Mimantean Crater Herschel Partially Overlies Oeta Chasma

Summary: Mimantean crater Herschel partially overlies Oeta Chasma with the crater’s north-northwest rim and hosts a set of lineaments across its interior.

“Mimas drifts along in its orbit against the azure backdrop of Saturn’s northern latitudes in this true color view”: Cassini Orbiter spacecraft narrow angle camera image, obtained Jan. 18, 2005, at an approximate distance of 1.4 million kilometers (870,000 miles) from Saturn; NASA ID PIA06176; image addition date 2005-02-08; image credit NASA/JPL/Space Science Institute (SSI): May be used for any purpose without prior permission, via NASA JPL Photojournal

Mimantean crater Herschel partially overlies Oeta Chasma, a chasm angling at the crater’s north-northwest rim, while a set of lineaments cross Herschel’s interior.

Herschel Crater lies on the leading hemisphere, the hemisphere facing the direction of motion, of its parent body, Saturnian moon Mimas. “The most prominent single feature on Mimas is Herschel, an unrelaxed complex crater 130 kilometers in diameter,” stated University of Arizona Lunar and Planetary Laboratory astrogeologist Steven K. Croft in his report, “Mimas: Tectonic Structure and Geologic History,” published by NASA in June 1991 (page 95).

The International Astronomical Union’s (IAU) Gazetteer of Planetary Nomenclature centers Herschel Crater at minus 1.38 degrees south latitude, 111.76 degrees west longitude. The large impact crater obtains north and south latitudinal extremes of 18.14 degrees north and minus 21.5 degrees south, respectively. It registers its eastern and western longitudinal extents at 90.91 degrees west and 131.1 degrees west, respectively. Herschel Crater’s diameter measures 139 kilometers.

Steven K. Croft’s June 1991 report considered two geologic features coincident with Herschel Crater. He examined a set of lineaments across the crater’s surface and a chasm partially superimposed by Herschel.

Croft defined lineaments as a class comprising “. . . a large number of long, narrow features. Lineament widths range from near the limit of resolution (1-2 km on the best images) to about 4 km. Lineament segments range in length from a few tens to several hundreds of kilometers” (page 95). He found that most lineaments “. . . are members of curvilinear sets of parallel structures with fairly constant spacings and distinct orientations.”

For convenience, Croft referred to Herschel’s set of unnamed lineaments as Herschel-Galahad. The name indicated the nearby feature, Galahad Crater.

Lying to the southwest of Herschel, Galahad is centered at minus 45.32 degrees south latitude, 145.31 degrees west longitude. It marks northernmost and southernmost latitudes at minus 40.42 degrees south and minus 50.42 degrees south, respectively. Its easternmost and westernmost longitudes occur at 138.63 degrees west and 152.63 degrees west, respectively. Galahad Crater has a diameter of 34 kilometers.

The set of Herschel-Galahad lineaments is centered at 30 degrees south latitude, 130 degrees west longitude, according to Croft’s determination. He placed their spacing at 15 to 30 kilometers and their direction at a northeast-to-southwest trend.

The second feature considered with respect to Herschel Crater is Oeta Chasma. The IAU’s Gazetteer of Planetary Nomenclature defines a chasma (plural: chasmata) as a “deep, elongated, steep-sided depression.”

“. . . Oeta Chasma is directly superposed by Herschel,” (page 96) noted University of Arizona Lunar and Planetary Laboratory astrogeologist Steven K. Croft in his report, “Mimas: Tectonic Structure and Geologic History,” published by NASA in June 1991. Herschel’s north-northwestern rim overlies southeastern portions of the elongated, northeast-to-southwest-oriented chasm.

Oeta Chasma is centered at 19 degrees north latitude and 122.7 degrees west longitude. The degraded chasm registers its northernmost and southernmost latitudes at 35 degrees north and 8 degrees north, respectively. It obtains easternmost and westernmost longitudes at 111.4 degrees west and 132 degrees west, respectively. Oeta Chasma’s diameter spans 110 kilometers.

