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Chao Meng-Fu (crater)
Chao Meng-Fu is a diameter crater on Mercury named after the Chinese painter and calligrapher Zhao Mengfu (1254–1322). Due to its location near Mercury's south pole (132.4° west, 87.3° south) and the planet's small axial tilt, an estimated 40% of the crater lies in permanent shadow. This combined with bright radar echoes from the location of the crater leads scientists to suspect that it may shelter large quantities of ice protected against sublimation into the near-vacuum by the constant temperatures. Radar evidence for ice Radar studies involving Arecibo (Puerto Rico), Goldstone (California, United States), and the Very Large Array (New Mexico, United States) detected a number of highly-radar-reflective depolarized areas on Mercury, including several locations at the planet's poles. Many of these reflective features appear to coincide with craters imaged by ''Mariner 10'', with the largest feature at the south pole corresponding to Chao Meng-Fu crater. The luminos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MESSENGER
''MESSENGER'' was a NASA robotic space probe that orbited the planet Mercury between 2011 and 2015, studying Mercury's chemical composition, geology, and magnetic field. The name is a backronym for "Mercury Surface, Space Environment, Geochemistry, and Ranging", and a reference to the messenger god Mercury from Roman mythology. ''MESSENGER'' was launched aboard a Delta II rocket in August 2004. Its path involved a complex series of flybys – the spacecraft flew by Earth once, Venus twice, and Mercury itself three times, allowing it to decelerate relative to Mercury using minimal fuel. During its first flyby of Mercury in January 2008, ''MESSENGER'' became the second mission, after Mariner 10 in 1975, to reach Mercury. ''MESSENGER'' entered orbit around Mercury on March 18, 2011, becoming the first spacecraft to do so. It successfully completed its primary mission in 2012. Following two mission extensions, the spacecraft used the last of its maneuvering propellant to deo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geographical Pole
A geographical pole or geographic pole is either of the two points on Earth where its axis of rotation intersects its surface. The North Pole lies in the Arctic Ocean while the South Pole is in Antarctica. North and South poles are also defined for other planets or satellites in the Solar System, with a North pole being on the same side of the invariable plane as Earth's North pole. Relative to Earth's surface, the geographic poles move by a few metres over periods of a few years. This is a combination of Chandler wobble, a free oscillation with a period of about 433 days; an annual motion responding to seasonal movements of air and water masses; and an irregular drift towards the 80th west meridian. As cartography requires exact and unchanging coordinates, the averaged locations of geographical poles are taken as fixed ''cartographic poles'' and become the points where the body's great circles of longitude intersect. See also * Earth's rotation * Polar motion * Poles of as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Analog Science Fiction And Fact
''Analog Science Fiction and Fact'' is an American science fiction magazine published under various titles since 1930. Originally titled ''Astounding Stories of Super-Science'', the first issue was dated January 1930, published by William Clayton, and edited by Harry Bates. Clayton went bankrupt in 1933 and the magazine was sold to Street & Smith. The new editor was F. Orlin Tremaine, who soon made ''Astounding'' the leading magazine in the nascent pulp science fiction field, publishing well-regarded stories such as Jack Williamson's '' Legion of Space'' and John W. Campbell's "Twilight". At the end of 1937, Campbell took over editorial duties under Tremaine's supervision, and the following year Tremaine was let go, giving Campbell more independence. Over the next few years Campbell published many stories that became classics in the field, including Isaac Asimov's ''Foundation'' series, A. E. van Vogt's ''Slan'', and several novels and stories by Robert A. Heinle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vacuum Diagrams
''Vacuum Diagrams'' is a collection of science fiction short stories by British writer Stephen Baxter. The collection connects the novels of the Xeelee Sequence and also shows the history of mankind in the Xeelee universe, and ultimately the universe. While each short story in the collection is self-contained, the stories are presented as being contained in the context of the first story, "Eve", about a man (seemingly Jack Raoul from the portion of the timeline concerned with the Silver Ghosts) who is forced to witness the events in the short stories by a god-like being. "Eve" acts as a structure for the short stories, with an introduction at the beginning of ''Vacuum Diagrams'', short scenes occurring between each "era" (with "Eve" character explaining and introducing the next section), and an ending that wraps up the plot for the "Eve" story itself. ''Vacuum Diagrams'' won the Philip K. Dick Award in 1999. At the end of the collection, a chronology of the Xeelee Sequence is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asimov's Science Fiction
''Asimov's Science Fiction'' is an American science fiction magazine which publishes science fiction and fantasy named after science fiction author Isaac Asimov. It is currently published by Penny Publications. From January 2017, the publication frequency is bimonthly (six issues per year). Circulation in 2012 was 22,593, as reported in the annual ''Locus Magazine survey. History ''Asimov's Science Fiction'' began life as the digest-sized ''Isaac Asimov's Science Fiction Magazine'' (or ''IASFM'' for short) in 1977. Joel Davis of Davis Publications approached Asimov to lend his name to a new science fiction magazine, after the fashion of ''Ellery Queen's Mystery Magazine'' or ''Alfred Hitchcock's Mystery Magazine''. Asimov refused to act as editor, but served instead as editorial director, writing editorials and replying to reader mail until his death in 1992. At Asimov's request George Scithers, the first editor, negotiated an acquisitions contract with the Science Fiction Writ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stephen Baxter (author)
