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Wahlund JE, Morooka MW, Hadid LZ, Persoon AM, Farrell WM, Gurnett DA, Hospodarsky G, Kurth WS, Ye SY, Andrews DJ, Edberg NJT, Eriksson AI, Vigren E. In situ measurements of Saturn's ionosphere show that it is dynamic and interacts with the rings. Science 2017; 359:66-68. [PMID: 29229651 DOI: 10.1126/science.aao4134] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 11/27/2017] [Indexed: 11/02/2022]
Abstract
The ionized upper layer of Saturn's atmosphere, its ionosphere, provides a closure of currents mediated by the magnetic field to other electrically charged regions (for example, rings) and hosts ion-molecule chemistry. In 2017, the Cassini spacecraft passed inside the planet's rings, allowing in situ measurements of the ionosphere. The Radio and Plasma Wave Science instrument detected a cold, dense, and dynamic ionosphere at Saturn that interacts with the rings. Plasma densities reached up to 1000 cubic centimeters, and electron temperatures were below 1160 kelvin near closest approach. The density varied between orbits by up to two orders of magnitude. Saturn's A- and B-rings cast a shadow on the planet that reduced ionization in the upper atmosphere, causing a north-south asymmetry.
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Affiliation(s)
- J-E Wahlund
- Swedish Institute of Space Physics, Box 537, SE-751 21 Uppsala, Sweden.
| | - M W Morooka
- Swedish Institute of Space Physics, Box 537, SE-751 21 Uppsala, Sweden
| | - L Z Hadid
- Swedish Institute of Space Physics, Box 537, SE-751 21 Uppsala, Sweden
| | - A M Persoon
- Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242, USA
| | - W M Farrell
- Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
| | - D A Gurnett
- Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242, USA
| | - G Hospodarsky
- Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242, USA
| | - W S Kurth
- Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242, USA
| | - S-Y Ye
- Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242, USA
| | - D J Andrews
- Swedish Institute of Space Physics, Box 537, SE-751 21 Uppsala, Sweden
| | - N J T Edberg
- Swedish Institute of Space Physics, Box 537, SE-751 21 Uppsala, Sweden
| | - A I Eriksson
- Swedish Institute of Space Physics, Box 537, SE-751 21 Uppsala, Sweden
| | - E Vigren
- Swedish Institute of Space Physics, Box 537, SE-751 21 Uppsala, Sweden
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Ogawa Y, Buchert SC, Häggström I, Rietveld MT, Fujii R, Nozawa S, Miyaoka H. On the statistical relation between ion upflow and naturally enhanced ion-acoustic lines observed with the EISCAT Svalbard radar. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2010ja015827] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Y. Ogawa
- National Institute of Polar Research; Tokyo Japan
| | | | | | | | - R. Fujii
- Solar-Terrestrial Environment Laboratory; Nagoya University; Nagoya Japan
| | - S. Nozawa
- Solar-Terrestrial Environment Laboratory; Nagoya University; Nagoya Japan
| | - H. Miyaoka
- National Institute of Polar Research; Tokyo Japan
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Abe T. Long-term variation of the polar wind velocity and its implication for the ion acceleration process: Akebono/suprathermal ion mass spectrometer observations. ACTA ACUST UNITED AC 2004. [DOI: 10.1029/2003ja010223] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Ogawa Y. Simultaneous EISCAT Svalbard radar and DMSP observations of ion upflow in the dayside polar ionosphere. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2002ja009590] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Zong QG, Wilken B, Reeves GD, Daglis IA, Doke T, Iyemori T, Livi S, Maezawa K, Mukai T, Kokubun S, Pu ZY, Ullaland S, Woch J, Lepping R, Yamamoto T. Geotail observations of energetic ion species and magnetic field in plasmoid-like structures in the course of an isolated substorm event. ACTA ACUST UNITED AC 1997. [DOI: 10.1029/97ja00076] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Schunk RW, Sojka JJ. Global ionosphere-polar wind system during changing magnetic activity. ACTA ACUST UNITED AC 1997. [DOI: 10.1029/97ja00292] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Daglis IA, Axford WI. Fast ionospheric response to enhanced activity in geospace: Ion feeding of the inner magnetotail. ACTA ACUST UNITED AC 1996. [DOI: 10.1029/95ja02592] [Citation(s) in RCA: 133] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Bernhardt PA, Ganguli G, Kelley MC, Swartz WE. Enhanced radar backscatter from space shuttle exhaust in the ionosphere. ACTA ACUST UNITED AC 1995. [DOI: 10.1029/95ja02836] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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