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Hayes AG, Corlies P, Tate C, Barrington M, Bell JF, Maki JN, Caplinger M, Ravine M, Kinch KM, Herkenhoff K, Horgan B, Johnson J, Lemmon M, Paar G, Rice MS, Jensen E, Kubacki TM, Cloutis E, Deen R, Ehlmann BL, Lakdawalla E, Sullivan R, Winhold A, Parkinson A, Bailey Z, van Beek J, Caballo-Perucha P, Cisneros E, Dixon D, Donaldson C, Jensen OB, Kuik J, Lapo K, Magee A, Merusi M, Mollerup J, Scudder N, Seeger C, Stanish E, Starr M, Thompson M, Turenne N, Winchell K. Pre-Flight Calibration of the Mars 2020 Rover Mastcam Zoom (Mastcam-Z) Multispectral, Stereoscopic Imager. Space Sci Rev 2021; 217:29. [PMID: 33678912 PMCID: PMC7892537 DOI: 10.1007/s11214-021-00795-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 01/12/2021] [Indexed: 05/28/2023]
Abstract
UNLABELLED The NASA Perseverance rover Mast Camera Zoom (Mastcam-Z) system is a pair of zoomable, focusable, multi-spectral, and color charge-coupled device (CCD) cameras mounted on top of a 1.7 m Remote Sensing Mast, along with associated electronics and two calibration targets. The cameras contain identical optical assemblies that can range in focal length from 26 mm ( 25.5 ∘ × 19.1 ∘ FOV ) to 110 mm ( 6.2 ∘ × 4.2 ∘ FOV ) and will acquire data at pixel scales of 148-540 μm at a range of 2 m and 7.4-27 cm at 1 km. The cameras are mounted on the rover's mast with a stereo baseline of 24.3 ± 0.1 cm and a toe-in angle of 1.17 ± 0.03 ∘ (per camera). Each camera uses a Kodak KAI-2020 CCD with 1600 × 1200 active pixels and an 8 position filter wheel that contains an IR-cutoff filter for color imaging through the detectors' Bayer-pattern filters, a neutral density (ND) solar filter for imaging the sun, and 6 narrow-band geology filters (16 total filters). An associated Digital Electronics Assembly provides command data interfaces to the rover, 11-to-8 bit companding, and JPEG compression capabilities. Herein, we describe pre-flight calibration of the Mastcam-Z instrument and characterize its radiometric and geometric behavior. Between April 26 t h and May 9 t h , 2019, ∼45,000 images were acquired during stand-alone calibration at Malin Space Science Systems (MSSS) in San Diego, CA. Additional data were acquired during Assembly Test and Launch Operations (ATLO) at the Jet Propulsion Laboratory and Kennedy Space Center. Results of the radiometric calibration validate a 5% absolute radiometric accuracy when using camera state parameters investigated during testing. When observing using camera state parameters not interrogated during calibration (e.g., non-canonical zoom positions), we conservatively estimate the absolute uncertainty to be < 10 % . Image quality, measured via the amplitude of the Modulation Transfer Function (MTF) at Nyquist sampling (0.35 line pairs per pixel), shows MTF Nyquist = 0.26 - 0.50 across all zoom, focus, and filter positions, exceeding the > 0.2 design requirement. We discuss lessons learned from calibration and suggest tactical strategies that will optimize the quality of science data acquired during operation at Mars. While most results matched expectations, some surprises were discovered, such as a strong wavelength and temperature dependence on the radiometric coefficients and a scene-dependent dynamic component to the zero-exposure bias frames. Calibration results and derived accuracies were validated using a Geoboard target consisting of well-characterized geologic samples. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1007/s11214-021-00795-x.
