DOCSLIB.ORG

Geologic Map of the Nemesis Tesserae Quadrangle (V–13), Venus

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Geologic Map of the Nemesis Tesserae Quadrangle (V–13), Venus Prepared for the National Aeronautics and Space Administration Geologic Map of the Nemesis Tesserae Quadrangle (V–13), Venus By Mikhail A. Ivanov and James W. Head, III Pamphlet to accompany Scientifiic Investigations Map 2870 75° 75° V–1 V–3 V–6 50° 50° V–4 V–5 V–11 V–16 V–12 V–15 V–13 V–14 25° 25° V–23 V–28 V–24 V–27 V–25 V–26 90° 120° 150° 180° 210° 240° 270° 0° 0° V–37 V–38 V–36 V–39 V–35 V–40 –25° –25° V–49 V–50 V–48 V–51 V–47 V–52 V–58 V–59 –50° –50° V–57 V–60 V–62 2005 –75° –75° U.S. Department of the Interior U.S. Geological Survey BLANK PAGE THE MAGELLAN MISSION of the surface can have a significant effect. Low-density layers such as crater ejecta or volcanic ash can absorb the The Magellan spacecraft orbited Venus from August incident energy and produce a lower observed echo. On 0, 990, until it plunged into the Venusian atmosphere on Venus, there also exists a rapid increase in reflectivity at October 2, 994. Magellan Mission objectives included a certain critical elevation, above which high-dielectric () improving the knowledge of the geological pro- minerals or coatings are thought to be present. This leads cesses, surface properties, and geologic history of Venus to very bright SAR echoes from virtually all areas above by analysis of surface radar characteristics, topography, that critical elevation. and morphology and (2) improving the knowledge of the The measurements of passive thermal emission from geophysics of Venus by analysis of Venusian gravity. Venus, though of much lower spatial resolution than the The Magellan spacecraft carried a 2.6-cm radar SAR data, are more sensitive to changes in the dielec- system to map the surface of Venus. The transmitter and tric constant of the surface than to roughness. As such, receiver systems were used to collect three data sets: () they can be used to augment studies of the surface and to synthetic aperture radar (SAR) images of the surface, (2) discriminate between roughness and reflectivity effects. passive microwave thermal emission observations, and Observations of the near-nadir backscatter power, col- (3) measurements of the backscattered power at small lected using a separate smaller antenna on the spacecraft, angles of incidence, which were processed to yield alti- were modeled using the Hagfors expression for echoes metric data. Radar imaging and altimetric and radiomet- from gently undulating surfaces to yield estimates of ric mapping of the Venusian surface was accomplished planetary radius, Fresnel reflectivity, and root-mean- in mission cycles , 2, and 3 from September 990 until square (rms) slope. The topographic data produced by September 992. Ninety-eight percent of the surface was this technique have horizontal footprint sizes of about 0 mapped with radar resolution on the order of 20 m. The km near periapsis and a vertical resolution on the order of SAR observations were projected to a 75-m nominal hor- 100 m. The Fresnel reflectivity data provide a compari- izontal resolution, and these full-resolution data compose son to the emissivity maps, and the rms slope parameter the image base used in geologic mapping. The primary is an indicator of the surface tilts, which contribute to the polarization mode was horizontal-transmit, horizontal- quasi-specular scattering component. receive (HH), but additional data for selected areas were collected for the vertical polarization sense. Incidence MAGELLAN SAR AND RELATED DATA angles varied between about 20° and 45°. High-resolution Doppler tracking of the space- The SAR instrument flown on the Magellan space- craft took place from September 992 through October craft (2.6 cm, S-band) provided the image data used in 994 (mission cycles 4, 5, 6). Some 950 orbits of high- our mapping and interpretation. SAR images are a record resolution gravity observations were obtained between of the echo (radar energy returned to the antenna), which September 992 and May 993 while Magellan was in is influenced by surface composition, slope, and wave- an elliptical orbit with a periapsis near 75 km and an length-scale surface roughness. Viewing and illumination apoapsis near 8,000 km. An additional ,500 orbits were geometry also will influence the appearance of surface obtained following orbit-circularization in mid-993. features in SAR images. Guidelines for geologic mapping These data exist as a 75° by 75° harmonic field. using Magellan SAR images and detailed background to Radar backscatter power is determined by () the aid in their interpretation can be found in Elachi (987), morphology of the surface at a broad range of scales and Saunders and others (992), Ford and Pettengill (992), (2) the intrinsic reflectivity, or dielectric constant, of the Tyler and others (992), and Tanaka (994). In the area material. Topography at scales of