Perseverance is a NASA autonomous vehicle that arrived at Jezero Crater (a now-dry former lake bed on Mars) on February 18, 2021. The rover is equipped with seven complex new science instruments dedicated to exploring the planet’s surface for for signs of possible past lives, collecting and depositing samples to bring back to Earth, testing new technologies for use in human exploration, and studying the planet’s atmosphere in detail. Regarding the objective of studying the atmosphere, MEDA (Mars Environmental Dynamics Analyzer) instrument obtained new results. The principal investigator of MEDA is José Antonio Rodríguez-Manfredi from the Center for Astrobiology (CAB) in Madrid, and a team from the Planetary Sciences Research Group of the UPV/EHU participated. The instrument includes an array of sensors that measure temperature, pressure, wind, humidity, and the properties of the ever-present dust suspended in the Martian atmosphere.
Perseverance it has now completed its study of the atmosphere through the first Martian year (which lasts about two Earth years). A summary of the results, which appears on the cover, is published today in the January issue of the journal. geoscience of nature. Specifically, the UPV/EHU team, made up of Agustín Sánchez-Lavega, Ricardo Hueso, Teresa del Río-Gaztelurrutia and doctoral student Asier Munguira, carried out the study of the seasonal and daily cycles of temperature and pressure, as well as its effects of variations in other time scales resulting from very different processes.
Throughout the seasons, the average air temperature in Jezero crater, located near the planet’s equator, is around minus 55 degrees Celsius, but it varies greatly between day and night, with typical temperature differences of a few 50 to 60 degrees. In broad daylight, the heating of the surface generates turbulent movements in the air due to the rise and fall of air masses (convection) that cease at nightfall, when the air stabilizes.
The pressure sensors, on the other hand, show in detail the seasonal change in the tenuous Martian atmosphere produced by the melting and freezing of atmospheric carbon dioxide in the polar caps, as well as a complex and variable daily cycle, modulated by thermal tides in the polar caps. atmosphere. “The pressure and temperature of the Martian atmosphere oscillate with the periods of the Martian solar day (slightly longer than that of Earth, it is 24 h 39.5 min on average) and with its submultiples, according to daily insolation. cycle strongly influenced by the amount of dust. and the presence of clouds in the atmosphere”, explains Agustín Sánchez-Lavega, professor at the Bilbao School of Engineering (EIB) and co-investigator of the Mars 2020 mission.
The two sensors also detect dynamic phenomena in the atmosphere that occur near the rover, for example, those produced by the passage of eddies called “dust devils” due to the dust they sometimes raise, or the generation of gravity waves. whose origin is still not well known. “Dust eddies are more abundant on Jezero than anywhere else on Mars, and can be very large, forming eddies more than 100 meters in diameter. With MEDA we were able to characterize not only their general aspects (size and abundance) but also to unravel the functioning of these vortices”, explains Ricardo Hueso, professor at the Faculty of Engineering of Bilbao (EIB).
MEDA has also detected the presence of storms thousands of kilometers away, of very similar origin to terrestrial storms, as shown by images from satellites in orbit, and that move along the edge of the north polar cap, formed by the ice deposit dry.
Within the rich variety of phenomena studied, MEDA was able to characterize in detail the changes that were produced in the atmosphere by one of the feared dust storms, such as the one that developed in early January 2022. Its passage over the rover took to sudden changes in temperature and pressure accompanied by strong gusts of wind, which raised dust and hit the instruments, damaging one of the wind sensors.
“MEDA provides high-precision meteorological measurements that make it possible for the first time to characterize the Martian atmosphere on a local scale just a few meters away, as well as on a global scale from the planet by collecting information about what is happening thousands of kilometers away. . All this will allow us to better understand the Martian climate and improve the predictive models we use”, says Sánchez-Lavega.
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