Russian spectrometric system WITHIN aboard the Mars reconnaissance Orbiter TGO project "Eczemas" registered absorption lines of carbon dioxide and ozone, which was not observed previously, neither on Earth nor in space. The results in the form of two articles (article 1, article 2) prepared for publication in the journal Astronomy & Astrophysics and posted on the journal’s website in free access.
Spectrometric system ACS (ACS — Atmospheric Chemistry Suite Complex for the study of the chemistry of the atmosphere of Mars) was established in the Institute of space research and is designed for detailed studies of the atmosphere of Mars using three infrared spectrometers. The devices are very high sensitivity designed to search primarily for small components of the atmosphere.
Methane is one of the main biomarkers, which can indicate possible life on Mars. Therefore, scientists were looking for before all traces of this gas in the atmosphere of the red planet.
The study included data collected over one Martian year, that is since the start of the TGO in the orbit of Mars in the spring of 2018. The analysis was performed in the mid-IR range 2.3 to 4.2 micrometer. In this area of the spectrum scientists would expect to find absorption bands of methane, located near 3.3 microns. In the same region of wavelengths there are absorption bands of water molecules and carbon dioxide, which makes up the bulk of the Martian atmosphere.
Due to the high sensitivity of the spectrometer MIR are part of ACS — it turned out that the carbon dioxide and ozone are manifested in the infrared range of the spectrum, where we expect signal detection from methane molecules.
The spectrometer observes in regime of solar eclipses: device "looks" on the edge of the world where through the atmosphere of Mars Shine the sun’s rays. Various substances in the atmosphere absorb some solar radiation and then appear in the spectrum "failures", the so — called absorption lines. Every substance absorbs radiation at certain wavelengths, leaving its own unique spectral footprint.
In this case, the absorption bands of carbon dioxide and ozone were in the same spectral range, which according to scientists, says about the interaction of CO2 and O3 molecules with each other and with sunlight.
"These results significantly advance us towards a better understanding of Mars to a higher level of precision and understanding of what is happening in the atmosphere — are in the press release IKI the words of Alexander Trokhimovskii, an employee of the Department of physics of planets, one of the authors of the study. — It all started with a small reduction of the signal at the individual wavelengths in the spectra obtained with the MIR instrument. Some time these features will not attract attention, rather, was considered an error that occurred during calibration is givention. However, after a more thorough treatment of these "artifacts" did not disappear, on the contrary — it was found about 30 weak absorption lines, the position of which is not consistent with any of those already contained in the spectral databases. The phenomenon was observed at low, below twenty miles, the elevation above the surface of Mars".
After theoretical analysis, it has been suggested that we are talking about the opening of new absorption bands of the main isotopolog carbon dioxide, consisting of the basic isotopes of carbon and oxygen 12C and 16O, which arises from the magnetic dipole transition. To work TGO this strip was prohibited, there was neither on Earth nor in space, so absent in spectroscopic databases.
In the case of ozone, the situation was somewhat different. Ozone in the Martian atmosphere a little, but he was diagnosed before. Now, with the help of the device MIR it was first recorded in the infrared range of the spectrum and at low altitudes above the surface.
The question of whether there is methane in the Martian atmosphere, still remains open. Observations from the Orbiter Mars Express (ESA) and the Mars Curiosity Rover (NASA) in Gale crater testify, however, are extremely sensitive spectrometers TGO mission "ExoMars-2016" these findings have not been confirmed.