several meters and larger of the Nemesis Tesserae quadrangle, incidence angles can produce quasi-specular echoes, with the strength of are such that backscatter is dominated by variations in the return greatest when the local surface is perpendicu- surface roughness at wavelength scales. Rough surfaces lar to the incident beam. This type of scattering is most appear relatively bright, whereas smooth surfaces appear important at very small angles of incidence, since natu- relatively dark. Variations also occur depending on the ral surfaces generally have few large tilted facets at high orientation of features relative to the incident radiation angles. The exception is in areas of steep slopes, such (illumination direction), with features normal to the illu- as ridges or rift zones, where favorably tilted terrain can mination direction being more prominent than those ori- produce very bright signatures in the radar image. For ented parallel to it. Full-resolution images have a pixel most other areas, diffuse echoes from roughness at scales size of 75 m; C-MIDRs contain the SAR data displayed comparable to the radar wavelength are responsible for at about 225 m/pixel. Altimetry data and stereo images variations in the SAR return. In either case, the echo were of extreme importance in establishing geologic and strength is also modulated by the reflectivity of the sur- stratigraphic relations between units. Also essential in the face material. The density of the upper few wavelengths analysis of the geology of the surface are data obtained by Magellan on the emissivity (passive thermal radiation), the quadrangle (Konopliv and Sjogren, 994; Konopliv reflectivity (surface electrical properties), and rms slope and others, 999). The area of Nemesis Tesserae quad- (distribution of radar wavelength scale slopes). Aspects rangle is the southern continuation of the large Atalanta of these measurements were used in unit characterization Planitia, which is characterized by a circular shape, low and interpretation; background on the characteristics of topography, and a –35-mGal gravity anomaly and a –55- these data and their interpretation can be found in Saun- m geoid anomaly. These features of Atalanta Planitia ders and others (992), Ford and Pettengill (992), Tyler have been cited as evidence for the region being the site and others (992), Tanaka (994), and Campbell (995). of large-scale mantle downwelling (Phillips and others, 99; Bindschadler and others, 992b). Thus, this region NEMESIS TESSERAE QUADRANGLE could represent a laboratory for the study of the evolu- tion of a flanking zone of a lowland, the formation of The Nemesis Tesserae quadrangle (V–3) is in the associated tectonic features, and their relation to mantle northern hemisphere of Venus and extends from lat 25° processes. In an attempt to address these issues, several to 50° N. and from long 150° to 180° E. (fig. 1A,B). It questions appear to be very important: What units make covers the area between Atalanta Planitia to the north, up the surface of the map area? What is the sequence of Vellamo Planitia to the west, and Llorona Planitia to the these units and what events in the geologic history of the southwest. Nemesis Tesserae consists of an elongated map area do they document? What is the history of large- centralized deformed lowland flooded by volcanic depos- scale topographic features in the area under study? What, its and surrounded by the Vedma Dorsa deformation belt if any, is the evidence for evolution of volcanic activities to the west (Kryuchkov, 990; Frank and Head, 990) and styles of tectonic activities in this area? These ques- and Nemesis and Athena Tesserae to the east (fig. 1A). In tions and issues are the basis for our geologic mapping contrast to more equidimensional lowlands (basins) such analysis. as Atalanta and Lavinia Planitiae, the area of the Nem- In our analysis we focused on the geologic mapping esis Tesserae quadrangle represents the class of elon- of the Nemesis Tesserae quadrangle using traditional gated lowland areas on Venus confined between elevated methods of geologic unit definition and characterization regions (fig. 1B). The Nemesis Tesserae quadrangle is an for the Earth (for example, North American Commission important region for the analysis of processes of basin on Stratigraphic Nomenclature, 983) and planets (for formation and volcanic flooding. example, Wilhelms, 1990) appropriately modified for Before the Magellan mission, the region of Nem- radar data (Tanaka, 1994). We defined units and mapped esis Tesserae quadrangle was known on the basis of key relations using the full resolution Magellan SAR data Pioneer-Venus altimetry to be a lowland area (Masursky (mosaicked full resolution basic image data records, C- and others, 980; Pettengill and others, 980). Venera- MIDRs , F-MIDRs, and F-Maps) and transferred these 5/6 radar images showed that the interior of the area results to the base map compiled at a scale of :5,000,000.
