The NASA Magellan spacecraft provided synthetic aperture radar (SAR) image coverage of 98% of the surface of the planet Venus, in addition to topography and several types of physical property data on the venusian surface (e.g., radar reflectivity, radar backscatter, emissivity, and rms slopes).(See Special Magellan Issue of J. Geophys. Res., v. 97, nos. E8 and E10, August 25 and Sept. 25, 1992.) This Open-File Report contains a listing (table 1) of impact craters based on interpretation of the Magellan data, and was compiled with the official sanction of the Magellan Science Team (Steve Saunders, Magellan Project Scientist, personal communication, 1990). This crater data base has been revised, updated, and expanded from those used by the authors in earlier publications (Schaber and others, 1992; Strom and others, 1994).
The Crater Database
The database tables include the name (where applied), coordinates, diameter, modification state, crater morphologic type, and mean elevation of 967 craters interpreted to be of impact origin within the area of the planet imaged by the Magellan spacecraft between 1990 and 1994. For more details on interpretations of the Venus impact cratering record, the reader is referred to Campbell and others, 1992, Phillips and others (1991, 1992), Schaber and others (1992), Chadwick and Schaber (1993), Alexopoulos and McKinnon (1994), Herrick (1994), Herrick and Phillips (1994), Nakimi and Solomon (1994), Price and Suppe (1994), Strom and others (1994), Price and others (1996), Herrick and others (1995), and Strom and others (1995).
An alternate Venus impact crater data base that includes additional information on crater morphology has been described by Herrick and Phillips (1994). An excellent source for the current thinking about impact craters on Venus and their implications can be found in the University of Arizona Press book, Venus II (Bougher and others - Editors, 1997). Relevant Chapters on impact cratering in the Venus II book were contributed by Basilevsky and others (1997), Herrick and others (1997), and McKinnon and others (1997).
Numerous impact craters >15 km in diameter on Venus have been named for famous women (last names). Some smaller impact craters <15 km in diameter have been given common female first names from various ethnic groups. During Summer 1997 the IAU Committee on Planetary Nomenclature approved the suggestion that first names of females from various ethnic groups be assigned to impact craters with diameters down to 5 km. As a result, the IAU Committee during 1997 approved a total of 323 new Venus crater names. These newly approved names can now be referenced in the literature and have been included in the revised U.S. Geological Survey/University of Arizona Venus impact crater data base shown in the tables. The reader is referred to the Gazetteer of Venusian Nomenclature (Russell, 1994) and to the Gazetteer of Planetary Nomenclature for name origins and the use of the proper diacritics (not indicated in table 1).
Larger versions of most sample images are available by selecting either the modification state image or crater name. The size of the larger image is given in kilobytes (kb). Large images are all at a scale of 225 m/pixel. The images retain the rull radiometric calibration (Pettengill and others. 1991).
Note: The modification state of the impact craters on the database is subject to individual interpretation and bias of the authors. Note also that many craters on the database have been assigned modification state designations that are a combination of two or maore of the individual sumbols shown below. For example. the crater heloise designated vhp1 in the database represents a slightly fractured crater (f1) which has been heavily embayed by volcanic lava plains (vh) durning the last global resurfacing event (p).
Note: The symbol p used alone in the modification state column of the table always represents a pristine (essentially unaltered) crater. Howerver, when p is used in combination with other symbols in the Modification State column, it never means pristine. Here, it symbolizes (in abbreviated form) a lava-embayed crater that is interpreted to have been embayed by lava plains deposits during the last global resurfacing episode - not subsequent to it.
Examples of the basic states of impact crater modification used are:
- p, pristine - Essentially unaltered crater ejecta and fluidized outflow deposits, where present (Chadwick and Schaber. 1993) Stuart (69 km diameter; 30.79°S, 20.22°E).
- vs, slightly embayed - Crater with ejecta slightly embayed by volcanic lava Ketzia (14.6 km diameter; 3.98°N 300.50°E).
- vm, moderately embayed - Crater with ejecta moderatly embayed by volcanic lava. Bernadette (12.8 km diameter; 46.64°S, 285.6°E).
- vh, heavily embayed - Crater with rim, ejecta (and often floor) heavily embayed by volcanic lava. Raisa (13.5 km diameter; 27.5°N, 280.3°E).
- vh3, heavily embayed and fractured - Crater heavily embayed with volcanic lava and is heavily fractured. Baranamtarra (25.5 km diameter; 17.94°N, 267.80°E).
- vhp1 - Crater that has a slightly fractured rim and has had its ejecta and rim heavily embayed (flooded) by lava plains that are interpreted to have been deposited during the last global resurfacing episode. Heloise, a doublet crater (16 km and 38 km diameters; 40.0°N, 51.9°E).
