The amount of187Osin meteorites resulting from beta decay of the long-lived187Renuclide has been used as a measure of the time span of nucleosynthesis in our galaxy. During the galactic history, however, the rhenium atoms can be “astrated” several times into newly forming stars, where they are stripped of most or all of their electrons. An experiment conducted at the ion storage ring ESR at Darmstadt showed that for bare187Reions, the lifetime is shortened by more thannine orders of magnitude. This observation strongly suggests that theeffectivelifetime of187Reduring the galactic evolution might differ significantly from the lifetime of neutral187Re.Furthermore, it enables a recalibration of the rhenium aeon clock in the framework of chemical-evolution models of our galaxy. Based on this new calibration, a preliminary lower limit of12×109&hthinsp;yrfor the age of our galaxy has been derived, which is, a fortiori, also a lower limit for the age of the universe. In combination with the Hubble constant, this limit provides narrow constraints for actual cosmological models. ©1999 American Institute of Physics.