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Affiliation(s)
- Alexander G. Hayes
- Department of Astronomy, Cornell University, Ithaca, NY 14850 USA
- Cornell Center for Astrophysics and Planetary Science, Cornell University, Ithaca, NY 14850 USA
| | - P. Corlies
- Department of Astronomy, Cornell University, Ithaca, NY 14850 USA
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
| | - C. Tate
- Department of Astronomy, Cornell University, Ithaca, NY 14850 USA
| | - M. Barrington
- Department of Astronomy, Cornell University, Ithaca, NY 14850 USA
| | - J. F. Bell
- School of Earth and Space Exploration, Arizona State University, Phoenix, AZ 85287 USA
| | - J. N. Maki
- Jet Propulsion Laboratory, Pasadena, CA 91109 USA
| | - M. Caplinger
- Malin Space Science Systems, San Diego, CA 92121 USA
| | - M. Ravine
- Malin Space Science Systems, San Diego, CA 92121 USA
| | - K. M. Kinch
- Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - K. Herkenhoff
- USGS Astrogeology Science Center, 2255 N. Gemini Drive, Flagstaff, AZ 86001 USA
| | - B. Horgan
- Earth, Atmospheric, and Planetary Sciences Department, Purdue University, West Lafayette, IN 47907 USA
| | - J. Johnson
- Johns Hopkins Applied Physics Laboratory, Laurel, MD 20723 USA
| | - M. Lemmon
- Space Science Institute, 4765 Walnut St., Suite B, Boulder, CO 80301 USA
| | - G. Paar
- Joanneum Research Forschungsgesellschaft mbH, Steyrergasse 17, 8010 Graz, Austria
| | - M. S. Rice
- Geology Department, Western Washington University, Bellingham, WA 98225 USA
| | - E. Jensen
- Malin Space Science Systems, San Diego, CA 92121 USA
| | - T. M. Kubacki
- Malin Space Science Systems, San Diego, CA 92121 USA
| | - E. Cloutis
- Geography Department, University of Winnepeg, 515 Portage Ave, Winnipeg, MB R3B 2E9 Canada
| | - R. Deen
- Jet Propulsion Laboratory, Pasadena, CA 91109 USA
| | - B. L. Ehlmann
- Jet Propulsion Laboratory, Pasadena, CA 91109 USA
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91101 USA
| | - E. Lakdawalla
- The Planetary Society, 60 S Los Robles, Pasadena, CA 91101 USA
| | - R. Sullivan
- Cornell Center for Astrophysics and Planetary Science, Cornell University, Ithaca, NY 14850 USA
| | - A. Winhold
- School of Earth and Space Exploration, Arizona State University, Phoenix, AZ 85287 USA
| | - A. Parkinson
- Centre for Terrestrial and Planetary Exploration, University of Winnipeg, 515 Portage Ave, Winnipeg, MB R3B 2E9 Canada
| | - Z. Bailey
- Jet Propulsion Laboratory, Pasadena, CA 91109 USA
| | - J. van Beek
- Jet Propulsion Laboratory, Pasadena, CA 91109 USA
| | - P. Caballo-Perucha
- Joanneum Research Forschungsgesellschaft mbH, Steyrergasse 17, 8010 Graz, Austria
| | - E. Cisneros
- School of Earth and Space Exploration, Arizona State University, Phoenix, AZ 85287 USA
| | - D. Dixon
- Malin Space Science Systems, San Diego, CA 92121 USA
| | - C. Donaldson
- Malin Space Science Systems, San Diego, CA 92121 USA
| | - O. B. Jensen
- Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - J. Kuik
- Centre for Terrestrial and Planetary Exploration, University of Winnipeg, 515 Portage Ave, Winnipeg, MB R3B 2E9 Canada
| | - K. Lapo
- Geology Department, Western Washington University, Bellingham, WA 98225 USA
| | - A. Magee
- Malin Space Science Systems, San Diego, CA 92121 USA
| | - M. Merusi
- Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - J. Mollerup
