mascon


mascon
/mas"kon'/, n. Geol.
a massive concentration of high-density material beneath the surface of the moon.
[1965-70; MAS(S) + CON(CENTRATION)]

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      a region of excess gravitational attraction on the surface of the Moon. The word is a contraction of mass concentration.

      Mascons were first identified by the observation of small anomalies in the orbits of Lunar Orbiter spacecraft launched in 1966–67. As the spacecraft passed over certain surface regions, the stronger gravity field caused the craft to dip slightly and speed up. Apollo space program (Apollo program) scientists used the data to correct for the observed gravity irregularities in order to improve the targeting accuracy of manned Moon landings. Later scientific study of these anomalies supported the interpretation that the Moon had a complex history of heating, differentiation (sinking of denser materials and rising of lighter ones to form a deep mantle and overlying crust), and modification by impacts and subsequent huge outflows of lava. Tracking of the velocities of the Clementine and Lunar Prospector spacecraft by their Doppler-shifted radio signals (see Doppler effect) as they orbited the Moon (1994 and 1998–99, respectively) provided detailed gravity maps, including mascon characteristics, of most of the lunar surface.

      The Moon's larger mascons coincide with circular, topographically low impact basins where particularly dense—and thus more massive and gravitationally attractive—magma upwelled from the mantle and solidified to form dark mare plains. Examples are the Imbrium, Serenitatis, Crisium, and Nectaris basins (maria), all of which are visible at full moon with the unaided eye from Earth. The survival, over the three billion years since they were formed, of these gravity anomalies testifies to the existence of a thick, rigid lunar crust. This, in turn, implies that the Moon's initial heat source is extinct. (For additional discussion of the Moon's geologic history, see Moon: Origin and evolution (Moon).)

James D. Burke
 

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Universalium. 2010.

Look at other dictionaries:

  • mascon — mascón s. n., pl. mascóni Trimis de siveco, 10.08.2004. Sursa: Dicţionar ortografic  MASCÓN s.n. Formaţie structurală a scoarţei Lunii, având o densitate mai mare decât densitatea formaţiilor înconjurătoare. [< engl. mascon]. Trimis de… …   Dicționar Român

  • mascon — ● mascon nom masculin (anglais mascon, contraction de mass concentration) Synonyme de réplétion. ● mascon (synonymes) nom masculin (anglais mascon, contraction de mass concentration) Synonymes : réplétion …   Encyclopédie Universelle

  • mascon — ☆ mascon [mas′kän΄ ] n. [mas(s) con(centration)] a local concentration of very dense material beneath the surface of the moon …   English World dictionary

  • Mascon — Se conoce como mascon a toda región de la corteza de un astro que posee una densidad de masa notoriamente superior al promedio de la corteza del astro en cuestión. Tal concentración suele provocar un casi ínfimo aunque mensurable aumento de la… …   Wikipedia Español

  • Mascon — Schwerefeldanomalien auf der erdnahen (links) und der erdfernen Seite des Mondes: rot = positive, blau = negative. Mascons sind großräumige Bereiche erhöhter Gesteinsdichte unter der Oberfläche des Mondes. Die massereichsten von ihnen liegen im… …   Deutsch Wikipedia

  • Mascon — Réplétion Cette page d’homonymie répertorie les différents sujets et articles partageant un même nom. En astronomie Cette figure permet de comparer la topogra …   Wikipédia en Français

  • mascon — noun Etymology: 2mass + concentration Date: 1968 any of the high density regions below the surface of lunar maria that are held to perturb the motion of spacecraft in lunar orbit …   New Collegiate Dictionary

  • mascon — noun A Lunar mare that has a greater density of rock than the surrounding area …   Wiktionary

  • mascon — ma·scon s.m.inv. ES ingl. {{wmetafile0}} TS astron. zona della superficie lunare, spec. di forma circolare e situata entro zone pianeggianti e non riflettenti della superficie lunare, caratterizzata da valori anormalmente alti della massa… …   Dizionario italiano

  • Mascon — Mas|con [ mæskən] das; s, s Kurzw. aus engl. mass concentration »Massenkonzentration«> Gebiet mit Schwereanomalien auf dem Mond …   Das große Fremdwörterbuch


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