Load more

Recommended publications
  • Copyrighted Material
    Index Abulfeda crater chain (Moon), 97 Aphrodite Terra (Venus), 142, 143, 144, 145, 146 Acheron Fossae (Mars), 165 Apohele asteroids, 353–354 Achilles asteroids, 351 Apollinaris Patera (Mars), 168 achondrite meteorites, 360 Apollo asteroids, 346, 353, 354, 361, 371 Acidalia Planitia (Mars), 164 Apollo program, 86, 96, 97, 101, 102, 108–109, 110, 361 Adams, John Couch, 298 Apollo 8, 96 Adonis, 371 Apollo 11, 94, 110 Adrastea, 238, 241 Apollo 12, 96, 110 Aegaeon, 263 Apollo 14, 93, 110 Africa, 63, 73, 143 Apollo 15, 100, 103, 104, 110 Akatsuki spacecraft (see Venus Climate Orbiter) Apollo 16, 59, 96, 102, 103, 110 Akna Montes (Venus), 142 Apollo 17, 95, 99, 100, 102, 103, 110 Alabama, 62 Apollodorus crater (Mercury), 127 Alba Patera (Mars), 167 Apollo Lunar Surface Experiments Package (ALSEP), 110 Aldrin, Edwin (Buzz), 94 Apophis, 354, 355 Alexandria, 69 Appalachian mountains (Earth), 74, 270 Alfvén, Hannes, 35 Aqua, 56 Alfvén waves, 35–36, 43, 49 Arabia Terra (Mars), 177, 191, 200 Algeria, 358 arachnoids (see Venus) ALH 84001, 201, 204–205 Archimedes crater (Moon), 93, 106 Allan Hills, 109, 201 Arctic, 62, 67, 84, 186, 229 Allende meteorite, 359, 360 Arden Corona (Miranda), 291 Allen Telescope Array, 409 Arecibo Observatory, 114, 144, 341, 379, 380, 408, 409 Alpha Regio (Venus), 144, 148, 149 Ares Vallis (Mars), 179, 180, 199 Alphonsus crater (Moon), 99, 102 Argentina, 408 Alps (Moon), 93 Argyre Basin (Mars), 161, 162, 163, 166, 186 Amalthea, 236–237, 238, 239, 241 Ariadaeus Rille (Moon), 100, 102 Amazonis Planitia (Mars), 161 COPYRIGHTED
    [Show full text]
  • Geologic Map of the Ganiki Planitia Quadrangle (V–14), Venus Eric B
    Claremont Colleges Scholarship @ Claremont Pomona Faculty Publications and Research Pomona Faculty Scholarship 1-1-2011 Geologic Map of the Ganiki Planitia Quadrangle (V–14), Venus Eric B. Grosfils Pomona College Sylvan M. Long Elizabeth M. Venechuk Debra M. Hurwitz Joseph W. Richards See next page for additional authors Recommended Citation Grosfils, E.B., Long, S.M., Venechuk, E.M., Hurwitz, D.M., Richards, J.W., Kastl, Brian, Drury, D.E., and Hardin, Johanna, 2011, Geologic map of the Ganiki Planitia quadrangle (V-14), Venus: U.S. Geological Survey Scientific nI vestigations Map 3121. This Report is brought to you for free and open access by the Pomona Faculty Scholarship at Scholarship @ Claremont. It has been accepted for inclusion in Pomona Faculty