Models of Saturn's equatorial ionosphere based on in situ data from Cassini's grand finale
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
We present new models of Saturn's equatorial ionosphere based on the first in situ measurements of its upper atmosphere. The neutral spectrum measured by Cassini's Ion and Neutral Mass Spectrometer, which includes substantial methane, ammonia, and organics in addition to the anticipated molecular hydrogen, helium, and water, serves as input for unexpectedly complex ionospheric chemistry. Heavy molecular ions are found to dominate Saturn's equatorial low‐altitude ionosphere, with a mean ion mass of 11 Da. Key molecular ions include H3O+ and HCO+; other abundant heavy ions depend upon the makeup of the mass 28 neutral species, which cannot be uniquely determined. Ion and Neutral Mass Spectrometer neutral species lead to generally good agreement between modeled and observed plasma densities, though poor reproduction of measured H+ and H3+ variability and an overabundance of modeled H3+ potentially hint at missing physical processes in the model, including a loss process that affects H3+ but not H+.
Date Issued
2018-09-27
Date Acceptance
2018-07-03
Citation
Geophysical Research Letters, 2018, 45 (18), pp.9398-9407
ISSN
0094-8276
Publisher
American Geophysical Union
Start Page
9398
End Page
9407
Journal / Book Title
Geophysical Research Letters
Volume
45
Issue
18
Copyright Statement
©2018. American Geophysical Union. All Rights Reserved.
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000447761300008&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Subjects
Science & Technology
Physical Sciences
Geosciences, Multidisciplinary
Geology
Saturn
Cassini
ionosphere
ATMOSPHERE
THERMOSPHERE
CHEMISTRY
INFLUX
SYSTEM
WATER
ION
Publication Status
Published
Date Publish Online
2018-09-25