Williams et al. Reply (to the Comment by Dumin on "Progress in Lunar   Laser Ranging Tests of Relativistic Gravity")
  A decreasing gravitational constant, G, coupled with angular momentum conservation is expected to increrase a planetary semimajor axis, a, as \dot a/a=-\dot G/G. Analysis of lunar laser ranging data strongly limits such temporal variations and constrains a local (~1 AU) scale expansion of the solar system as \dot a/a=-\dot G/G =-(4\pm9)\times10^{-13} yr^{-1}, including that due to cosmological effects. 
James G. Williams, Slava G. Turyshev, Dale H. Boggs