Publications and Research by an authorized administrator of Scholarship @ Claremont. For more information, please contact [email protected]. Authors Eric B. Grosfils, Sylvan M. Long, Elizabeth M. Venechuk, Debra M. Hurwitz, Joseph W. Richards, Brian Kastl, Dorothy E. Drury, and Johanna S. Hardin This report is available at Scholarship @ Claremont: http://scholarship.claremont.edu/pomona_fac_pub/303 Prepared for the National Aeronautics and Space Administration Geologic Map of the Ganiki Planitia Quadrangle (V–14), Venus By Eric B. Grosfils, Sylvan M. Long, Elizabeth M. Venechuk, Debra M. Hurwitz, Joseph W. Richards, Brian Kastl, Dorothy E. Drury, and Johanna Hardin Pamphlet to accompany Scientific Investigations Map 3121 75° 75° V–1 V–3 V–6 50° 50° V–4 V–5 V–11 V–16 V–12 V–15 V–13 V–14 25° 25° V–23 V–28 V–24 V–27 V–25 V–26 90° 120° 150° 180° 210° 240° 270° 0° 0° V–37 V–38 V–36 V–39 V–35 V–40 –25° –25° V–49 V–50 V–48 V–51 V–47 V–52 V–58 V–59 –50° –50° V–57 V–60 2011 V–62 –75° –75° U.S.
    [Show full text]
  • VENUS Corona M N R S a Ak O Ons D M L YN a G Okosha IB E .RITA N Axw E a I O
    N N 80° 80° 80° 80° L Dennitsa D. S Yu O Bachue N Szé K my U Corona EG V-1 lan L n- H V-1 Anahit UR IA ya D E U I OCHK LANIT o N dy ME Corona A P rsa O r TI Pomona VA D S R T or EG Corona E s enpet IO Feronia TH L a R s A u DE on U .TÜN M Corona .IV Fr S Earhart k L allo K e R a s 60° V-6 M A y R 60° 60° E e Th 60° N es ja V G Corona u Mon O E Otau nt R Allat -3 IO l m k i p .MARGIT M o E Dors -3 Vacuna Melia o e t a M .WANDA M T a V a D o V-6 OS Corona na I S H TA R VENUS Corona M n r s a Ak o ons D M L YN A g okosha IB E .RITA n axw e A I o U RE t M l RA R T Fakahotu r Mons e l D GI SSE I s V S L D a O s E A M T E K A N Corona o SHM CLEOPATRA TUN U WENUS N I V R P o i N L I FO A A ght r P n A MOIRA e LA L in s C g M N N t K a a TESSERA s U . P or le P Hemera Dorsa IT t M 11 km e am A VÉNUSZ w VENERA w VENUE on Iris DorsaBARSOVA E I a E a A s RM A a a OLO A R KOIDULA n V-7 s ri V VA SSE e -4 d E t V-2 Hiei Chu R Demeter Beiwe n Skadi Mons e D V-5 S T R o a o r LI s I o R M r Patera A I u u s s V Corona p Dan o a s Corona F e A o A s e N A i P T s t G yr A A i U alk 1 : 45 000 000 K L r V E A L D DEKEN t Baba-Jaga D T N T A a PIONEER or E Aspasia A o M e s S a (1 MM= 45 KM) S r U R a ER s o CLOTHO a A N u s Corona a n 40° p Neago VENUS s s 40° s 40° o TESSERA r 40° e I F et s o COCHRAN ZVEREVA Fluctus NORTH 0 500 1000 1500 2000 2500 KM A Izumi T Sekhm n I D .