- f1, slightly fractured - Crater estimated visually to have less than 50% of the crater floor, wall, and rim deposits affected by fractures (evidence of low to moderate local or regional extension). Missing Magellan orbits (black) appear at bottom. Wheatley (74.8 km diameter; 16.62°N, 268.03°E).
- f2, heavily fractured - Crater estimated visually to have more than 50% of its floor, wall, and rim deposits affected by fractures (evidence of moderate to moderately high, local or regional extension). Tubman (42.9 km diameter; 23.63°N, 204.57°E).
- f3, greatly disrupted - Crater that is greatly disrupted; ejecta, rim and floor have been very degraded by fracturing with considerable extension. Balch (40-km diameter; 29.90°N, 282.91°E).
- fc1, compressed fracture - Crater that has been slightly fractured (f1) by one or more compressive faults (fc). Barrymore (57-km diameter; 52.34°S, 195.68°E).
- e, ejecta mantled - Crater mantled by ejecta from younger impact crater nearby. Alimat (13.5-km diameter; 29.5°S, 205.9°E).
Larger versions of most sample images are available by selecting either the modification class, the thumbnail image or crater name. The size of the larger image is given in kilobytes (kb). Large images are all at a scale of 225 m/pixel. They have not been stretched to enhance contrast, but retain the full radiometric calibration Pettengill and others, 1991.
The types of crater morphologies listed on the data base are as follows:
- B, multi-ring basin - Large crater containing more than one concentric ring of low ridges or hills protruding above the floor inside the crater's dominant rim. Mona Lisa (79 km in diameter; 25.61°N, 25.15°E).
- D, double-ring basin - Large crater containing only a single concentric ring inside the crater rim. Cochran (100 km in diameter; 51.86°N, 143.36°E).
- P, central peak - Crater containing a single peak or closely grouped cluster of peaks or hills that is more or less centered on and rises above the crater floor deposits. Saskia (37 km in diameter; 28.58°S, 337.12°E).
- S, structureless floor - Crater containing no recognizable structures on the crater floor; crater floor sometimes flooded with impact-generated lava from below, or (rarely) a local volcanic source. Sabira (15.7 km in diameter; 5.75°S, 239.86°E).
- I,P, irregular(I) with central peak(P) - Crater characterized by an generally non-circular (irregular) rim and hummocky wall and floor deposits; thought to result from a cluster of parent asteroid or cometary material disrupted and slowed down by the venusian atmosphere prior to impact. Lotta (12 km in diameter; 51.06°N, 335.91°E).
- M, multiple - Impact crater, thought to result from the impact of a parent asteroid or cometary nucleus that was totally disrupted and whose fragments were dispersed low in the atmosphere into separate individual trajectories just prior to impact. Note: diameters given for multiple craters is associated with the largest crater within the crater group, and not for the diameter of the entire group of craters. Terhi; multiple crater; largest crater in field, 10.7 km in diameter; total size of field 30X52 km (45.71°N, 253.09°E).
The mean elevation values given are derived from the Magellan radar altimetry( Pettengill and others, 1991; Ford and Pettengill, 1992) and represent the pre-impact surface, assuming no tectonic deformation. The mean elevation included in the data base was determined from root 3 and 2 crater radii--outside the range of the average hummocky and radial crater rim deposits (but not the bright crater outflow deposits) (see Kirk and others, 1995). Mean elevation values based on Magellan altimetry data have a vertical accuracy from 80 m to 200 m (Ford and Pettengill, 1992).
- Alexopoulos J.S., and McKinnon, W.B., 1994, Large impact craters and basins on Venus, with implications for ring mechanics on the terrestrial planets, in Large Meteorite Impacts and Planetary Evolution, Geological Society of America Special Paper 293, p. 29-50.
- Basilevsky, A.T., Head, James W., Schaber, G.G., and Strom, R.G., 1997, The resurfacing history of Venus, part VII in Venus II - Geology, Geophysics, Atmosphere, and Solar Wind Experiment, S.W. Bougher, D.M. Hunten, and R.J. Phillips Eds., The University of Arizona Press, Tucson, Arizona, pp. 1047-1086.
- Bougher, S.W., Hunten, D.M., and Phillips, R.J.-Eds. 1997, Venus II - Geology, Geophysics, Atmosphere, and Solar Wind Environment, 1330 pp., Space Science Series, The University of Arizona Press, Tucson, Arizona.
- Campbell, D.B., Stacy, N.J.S., Newman, W.I., Arvidson, R.E., Jones, E.M., Musser, G.S., Roper, A.Y., and Schaller, C., 1992, Magellan observations of extended impact crater related features on the surface of Venus, J. Geophys. Res., v. 97, no. E10, p.16,249- 16,277.
