D J Southwood | PubMed Health

PubMed2005

Cassini magnetometer observations during Saturn orbit insertion.

Cassini's successful orbit insertion has provided the first examination of Saturn's magnetosphere in 23 years, revealing a dynamic plasma and magnetic environment on short and long time scales. There has been no noticeable change in the internal magnetic field, either in its strength or its near-alignment with the rotation axis. However, the external magnetic field is different compared with past spacecraft observations. The current sheet within the magnetosphere is thinner and more extended, and we observed small diamagnetic cavities and ion cyclotron waves of types that were not reported before.

Journal Article↗

PubMed1997

Europa's magnetic signature: report from Galileo's pass on 19 December 1996.

On 19 December 1996 as Galileo passed close to Jupiter's moon, Europa, the magnetometer measured substantial departures from the slowly varying background field of Jupiter's magnetosphere. Currents coupling Europa to Jupiter's magnetospheric plasma could produce perturbations of the observed size. However, the trend of the field perturbations is here modeled as the signature of a Europa-centered dipole moment whose maximum surface magnitude is approximately 240 nanotesla, giving a rough upper limit to the internal field. The dipole orientation is oblique to Europa's spin axis. This orientation may not be probable for a field generated by a core dynamo, but higher order multipoles may be important as they are at Uranus and Neptune. Although the data can be modeled as contributions of an internal field of Europa, they do not confirm its existence. The dipole orientation is also oblique to the imposed field of Jupiter and thus not directly produced as a response to that field. Close to Europa, plasma currents appear to produce perturbations with scale sizes that are small compared with a Europa radius.

Extraterrestrial Environment↗