    [Show full text]
  • O Lunar and Planetary Institute Provided by the NASA Astrophysics Data System 70 STRATIGRAPHY of VENUS: BASILEVSKY, A
    LPS XXVII R-EGIONAL AND GLOBAL STRATIGRAPHY OF VENUS: A PRELIMINARY ASSESSMENT AND IMPLICATIONS FOR THE GEOLOGIC HISTORY OF VENUS; A. T. ~asilevsk~l~2and J. W. ~ead2,l~ernadsk~ Inst., Russian Academy of Sciences, Moscow 117975, Russia, [email protected]; 2~ept.Geol. Sci., Brown Univ., Providence, RI 02912 USA. INTRODUCTION. Analysis of the Magellan imagery in numerous representative sample areas of Venus led to establishing the stratigraphic sequence of geologic formations of the planet starting with heavily deformed tessera-forming materials, followed by the suite of plains-forming volcanics, moderately deformed by widespread deformation, which, in turn, are locally overlapped by younger volcanics mostly associated with rifts. This sequence and the resulting scenario of the geologic history of Venus, put constraints on the character and rate of processes in the planet interior. The global high-resolution Magellan coverage of Venus [l] provided a basis for establishing the characteristics of the major geologic units and structures of this planet, for assessing their stratigraphic relations, and for interpreting the geologic history of the planet. Such an endeavor will require many years of intensive mapping and analysis of the data before a detailed picture emerges. Here we report on an initial analysis of widely distributed areas on the planet and a preliminary assessment of regional stratigraphic units into the model of global stratigraphy of Venus. Further detailed studies, especially made through the NASA-sponsored Venus Geologic Mapping Program, are necessary to test the suggested stratigraphy model. VENUS STRATIGRAPHY MODEL. Using the Magellan C1- and F-MIDRP mosaics both in hard copy and in digital format (and related altimetry and physical property data) we first studied stratigraphic relations in thirty-six 1,000 x 1,000 km areas randomly spaced on Venus [2,3].
    [Show full text]
  • Alexander T. Basilevsky
    1 CURRICULUM VITAE Alexander T. Bazilevskiy (in publications use spelling Basilevsky) Born: 4 October, 1937 in Voronezh, Russia Education and Scientific Degrees: 1959, Master of Science in Geology, Voronezh State University, Voronezh. 1968, Doctor of Philosophy in Geochemistry, Vernadsky Institute of Geochemistry and Analytical Chemistry, USSR Academy of Sciences, Moscow. 1986, Doctor of Sciences in Geochemistry and Planetary Science, Vernadsky Institute of Geochemistry and Analytical Chemistry, USSR Academy of Sciences, Moscow. 2007, Professor in Geochemistry, Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, Moscow. Professional Career 1954-1959, Student of Geological Department of Voronezh State University, Voronezh; 1959-1963, Junior Geologist, Geologist, Senior Geologist of the Geologic Mapping Expedition, Geologic Office of Central Regions, USSR Ministry of Geology and Protection of Earth Interiors, Moscow; 1:200,000 Geologic mapping in Moscow, Tambov, Vladimir and Voronezh provinces; 1963-1966, PhD Student of Geological Department of Moscow State University, Moscow; Experimental petrology of mafic and ultramafic rocks; 1966-1968, Senior Geologist of the Geologic Mapping Expedition, Geologic Office of Central Regions, USSR Ministry of Geology and Protection of Earth Interiors, Moscow; Geochemical Prospecting for Ore Deposits in Belgorod, Kursk, Lipetsk and Voronezh provinces of Central Russia; 1968-1975, Junior Scientist, Senior Scientist of Institute for Space Research, USSR Academy of Sciences,
    [Show full text]
  • 12 Mar 2020 Euinhbtbeciaeseais Oeigvenus Modeling Scenarios: Climate Habitable Venusian Orsodn Uhr ..Way, M.J
