Rates of temperature change of airless landscapes and implications for thermal stress weathering

Thermal stress weathering may play a role in the evolution of terrestrial-planet landscapes, particularly those without atmospheres, by contributing to rock breakdown, regolith production, and crater degradation. Damage occurs in the form of microscopic cracks that result from a thermal cycle or thermal shock. Terrestrial studies typically evaluate the efficacy of this process by measuring the rate of surface temperature change (dT/dt), using a damage threshold of 2 K/min. While the extent of this damage is unknown, we investigate its relative efficacy by modeling rates of temperature change on various airless surfaces. The magnitude of dT/dt values is primarily controlled by sunrise/set durations on quickly rotating bodies, such as Vesta, and by distance to the sun on slowly rotating bodies, such as Mercury. The strongest temperature shocks are experienced by highly sloped east- or west-facing surfaces. Hot thermal shocks (dT/dt > 0) tend to be stronger than cold shocks (dT/dt < 0), and on some bodies, daytime shadowing may produce higher dT/dt values than those caused by diurnal sunrise/set if the topography is optimally oriented. We find that high dT/dt values are not, however, always correlated with high temperature gradients within the rock. This adds to the ambiguity of the poorly understood damage threshold, warranting further research on the topic that goes beyond the simple 2 K/min criterion.