- Geology Department, Western Washington University, Bellingham, WA 98225 USA
| | - N. Scudder
- Earth, Atmospheric, and Planetary Sciences Department, Purdue University, West Lafayette, IN 47907 USA
| | - C. Seeger
- Geology Department, Western Washington University, Bellingham, WA 98225 USA
| | - E. Stanish
- Centre for Terrestrial and Planetary Exploration, University of Winnipeg, 515 Portage Ave, Winnipeg, MB R3B 2E9 Canada
| | - M. Starr
- Malin Space Science Systems, San Diego, CA 92121 USA
| | - M. Thompson
- Jet Propulsion Laboratory, Pasadena, CA 91109 USA
| | - N. Turenne
- Centre for Terrestrial and Planetary Exploration, University of Winnipeg, 515 Portage Ave, Winnipeg, MB R3B 2E9 Canada
| | - K. Winchell
- Malin Space Science Systems, San Diego, CA 92121 USA
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Bell JF, Maki JN, Mehall GL, Ravine MA, Caplinger MA, Bailey ZJ, Brylow S, Schaffner JA, Kinch KM, Madsen MB, Winhold A, Hayes AG, Corlies P, Tate C, Barrington M, Cisneros E, Jensen E, Paris K, Crawford K, Rojas C, Mehall L, Joseph J, Proton JB, Cluff N, Deen RG, Betts B, Cloutis E, Coates AJ, Colaprete A, Edgett KS, Ehlmann BL, Fagents S, Grotzinger JP, Hardgrove C, Herkenhoff KE, Horgan B, Jaumann R, Johnson JR, Lemmon M, Paar G, Caballo-Perucha M, Gupta S, Traxler C, Preusker F, Rice MS, Robinson MS, Schmitz N, Sullivan R, Wolff MJ. The Mars 2020 Perseverance Rover Mast Camera Zoom (Mastcam-Z) Multispectral, Stereoscopic Imaging Investigation. Space Sci Rev 2021; 217:24. [PMID: 33612866 PMCID: PMC7883548 DOI: 10.1007/s11214-020-00755-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 09/25/2020] [Indexed: 05/16/2023]
Abstract
Mastcam-Z is a multispectral, stereoscopic imaging investigation on the Mars 2020 mission's Perseverance rover. Mastcam-Z consists of a pair of focusable, 4:1 zoomable cameras that provide broadband red/green/blue and narrowband 400-1000 nm color imaging with fields of view from 25.6° × 19.2° (26 mm focal length at 283 μrad/pixel) to 6.2° × 4.6° (110 mm focal length at 67.4 μrad/pixel). The cameras can resolve (≥ 5 pixels) ∼0.7 mm features at 2 m and ∼3.3 cm features at 100 m distance. Mastcam-Z shares significant heritage with the Mastcam instruments on the Mars Science Laboratory Curiosity rover. Each Mastcam-Z camera consists of zoom, focus, and filter wheel mechanisms and a 1648 × 1214 pixel charge-coupled device detector and electronics. The two Mastcam-Z cameras are mounted with a 24.4 cm stereo baseline and 2.3° total toe-in on a camera plate ∼2 m above the surface on the rover's Remote Sensing Mast, which provides azimuth and elevation actuation. A separate digital electronics assembly inside the rover provides power, data processing and storage, and the interface to the rover computer. Primary and secondary Mastcam-Z calibration targets mounted on the rover top deck enable tactical reflectance calibration. Mastcam-Z multispectral, stereo, and panoramic images will be used to provide detailed morphology, topography, and geologic context along the rover's traverse; constrain mineralogic, photometric, and physical properties of surface materials; monitor and characterize atmospheric and astronomical phenomena; and document the rover's sample extraction and caching locations. Mastcam-Z images will also provide key engineering information to support sample selection and other rover driving and tool/instrument operations decisions.