    manuscript submitted to JGR: Planets Venusian Habitable Climate Scenarios: Modeling Venus through time and applications to slowly rotating Venus-Like Exoplanets M.J. Way1,2,3, and Anthony D. Del Genio1 1NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY, 10025, USA 2GSFC Sellers Exoplanet Environments Collaboration 3Theoretical Astrophysics, Department of Physics and Astronomy, Uppsala University, Uppsala, SE-75120, Sweden Key Points: • Venus could have had habitable conditions for nearly 3 billion years. • Surface liquid water is required for any habitable scenario. • Solar insolation through time is not a crucial factor if a carbonate-silicate cycle is in action. arXiv:2003.05704v1 [astro-ph.EP] 12 Mar 2020 Corresponding author: M.J. Way, [email protected] –1– manuscript submitted to JGR: Planets Abstract One popular view of Venus’ climate history describes a world that has spent much of its life with surface liquid water, plate tectonics, and a stable temperate climate. Part of the basis for this optimistic scenario is the high deuterium to hydrogen ratio from the Pioneer Venus mission that was interpreted to imply Venus had a shallow ocean’s worth of water throughout much of its history. Another view is that Venus had a long lived (∼ 100 million year) primordial magma ocean with a CO2 and steam atmosphere. Venus’ long lived steam atmosphere would sufficient time to dissociate most of the water vapor, allow significant hydrogen escape and oxidize the magma ocean. A third scenario is that Venus had surface water and habitable conditions early in its history for a short period of time (< 1Gyr), but that a moist/runaway greenhouse took effect because of a grad- ually warming sun, leaving the planet desiccated ever since.
    [Show full text]
  • Preliminary Thermorheological Modeling of Silicate Melts in Venusian Canali
    Lunar and Planetary Science XLVIII (2017) 1334.pdf PRELIMINARY THERMORHEOLOGICAL MODELING OF SILICATE MELTS IN VENUSIAN CANALI. E. Harrington1,2, G. Williams-Jones2 1Centre for Planetary Science and Exploration / Department of Earth Sciences, University of Western Ontario, London Ontario, Canada, N6A 5B7; 2Department of Earth Sciences, Simon Fraser University, Burnaby, British Columbia, Canada, V5A 1S6. ([email protected]) Introduction: Canali are long (few 100s to over Limitations within the FLOWGO model (optimized 7000 km), narrow (1-5 km wide), sinuous channels for basalt) prevent accurate modeling of very low vis- found predominantly on the Venusian volcanic plains cosity melts, such as carbonatite or sulphur. Thus, only [1]. The channels show distinctively fluvial characteris- silicate melts have been tested thus far. tics, including point bars, oxbows, and their meander Rhyolite: Due to its high viscosity, rhyolite was not wavelengths [2,3]. Given the hot ambient temperatures expected to flow far under Venusian conditions, nor has on Venus (~740 K at mean planetary datum), and as- rhyolite been conclusively found on Venus. Rather, rhy- suming similar ambient conditions during their for- olite is included as a proof-of-concept to compare dif- mation, canali are unlikely to have contained water. As ferences between terrestrial and hypothetical Venusian such, diverse formation mechanisms have been pro- rhyolite flows, as well as for comparison with other sil- posed to explain their formation including thermome- icate melts. As expected, rhyolite flows move extremely chanical erosion from lava, constructive emplacement slowly on the flat Venusian plans, with a 150-m thick of lavas, and mechanical erosion by low temperature rhyolite flow travelling 12.5 km before stopping.