Stephen Baxter (born 13 November 1957) is an English hard science fiction author. He has degrees in mathematics and engineering. Writing style Strongly influenced by SF pioneer H. G. Wells, Baxter has been Vice-President of the international H. G. Wells Society since 2006. His fiction falls into three main categories of original work plus a fourth category, extending other authors' writing; each has a different basis, style, and tone. Baxter's "Future History" mode is based on research into hard science. It encompasses the Xeelee Sequence, which consists of nine novels (including the ''Destiny's Children'' trilogy and Vengeance/Redemption duology that is set in alternate timeline), plus three volumes collecting the 52 short pieces (short stories and novellas) in the series, all of which fit into a single timeline stretching from the Big Bang singularity of the past to his ''Timelike Infinity'' singularity of the future. These stories begin in the present day and end when th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Wind
The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona. This plasma mostly consists of electrons, protons and alpha particles with kinetic energy between . The composition of the solar wind plasma also includes a mixture of materials found in the solar plasma: trace amounts of heavy ions and atomic nuclei such as C, N, O, Ne, Mg, Si, S, and Fe. There are also rarer traces of some other nuclei and isotopes such as P, Ti, Cr, 54Fe and 56Fe, and 58Ni, 60Ni, and 62Ni. Superposed with the solar-wind plasma is the interplanetary magnetic field. The solar wind varies in density, temperature and speed over time and over solar latitude and longitude. Its particles can escape the Sun's gravity because of their high energy resulting from the high temperature of the corona, which in turn is a result of the coronal magnetic field. The boundary separating the corona from the solar wind is called the Alfvén surface. At a distance of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Outgassing
Outgassing (sometimes called offgassing, particularly when in reference to indoor air quality) is the release of a gas that was dissolved, trapped, frozen, or absorbed in some material. Outgassing can include sublimation and evaporation (which are phase transitions of a substance into a gas), as well as desorption, seepage from cracks or internal volumes, and gaseous products of slow chemical reactions. Boiling is generally thought of as a separate phenomenon from outgassing because it consists of a phase transition of a liquid into a vapor of the same substance. In a vacuum Outgassing is a challenge to creating and maintaining clean high-vacuum environments. NASA and ESA maintain lists of materials with low-outgassing properties suitable for use in spacecraft, as outgassing products can condense onto optical elements, thermal radiators, or solar cells and obscure them. Materials not normally considered absorbent can release enough lightweight molecules to interfere with industr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comets
A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena are due to the effects of solar radiation and the solar wind acting upon the nucleus of the comet. Comet nuclei range from a few hundred meters to tens of kilometers across and are composed of loose collections of ice, dust, and small rocky particles. The coma may be up to 15 times Earth's diameter, while the tail may stretch beyond one astronomical unit. If sufficiently bright, a comet may be seen from Earth without the aid of a telescope and may subtend an arc of 30° (60 Moons) across the sky. Comets have been observed and recorded since ancient times by many cultures and religions. Comets usually have highly eccentric elliptical orbits, and they have a wide range of orbital periods, ranging from several years to potentially several milli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meteorites
A meteorite is a solid piece of debris from an object, such as a comet, asteroid, or meteoroid, that originates in outer space and survives its passage through the atmosphere to reach the surface of a planet or moon. When the original object enters the atmosphere, various factors such as friction, pressure, and chemical interactions with the atmospheric gases cause it to heat up and radiate energy. It then becomes a meteor and forms a fireball, also known as a shooting star; astronomers call the brightest examples " bolides". Once it settles on the larger body's surface, the meteor becomes a meteorite. Meteorites vary greatly in size. For geologists, a bolide is a meteorite large enough to create an impact crater. Meteorites that are recovered after being observed as they transit the atmosphere and impact the Earth are called meteorite falls. All others are known as meteorite finds. Meteorites have traditionally been divided into three broad categories: stony meteorites that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding the National Advisory Committee for Aeronautics (NACA), to give the U.S. space development effort a distinctly civilian orientation, emphasizing peaceful applications in space science. NASA has since led most American space exploration, including Project Mercury, Project Gemini, the 1968-1972 Apollo Moon landing missions, the Skylab space station, and the Space Shuttle. NASA supports the International Space Station and oversees the development of the Orion spacecraft and the Space Launch System for the crewed lunar Artemis program, Commercial Crew spacecraft, and the planned Lunar Gateway space station. The agency is also responsible for the Launch Services Program, which provides oversight of launch operations and countdown management f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metal
A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typically ductile (can be drawn into wires) and malleable (they can be hammered into thin sheets). These properties are the result of the ''metallic bond'' between the atoms or molecules of the metal. A metal may be a chemical element such as iron; an alloy such as stainless steel; or a molecular compound such as polymeric sulfur nitride. In physics, a metal is generally regarded as any substance capable of conducting electricity at a temperature of absolute zero. Many elements and compounds that are not normally classified as metals become metallic under high pressures. For example, the nonmetal iodine gradually becomes a metal at a pressure of between 40 and 170 thousand times atmospheric pressure. Equally, some materials regarded as metals ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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