Upper atmosphere and ionosphere

Temperature and pressure profiles of the upper atmosphere were obtained from the frequent Mars 2 radio occuRations, as was data showing there to be a neutral upper atmosphere made almost entirely of carbon dioxide with about 2% atomie oxygen. A night-side airglow was detected 200 km beyond the terminator. The base of the ionosphere was at 80 to 110 km. From 100 to 800 km, the carbon dioxide became increasingly dissoeiated into atomie oxygen and carbon monoxide. And the Lyman – alpha experiment detected an atomic hydrogen corona out to 20,000 km. There was less atomic hydrogen than Mariner 6 and 7 had found in 1969. presumably because the hydrogen atoms derived from w ater dissociation and during the dust storm there was less water present in the atmosphere. Charged particles were measured in the ionosphere, and the bow shock that defines the interaction of the solar wind with the planetary ionosphere was detected.

Lower atmosphere

The data obtained included temporal and spatial changes of temperature in the low er atmosphere, and waiter vapor concentrations 5.000 times weaker than in the Earth’s atmosphere. Images of the limb showed the layered structure of the atmosphere and its extent out to 200 km. Clouds were observed in the low er atmosphere composed of sub-micron particles at altitudes as high as 40 km. The composition was reported to be 90% carbon dioxide, 0.027% molecular nitrogen, 0.02% molecular oxygen.

0. 016% argon, and water vapor variable in the range 10 to 20 precipitable microns.