Imperial College London
Alternate

Professor Southwood

Faculty of Natural Sciences, Department of Physics

Senior Research Investigator
 
 
 
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Contact

 

+44 (0)20 7594 7770d.southwood CV

 
 
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Location

 

711AHuxley BuildingSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Dougherty:2018:10.1126/science.aat5434,
author = {Dougherty, MK and Cao, H and Khurana, KK and Hunt, GJ and Provan, G and Kellock, S and Burton, ME and Burk, TA and Bunce, EJ and Cowley, SWH and Kivelson, MG and Russell, CT and Southwood, DJ},
doi = {10.1126/science.aat5434},
journal = {Science},
pages = {1--9},
title = {Saturn's magnetic field revealed by the Cassini Grand Finale},
url = {http://dx.doi.org/10.1126/science.aat5434},
volume = {362},
year = {2018}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - INTRODUCTIONStarting on 26 April 2017, the Grand Finale phase of the Cassini mission took the spacecraft through the gap between Saturn’s atmosphere and the inner edge of its innermost ring (the D-ring) 22 times, ending with a final plunge into the atmosphere on 15 September 2017. This phase offered an opportunity to investigate Saturn’s internal magnetic field and the electromagnetic environment between the planet and its rings. The internal magnetic field is a diagnostic of interior structure, dynamics, and evolution of the host planet. Rotating convective motion in the highly electrically conducting layer of the planet is thought to maintain the magnetic field through the magnetohydrodynamic (MHD) dynamo process. Saturn’s internal magnetic field is puzzling because of its high symmetry relative to the spin axis, known since the Pioneer 11 flyby. This symmetry prevents an accurate determination of the rotation rate of Saturn’s deep interior and challenges our understanding of the MHD dynamo process because Cowling’s theorem precludes a perfectly axisymmetric magnetic field being maintained through an active dynamo.RATIONALEThe Cassini fluxgate magnetometer was capable of measuring the magnetic field with a time resolution of 32 vectors per s and up to 44,000 nT, which is about twice the peak field strength encountered during the Grand Finale orbits. The combination of star cameras and gyroscopes onboard Cassini provided the attitude determination required to infer the vector components of the magnetic field. External fields from currents in the magnetosphere were modeled explicitly, orbit by orbit.RESULTSSaturn’s magnetic equator, where the magnetic field becomes parallel to the spin axis, is shifted northward from the planetary equator by 2808.5 ± 12 km, confirming the north-south asymmetric nature of Saturn’s magnetic field. After removing the systematic variation with distance from the spin axis, the peak-to-peak
AU  - Dougherty,MK
AU  - Cao,H
AU  - Khurana,KK
AU  - Hunt,GJ
AU  - Provan,G
AU  - Kellock,S
AU  - Burton,ME
AU  - Burk,TA
AU  - Bunce,EJ
AU  - Cowley,SWH
AU  - Kivelson,MG
AU  - Russell,CT
AU  - Southwood,DJ
DO  - 10.1126/science.aat5434
EP  - 9
PY  - 2018///
SN  - 0036-8075
SP  - 1
TI  - Saturn's magnetic field revealed by the Cassini Grand Finale
T2  - Science
UR  - http://dx.doi.org/10.1126/science.aat5434
UR  - https://www.webofscience.com/api/gateway?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000446547100032&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
UR  - https://www.science.org/doi/10.1126/science.aat5434
VL  - 362
ER  -
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