Communication - Specifications (page 4 of 11) 



Atmosphere of Venus [http://www.enchantedlearning.com]

The Attenuation of RF signals in CO2 is shown below [Laboratory Measurements of the 3.7-20cm wavelength Opacity of S02 and CO­2 under Simulated Conditions for the Deep Atmosphere of Venus.]. It can be observed that the attenuation is lower as the frequency goes down. Hence 1.5GHz was employed as the transmission frequency between the surface of Venus and the Orbiter. At 1.5GHz, the attenuation is 0.08dB/km, resulting in a total loss of 4dB.



(Image from the Reference Paper)

For the transmission of data from the Orbiter to Earth station, since there are no CO2 losses to account for, and since the free space path loss is lower at higher frequencies, X-band frequency of 8.42GHz is employed.