- Chadwick, D.J., and Schaber, G.G., 1993, Impact crater outflows on Venus: Morphology and emplacement mechanisms, J. Geophys. Res., v. 98, no. E11, p. 20,891-20,902.
- Ford, P.G., and Pettengill, G.H., 1992, Venus topography and kilometer-scale slopes, J. Geophys. Res., v. 97, no. E8, p. 13,103-13,114.
- Herrick, R.R., 1994, Resurfacing history of Venus, Geology, v. 22, p. 703-706.
- Herrick, R.R., and Phillips, R.J., 1994, Implications of a global survey of venusian impact craters, Icarus, v. 111, p. 387-416.
- Herrick, R.R., Izenberg, Noam, and Phillips, R.J., 1995, Comment on "The global resurfacing of Venus" by R.G. Strom, G.G. Schaber, and D.D. Dawson, J. Geophys. Res., vol. 100, E11, pp. 23,355-23,360
- Herrick, R.R., Sharpton, V.L., Malin, M.C., Lyons, S.N., and Feely, K., Morphology and Morphometry of impact craters, part VIII in Venus II - Geology, Geophysics, Atmosphere, and Solar Wind Experiment, S.W. Bougher, D.M. Hunten, and R.J. Phillips Eds., The University of Arizona Press, Tucson, Arizona, pp. 1015-1046.
- Kirk, R.L., Schaber. G.G., and Strom, R.G., 1995, New statistical results on the spatial distribution and physical properties of impact craters on Venus, LPSC XXVI, part 2, Lunar and Planetary Institute, Houston, p. 757-758.
- McKinnon, W.B., Kahnle, K.J., Ivanov, B.A., and Melosh, H.J., 1997 Cratering on Venus: Models and Observations, in Venus II - Geology, Geophysics, Atmosphere, and Solar Wind Experiment, S.W. Bougher, D.M. Hunten, and R.J. Phillips Eds., The University of Arizona Press, Tucson, Arizona, pp. 1047-1086.
- Nakimi, K., and Solomon, S.C., 1994, Impact crater densities on volcanoes and coronae on Venus: Implications for volcanic resurfacing, Science, v. 265, p. 929-933.
- Pettengill, G.H., Eliason. E., Ford, P.G., Johnson, W.T.K., Raney, R.K., and Soderblom, L.A., 1991, Magellan: Radar performance and data products, Science, v. 252, p. 260-265.
- Phillips, R.J., Arvidson, R.E., Boyce, J.M., Campbell, D.B., Guest, J.E., Schaber, G.G., and Soderblom, L.A., 1991, Impact craters on Venus: Initial analysis from Magellan, Science, v. 252, p. 288- 297.
- Phillips, R.J., Raubertas, R.F., Arvidson, R.E., Sarkar, I.C., Herrick, R.R., Izenberg, Noam, and Grimm, R.E., 1992, Impact craters and Venus resurfacing history, J. Geophys. Res., v. 97, no. E10, p. 15,923-15,948.
- Price, M. and Suppe, J., 1994, Mean age of rifting and volcanism on Venus deduced from impact crater densities, Nature, v. 372, p. 756-759.
- Price, M., Watson, G., Suppe, J.H., and Brankman.,C., 1996, Dating volcanism and rifting on Venus using impact crater densities, J. Geophys. Res.-planets, v. 101, No. 2, pp 4654-4671.
- Russell, J.F., 1994, Gazetteer of venusian nomenclature, U.S. Geological Survey Open-File Report 94-235, 28 p.
- Schaber, G.G., Strom, G.H., Moore, H.J.,, Soderblom, L.A., Kirk, R.L., Chadwick, D.J., Dawson, D.D., Gaddis, L.R., Boyce, J.M., and Russell, Joel, 1992, Geology and distribution of impact craters on Venus: What are they telling us?, J. Geophys. Res., v. 97, no. E8, p. 13,257-13,301.
- Schaber. G.G., Strom, R.G., and Kirk, R.L., 1995, Update on the USGS crater database for Venus, LPSC XXVI, part 3, Lunar and Planetary Institute, Houston, pp. 1227-1228.
- Strom, R.G., Schaber, G.G., and Dawson, D.D., 1994, The global resurfacing of Venus, J. Geophys. Res., v. 99, no. E5, p. 10,899- 10,926.
- Strom, R.G., Schaber, G.G., Dawson, D.D., and Kirk, R.L., 1995, Reply (to comment on "The Global resurfacing of Venus" by R.G. Strom, G.G. Schaber, and D.D. Dawson, J. Geophys. Res. v. 99, no. E5, p. 10,899-10,926), J. Geophys. Res., vol. 100, E1 1, pp. 23,361-23,365.