Never seen so much ‘traffic‘his Mars: after the arrival of the Hope Emirati probe, also there Chinese Tianwen-1 has managed to successfully enter orbit around the planet. China thus becomes the sixth world power to reach this milestone after the USA, the former USSR, the European Space Agency, India and the United Arab Emirates. If operations proceed as planned in the coming months, China will also be the first to deploy an orbiter, lander and rover in a single mission to Mars. The challenge is launched to the United States, which on February 18, with the Mars 2020 mission, will try to place their fifth rover, Perseverance, on the surface of the planet, with the aim of returning the first samples to Earth by 2031.
Europe, which seemed destined to remain at the window after the postponement of his new mission to Mars due to technical delays, it returns instead to make its voice heard with two important discoveries that shed new light on the planet’s atmosphere and its climate changes. Both published in the magazine Science Advances, bear the signature of Sonda Tgo (Trace Gas Orbiter) of ExoMars, the joint mission of the European Space Agency (ESA) and the Russian Roscosmos already in orbit for over three years.
His instruments made it possible to detect the presence of a gas never seen before in the atmosphere of Mars: it is the hydrogen chloride (HCl), probably due to sea salt fixed in the dusty surface of the planet and released into the air during the hot season. “This is the first detection of halogen gas in the Martian atmosphere and represents a new chemical cycle to study,” says Kevin Olsen of the University of Oxford.
Schematic representation of the mechanism underlying the ‘escape’ of water from the surface of Mars, reconstructed thanks to the Tgo probe (source: ESA)
His team first spotted the gas during the great dust storm of 2018, observing it appear simultaneously in both the Northern and Southern hemisphere, and then witnessed its rapid disappearance at the end of the dusty period. The team is already looking at the data collected during the following dusty season where HC1 already appears to grow again.
The Tgo probe also made it possible to “explore the atmosphere in 3D”, underlines Ann Carine Vandaele, head of the Nomad instrument who studied the movements of water vapor and ‘semi-heavy’ water (where a hydrogen atom is replaced from an atom of deuterium, a form of hydrogen with an extra neutron).
The data show that “Mars has lost much of its original water, probably due to transport mechanisms at high altitudes such as those observed by Nomad, where the molecule is then broken up by solar ultraviolet rays and dispersed into space”, explains Giancarlo Bellucci , researcher at the National Institute of Astrophysics (INAF) and head of the Italian scientific team of the Nomad instrument. “These results – continues Bellucci – were obtained thanks to the important contribution of the Italian Space Agency which also supported the Italian group involved in the scientific activities of the Nomad instrument”.
ExoMars data collected between April 2018 and April 2019 also showed three situations that accelerated the loss of water from the atmosphere: the great dust storm of 2018 that swept across the planet, a brief but intense regional storm in January 2019 and the release of water from the South Polar Ice Cap during the summer months related to seasonal change. Of particular note is a plume of water vapor evident during the summer in the southern hemisphere of Mars, which could release water vapor into the upper layers of the Martian atmosphere both seasonally and annually.
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