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Baltis Vallis
Baltis Vallis is a sinuous channel on Venus ranging from wide and ~ long, slightly longer than the Nile and the longest known channel of any kind in the Solar System. It is thought the channel once held a river of lava. It is a single channel over most of its length, but anastomoses in several sections, for lengths of up to . There appear to be other, smaller channels in the same area, down to the limit of resolution, some of which seem to be tributaries of Baltis Vallis. The lava must have had a very low viscosity, possibly due to a carbonatite composition. At the volcano Ol Doinyo Lengai in Tanzania, natrocarbonatite lava erupts at around , not far above Venus's mean ambient temperature of . Analysis of cross-sectional profiles (using brightness data from '' Magellan'' synthetic aperture radar Synthetic-aperture radar (SAR) is a form of radar that is used to create two-dimensional images or three-dimensional reconstructions of objects, such as landscapes. SAR uses ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Icarus (journal)
''ICARUS'' is a scientific journal dedicated to the field of planetary science. It is officially endorsed by the American Astronomical Society's Division for Planetary Sciences (DPS). The journal contains articles discussing the results of new research on astronomy, geology, meteorology, physics, chemistry, biology, and other scientific aspects of the Solar System or extrasolar systems. The journal was founded in 1962, and became affiliated with the DPS in 1974. Its original owner and publisher was Academic Press, which was purchased by Elsevier in 2000. The journal is named for the mythical Icarus, and the frontispiece of every issue contains an extended quotation from Sir Arthur Eddington equating Icarus' adventurousness with the scientific investigator who "strains his theories to the breaking-point till the weak joints gape." Abstracting and indexing This journal is indexed by the following services: * Science Citation Index * Current Contents /Physical, Chemic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanism On Venus
The surface of Venus is dominated by volcanic features and has more volcanoes than any other planet in the Solar System. It has a surface that is 90% basalt, and about 65% of the planet consists of a mosaic of volcanic lava plains, indicating that volcanism played a major role in shaping its surface. There are more than 1,000 volcanic structures and possible periodic resurfacing of Venus by floods of lava. The planet may have had a major global resurfacing event about 500 million years ago, from what scientists can tell from the density of impact craters on the surface. Venus has an atmosphere rich in carbon dioxide, with a density that is 90 times that of Earth's atmosphere. Even though there are over 1,600 major volcanoes on Venus, none are known to be erupting at present and most are probably long extinct. However, radar sounding by the '' Magellan'' probe revealed evidence for comparatively recent volcanic activity at Venus's highest volcano Maat Mons, in the form of ash flows ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Venera 15 And 16
Venera 4V-2 (russian: Венера 4В-2) was a series of two identical spacecraft sent to Venus by the Soviet Union, consisting of Venera 15 and Venera 16. Both unmanned orbiters were to map the surface of Venus using high resolution imaging systems. The spacecraft were identical and based on modifications to the earlier Venera space probes. Mission profile Venera 15 was launched on June 2, 1983, at 02:38:39 UTC, and Venera 16 on June 7, 1983, at 02:32:00 UTC. Venera 15 and Venera 16 both reached Venus' orbit (on October 10, 1983, and October 14, 1983, respectively). The two spacecraft were inserted into Venus orbit a day apart with their orbital planes shifted by an angle of approximately 4° relative to one another. This made it possible to reimage an area if necessary. Each spacecraft was in a nearly polar orbit with a periapsis ~1000 km, at 62°N latitude, and apoapsis ~65000 km, with an inclination ~90°, the orbital period being ~24 hours. In June 1984, Venus was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wrinkle Ridge
A wrinkle ridge is a type of feature commonly found on lunar maria, or basalt plains. These features are low, sinuous ridges formed on the mare surface that can extend for up to several hundred kilometers. Wrinkle ridges are tectonic features created after the lava cooled and solidified. They frequently outline ring structures buried within the mare, follow circular patterns outlining the mare, or intersect protruding peaks. They are sometimes called ''veins'' due to their resemblance to the veins that protrude from beneath the skin. Wrinkle ridges are named with the Latin designation ''dorsum'' (plural ''dorsa''). The standard IAU nomenclature uses the names of people (generally scientists) to identify wrinkle ridges on the Moon. For example, the Dorsa Burnet are named for Thomas Burnet, and the Dorsum Owen is named after George Owen of Henllys. Wrinkle ridges can also be found on Mars, for example in Chryse Planitia, on several of the asteroids that have been visited by sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synthetic Aperture Radar
Synthetic-aperture radar (SAR) is a form of radar that is used to create two-dimensional images or three-dimensional reconstructions of objects, such as landscapes. SAR uses the motion of the radar antenna over a target region to provide finer spatial resolution than conventional stationary beam-scanning radars. SAR is typically mounted on a moving platform, such as an aircraft or spacecraft, and has its origins in an advanced form of side looking airborne radar (SLAR). The distance the SAR device travels over a target during the period when the target scene is illuminated creates the large ''synthetic'' antenna aperture (the ''size'' of the antenna). Typically, the larger the aperture, the higher the image resolution will be, regardless of whether the aperture is physical (a large antenna) or synthetic (a moving antenna) – this allows SAR to create high-resolution images with comparatively small physical antennas. For a fixed antenna size and orientation, objects which a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magellan (spacecraft)
