TIMM-2 is a solar occultation spectrometer designed to study Mars’s atmosphere within several spectral ranges between 2.3 and 4.1 µm, with a / resolution of over 20,000 in the spectral range.
TIMM-2 (Zelenyi et al., 2010, Marov et al. 2010) completed and extended the capabilities of the AOTF (Acousto-optic tunable filters) interferometer (Korablev et al., 2009) in solar occultation, providing 10 times higher spectral resolution, and a narrow field of view for a limited number of spectral intervals.
The experiment focused on delicate measurements on methane, deuterium/hydrogen profiles, and other atmospheric gases (H2O, O3, CO, and CO2 isotopes, search for undetected chemical species that may or may not be linked to geophysical or astrobiology, as well as aerosol profiling and description.
The instrument comprised two key elements: an echelle grating and an adjustable acoustic-optical filter (AOTF) used to preselect the orders of diffraction. It was equipped with various networks (24.4 gr/mm, reflecting an angle of 70°) for spectral range sampling (with distant diffraction orders). It was to be oriented parallel to the limb. The device included five channels at 250 (ozone), 340, 405, 520, and 700 nm in order to probe ultraviolet rays and determine aerosols’ optical properties. TIMM-2 was 3.5 kg in mass and used 12 W of power.
TIMM-2 was designed based on flight-proven instruments (SOIR on board Venus Express and RUSALKA on the ISS). It was developed by IKI with the help of LATMOS. This instrument was an addition to Phobos-Grunt’s payload made possible by the launch delay.