• Publications
  • Influence
A test of general relativity using radio links with the Cassini spacecraft
TLDR
A measurement of the frequency shift of radio photons to and from the Cassini spacecraft as they passed near the Sun agrees with the predictions of standard general relativity with a sensitivity that approaches the level at which, theoretically, deviations are expected in some cosmological models. Expand
The Tides of Titan
TLDR
Gravity data from six flybys of Saturn's moon, Titan, by the Cassini spacecraft suggest that Titan's interior is flexible on tidal time scales with the magnitude of the observed tidal deformations being consistent with the existence of a global subsurface water ocean. Expand
The Gravity Field and Interior Structure of Enceladus
TLDR
The quadrupole gravity field of Enceladus and its hemispherical asymmetry is determined using Doppler data from three spacecraft flybys to indicate the presence of a negative mass anomaly in the south-polar region, largely compensated by a positive subsurface anomaly compatible with the existence of a regional subsurfaced sea at depths of 30 to 40 kilometers. Expand
Gravity Field, Shape, and Moment of Inertia of Titan
TLDR
Gravity data from four flybys of the Cassini spacecraft past Saturn's moon, Titan, is used to model the moon's gravity field and probe its deep interior structure, implying that Titan is a partially differentiated body with a core consisting of a mix of ice and rock or hydrated silicates. Expand
Titan's Rotation Reveals an Internal Ocean and Changing Zonal Winds
TLDR
Cassini radar observations of Saturn's moon Titan over several years show that its rotational period is changing and is different from its orbital period, which is consistent with seasonal exchange of angular momentum between the surface and Titan's dense superrotating atmosphere. Expand
Stochastic Gravitational Wave Background: Upper Limits in the 10–6 to 10–3 Hz Band
We have used precision Doppler tracking of the Cassini spacecraft during its 2001-2002 solar opposition to derive improved observational limits to an isotropic background of low-frequencyExpand
ERRATUM: “DETERMINING TITAN'S SPIN STATE FROM CASSINI RADAR IMAGES” (2008, AJ, 135, 1669)
We previously reported an initial determination of Titan's rotational state from fits to overlapping radar images. We have since discovered a coding error in software used to make these fits, whichExpand
Jupiter’s atmospheric jet streams extend thousands of kilometres deep
TLDR
It is reported that the measured odd gravitational harmonics J3, J5, J7 and J9 indicate that the observed jet streams extend down to depths of thousands of kilometres beneath the cloud level, probably to the region of magnetic dissipation at a depth of about 3,000  kilometres. Expand
Measurement and implications of Saturn’s gravity field and ring mass
TLDR
The results show that Saturn's rings are substantially younger than the planet itself and constrain models of their origin, and five small moons located in and around the rings are presented, confirming that the flows are very deep and likely extend down to the levels where magneticipation occurs. Expand
Hyperion's sponge-like appearance
TLDR
High-resolution images of Hyperion reveal a unique sponge-like appearance at scales of a few kilometres that may enhance preservation of craters by minimizing the amount of ejecta produced or retained, and accordingly may be the crucial factor in crafting this unusual surface. Expand
...
1
2
3
4
5
...