Properties of the lunar exosphere during the perseid 2009 meteor shower
  Influence of the meteoroid bombardment on properties of the lunar exosphere has been confirmed. Quick increase in the zenith column density of Na atoms above the lunar north pole on August 13, 2009 at 0-1 UT is detected and explained by numerous collisions of relatively small Perseid meteoroids (< 1 kg) with the Moon during maximum of the Perseid meteor shower. New stringent upper limits of the column densities for Ca, Ba, and Ti atoms in the lunar exosphere are obtained as 5*10^7, 2.2*10^6, and 6.9*10^8 cm^-2, respectively. It is found that the content of impact-produced Ca and Al atoms in the lunar exosphere is depleted as compared to that of Na atoms. 
A.A. Berezhnoy, K.I. Churyumov, V.V. Kleshchenok, E.A. Kozlova, V.   Mangano, Yu.V. Pakhomov, V.O. Ponomarenko, V.V. Shevche...
astro-ph.EP