Croft’s study of Herschel Crater in the context of its parent body’s tectonic structure and geologic history proposed a sequence for the crater, its lineaments and Oeta Chasma. The formation of Oeta Chasma occurred before the impact that punched Herschel Crater into the Mimantean surface. “The degraded chasmata formed first, followed by the Herschel impact, and then the lineaments . . .” (page 96). The set of Herschel-Galahad lineaments “. . . crosses Herschel, indicating structural activity after Herschel’s formation.”

The takeaway for Mimantean crater Herschel’s partial overlying of Oeta Chasma and for the presence of a set of lineaments across the crater’s floor is that the sequence of events for Herschel Crater, its chasm and its curvilinear set probably occurred firstly with Oeta Chasma’s formation, secondly with Herschel Crater’s impact and then, thirdly, with the Herschel-Galahad lineaments’ crosscut of Herschel Crater.

Geologic sketch map of Mimas shows Herschel Crater (left center), with Oeta Chasma angled at the crater’s north-northwest rim, Herschel-Galahad set’s curvilinear crosscut of Herschel’s surface and Galahad Crater (lower left); S.K. Croft, Mimas: Tectonic Structure and Geologic History (1991), page 97: Public Domain, via NASA NTRS (NASA Technical Reports Server)

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

“Mimas drifts along in its orbit against the azure backdrop of Saturn’s northern latitudes in this true color view”: Cassini Orbiter spacecraft narrow angle camera image, obtained Jan. 18, 2005, at an approximate distance of 1.4 million kilometers (870,000 miles) from Saturn; NASA ID PIA06176; image addition date 2005-02-08; image credit NASA/JPL/Space Science Institute (SSI): May be used for any purpose without prior permission, via NASA JPL Photojournal @ https://photojournal.jpl.nasa.gov/catalog/PIA06176; Generally not subject to copyright in the United States; may use this material for educational or informational purposes, including photo collections, textbooks, public exhibits, computer graphical simulations and Internet Web pages; general permission extends to personal Web pages, via NASA Image and Video Library @ https://images.nasa.gov/details/PIA06176

Geologic sketch map of Mimas shows Herschel Crater (left center), with Oeta Chasma angled at the crater’s north-northwest rim, Herschel-Galahad set’s curvilinear crosscut of Herschel’s surface and Galahad Crater (lower left); S.K. Croft, Mimas: Tectonic Structure and Geologic History (1991), page 97: Public Domain, via NASA NTRS (NASA Technical Reports Server) @ https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19920001510.pdf

For further information:

Albers, Steve; Space Science Institute; and Paul Schenk. “Mimas: Saturn’s Moon.” NOAA SOS (National Oceanic and Atmospheric Administration Science on a Sphere).
Available @ https://sos.noaa.gov/datasets/mimas-saturns-moon/

Batson, Raymond M. (Milner). Voyager 1 and 2 Atlas of Six Saturnian Satellites. NASA SP-464. Washington DC: National Aeronautics and Space Administration Scientific and Technical Information Branch, 1984.
Available via NASA NTRS (NASA Technical Reports Server) @ https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19840027171.pdf

Batson, Raymond M.; and Joel F. Russell, eds. Gazetteer of Planetary Nomenclature 1994. U.S. Geological Survey Bulletin 2129. Washington DC: United States Government Printing Office, 1995.
Available via USGS Publications Warehouse @ https://pubs.er.usgs.gov/publication/b2129

Croft, Steven K. “Mimas: Tectonic Structure and Geologic History.” In: NASA Office of Space Science and Applications, ed. Reports of Planetary Geology and Geophysics Program, 1990: 95.97. NASA Technical Memorandum 4300. Washington DC: National Aeronautics and Space Administration Scientific and Technical Information Program, June 1991.
Available via NASA NTRS (NASA Technical Reports Server) @ https://ntrs.nasa.gov/search.jsp?R=19920001510

