Launch (HASTOL) study, published in 2000, proposed a 600 km-long tether, in an equatorial orbit at 610–700 km altitude, rotating with a tip speed of 3.5 km/s. This would give the tip a ground speed of 3.6 km/s (Mach 10), which would be matched by a hypersonic airplane carrying the payload module, with transfer at an altitude of 100 km. The tether would be made of existing commercially available materials: mostly Spectra 2000 (a kind of ultra-high- molecular-weight polyethylene), except for the outer 20 km which would be made of heat-resistant Zylon PBO. With a nominal payload mass of 14 tonnes, the Spectra/Zylon tether would weigh 1300 tonnes, or 90 times the mass of the payload. The authors stated: > The primary message we want to leave with the Reader is: "We don't need > magic materials like 'Buckminster-Fuller-carbon-nanotubes' to make the space > tether facility for a HASTOL system. Existing materials will do." The second phase of the HASTOL study, published in 2001, proposed increasing the intercept airspeed to Mach 15–17, and increasing the intercept altitude to 150 km, which would reduce the necessary tether mass by a factor of three. The higher speed would be achieved by using a reusable rocket stage instead of a purely air-breathing aircraft. The study concluded that although there are no "fundamental technical show-stoppers", substantial improvement in technology would be needed. In particular, there was concern that a bare Spectra 2000 tether would be rapidly eroded by atomic oxygen; this component was given a technology readiness level of 2. See also *Mass driver *Orbital ring *Railgun *Space elevator *Space tether missions ReferencesExternal links * Megastructures Space elevator Spacecraft propulsion Vertical transport devices "
"Potassium cyanide is a compound with the formula KCN. This colorless crystalline salt, similar in appearance to sugar, is highly soluble in water. Most KCN is used in gold mining, organic synthesis, and electroplating. Smaller applications include jewellery for chemical gilding and buffing.Andreas Rubo, Raf Kellens, Jay Reddy, Joshua Wooten, Wolfgang Hasenpusch "Alkali Metal Cyanides" in Ullmann's Encyclopedia of Industrial Chemistry 2006 Wiley-VCH, Weinheim, Germany. Potassium cyanide is highly toxic. The moist solid emits small amounts of hydrogen cyanide due to hydrolysis, which smells like bitter almonds. Not everyone, however, can smell this; the ability to do so is a genetic trait. The taste of potassium cyanide has been described as acrid and bitter, with a burning sensation similar to lye. Production KCN is produced by treating hydrogen cyanide with an aqueous solution of potassium hydroxide, followed by evaporation of the solution in a vacuum:Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw- Hill, 2002, :HCN + KOH → KCN + H2O About 50,000 tons of potassium cyanide are produced yearly. =Historical production= Before 1900 and the invention of the Castner process, potassium cyanide was the most important source of alkali metal cyanides. In this historical process, potassium cyanide was produced by decomposing potassium ferrocyanide: K4[Fe(CN)6] → 4 KCN + FeC2 \+ N2 Structure In aqueous solution, KCN is dissociated into hydrated potassium (K+) ions and cyanide (CN−) ions. The common form of solid KCN, stable at ambient pressure and temperature, has the same cubic crystal structure as sodium chloride, with each potassium ion surrounded by six cyanide ions, and vice versa. Despite the cyanide ions being diatomic, and thus less symmetric than chloride, they rotate so rapidly, their time-averaged shape is spherical. At low temperature and high pressure, this free rotation is hindered, resulting in a less symmetric crystal structure with the cyanide ions arranged in sheets. Crystallography Open Database, Structure of KCN. Applications KCN and sodium cyanide (NaCN) are widely used in organic synthesis for the preparation of nitriles and carboxylic acids, particularly in the von Richter reaction. It also finds use for the synthesis of hydantoins, which can be useful synthetic intermediates, when reacted with a carbonyl compound such as an aldehyde or ketone in the presence of ammonium carbonate. KCN is used as a photographic fixer in the wet plate collodion process.J. Towler, MD. "The Silver Sunbeam (Facsimile 1864 edition, 1969)" pg 119 The KCN dissolves silver where it has not been made insoluble by the developer. This reveals and stabilizes the image, making it no longer sensitive to light. Modern wet plate photographers may prefer less toxic fixers, often opting for the less toxic sodium thiosulfate, but KCN is still used. It was extensively used by high ranking Nazi officials to commit suicide in the last days of World War II. =Potassium gold cyanide= In gold mining, KCN forms