Atmosphere of Mars slowly decreased to very low concentrations, with no layer detectable above 35 km. The reporting scientists think that the observed polar ozone layers are the result of the same atmospheric circulation pattern that creates a distinct oxygen emission identified in the polar night and also present in Earth's atmosphere. This circulation takes the form of a huge Hadley cell in which warmer air rises and travels toward the south pole before cooling and sinking at higher latitudes. Mars is on a quite elliptical orbit and has a large axial tilt, which causes extreme seasonal variations in temperature amongst the northern
Atmosphere of Venus are investigation of the structure and chemical composition of the atmosphere and investigation of the upper atmosphere, ionosphere, electrical activity, magnetosphere and escape rate. It has been proposed to fly together with Venera-D an inflatable aircraft designed by Northrop Grumman, called Venus Atmospheric Maneuverable Platform (VAMP). The High Altitude Venus Operational Concept (HAVOC) is a NASA concept for a manned exploration of Venus. Rather than traditional landings, it would send crews into the upper atmosphere, using dirigibles. Other proposals from the late 2010s include VERITAS, Venus Origins Explorer, VISAGE, and VICI. In June 2018, NASA also awarded a contract to