A weird new kind of dust has been discovered in the Martian atmosphere by scientists using ultraviolet and infrared imaging techniques. A group of Russian and French scientists analysed satellite-acquired data and concluded that the dust particles in the planet’s atmosphere can be of two types.
Researchers from the Moscow Institute of Physics and Technology and the Paris Observatory and LATMOS research laboratory carried out a simultaneous analysis of the ultraviolet and infrared atmospheric extinctions from SPICAM, the spectrometer on the board of the orbital station Mars Express.
The results were received during the solar occultations at the beginning of Northern summer on Mars. Before the Sun is completely eclipsed by the planetary disk, its rays pierce through the atmosphere and then get “caught” by the spectrometer’s detector. Having gone through the atmosphere, the solar rays show adifferent spectrum with the changes hinting at the atmosphere’s makeup, the amount of various aerosols and the size of their particles.
This method was applied in order to understand the way the particles are distributed in the atmosphere. The researchers have found out that the dust particles in the Martian atmosphere are not homogeneous, but can be roughly grouped into two modes.
The first – coarser – mode is represented by both H2O ice grains with the average radius of 1.2 micro metres, and slightly smaller dust particles.
The second mode is a lot finer, it is an aerosol which consists of much smaller particles with a radius of 0.04–0.07 micro metre. The density number of the both modes is not that high. Even in the most “dusty” layers of the planet’s atmosphere at altitudes of 20–30 km there are about 3.000 particles of the finer mode per 1 cubic centimetre, and not more than 2 particles of the coarser mode per 1 cubic centimetre.
If compared with what is considered the norm on Earth, the air with such dust density is rather clean; yet, aerosols are important because they, according to scientists, play a key role in forming the planet’s climate. Because of fine dust particles in the higher layers of the atmosphere, ice “embryos” are formed faster, which, in turn, influences clouds’ build-up.
The clouds are responsible for both precipitation and temperature condition on the planet’s surface. Analysing the way the dust is spread in the atmosphere of the planet with regard to the altitude and geographical coordinates is crucial for forming the full picture of what is happening on Mars. The research was published in the journal Icarus.
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