Figure 6

Viking plasma temperatures. Temperature profiles measured by the two Vikings [5,16] were nearly identical. On the Viking 1 entry (right), the ion temperature increased from the low altitude neutral temperature T_n (deduced from the neutral scale height) to the measured thermal electron temperature T_e1at high altitudes. The electron temperatures T_e2 and T_e3 are inferred estimates of the presence of photoelectrons and a hotter population from the magnetosheath. Tr and Tc are theoretical models of the electron temperature from [4] and [17].