Hamilton, Calvin J. “Mimas Saturn I.” Views of the Solar System > Saturn > Saturn’s Moons.
Available @ http://solarviews.com/eng/mimas.htm

International Astronomical Union. “Galahad.” USGS Astrogeology Science Center > Gazetteer of Planetary Nomenclature. Last updated Aug. 14, 2008.
Available @ https://planetarynames.wr.usgs.gov/Feature/2062

International Astronomical Union. “Herschel .” USGS Astrogeology Science Center > Gazetteer of Planetary Nomenclature. Last updated Aug. 14, 2008.
Available @ https://planetarynames.wr.usgs.gov/Feature/2478

International Astronomical Union (IAU) / U.S. Geological Survey (USGS) Gazetteer of Planetary Nomenclature. “Descriptor Terms (Feature Types).” USGS Astrogeology Science Center > Gazetteer of Planetary Nomenclature.
Available @ https://planetarynames.wr.usgs.gov/DescriptorTerms

International Astronomical Union (IAU) / U.S. Geological Survey (USGS) Gazetteer of Planetary Nomenclature. “Target: Mimas.” USGS Astrogeology Science Center > Gazetteer of Planetary Nomenclature > Nomenclature > Saturn.
Available @ https://planetarynames.wr.usgs.gov/Page/MIMAS/target

Lavoie, Sue, site manager. “PIA06176: Mimas Blues.” NASA Jet Propulsion Laboratory Photojournal. Image addition date Feb. 8, 2005.
Available @ https://photojournal.jpl.nasa.gov/catalog/PIA06176

Levy, David H. Skywatching. Revised and updated. San Francisco CA: Fog City Press, 1994.

Marriner, Derdriu. “Mimantean Crater Herschel Honors Mimas Discoverer William Herschel.” Earth and Space News. Wednesday, Sept. 7, 2011.
Available @ https://earth-and-space-news.blogspot.com/2011/09/mimantean-crater-herschel-honors-mimas.html

Marriner, Derdriu. “William Herschel Discovered Mimas With Newly Built 40-Foot Telescope.” Earth and Space News. Wednesday, Sep. 21, 2019.
Available @ https://earth-and-space-news.blogspot.com/2011/09/william-herschel-discovered-mimas-with.html

Marriner, Derdriu. “William Herschel Discovered Saturnian Moon Mimas Sept. 17, 1789.” Earth and Space News. Wednesday, Sept. 14, 2011.
Available @ https://earth-and-space-news.blogspot.com/2011/09/william-herschel-discovered-saturnian.html

Moore, Jeffrey M.; Paul M. Schenk; Lindsey S. Bruesch; Erik Asphaug; and William B. McKinnon. “Large Impact Features on Middle-Sized Icy Satellites.” Icarus, vol. 171, issue 2 (October 2004): 421-443.
Available via Royal Observatory of Belgium Operational Direction Reference Systems and Planetology @ http://planets.oma.be/ISY/pdf/article_Icy.pdf
Available via ScienceDirect @ https://www.sciencedirect.com/science/article/abs/pii/S0019103504001666

Moore, Patrick, Sir. Philip’s Atlas of the Universe. Revised edition. London UK: Philip’s, 2005.

NASA Office of Space Science and Applications, ed. Reports of Planetary Geology and Geophysics Program, 1990: 95.97. NASA Technical Memorandum 4300. Washington DC: National Aeronautics and Space Administration Scientific and Technical Information Program, June 1991.
Available via NASA NTRS (NASA Technical Reports Server) @ https://ntrs.nasa.gov/search.jsp?R=19920001510

Nemiroff, Robert; and Jerry Bonnell. “Mimas, Crater, and Mountain.” NASA Astronomy Picture of the Day (APOD). Jan. 11, 2017.
Available @ https://apod.nasa.gov/apod/ap170111.html

Shekhtman, Lonnie; and Jay Thompson. “Mimas: By the Numbers.” NASA Solar System Exploration > Moons > Saturn Moons.
Available @ https://solarsystem.nasa.gov/moons/saturn-moons/mimas/by-the-numbers/

