Spectroscopy of molecular oxygen in the atmospheres of Venus and Mars

The abundances of molecular oxygen in the atmospheres of Venus and Mars are sensitive to fundamental photochemical processes. A new upper limit is reported for the molecular oxygen mixing ratio (O2/CO2 less than 3 x 10 to the -7th) in the integrated column above the visible cloud tops of Venus, based on spectroscopic observations carried out in early spring, 1982. During the same observing period, an O2 column abundance of 8.5 cm-am for the atmosphere of Mars was measured, slightly below the O2 abundances measured a decade earlier.