Observations of the J = 1-0 CO lines in the Mars atmosphere: Radiodetection of 13CO and monitoring of 12CO

Repeated millimeter-wave observations of Mars, performed in September and October 1986 and January 1987, allowed a high-resolution recording of the J = 1-0 12CO line, and the first radiodetection of 13CO. In the hypothesis where the thermal profile has the structure measured by the Viking spacecrafts, our observations are not compatible with a terrestrial 12C/13C isotopic ratio. If the isotope ratio is assumed terrestrial, then the observations imply that the thermal profile is very different from the profile in dust-free conditions, especially in its lower part, and that the CO abundance could vary by a factor of about 2 over a period of a few months.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28079/1/0000524.pd