A green sky on Mars? This light phenomenon on the red planet intrigues researchers

Mars, the red planet, is not only red. For example, During the night. Similarly, the planet is adorned with green lights, some similar to the northern boreal or southern people occurring on earth. Furthermore, These lights are so intense that they could be observed with the naked eye by future astronauts in orbit. Meanwhile, on the surface of Mars. In addition, But in addition to the aurora. Similarly, astronauts will also be able to see another night light phenomenon called ” nightglow “, What could be translated as” night light “.

Aurora. Meanwhile, Martian night glows were well known in the ultraviolet and infrared, mainly thanks to the Mars green sky mars? this light Express (since 2003) and Maven missions (since 2013). Similarly, But it is only since 2023 that we were able to detect them in the field of the visible. Meanwhile, thanks to the Exomars mission of the European Space Agency (ESA) and the observations of the Rover Perseverance of NASA.

These observations open the way to future studies with instruments designed in the visible. However, simpler, lighter and less expensive than those designed to observe ultraviolets. Meanwhile, In particular. For example, the nightglow must teach us more about the dynamics and the composition of the Martian atmosphere; While the dawn tell us about the interactions between the solar wind and the red planet … Moreover, and green.

Aurore or “Nightglow”? – Green sky mars? this light

Even if these two types of light. In addition, Aurore and nightglowproduce lights in the atmosphere, the processes in play are completely different.

Aurorae are the result green sky mars? this light of the interaction of energy particles from space with atoms. Moreover, molecules of the neutral atmosphere of the planet, for example nitrogen or oxygen on earth, and Co₂ on Mars. Consequently, On Earth. Nevertheless, the aurora is formed near the poles, because it is there that the lines of the terrestrial magnetic field converge that the electrons of the solar wind follow.

But on Mars. Consequently, reality is much more complex, because the nucleus of the planet Mars does not generate a magnetic field like that of the planet Earth. Moreover, It is for this reason that the scientific community did not expect to find northern dawn in the Martian atmosphere. For example, until the discovery of ultraviolet auroral emissions, in 2005, with the SPICAM instrument of Mars Express (ESA).

The nightglow is formed differently, by a series of “photochemical” reactions. For example, On the side of the green sky mars? this light planet where it is day. Furthermore, the molecules naturally present in the atmosphere are dissociated by the photons emitted by the sun. For example, photons can break a CO molecule₂ in carbon and oxygen atoms. For example, The newly created atoms are transported by atmospheric circulation caused by a temperature difference. towards the night side, where it is much colder. The atoms then recombine to reform a molecule. The molecule is found this time in an excited state: it will emit light to a characteristic wavelength by. returning to its fundamental state. It is this program that we call nightglow.

The sources of these light shows (dawn. nightglow) Being different, they allow us to study different parameters of the atmosphere, in different places and different altitudes of the atmosphere.

The dawn of March seen from the orbit

Thanks to the SPICAM instrument of Mars Express. our team green sky mars? this light was able to observe about twenty dawn on Mars. All were in places where the residual magnetic field trapped in the rock on the surface of Mars is the strongest – a region extends mainly into the southern hemisphere. between 120 ° and 250 ° longitude.

In this place, the magnetic field lines form arches which act like shields against energy particles, a bit like a mini terrestrial magnetic field.

Between two arcades. the field lines are open and form kinds of canyons, in which electrons coming from the solar wind rush and interact with the atoms and neutral molecules of the atmosphere, mainly carbon dioxide and oxygen. These atoms. molecules are then found in an unstable excited state and, when they desexcate to find in their fundamental state, emit photons to very characteristic wavelengths. This is how we will mainly find carbon monoxide emissions (CO). ionized carbon dioxide (Co₂⁺) and oxygen (o) in ultraviolet and oxygen emissions in the distant ultraviolet. These emissions occur at around 135 kilometers above sea level.

Since 2013. thanks to the IUVS instruments of the NASA Maven Mission and has been on board Emirates Mars Mission green sky mars? this light much more sensitive than Spicam, we are constantly surprised!

Indeed, we now know that auroral emissions also occur outside the area of strong residual magnetic field. They are less intense, but much more frequent in the northern hemisphere, for example.

Other types of dawn have also been observed: winding dawn. with a form of snake whose length can cover an entire hemisphere by moving very quickly, or even diffuse dawn which can cover the whole night side of the planet! These diffuse dawn occur lower at altitude, about 60 kilometers at 80 kilometers. They occur quite rarely because they require the presence of sep events (for Solar Energetic Particle) during which the particles emitted by the Sun. mainly protons, are very accelerated.

Aurora and solar activity are therefore intimately linked. Martian dawn can have, as on earth, privileged training places, but are generally very variable and quite green sky mars? this light difficult to predict.

Green sky mars? this light

Observe Aurora from the surface of March

We know that one of the auroral emissions previously observed in the UV (the excited oxygen atoms emitting to 297 nanometers) has a counterpart in the field of the visible – it is the line of oxygen to 557 nanter. which gives its green color to terrestrial dawn. This component should also be observable in the Martian atmosphere.

And this is the feat that the Rover Perseverance team achieved by detecting the first dawn visible in. the Martian sky in March 2024. The team watched for the appearance of SEP events at the sun level to order the rover from observing. Additionally, the sky green sky mars? this light during the corresponding nights. A fruitful strategy, since the 557 nanometers emission was detected by the Perseverance spectrometer! It is therefore the first time that an image of an dawn has been taken from the ground of. a planet other than that of the earth.

The intensity of this event would probably have been too weak to be able to be perceptible by a human eye. but other dawn, more intense, could completely be detected with the naked eye by future astronauts on the surface or in orbit around Mars.

Mars’ Nightglow would be visible by future astronauts

In the case of March. the photons emitted by the sun interact with the CO molecules₂ Mostly present in the Martian atmosphere (~ 96 %), mainly at the level of the summer pole, lit and heated by the sun.

CO molecules₂ Are then dissociated. the oxygen atoms are green sky mars? this light transported to the winter pole plunged into the night and the cold, by what is called summer-winter circulation. There. oxygen atoms recombine to form a molecule of o₂ In an excited state, which then emits a light emission to a characteristic wavelength by returning to its fundamental state. It is this program that we observe in the Martian Winter Pole night, which we call nightglow.

Ce nightglow was first observed in the infrared, at 1.27 micrometer, from the Martian orbit, by the MRO mission (for March Recognition Orbiter), launched in 2005, by NASA.

But it was in 2023 that this oxygen emission was observed for the very first time in the visible area. about 50 kilometers above sea level. Unlike the dawn, variable and difficult to predict, the nightglow is very homogeneous in time and space.

In addition. its intensity is such that future astronauts would have no difficulty in observing a green sky above the winter pole during a beautiful starry night.

Future missions

Thanks to these major advances in the visible field. we now know that we can continue to study the atmosphere of March using simpler, lighter and less expensive instruments using the visible area rather than green sky mars? this light that of Ultraviolet.

This is what we want to do with the Auroral M-AC camera aboard Mantisse. a mission that we have offered to the European Space Agency (ESA) and which is currently in the selection phase. Two orbiters would take on different instruments on board to analyze the environment of Mars. as well as a camera with a filter to observe green emissions around 557 nanometers.

Thanks to M-AC. we could photograph and take videos of the Martian aurora with a resolution and a sensitivity never reached before. If it is accepted by ESA, this mission should be launched in 2037 towards the red planet … and green!

Follow all the news in your favorite cities and media by registering for my news.

• #Aurores Boreales
• #Space