A deep search for Martian dust rings and inner moons using the Hubble Space Telescope |
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| Institution: | 1. Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301, USA;2. NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA;3. Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109, USA;4. Malin Space Science Systems, 5880 Pacific Center Blvd., San Diego, CA 92121, USA;5. John Hopkins University Applied Physics Laboratory, Columbia, MD 20723, USA;6. Laboratoire Atmosphères Milieux Observations Spatiales, Paris, France;7. Royal Belgian Institute for Space Aeronomy BIRA-IASB, Brussels, Belgium;1. Department of Astronomy, University of Maryland, College Park, MD 20742, United States;2. NASA Goddard Space Flight Center, Greenbelt, MD 20771, United States;3. Space Science Institute, Boulder, CO 80301, United States;4. Planetary Science Institute, Tucson, AZ 85719, United States;5. Texas A&M University, College Station, TX 77843, United States;6. Los Alamos National Laboratory, Los Alamos, NM 87544, United States;7. Institut de Recherche en Astrophysique et Planetologie, Toulouse, France;8. Finnish Meteorological Institute, Helsinki, Finland;9. Kansas State University, Manhattan, KS 66506, United States;10. Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI 48109, United States;11. Jet Propulsion Laboratory, Pasadena, CA 91109, United States;12. Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723-6005, United States;13. Arizona State University, Tempe, AZ 85287-0002, United States;1. IAPS-INAF, Via del Fosso del Cavaliere 100, 00133 Rome, Italy;2. Italian Space Agency ASI, Rome, Italy;3. The University of Texas, Austin, TX, USA;4. IASB-BIRA, Bruxelles, Belgium;5. LMD, CNRS, Paris, France |
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| Abstract: | It has long been suspected that Mars might be encircled by two faint rings, one originating from each of its moons Phobos and Deimos. Meteoroid impacts into these moons should release clouds of dust that quickly spread out to become rings; similar dust rings have been associated with several small inner moons of the gas giants. On May 28, 2001 Mars’ hypothetical ring plane appeared edge-on to Earth within weeks of its opposition, providing the best Earth-based opportunity to detect these rings in several decades. Using the Wide Field/Planetary Camera 2 (WFPC2) on the Hubble Space Telescope, we obtained a set of deep exposures off the east and west limbs of Mars to search for these hypothetical rings. No rings were detected. This result limits normal optical depths to ～3×10?8 for the Phobos ring and ～10?7 for the Deimos ring. These limits fall at the low end of prior dynamical predictions and a factor of 1000 below previous observational limits. However, our limit for the Deimos ring is more tentative because of large uncertainties about this ring's expected shape, size and orientation. Our data set is also sensitive to small, previously undetected inner moons. No moons were detected down to a radius limit of 75–125 m. Longitudinal coverage of the region near and between Phobos and Deimos is 40–80% complete. We conclude by describing a promising opportunity for further Martian ring viewing in December 2007. |
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