The ''Magellan'' spacecraft was a robotic space probe launched by NASA of the United States, on May 4, 1989, to map the surface of Venus by using synthetic-aperture radar and to measure the planetary gravitational field. The ''Magellan'' probe was the first interplanetary mission to be launched from the Space Shuttle, the first one to use the Inertial Upper Stage booster, and the first spacecraft to test aerobraking as a method for circularizing its orbit. ''Magellan'' was the fifth successful NASA mission to Venus, and it ended an eleven-year gap in U.S. interplanetary probe launches. History Beginning in the late 1970s, scientists advocated for a radar mapping mission to Venus. They first sought to construct a spacecraft named the '' Venus Orbiting Imaging Radar'' (VOIR), but it became clear that the mission would be beyond the budget constraints during the ensuing years. The VOIR mission was canceled in 1982. A simplified radar mission proposal was recommended by the S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natrocarbonatite
Natrocarbonatite is a rare carbonatite lava which erupts from the Ol Doinyo Lengai volcano in Tanzania within the East African Rift of eastern Africa. Natrocarbonatite lavas were first documented in 1962, by J B Dawson. Composition Whereas most lavas are rich in silicate minerals, the natrocarbonatite lavas of Ol Doinyo Lengai are rich in the rare sodium and potassium carbonate minerals, nyerereite and gregoryite. Due to this unusual composition, the lava is erupted at relatively low temperatures (approximately 500-600 °C).https://www.science.org/doi/10.1126/science.245.4914.168 This temperature is so low that the molten lava appears black in sunlight, rather than having the red glow common to most lavas. It is also much more fluid than silicate lavas. Impact The sodium and potassium carbonate minerals of the lavas erupted at Ol Doinyo Lengai are unstable at the Earth's surface and susceptible to rapid weathering, the minerals are anhydrous A substance is anhydrous if i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ol Doinyo Lengai
Ol Doinyo Lengai (Oldoinyo Lengai), "Mountain of God" in the Maasai language, is an active volcano located in the Gregory Rift, south of Lake Natron within the Arusha Region of Tanzania, Africa. Part of the volcanic system of the East African Rift, it uniquely produces natrocarbonatite lava. The 1960 eruption of Ol Doinyo Lengai led to geological investigations that finally confirmed the view that carbonatite rock is derived from magma. Geology Ol Doinyo Lengai is unique among active volcanoes in that it produces natrocarbonatite lava, a unique occurrence of volcanic carbonatite. A few older extinct carbonatite volcanoes are located nearby, including Homa Mountain. Lava Whereas most lavas are rich in silicate minerals, the lava of Ol Doinyo Lengai is a carbonatite. It is rich in the rare sodium and potassium carbonates, nyerereite and gregoryite. Due to this unusual composition, the lava erupts at relatively low temperatures of approximately . This temperature is so low that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbonatite
Carbonatite () is a type of intrusive or extrusive igneous rock defined by mineralogic composition consisting of greater than 50% carbonate minerals. Carbonatites may be confused with marble and may require geochemical verification. Carbonatites usually occur as small plugs within zoned alkalic intrusive complexes, or as dikes, sills, breccias, and veins. They are almost exclusively associated with continental rift-related tectonic settings. It seems that there has been a steady increase in the carbonatitic igneous activity through the Earth's history, from the Archean eon to the present. Nearly all carbonatite occurrences are intrusives or subvolcanic intrusives. This is because carbonatite lava flows, being composed largely of soluble carbonates, are easily weathered and are therefore unlikely to be preserved in the geologic record. Carbonatite eruptions as lava may therefore not be as uncommon as thought, but they have been poorly preserved throughout the Earth's history. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magellan Probe
The ''Magellan'' spacecraft was a robotic Robotics is an interdisciplinary branch of computer science and engineering. Robotics involves design, construction, operation, and use of robots. The goal of robotics is to design machines that can help and assist humans. Robotics integrate ... space probe launched by NASA of the United States, on May 4, 1989, to map the surface of Venus by using synthetic-aperture radar and to measure the planetary gravitational field. The ''Magellan'' probe was the first interplanetary mission to be launched from the Space Shuttle, the first one to use the Inertial Upper Stage booster, and the first spacecraft to test aerobraking as a method for circularizing its orbit. ''Magellan'' was the fifth successful NASA mission to Venus, and it ended an eleven-year gap in U.S. interplanetary probe launches. History Beginning in the late 1970s, scientists advocated for a radar mapping mission to Venus. They first sought to construct a spacecraft nam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lunar And Planetary Science Conference
The Lunar and Planetary Science Conference (LPSC), jointly sponsored by the Lunar and Planetary Institute (LPI) and NASA Johnson Space Center (JSC), brings together international specialists in petrology, geochemistry, geophysics, geology, and astronomy to present the latest results of research in planetary science. Since its beginning in 1970, the LPSC has been a significant focal point for planetary science research, with more than 2000 planetary scientists and students attending from all over the world. History In a speech delivered at the Manned Spacecraft Center (MSC) in Houston, Texas in March 1968, President Lyndon B. Johnson announced the formation of the Lunar Science Institute (LSI). The creation of the LSI was the culmination of meetings and events involving the National Aeronautics and Space Administration, the National Academy of Sciences, Universities Research Association, and several major universities. Initially operated by the National Academy of Sciences, the Uni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