    [Show full text]
  • Hamilton, W. B., Plumeless Venus Preserves an Ancient Impact
    Geological Society of America Special Paper 388 2005 Plumeless Venus preserves an ancient impact-accretionary surface Warren B. Hamilton* Department of Geophysics, Colorado School of Mines, Golden, Colorado 80401, USA ABSTRACT Venus displays thousands of old circular structures, with topographic rims 5– 2000 km in diameter, that have the morphology and cookie-cutter superposition required of impact craters and basins. Many structures have interior central or ring uplifts or broad, low volcanic constructs. Many are multiring. Old uplands are satu- rated with variably degraded structures, whereas lowland structures are variably buried by sediments. The youngest include three of the largest (rim diameters of 800–2000 km), for which analogy with the dated Imbrium impact basin on the Moon indicates likely ages of ca. 3.90 Ga. Venus is argued here to preserve much of its sur- face of late-stage main planetary accretion. The Venus of conventional interpretation, by contrast, was wholly resurfaced, mostly by plume-driven processes, no earlier than 1 Ga, and preserves no ancient fea- tures. This speculation is extrapolated from terrestrial conjectures, and rationalizes away voluminous contrary evidence from Venus itself. Interpreters of early Venusian radar imagery accepted the possible impact origin and great age of the structures, but impact explanations were soon replaced, almost without analysis, by plume conjectures. Nearly all specialists now assume that Venus has internal mobility comparable to the exaggerated mobility assumed for Earth, and that the only Venusian impact structures are “pristine” small- to mid-size craters and basins with an age younger than 1.0 Ga. (Ages to 3.9 Ga for these are advocated here.) The older circular structures are con- ventionally attributed to mantle plumes and upwellings that deformed crust and upper mantle from beneath, with or without lava extrusion.
    [Show full text]
  • Geologic Map of the Mylitta Fluctus Quadrangle (V–61), Venus
    Prepared for the National Aeronautics and Space Administration Geologic Map of the Mylitta Fluctus Quadrangle (V–61), Venus By Mikhail A. Ivanov and James W. Head, III Pamphlet to accompany Scientifiic Investigations Map 2920 75° 75° V–1 V–6 V–3 50° 50° V–7 V–2 V–17 V–10 V–18 V–9 V–19 V–8 25° 25° V–29 V–22 V–30 V–21 V–31 V–20 270° 300° 330° 0° 30° 60° 90° 0° 0° V–43 V–32 V–42 V–33 V–41 V–34 –25° –25° V–55 V–44 V–54 V–45 V–53 V–46 V–61 V–56 –50° –50° V–60 V–57 V–62 2006 –75° –75° U.S. Department of the Interior U.S. Geological Survey INTRODUCTION nic ash, can absorb the incident energy and produce a lower observed echo. On Venus, there also exists a rapid increase in THE MAGELLAN MISSION reflectivity at a certain critical elevation, above which high- The Magellan spacecraft orbited Venus from August 0, dielectric minerals or coatings are thought to be present. This 990, until it plunged into the Venusian atmosphere on October leads to very bright SAR echoes from virtually all areas above 2, 994. Magellan Mission objectives included: () improv- that critical elevation. ing knowledge of the geological processes, surface properties, The measurements of passive thermal emission from and geologic history of Venus by analysis of surface radar Venus, though of much lower spatial resolution than the SAR characteristics, topography, and morphology, and (2) improv- data, are more sensitive to changes in the dielectric constant of ing the knowledge of the geophysics of Venus by analysis of the surface than to roughness.
    [Show full text]
  • Introduction: the Map of the Area of Venus Lo- Cated Within 35 to 90° S, and 80 to 200° E Was
    Lunar and Planetary Science XXXI 1185.pdf LAIDAMLULUM VALLIS, THE THIRD LONGEST LAVA CHANNEL ON VENUS: DISCOVERY REPORT G.A.Burba Vernadsky Institute of Geochemistry and Analytical Chemistry, Russia’s Academy of Sciences, 19 Kosygin Str., Moscow 117975, Russia <[email protected]> Introduction: The map of the area of Venus lo- fornia. It is name of the Morning Star Woman, wife of cated within 35 to 90° S, and 80 to 200° E was com- Kuksu, the first man. The name from the culture of piled within the frames of VENGLOBGEK project on Californian people have been chosen to produce a link the global geologic mapping of Venus [1,2,3]. This with the Magellan mission, which was controlled with area, as the most of the Southern Venus, is known as the California-located facilities of the Deep Space the lowlands since the Pioneer Venus altimetric survey Communication Network and the Jet Propulsion Labo- in 1979. It was imaged for the first time with the Ma- ratory. gellan SAR in 1991-92. In the course of the mapping Geologic setting: The channel is located on the a very prominent, still unknown lava channel was find plain with wrinkle ridges, the geologic unit, which out. This feature belongs to canali type of Venus occupies the largest area on Venus. It looks the chan- channels [4,5]. nel was formed either simultaneously with the wrin- Location: The terminals of this new channel are kle-ridged plains emplacement, or just after it. The at 83.5°S, 160.0°E and 62.0°S, 142.5°E.