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Affiliation(s)
| | | | | | - M. A. Ravine
- Malin Space Science Systems, Inc., San Diego, CA USA
| | | | | | - S. Brylow
- Malin Space Science Systems, Inc., San Diego, CA USA
| | | | | | | | | | | | | | - C. Tate
- Cornell Univ., Ithaca, NY USA
| | | | | | - E. Jensen
- Malin Space Science Systems, Inc., San Diego, CA USA
| | - K. Paris
- Arizona State Univ., Tempe, AZ USA
| | | | - C. Rojas
- Arizona State Univ., Tempe, AZ USA
| | | | | | | | - N. Cluff
- Arizona State Univ., Tempe, AZ USA
| | | | - B. Betts
- The Planetary Society, Pasadena, CA USA
| | | | - A. J. Coates
- Mullard Space Science Laboratory, Univ. College, London, UK
| | - A. Colaprete
- NASA/Ames Research Center, Moffett Field, CA USA
| | - K. S. Edgett
- Malin Space Science Systems, Inc., San Diego, CA USA
| | - B. L. Ehlmann
- JPL/Caltech, Pasadena, CA USA
- Caltech, Pasadena, CA USA
| | | | | | | | | | | | - R. Jaumann
- Inst. of Geological Sciences, Free University Berlin, Berlin, Germany
| | | | - M. Lemmon
- Space Science Inst., Boulder, CO USA
| | - G. Paar
- Joanneum Research, Graz, Austria
| | | | | | | | - F. Preusker
- DLR/German Aerospace Center, Berlin, Germany
| | - M. S. Rice
- Western Washington Univ., Bellingham, WA USA
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Herkenhoff KE, Squyres SW, Arvidson R, Bass DS, Bell JF, Bertelsen P, Cabrol NA, Gaddis L, Hayes AG, Hviid SF, Johnson JR, Kinch KM, Madsen MB, Maki JN, McLennan SM, McSween HY, Rice JW, Sims M, Smith PH, Soderblom LA, Spanovich N, Sullivan R, Wang A. Textures of the Soils and Rocks at Gusev Crater from Spirit's Microscopic Imager. Science 2004. [DOI: 10.1126/science.3050824] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- K. E. Herkenhoff
- U.S. Geological Survey Astrogeology Team, Flagstaff, AZ 86001, USA
- Department of Astronomy, Space Sciences Building, Cornell University, Ithaca, NY 14853, USA
- Department of Earth and Space Sciences, Washington University, St. Louis, MO 63130, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
- Center for Planetary Science, Danish Space Research Institute and Niels Bohr Institute for Astronomy, Physics, and Geophysics, University of Copenhagen, Denmark
| | - S. W. Squyres
- U.S. Geological Survey Astrogeology Team, Flagstaff, AZ 86001, USA
- Department of Astronomy, Space Sciences Building, Cornell University, Ithaca, NY 14853, USA
- Department of Earth and Space Sciences, Washington University, St. Louis, MO 63130, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
- Center for Planetary Science, Danish Space Research Institute and Niels Bohr Institute for Astronomy, Physics, and Geophysics, University of Copenhagen, Denmark
| | - R. Arvidson
- U.S. Geological Survey Astrogeology Team, Flagstaff, AZ 86001, USA
- Department of Astronomy, Space Sciences Building, Cornell University, Ithaca, NY 14853, USA
- Department of Earth and Space Sciences, Washington University, St. Louis, MO 63130, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
- Center for Planetary Science, Danish Space Research Institute and Niels Bohr Institute for Astronomy, Physics, and Geophysics, University of Copenhagen, Denmark
| | - D. S. Bass
- U.S. Geological Survey Astrogeology Team, Flagstaff, AZ 86001, USA
- Department of Astronomy, Space Sciences Building, Cornell University, Ithaca, NY 14853, USA
- Department of Earth and Space Sciences, Washington University, St. Louis, MO 63130, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
- Center for Planetary Science, Danish Space Research Institute and Niels Bohr Institute for Astronomy, Physics, and Geophysics, University of Copenhagen, Denmark
| | - J. F. Bell
- U.S. Geological Survey Astrogeology Team, Flagstaff, AZ 86001, USA
- Department of Astronomy, Space Sciences Building, Cornell University, Ithaca, NY 14853, USA
- Department of Earth and Space Sciences, Washington University, St. Louis, MO 63130, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
- Center for Planetary Science, Danish Space Research Institute and Niels Bohr Institute for Astronomy, Physics, and Geophysics, University of Copenhagen, Denmark
| | - P. Bertelsen
- U.S. Geological Survey Astrogeology Team, Flagstaff, AZ 86001, USA
