Perseverance detects storms in the north polar cap of Mars

Jan. 18 () –

MEDA, the weather station aboard the Perseverance rover, has detected thousands of kilometers the formation of storms very similar to those of the Earth in the north polar cap of Mars.

The NASA rover has now just completed the investigation of the atmosphere throughout the first martian year (which lasts for about two Earth years). A preview of the results, taken to the front page, is published in the January issue of the magazine Nature Geoscience.

A team from the UPV/EHU (University of the Basque Country) has led the study of the seasonal and daily cycles of temperature and pressure, as well as their strong variations on other time scales produced by very different processes. MEDA (Mars Environmental Dynamics Analyzer) has as principal investigator José Antonio Rodríguez Manfredi from the Center for Astrobiology in Madrid.

Throughout the seasons, the average air temperature in Jezero Crater, located near the planet’s equator and home to Perseverance, hovers around 55 degrees below zero, but it varies strongly between night and day, with typical differences of about 50 to 60 degrees. In the central hours of the day, 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 becomes stable.

The pressure sensors, for their part, show in detail the seasonal change of 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 the tides. thermal in the atmosphere: “The pressure and temperature of the atmosphere of Mars oscillate with periods of the Martian solar day (slightly longer than the terrestrial, the Martian solar day is on average 24 hours and 39.5 minutes) and with their submultiples, following the daily cycle of insolation strongly influenced by the amount of dust and the presence of clouds in the atmosphere”, indicates it’s a statement Agustín Sánchez Lavega, professor at the Bilbao School of Engineering (EIB) and co-investigator on the Mars 2020 mission.

Both sensors have also been detecting dynamic phenomena in the atmosphere that occur in the vicinity of the rover, for example, those produced by the passage of eddies of wind known as eddies known as ‘dust devils’, or to the generation of gravity waves of origin not yet well understood.

“Dust eddies are more abundant on Jezero than elsewhere on Mars, and can be very large, forming eddies of more than 100 meters in diameter. With MEDA we have been able to characterize not only their general aspects (size and abundance) but also also unravel how these eddies work”, says Ricardo Hueso, professor at the EIB.

The presence of storms thousands of kilometers away has also been detected with MEDA, “very similar in origin to terrestrialas the images from orbiting satellites show us, and that move along the edge of the north polar cap, formed by the deposition of carbonic snow”.

Within the rich variety of phenomena studied, MEDA has been able to characterize in detail the changes produced in the atmosphere by one of the feared dust storms like the one that took place at the beginning of January 2022. Its passage over the rover produced abrupt 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 is providing high-precision meteorological measurements that allow for the first time to characterize the atmosphere of Mars from local scales at distances of a few meters, as well as on the global scale of the planet, collecting information on what happens thousands of kilometers away. All of this will result in in a greater knowledge of the Martian climate and in the improvement of the predictive models that we use”, indicates Sánchez Lavega.