    [Show full text]
  • Mercury and Venus the Inner Planets
    Modern Astronomy: Voyage to the Planets Lecture 3 Mercury and Venus the inner planets University of Sydney Centre for Continuing Education Spring 2011 1 This week we’ll look at the inferior planets, Mercury and Venus. Because they orbit closer to the Sun than the Earth, we never see them very far away from the Sun., and they show a full range of phases. 2 The furthest Venus ever gets from the sun (its maximum elongation) is 47o; for Mercury it is 28o. 3 Mercury's successive positions during March of 2000. Each picture was taken from the same location in Spain when the Sun itself was 10 degrees below the horizon and superposed on the single most photogenic sunset. 4 Mercury 5 Basic data Mercury Mercury/Earth Mass 0.3302 x 1024 kg 0.0553 Radius 2440 km 0.383 Mean density 5.427 g/cm3 0.983 Gravity 3.70 m/s2 0.378 Semi-major axis 57.91 x 106 km 0.387 Period 87.969 d 0.241 Orbital inclination 7.0o - Orbital eccentricity 0.2056 12.311 Rotation period 1407.6 h 58.78 Length of day 4222.6 h 175.94 6 Mercury’s period of rotation (58.7 days) is exactly two- thirds of the orbital period (88.0 days, the Mercurian year). This 3:2 resonance means that the solar day on Mercury – the time between noon and noon – is 176 (Earth) days long, twice the length of the year! 7 8 Mercury’s orbit is the most elliptical of any planet except Pluto.
    [Show full text]
  • Mercury and Venus the Inner Planets Presented by Dr Helen Johnston School of Physics
    Voyage to the Planets Lecture 3: Mercury and Venus the inner planets Presented by Dr Helen Johnston School of Physics Spring 2017 The University of Sydney Page see https://www.aao.gov.au/public/allison-levick for details This week we’ll look at the inferior planets, Mercury and Venus. Because they orbit closer to the Sun than the Earth, we never see them very far away from the Sun., and they show a full range of phases. The University of Sydney Page 3 The furthest Venus ever gets from the sun (its maximum elongation) is 47o; for Mercury it is 28o. The University of Sydney Page 4 Mercury's successive positions during March of 2000. Each picture was taken from the same location in Spain when the Sun itself was 10 degrees below the horizon and superposed on the single most photogenic sunset. The University of Sydney Page 5 Mercury Basic data Mercury Mercury/Earth Mass 0.3302 x 1024 kg 0.0553 Radius 2440 km 0.383 Mean density 5.427 g/cm3 0.983 Gravity 3.70 m/s2 0.378 Semi-major axis 57.91 x 106 km 0.387 Period 87.969 d 0.241 Orbital inclination 7.0o - Orbital eccentricity 0.2056 12.311 Rotation period 1407.6 h 58.78 The University of Sydney Length of day 4222.6 h 175.94 Page 7 Mercury’s period of rotation (58.7 days) is exactly two-thirds of the orbital period (88.0 days, the Mercurian year). This 3:2 resonance means that the solar day on Mercury – the time between noon and noon – is 176 (Earth) days long, twice the length of the year! The University of Sydney Page 8 Mercury’s orbit is the most elliptical of any planet except Pluto.
    [Show full text]