Herschel Crater Vicinity Has Weaker Infrared Brightness Than Mimas Norm

Summary: The Herschel Crater vicinity has weaker infrared brightness than the Mimas norm, according to the Cassini-Huygens spacecraft’s Aug. 2, 2005, images.

Clear-filter image (left), processed for surface feature brightness and sharpness, and composite image (right) of clear-filter’s brightness image and color map of three color images (ultraviolet, green, infrared) reveal color-differentiated variations in the composition or texture of surface materials on seventh-known Saturnian moon Mimas; blue materials = weaker infrared brightness, green materials = average Mimas surface materials; images processed from images obtained Aug. 2, 2005, by the Cassini-Huygens spacecraft’s narrow-angle camera (NAC), from a distance of 228,000 kilometers (142,500 miles); sun-Mimas-spacecraft (phase) angle at 45 degrees: NASA ID PIA06257; image addition date 2005-08-05; image credit NASA/JPL/Space Science Institute: May be used for any purpose without prior permission, via NASA JPL Photojournal

The Herschel Crater vicinity has weaker infrared brightness than the Mimas norm, according to images obtained Aug. 2, 2005, by the Cassini-Huygens spacecraft’s Cassini orbiter.

The Cassini orbiter obtained multi-spectral views of Saturnian moon Mimas with its narrow-angle camera (NAC). One image was taken with a clear filter. Three color images were obtained with ultraviolet, green and infrared filters.

The Cassini Imaging Central Laboratory for Operations (CICLOPS), based at the Space Science Institute in Boulder, Colorado, serves as the imaging operations center for the Cassini-Huygens Mission to Saturn. CICLOPS initially processed the clear-filter image separately from the color images. The separate processing allowed for enhancement of bright and sharp contrasts in the clear-filter image’s visible features.

The imaging team created a color map by combining the three color images into a single black-and-white image. The color map allowed for mapping isolated regional color differences.

“This ‘color map’ was then superimposed over the clear-filter image . . .,” notes California Institute of Technology’s (Caltech) Susan M. Watanabe in her multimedia feature, “Mimas Showing False Colors -- 1,” published Aug. 5, 2005, on the National Aeronautics and Space Administration’s (NASA) Cassini-Huygens mission page.

The image produced by combining the color map with the brightness image allowed for associating color-differentiated Mimantean surface materials with geological features. “Shades of blue and violet in the image . . . are used to identify surface materials that are bluer in color and have a weaker infrared brightness than average Mimas materials, which are represented by green,” Watanabe explains.

Watanabe’s article includes the separately-processed clear-filter image and the composite image yielded by combining the color map with the processed clear-filter image. Mimas’ prominent feature, Herschel Crater, dominates both images.

The false color image reveals a broad surround of Herschel Crater by the unusual bluer surface materials. Yet, distribution of these materials in and around Herschel is not uniform. The greatest concentration of blueness occurs in the crater’s western environs.

“The origin of the color differences is not yet understood,” Watanabe observes. “It may represent ejecta material that was excavated from inside Mimas when the Herschel impact occurred. The bluer color of these materials may be caused by subtle differences in the surface composition or the sizes of grains making up the icy soil.”

The Cassini-Huygens spacecraft’s Imaging Science Subsystem (ISS) narrow-angle camera (NAC) obtained the four multi-spectral images on Aug. 2, 2005, from a distance of 228,000 kilometers (142,500 miles) from Mimas. The sun-Mimas-spacecraft (phase) angle measured 45 degrees.

At the time of the images, the Cassini-Huygens spacecraft’s position above Mimas was calculated at 25 degrees south latitude, 134 degrees west longitude. Herschel Crater is centered at minus 1.38 degrees south latitude, 111.76 degrees west longitude, according to the International Astronomical Union’s (IAU) Gazetteer of Planetary Nomenclature. The crater’s northernmost and southernmost latitudes reach to 18.14 degrees north and minus 21.5 degrees south, respectively. Its easternmost and westernmost longitudes extend to 90.91 degrees west and 131.1 degrees west, respectively.

Herschel Crater’s diameter, which spans 139 kilometers, approximates one-third of its parent body’s diameter. Mimas has a diameter of 394 kilometers, according to U.S. Astrogeology Science Center astrogeologist Raymond Milner Batson (July 8, 1931-May 5, 2013) in his 1984 NASA-published report, Voyage 1 and 2 Atlas of Six Saturnian Satellites.

The takeaways for the occurrence of infrared brightness in the Herschel Crater vicinity that is weaker than the Mimas norm are that a composite of four images obtained Aug. 2, 2005, by the Cassini-Huygens spacecraft’s narrow-angle camera (NAC) reveals color-differentiated surface materials on Saturnian moon Mimas; that the color variations are associated with geological features; that bluer materials, which have a weaker-than-average infrared brightness, surround Herschel Crater, with the greatest concentration occurring in the crater’s western environs; and that the color differences have a not-yet-understood origin.