- Department of Astronomy, Space Sciences Building, Cornell University, Ithaca, NY 14853, USA
- Department of Earth and Space Sciences, Washington University, St. Louis, MO 63130, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
- Center for Planetary Science, Danish Space Research Institute and Niels Bohr Institute for Astronomy, Physics, and Geophysics, University of Copenhagen, Denmark
| | - N. A. Cabrol
- U.S. Geological Survey Astrogeology Team, Flagstaff, AZ 86001, USA
- Department of Astronomy, Space Sciences Building, Cornell University, Ithaca, NY 14853, USA
- Department of Earth and Space Sciences, Washington University, St. Louis, MO 63130, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
- Center for Planetary Science, Danish Space Research Institute and Niels Bohr Institute for Astronomy, Physics, and Geophysics, University of Copenhagen, Denmark
| | - L. Gaddis
- U.S. Geological Survey Astrogeology Team, Flagstaff, AZ 86001, USA
- Department of Astronomy, Space Sciences Building, Cornell University, Ithaca, NY 14853, USA
- Department of Earth and Space Sciences, Washington University, St. Louis, MO 63130, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
- Center for Planetary Science, Danish Space Research Institute and Niels Bohr Institute for Astronomy, Physics, and Geophysics, University of Copenhagen, Denmark
| | - A. G. Hayes
- U.S. Geological Survey Astrogeology Team, Flagstaff, AZ 86001, USA
- Department of Astronomy, Space Sciences Building, Cornell University, Ithaca, NY 14853, USA
- Department of Earth and Space Sciences, Washington University, St. Louis, MO 63130, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
- Center for Planetary Science, Danish Space Research Institute and Niels Bohr Institute for Astronomy, Physics, and Geophysics, University of Copenhagen, Denmark
| | - S. F. Hviid
- U.S. Geological Survey Astrogeology Team, Flagstaff, AZ 86001, USA
- Department of Astronomy, Space Sciences Building, Cornell University, Ithaca, NY 14853, USA
- Department of Earth and Space Sciences, Washington University, St. Louis, MO 63130, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
- Center for Planetary Science, Danish Space Research Institute and Niels Bohr Institute for Astronomy, Physics, and Geophysics, University of Copenhagen, Denmark
| | - J. R. Johnson
- U.S. Geological Survey Astrogeology Team, Flagstaff, AZ 86001, USA
- Department of Astronomy, Space Sciences Building, Cornell University, Ithaca, NY 14853, USA
- Department of Earth and Space Sciences, Washington University, St. Louis, MO 63130, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
- Center for Planetary Science, Danish Space Research Institute and Niels Bohr Institute for Astronomy, Physics, and Geophysics, University of Copenhagen, Denmark
| | - K. M. Kinch
- U.S. Geological Survey Astrogeology Team, Flagstaff, AZ 86001, USA
- Department of Astronomy, Space Sciences Building, Cornell University, Ithaca, NY 14853, USA
- Department of Earth and Space Sciences, Washington University, St. Louis, MO 63130, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
- Center for Planetary Science, Danish Space Research Institute and Niels Bohr Institute for Astronomy, Physics, and Geophysics, University of Copenhagen, Denmark
| | - M. B. Madsen
- U.S. Geological Survey Astrogeology Team, Flagstaff, AZ 86001, USA
- Department of Astronomy, Space Sciences Building, Cornell University, Ithaca, NY 14853, USA
- Department of Earth and Space Sciences, Washington University, St. Louis, MO 63130, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
- Center for Planetary Science, Danish Space Research Institute and Niels Bohr Institute for Astronomy, Physics, and Geophysics, University of Copenhagen, Denmark
| | - J. N. Maki
- U.S. Geological Survey Astrogeology Team, Flagstaff, AZ 86001, USA
- Department of Astronomy, Space Sciences Building, Cornell University, Ithaca, NY 14853, USA
- Department of Earth and Space Sciences, Washington University, St. Louis, MO 63130, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
- Center for Planetary Science, Danish Space Research Institute and Niels Bohr Institute for Astronomy, Physics, and Geophysics, University of Copenhagen, Denmark
| | - S. M. McLennan
- U.S. Geological Survey Astrogeology Team, Flagstaff, AZ 86001, USA
