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A test of general relativity using radio links with the Cassini spacecraft
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.
The Gravity Field and Interior Structure of Enceladus
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.
The Tides of Titan
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.
Gravity Field, Shape, and Moment of Inertia of Titan
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.
Titan's Rotation Reveals an Internal Ocean and Changing Zonal Winds
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.
Measurement and implications of Saturn’s gravity field and ring mass
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.
Measurement of Jupiter’s asymmetric gravity field
Measurements of Jupiter’s gravity harmonics are reported through precise Doppler tracking of the Juno spacecraft in its polar orbit around Jupiter, finding a north–south asymmetry, which is a signature of atmospheric and interior flows.
Jupiter’s atmospheric jet streams extend thousands of kilometres deep
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.
A suppression of differential rotation in Jupiter’s deep interior
It is found that the deep interior of the planet rotates nearly as a rigid body, with differential rotation decreasing by at least an order of magnitude compared to the atmosphere, making it fully consistent with the constraints obtained independently from the odd gravitational harmonics.
Spacecraft Doppler tracking: Noise budget and accuracy achievable in precision radio science observations
We discuss noise in Doppler tracking of deep space probes and provide a detailed noise model for Doppler radio science experiments. The most sensitive current experiments achieve fractional frequency…