View of icy Mimas beyond Saturn’s limb looks, from about 3 degrees above Saturn’s ringplane, toward the rings’ sunlit side; natural color view created from red, green and blue spectral-filter images acquired Sept. 4, 2007, by the Cassini-Huygens spacecraft’s narrow-angle camera (NAC) at approximate distances of 2.7 million kilometers (1.7 million miles) from Saturn and 2.8 million kilometers (1.8 million miles) from Mimas: courtesy NASA / JPL (Jet Propulsion Laboratory) / SSI (Space Science Institute), via NASA Cassini-Huygens mission pages

Acknowledgment

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

Image credits:

Clear-filter image (left), processed for surface feature brightness and sharpness, and composite image (right) of clear-filter’s brightness image and color map of three color images (ultraviolet, green, infrared) reveal color-differentiated variations in the composition or texture of surface materials on seventh-known Saturnian moon Mimas; blue materials = weaker infrared brightness, green materials = average Mimas surface materials; images processed from images obtained Aug. 2, 2005, by the Cassini-Huygens spacecraft’s narrow-angle camera (NAC), from a distance of 228,000 kilometers (142,500 miles); sun-Mimas-spacecraft (phase) angle at 45 degrees: NASA ID PIA06257; image addition date 2005-08-05; image credit NASA/JPL/Space Science Institute: May be used for any purpose without prior permission, via NASA JPL Photojournal @ https://photojournal.jpl.nasa.gov/catalog/PIA06257; 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/PIA06257; via NASA Cassini-Huygens mission pages @ https://www.nasa.gov/mission_pages/cassini/multimedia/pia06257.html

View of icy Mimas beyond Saturn’s limb looks, from about 3 degrees above Saturn’s ringplane, toward the rings’ sunlit side; natural color view created from red, green and blue spectral-filter images acquired Sept. 4, 2007, by the Cassini-Huygens spacecraft’s narrow-angle camera (NAC) at approximate distances of 2.7 million kilometers (1.7 million miles) from Saturn and 2.8 million kilometers (1.8 million miles) from Mimas: courtesy NASA / JPL (Jet Propulsion Laboratory) / SSI (Space Science Institute), via NASA Cassini-Huygens mission pages @ https://www.nasa.gov/mission_pages/cassini/multimedia/pia10478.html

For further information:

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

Herschel, William. “Account of the Discovery of a Sixth and Seventh Satellite of the Planet Saturn; With Remarks on the Construction of Its Ring, Its Atmosphere, Its Rotation on an Axis, and Its Spheroidical Figure. Read November 12, 1789.” Philosophical Transactions of the Royal Society of London, vol. LXXX, for the Year 1790, Part I: 1-20. London UK: Lockyer Davis and Peter Elmsly, Printers to The Royal Society, MDCCXC (1790).
Available via Biodiversity Heritage Library @ https://biodiversitylibrary.org/page/51828893

Herschel, William. “Description of a Forty-Feet Reflecting Telescope. Read June 11, 1795.” Philosophical Transactions of the Royal Society of London for the Year MDCCXCV, vol. LXXXV, Part II: 347-409. London UK: Peter Elmsly, Printer to The Royal Society, 1795.
Available via Biodiversity Heritage Library @ https://biodiversitylibrary.org/page/51831451

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

Lavoie, Sue, site manager. “PIA06259: Mimas Showing False Colors #1.” NASA Jet Propulsion Laboratory Photojournal. Image addition date Aug. 5, 2005.
Available @ https://photojournal.jpl.nasa.gov/catalog/PIA06257

Lavoie, Sue, site manager. “PIA06259: Mimas Showing False Colors #2.” NASA Jet Propulsion Laboratory Photojournal. Image addition date Aug. 8, 2005.
Available @ https://photojournal.jpl.nasa.gov/catalog/PIA06259

Lavoie, Sue, site manager. “PIA10478: Mimas Adrift.” NASA Jet Propulsion Laboratory Photojournal. Image addition date Sept. 26, 2008.
Available @ https://photojournal.jpl.nasa.gov/catalog/PIA10478

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

Marriner, Derdriu. “Mimantean Crater Herschel Displays Subtle Colors in Close Flyby View.” Earth and Space News. Wednesday, Oct. 12, 2011.
Available @ https://earth-and-space-news.blogspot.com/2011/10/mimantean-crater-herschel-displays.html

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. “Mimantean Crater Herschel Partially Overlies Oeta Chasma.” Earth and Space News. Wednesday, Oct. 5, 2011.
Available @ https://earth-and-space-news.blogspot.com/2011/09/mimantean-crater-herschel-partially.html

Marriner, Derdriu. “Mimantean Crater Herschel Reveals Dark Areas in Close Flyby View.” Earth and Space News. Wednesday, Oct. 19, 2011.
Available @ https://earth-and-space-news.blogspot.com/2011/10/mimantean-crater-herschel-reveals-dark.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, Patrick, Sir. Philip’s Atlas of the Universe. Revised edition. London UK: Philip’s, 2005.

NASA’s Jet Propulsion Laboratory, Pasadena, California. “Space Images for NASA / JPL.” NASA Tech Briefs, vol. 34, no. 9 (September 2010): 46-47.
Available via NASA NTRS (NASA Technical Reports Server) @ https://ntrs.nasa.gov/search.jsp?R=20100033535
Available via NASA NTRS (NASA Technical Reports Server) @ https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20100033566.pdf
Available via Tech Briefs @ https://www.techbriefs.com/component/content/article/tb/issue-archive/10999

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

Whatmore, Rebecca, ed. “Bizarre Temperatures on Mimas.” NASA > Mission Pages > Cassini-Huygens Mission to Saturn > Multimedia. March 29, 2010.
Available @ https://www.nasa.gov/mission_pages/cassini/multimedia/pia12867.html

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. “Streaked Craters in False-Color.” NASA > Mission Pages > Cassini-Huygens Mission to Saturn > Multimedia. March 29, 2010. Available @ https://www.nasa.gov/mission_pages/cassini/multimedia/pia12571.html

Whatmore, Rebecca, ed. “Streaks and Markings on Mimas.” NASA > Mission Pages > Cassini-Huygens Mission to Saturn > Multimedia. March 29, 2010.
Available @ https://www.nasa.gov/mission_pages/cassini/multimedia/pia12571.html