- Department of Astronomy, Space Sciences Building, Cornell University, Ithaca, NY 14853, USA
- Department of Earth and Space Sciences, Washington University, St. Louis, MO 63130, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
- Center for Planetary Science, Danish Space Research Institute and Niels Bohr Institute for Astronomy, Physics, and Geophysics, University of Copenhagen, Denmark
| | - H. Y. McSween
- U.S. Geological Survey Astrogeology Team, Flagstaff, AZ 86001, USA
- Department of Astronomy, Space Sciences Building, Cornell University, Ithaca, NY 14853, USA
- Department of Earth and Space Sciences, Washington University, St. Louis, MO 63130, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
- Center for Planetary Science, Danish Space Research Institute and Niels Bohr Institute for Astronomy, Physics, and Geophysics, University of Copenhagen, Denmark
| | - J. W. Rice
- U.S. Geological Survey Astrogeology Team, Flagstaff, AZ 86001, USA
- Department of Astronomy, Space Sciences Building, Cornell University, Ithaca, NY 14853, USA
- Department of Earth and Space Sciences, Washington University, St. Louis, MO 63130, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
- Center for Planetary Science, Danish Space Research Institute and Niels Bohr Institute for Astronomy, Physics, and Geophysics, University of Copenhagen, Denmark
| | - M. Sims
- U.S. Geological Survey Astrogeology Team, Flagstaff, AZ 86001, USA
- Department of Astronomy, Space Sciences Building, Cornell University, Ithaca, NY 14853, USA
- Department of Earth and Space Sciences, Washington University, St. Louis, MO 63130, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
- Center for Planetary Science, Danish Space Research Institute and Niels Bohr Institute for Astronomy, Physics, and Geophysics, University of Copenhagen, Denmark
| | - P. H. Smith
- U.S. Geological Survey Astrogeology Team, Flagstaff, AZ 86001, USA
- Department of Astronomy, Space Sciences Building, Cornell University, Ithaca, NY 14853, USA
- Department of Earth and Space Sciences, Washington University, St. Louis, MO 63130, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
- Center for Planetary Science, Danish Space Research Institute and Niels Bohr Institute for Astronomy, Physics, and Geophysics, University of Copenhagen, Denmark
| | - L. A. Soderblom
- U.S. Geological Survey Astrogeology Team, Flagstaff, AZ 86001, USA
- Department of Astronomy, Space Sciences Building, Cornell University, Ithaca, NY 14853, USA
- Department of Earth and Space Sciences, Washington University, St. Louis, MO 63130, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
- Center for Planetary Science, Danish Space Research Institute and Niels Bohr Institute for Astronomy, Physics, and Geophysics, University of Copenhagen, Denmark
| | - N. Spanovich
- U.S. Geological Survey Astrogeology Team, Flagstaff, AZ 86001, USA
- Department of Astronomy, Space Sciences Building, Cornell University, Ithaca, NY 14853, USA
- Department of Earth and Space Sciences, Washington University, St. Louis, MO 63130, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
- Center for Planetary Science, Danish Space Research Institute and Niels Bohr Institute for Astronomy, Physics, and Geophysics, University of Copenhagen, Denmark
| | - R. Sullivan
- U.S. Geological Survey Astrogeology Team, Flagstaff, AZ 86001, USA
- Department of Astronomy, Space Sciences Building, Cornell University, Ithaca, NY 14853, USA
- Department of Earth and Space Sciences, Washington University, St. Louis, MO 63130, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
- Center for Planetary Science, Danish Space Research Institute and Niels Bohr Institute for Astronomy, Physics, and Geophysics, University of Copenhagen, Denmark
| | - A. Wang
- U.S. Geological Survey Astrogeology Team, Flagstaff, AZ 86001, USA
- Department of Astronomy, Space Sciences Building, Cornell University, Ithaca, NY 14853, USA
- Department of Earth and Space Sciences, Washington University, St. Louis, MO 63130, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
- Center for Planetary Science, Danish Space Research Institute and Niels Bohr Institute for Astronomy, Physics, and Geophysics, University of Copenhagen, Denmark
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