A team of scientists from the Lunar and Planetary Laboratory at the University of Arizona, TU Delft, and Caltech has developed a new method to compute how tides affect the interiors of planets and moons in the Solar System. Importantly, they’ve looked at the effects of body tides on objects that don’t have a perfectly spherical interior structure.
The surface of Europa looms large in this newly-reprocessed color view; image scale is 1.6 km per pixel; north on Europa is at right. Image credit: NASA / JPL-Caltech / SETI Institute.
Body tides refer to the deformations experienced by celestial bodies when they gravitationally interact with other objects.
Think of how the powerful gravity of Jupiter tugs on its icy moon Europa.
Because Europa’s orbit isn’t circular, the crushing squeeze of Jupiter’s gravity on the moon varies as it travels along its orbit.
When Europa is at its closest to Jupiter, the planet’s gravity is felt the most.
The energy of this deformation is what heats up Europa’s interior, allowing an ocean of liquid water to exist beneath the moon’s icy surface.
“The same is true for Saturn’s moon Enceladus,” said Dr. Alexander Berne, a researcher at Caltech.
“Enceladus has an ice shell that is expected to be much more non-spherically symmetric than that of Europa.”
The body tides experienced by celestial bodies can affect how the worlds evolve over time and, in cases like Europa and Enceladus, their potential habitability for life as we know it.
“While the tidal response of a spherically symmetric body has the same wavelength as the tidal force; lateral heterogeneities produce an additional tidal response with a spectra that depends on the spatial pattern of such variations,” the researchers said.
“For Mercury, the Moon, and Io, the amplitude of this signal is as high as 1-10% of the main tidal response for long-wavelength shear modulus variations higher than approximately 10% of the mean shear modulus.”
“For Europa, Ganymede, and Enceladus, shell-thickness variations of 50% of the mean shell thickness can cause an additional signal of approximately 1% and approximately 10% for the Jovian moons and Enceladus, respectively.”
The authors also discussed how the results could help scientists interpret observations made by missions to a variety of different worlds, ranging from Mercury to the Moon to the outer planets of our Solar System.
“Future missions, such as BepiColombo and JUICE, might measure these signals,” they said.
“Lateral variations of viscosity affect the distribution of tidal heating.”
“This can drive the thermal evolution of tidally active bodies and affect the distribution of active regions.”
The findings appear in the Planetary Science Journal.
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Marc Rovira-Navarro et al. 2024. A Spectral Method to Compute the Tides of Laterally Heterogeneous Bodies. Planet. Sci. J 5, 129; doi: 10.3847/PSJ/ad381f
This article is a version of a press-release provided by NASA.