the water-soluble salt potassium gold cyanide (or gold potassium cyanide) and potassium hydroxide from gold metal in the presence of oxygen (usually from the surrounding air) and water: :4 Au + 8 KCN + O2 \+ 2 H2O → 4 K[Au(CN)2] + 4 KOH A similar process uses NaCN to produce sodium gold cyanide (NaAu(CN2)). Toxicity Potassium cyanide is a potent inhibitor of cellular respiration, acting on mitochondrial cytochrome c oxidase, hence blocking oxidative phosphorylation. Lactic acidosis then occurs as a consequence of anaerobic metabolism. Initially, acute cyanide poisoning causes a red or ruddy complexion in the victim because the tissues are not able to use the oxygen in the blood. The effects of potassium cyanide and sodium cyanide are identical, and symptoms of poisoning typically occur within a few minutes of ingesting the substance: the person loses consciousness, and brain death eventually follows. During this period the victim may suffer convulsions. Death is caused by cerebral hypoxia. The expected LD100 dose (human) for potassium cyanide is 200–300 mg while LD50 is estimated at 140 mg.John Harris Trestrail III. Criminal Poisoning - Investigational Guide for Law Enforcement, Toxicologists, Forensic Scientists, and Attorneys (2nd edition). p. 119 A number of prominent persons were killed or committed suicide using potassium cyanide, including members of the Young Bosnia and infamous personalities in Nazi Germany, such as Erwin Rommel, Hitler's longtime companion Eva Braun, Joseph Goebbels, Heinrich Himmler, and Hermann Göring. It was also used by World War II–era British agents (as purpose-made suicide pills), computer scientist Alan Turing, polymer chemist Wallace Carothers, and 19th-century German chemist Viktor Meyer, and in various religious cult suicides such as by the Peoples Temple, Danish writer Gustav Wied in 1914, members of the LTTE involved in the assassination of Indian prime minister Rajiv Gandhi, Bengal's first woman martyr Pritilata Waddedar, Jason Altom, who was a promising graduate student in the lab of Nobel Prize–winning chemist EJ Corey at Harvard, and John B. Mclemore, an Alabamian man whose life and suicide were the subject of the popular podcast "S-town". Slobodan Praljak, a wartime general in Republic of Croatia and convicted war criminal, committed suicide by drinking from a vial containing potassium cyanide during the reading of his sentence in The Hague on International Criminal Tribunal for the former Yugoslavia (ICTY) on 29 November 2017. It is used by professional entomologists as a killing agent in collecting jars, as insects succumb within seconds to the HCN fumes it emits, thereby minimizing damage to even highly fragile specimens. KCN can be detoxified most efficiently with hydrogen peroxide or with a solution of sodium hypochlorite. Such solutions should be kept alkaline whenever possible so as to eliminate the possibility of generation of hydrogen cyanide: : KCN + H2O2 → KOCN + H2O ReferencesExternal links * International Chemical Safety Card 0671 * Hydrogen cyanide and cyanides (CICAD 61) * National Pollutant Inventory - Cyanide compounds fact sheet * NIOSH Pocket Guide to Chemical Hazards * CSST (Canada) * NIST Standard Reference Database * Institut national de recherche et de sécurité (1997). "Cyanure de sodium. Cyanure de potassium". Fiche toxicologique n° 111, Paris:INRS, 6pp. Cyanides Photographic chemicals Potassium compounds "
"3318 Blixen, provisionally designated , is a stony Eoan asteroid from the outer region of the asteroid belt, approximately 23 kilometers in diameter. It was discovered by Danish astronomers Poul Jensen and Karl Augustesen at Brorfelde Observatory on 23 April 1985. Blixen is a member of the Eos family (), the largest asteroid family in the outer main belt consisting of nearly 10,000 asteroids. It orbits the Sun at a distance of 2.9–3.2 AU once every 5 years and 3 months (1,905 days). Its orbit has an eccentricity of 0.05 and an inclination of 12° with respect to the ecliptic. Photometric observations of this asteroid collected during 2006 show a rotation period of 6.456 ± 0.003 hours with a brightness variation of 0.20 ± 0.02 magnitude. This minor planet was named after Danish novelist Karen Blixen (1885–1962), best known for the memoir Out of Africa. The approved naming citation was published by the Minor Planet Center on 18 September 1986 (). References External links * Lightcurve plot of 3318 Blixen, Palmer Divide Observatory, B. D. Warner (2006) * Asteroid Lightcurve Database (LCDB), query form (info) * Dictionary of Minor Planet Names, Google books * Asteroids and comets rotation curves, CdR – Observatoire de Genève, Raoul Behrend * Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center Eos asteroids Blixen Blixen Blixen Blixen Karen Blixen 19850423 "