Source of Evolution of Gas from the Lunar Crater Alphonsus

Abstract

KOZYREV's^1,2 observation of Swan bands being emitted by C₂ molecules emanating from the lunar crater Alphonsus on the west shore of Mare Nubium is now widely accepted. However, his assertion that the gas evolved as a result of volcanic eruption is not as generally accepted by selenologists. There are more plausible mechanisms than volcanic eruption to account for the gas issuing periodically from Alphonsus. Urey³ has pointed out the black areas on the crater floor of Alphonsus and suggests they may be due to explosion of acetylene which could produce graphite and hydrogen. The source of the acetylene could be a stable solid carbide such as calcium carbide according to Urey³. It is interesting to note that comets are known to give the Swan band emission. There are six prominent black spots in Alphonsus, each surrounding one or more small craters as illustrated in Fig. 1. Kozyrev observed the gas evolution, however, from the centre of the elongated central peak roughly paralleling the shore of Mare Nubium. Baldwin⁴ considers the emanation of this gas to be a lunar degassing process rather than volcanism. For reasons presented here it is plausible that most of the gas evolution is from the region of the central peak. However, this does not preclude that the dark areas mentioned by Urey³ were not also caused by gas evolution.