Publication Date:
2019-08-28
Description:
Solar occultation observations of the Martian atmosphere near the limb of the planet were performed during the Phobos mission by means of the Auguste infrared spectrometer in the ranges 2707-2740 and 5392-5272/cm with a resolving power of approximately = 1300. The spectra exhibit features at 2710 and 2730/cm which have not been identified previously. After applying a set of corrections to the data and examining the spectra of various molecules, we are led to conclude that the best candidate for the above-mentioned features is formaldehyde (CH2O). It was observed in eight of the nine successful occultation sequences, mainly between 8 and 20 km with an average mixing ratio of 0.5 (+0.8, - 0.3) ppm (there are no good data below 8 km). The observations are performed in equatorial spring conditions. The altitude distribution of formaldehyde reveals correlation with the permanent haze opacity.
Keywords:
ASTROPHYSICS
Type:
Planetary and Space Science (ISSN 0032-0633); 41; 6; p. 441-451
Format:
text
Permalink
