Exploration of Venus with the Venera-15 IR Fourier spectrometer and the Venus Express planetary Fourier spectrometer

The infrared spectrometry of Venus in the range 6–45 μm allows one to sound the middle atmosphere of Venus in the altitude range 55–100 km and its cloud layer. This experiment was carried out onboard the Soviet automatic interplanetary Venera-15 station, where the Fourier spectrometer for this spectral range was installed. The measurements have shown that the main component of the cloud layer at all measured latitudes in the northern hemisphere is concentrated sulfuric acid (75–85%). The vertical profiles of temperature and aerosol were reconstructed in a self-consistent manner: the three-dimensional fields of temperature and zonal wind in the altitude range 55–100 km and aerosol at altitudes 55–70 km have been obtained, as well as vertical SO2 profiles and H2O concentration in the upper cloud layer. The solar-related waves at isobaric levels in the fields of temperature, zonal wind, and aerosol were investigated. This experiment has shown the efficiency of the method for investigation of the Venusian atmosphere. The Planetary Fourier Spectrometer has the spectral interval 0.9–45 μm and a spectral resolution of 1.8 cm−1. It will allow one to sound the middle atmosphere (55–100 km) of Venus and its cloud layer on the dayside, as well as the lower atmosphere and the planetary surface on the night side.