2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/34807The detected anomalous frequency drift acceleration in Pioneer's radar data finds its explanation in a Berry phase that obtains the quantum state of a photon that propagates within an expanding space-time. The clock acceleration is just the adiabatic expansion rate and an analogy between the effect and Foucault's experiment is fully suggested. In this sense, light rays play a similar role in the expanding space than Foucault's Pendulum does while determining Earth's rotation. On the other hand, one could speculate about a suitable future experiment at "laboratory" scales able to measure the local cosmological expansion rate using the procedure outlined in this paper.7 pages, The references are now correctGeneral Relativity and Quantum Cosmologytext