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Plasma Escape from Unmagnetized BodiesA considerable fraction of atmospheric loss at Venus and Titan is in the form of plasma escape. This is due in part to the fact that the ionospheres of these unmagnetized bodies interact directly with the high speed plasmas flowing around them. The similarities of the interactions help reinforce interpretations of measurements made at each body, especially when instruments and measurement sites differ. For example, it is well established through this method that ions born in the exospheres above the ionopauses are picked up and carried away by the solar wind at Venus and the rotating plasma in Saturn's magnetosphere. On the other hand, it is more difficult to relate the observations associated with escape of cooler ionospheric plasma down the ionotails of each body. A clear example of ionospheric plasma escaping Titan was observed as it flowed down its ionotail (1). Measurements at Venus have not as yet clearly distinguished between ionospheric and pickup ion escape in the ionotail; however, cold ions detected in the distant wake at 1 AU by the CELIAS/CTOF instrument on SOHO have been interpreted as ionospheric in origin (2). An algorithm to determine ionospheric flow from Pioneer Venus aeronomical measurements is used to show that escape of cold ionospheric plasma is likely to occur. These results along with plasma flow measurements made in the ionotail of Venus are combined and compared to the corresponding flow at Titan.
Document ID
19990116523
Acquisition Source
Goddard Space Flight Center
Document Type
Preprint (Draft being sent to journal)
Authors
Hartle, R. E.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Grebowsky, J. M.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Intriligator, D. S.
(Carmel Research Center Santa Monica, CA United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 1998
Subject Category
Lunar And Planetary Exploration
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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