A REEVALUATION OF THE SOLAR-WIND SPUTTERING RATE ON THE LUNAR-SURFACE

Knowledge of the retention efficiency for solar-wind-implanted Ar-36 in lunar surface material and measurement of the Ar-36 concentration in a sputtered surface enable us to calculate an upper limit to the effective sputtering rate at which that surface has been eroded. Using data for 71501 plagioclase and the glass of rock 12054, we derive a value for the sputter-erosion rate equal to <0.0024 +/- 0.001 angstrom/yr, in good agreement with the limit of <0.0035 angstrom/yr previously calculated by Zinner et al. (1977).