Shekhtman, Lonnie; and Jay Thompson. “Mimas: Closer Than Ever Before.” NASA Solar System Exploration > More > Resources. Photojournal PIA06255. Aug. 5, 2005.
Available @ https://solarsystem.nasa.gov/resources/12641/mimas-closer-than-ever-before/

Shekhtman, Lonnie; and Jay Thompson. “Mimas: In Depth.” NASA Solar System Exploration > Moons > Saturn Moons. Page updated Sept. 17, 2019.
Available @ https://solarsystem.nasa.gov/moons/saturn-moons/mimas/in-depth/

Smith, Bradford A.; Laurence Soderblom, Reta Beebe, Joseph Boyce, Geoffery Briggs, Anne Bunker, Stewart A. Collins, Candice J. Hansen, Torrence V. Johnson, Jim L. Mitchell, Richard J. Terrile, Michael Carr, Allen F. Cook, Jeffrey Cuzzi, James B. Pollack, G. Edward Danielson, Andrew Ingersoll, Merton E. Davies, Garry E. Hunt, Harold Masursky, Eugene Shoemaker, David Morrison, Tobias Owen, Carl Sagan, Joseph Veverka, Robert Strom and Verner E. Suomi. “Encounter With Saturn: Voyager 1 Imaging Science Results.” Science, new series, vol. 212, no. 4491 (April 10, 1981): 163-191.
Available via JSTOR @ https://www.jstor.org/stable/1685661
Available via Science Magazine @ https://science.sciencemag.org/content/212/4491/163

U.S. Geological Survey. “Preliminary Pictorial Map of Mimas.” Atlas of the Saturnian Satellites. IMAP 1482. Prepared for the Voyager Imaging Team in cooperation with the Jet Propulsion Laboratory, California Institute of Technology and the National Aeronautics and Space Administration. Directed by R.M. (Raymond Milner) Batson / U.S. Geological Survey Branch of Astrogeologic Studies. Airbrush representation by Jay L. Inge. Data preparation and preliminary image processing by K.F. Mullins, Christopher Isbell, E.M. Lee, H.G. Morgan and B.A. Skiff. Reston VA: U.S. Geological Survey, 1982.
Available @ https://pubs.er.usgs.gov/publication/i1489
Available @ http://171.67.35.48/view/6829740

Watanabe, Susan, ed. “Mimas Showing False Colors -- 1.” NASA > Mission Pages > Cassini-Huygens Mission to Saturn > Multimedia. Aug. 5, 2005. Page last updated April 29, 2008.
Available @ https://www.nasa.gov/mission_pages/cassini/multimedia/pia06257.html

Watanabe, Susan, ed. “Up Close to Mimas.” NASA > Mission Pages > Cassini-Huygens Mission to Saturn > Multimedia. Aug. 5, 2005. Page last updated April 29, 2008.
Available @ https://www.nasa.gov/mission_pages/cassini/multimedia/pia06258.html

West, Richard M., ed. XVIIIth General Assembly – Transactions of the IAU Vol. XVIII B Proceedings of the 18th General Assembly Patras, Greece, August 17-26, 1982. Dordrecht, Holland: D. Reidel Publishing Company, Jan. 1, 1983.
Available @ https://www.iau.org/publications/iau/transactions_b/

Whatmore, Rebecca, ed. “Color Near Herschel Crater.” NASA > Mission Pages > Cassini-Huygens Mission to Saturn > Multimedia. March 29, 2010. Page last updated May 12, 2010.
Available @ https://www.nasa.gov/mission_pages/cassini/multimedia/pia12572.html

Whatmore, Rebecca, ed. “Examining Herschel Crater.” NASA > Mission Pages > Cassini-Huygens Mission to Saturn > Multimedia. March 29, 2010.
Available @ https://www.nasa.gov/mission_pages/cassini/multimedia/pia12568.html