Characteristic green hue Polar Aurora The production of the earth is due to the emission of oxygen. When charged electrons from interplanetary space collide with the upper atmosphere, the oxygen emits light.
But this gorgeous phenomenon is just one way The atmosphere of the planet shines Like ours or Mars. In fact, as long as sunlight interacts with atmospheric elements, there will be luminescence at any time, although the luminescence at night and during the day is caused by a different mechanism: when the decomposed molecules recombine, there will be luminescence at night, and when the sunlight directly excites the molecules There will be daylight glow when it is in contact with the atom. Like oxygen.
As far as the earth is concerned, the green glow is very faint, so it is best to look at it from the edge, as shown by the many spectacular images taken from the earth. International Space Station (International Space Station, Its English abbreviation).
The green light on the earth as seen from the International Space Station. /NASA
In principle, the weakness of this glow is a problem when searching for other planets, because their surface brightness can cover it, but now, due to the first green detection of Mars, this green illumination is due to Satellite for Research on Trace Gas (TGO) Task Mars alienIt has been orbiting our neighboring planet since October 2016.
He said: “One of the brightest emissions observed on Earth is night-time luminescence, especially from oxygen atoms that emit light of a specific wavelength. This light has never been seen around another planet.” Jean-Claude GérardA researcher from the University of Liège (Belgium) said: “However, this emission was predicted to exist on Mars 40 years ago, and now we have found it.”
Jean-Claude and his colleagues published their research in the journal Natural astronomy, This emission has been detected using an instrument called TGO Orbiter NOMAD (Nadir and occultation, discovery of Mars).This includes Ultraviolet Visible Spectrometer (UVIS) You can observe in various configurations, one of which points directly to the surface of Mars, also called a channel lowest point.
“Previous observations have not captured any green glow on Mars, so we decided to realign the UVIS Nadir Channel to the’edge’ of Mars, similar to the perspective view seen from the Earth image taken by the International Space Station.” Author Ann Carine Vandaele Lead researcher from the Royal Institute of d’Aéronomie Spatiale and NOMAD in Belgium.
Between April 24 and December 1, 2019, the team used these instruments to track altitudes from 20 to 400 kilometers above the surface of Mars, twice in each orbit. When they analyzed these data sets, they found green oxygen emissions in all these elements. “although The strongest launch at an altitude of about 80 kilometers (There is another weaker mountain at 120 kilometers.) Its change depends on the distance between Mars and the sun,” Ann Carlin pointed out.
Studying the glow of planetary atmospheres can not only provide a wealth of information about the composition and dynamics of the atmosphere, but also reveal how the energy from the sun and the solar wind and the flow of charged particles from the stars are deposited.
El Co2 pcs Becomes CO and O
In order to better understand this green glow on Mars and compare it with the glow we see on our own planet, Jean-Claude and his colleagues delved into how it formed: “We are This emission was modeled and found that it was mainly carbon dioxide (CO2) and divided into its components, carbon monoxide (CO) and oxygen (O). We saw the generated oxygen atoms glow Under visible light and ultraviolet light“.
Comparing these two types of emission at the same time shows that the intensity of visible emission is 16.5 times higher than that of ultraviolet emission. Jean-Claude pointed out: “The observations of Mars are consistent with previous theoretical models, but are inconsistent with the actual brightness we see around the earth. Around the earth, the emission of visible light is much weaker, which shows that we have more knowledge. To learn. The behavior of oxygen atoms, which is very important for our understanding of atomic and quantum physics.”
This information is essential for characterizing planetary atmospheres and related phenomena (such as aurora). By interpreting the structure and behavior of this bright green layer of the Martian atmosphere, scientists can gain insights into the largely unexplored range of altitudes and monitor how it changes with changes in the sun and Martian activities. Our star.
“Considering this research, we have demonstrated the high sensitivity and optical quality of the NOMAD instrument A day on mars, It’s brighter than night, which makes it more difficult to detect this weak emission,” he emphasized Håkan Svedhem, ESA’s TGO project scientist.
The author believes that understanding the properties of the Martian atmosphere is not only scientifically meaningful, but also essential for manipulating the Martian atmosphere. Future tasks Was sent to the Red Planet. For example, atmospheric density directly affects the drag experienced by orbiting satellites and parachutes used to land probes on the surface of Mars.
“This remote sensing observation and measurement In situ At higher altitudes, it can help us predict how the Martian atmosphere will respond to seasonal changes and changes in solar activity,” Hakan added: “Predicting changes in atmospheric density is particularly important for upcoming missions (including missions). ExoMars in 2022 This will send a Wanderer There is also a surface science platform for exploring the Red Planet. “
Scientist from Andalusian Institute of Astrophysics (IAA-CSIC), what Jose Juan Lopez-Moreno, Pointed out: “The atomic oxygen green line was discovered in the Martian atmosphere, which opened a window for studying the behavior and photochemistry of the planet, and provided us with a tool to understand the interaction of the sun. It radiates the Martian atmosphere.”
Co-author and researcher of IAA Miguel Angel López-Valverde, Commented: “This is expected, but it is difficult to observe. We finally found it, and the good fit obtained through the photochemical model shows that our description of the atmospheric oxygen excitation mechanism is correct in an environment completely different from the terrestrial environment , So it can be exported to other worlds”.
“Furthermore, he added that this may be of great interest to studying the atmospheres of other planets in the solar system and looking for signs of life. The luminescence of oxygen reveals the existence of this compound, because this compound is very abundant on Earth Photosynthesis. Therefore, if the green line on the exoplanet is much stronger than the emission intensity we just discovered on Mars, and is equal to or greater than the intensity observed on Earth, then it may be an indirect way of life capable of this process. index. Photosynthesis”.
J.-C. Gérard et al. “Detect green line emission According to NOMAD-TGO’s observations, in the daytime atmosphere of Mars.” Natural astronomy 2020.