Infrared spectrometry of Venus: IR Fourier spectrometer on Venera 15 as a precursor of PFS for Venus express Original Research Article

Thermal infrared spectrometry in the range 6–40 μm with spectral resolution of 4.5–6.5 cm−1 was realized onboard of Venera 15 for the middle atmosphere of Venus investigations. The 3-D temperature and zonal wind fields (h, ϕ, LT) in the range 55–100 km and the 3-D aerosol field (h, ϕ, LT) in the range 55–70 km were retrieved and analyzed. The solar related waves at isobaric levels, generated by the absorbed solar energy, were investigated. In the thermal IR spectral range the, ν1, ν2 and ν3 SO2 and the H2O rotational (40 μm) and vibro-rotational (6.3 μm) absorption bands are observed and used for minor compounds retrieval. An advantage of the thermal infrared spectrometry method is that both the temperature and aerosol profiles, which need for retrieval of the vertical profiles of minor compounds, are evaluated from the same spectrum. The Fourier spectrometer on Venera-15 may be considered as a precursor of the Planetary Fourier Spectrometer (PI Prof. V. Formisano), which is included in the payload of the planned Venus Express mission. It has a spectral range 0.9–45 μm, separated into two channels: a short wavelength channel (SWC) in the range 0.9–5 μm and a long wavelength channel (LWC) from 6 to 45 μm, and spectral resolution of 1–2 cm−1. In the history of planetary Fourier spectrometry the PFS is a unique instrument, which possesses a short wavelength channel. A functioning of this instrument on the polar orbit with a good spatial and local time coverage will advance our knowledge in the fundamental problems of the Venus atmosphere.