A new concept for seismology on Venus using orbiting radar instead of landers

Magellan images of Venus show extensive faulting and fracturing, suggesting movement of the planet's crust and the current possibility of frequent Venus quakes. The high surface temperature and pressure of the planet is, however, such that a long lived network would be extremely challenging and probably financially prohibitive. We propose therefore to use the strong coupling between the atmosphere and the solid planet for detecting surface waves generated by quakes on Venus. After a quake, the surface of a planet is vibrating horizontally and vertically. By continuity, the atmosphere at the surface must move with a vertical velocity equal to the surface vertical velocity, and this vibration is then propagated upward. Its kinetic energy is conserved as long as the atmospheric viscosity does not produce significant attenuation. Due to the exponential decay of density with altitude, the amplitude of the wave increases exponentially and produces significant perturbations of the electron density in the ionosphere. Such signals are now commonly observed on the Earth for large quakes, both with ground Doppler HF sounders and space-based GPS satellites. We show that the dense atmosphere of Venus amplifies this effect by a factor of about 100 compared to the Earth. Moreover, the structure of the ionosphere makes radar observations of these signals from above easier than on Earth. We present simulations and estimates of the detection threshold of this new strategy for Venus seismology. A general concept of the experiment is then proposed.