NASA’s Perseverance rover has completed its investigation of Mars’ atmosphere, which has revealed crucial information about the planet’s meteorology. This information is crucial for preparing for future human expeditions to Mars.
The rover completed an investigation that lasted for one Martian year, which is equivalent to two years on Earth. The research was led by José Antonio Rodríguez-Manfredi of the Centre for Astrobiology (CAB) in Madrid, and it has had the participation of a team from the UPV/EHU’s Planetary Sciences Research Group. The team studied the seasonal and daily cycles on Mars’ atmosphere, including temperature and pressure, as well as significant variations on other time scales resulting from different processes.
A paper detailing the results is published in Nature Geoscience.
The Perseverance rover
Perseverance is a NASA autonomous vehicle that arrived at the Jezero Crater (the bed of an ancient, now dried-up lake on Mars) on 18 February 2021.
The rover is equipped with seven novel, complex scientific instruments dedicated to exploring Mars’ atmosphere in search of signs of possible past life, collecting and depositing samples to be brought back to Earth, testing new technologies for use in human exploration, and studying the planet’s atmosphere in detail.
To study the atmosphere, the Mars Environmental Dynamics Analyzer (MEDA) instrument has been obtaining novel results. Throughout the seasons, the average air temperature at the Jezero Crater, located near the planet’s equator, is around -55°C, but varies greatly between day and night, with typical differences of around 50-60°C. In the middle of the day, the heating of the surface generates turbulent movements in the air as a result of the rise and fall of air masses which cease in the evening, when the air settles.
What can pressure sensors reveal about life on Mars?
Pressure sensors show detailed seasonal changes on Mars’ atmosphere, produced by the melting and freezing of atmospheric carbon dioxide at the polar caps, as well as by a complex, variable daily cycle, modulated by thermal tides in the atmosphere.
“The pressure and temperature of Mars’ atmosphere oscillate with periods of the Martian solar day with their submultiples, following the daily cycle of sunshine greatly influenced by the amount of dust and the presence of clouds in the atmosphere,” explained Agustín Sánchez-Lavega, professor at the Faculty of Engineering – Bilbao (EIB) and co-researcher of the study.
Both sensors are also detecting dynamic phenomena in the atmosphere that occur in the vicinity of the rover, for example, those produced by the passage of whirlwinds known as ‘dust devils’ because of the dust they sometimes kick up, or the generation of gravity waves whose origin is not yet well understood.
“The dust devils are more abundant at Jezero than elsewhere on Mars’ atmosphere and can be very large, forming whirlwinds more than 100 metres in diameter. With MEDA we have been able to characterise not only their general aspects (size and abundance) but also to unravel how these whirlwinds function,” said Ricardo Hueso, a lecturer at EIB.
Furthermore, MEDA has also detected the presence of storms thousands of kilometres away, which are similar in origin to terrestrial storms, as shown by the images from orbiting satellites. These storms 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 characterise in detail the changes that have taken place on Mars’ atmosphere by one of the dust storms, such as the one that developed in early January 2022. Its passage over the rover led to abrupt changes in temperature and pressure, accompanied by strong gusts of wind, which kicked up dust and hit the instruments, damaging one of the wind sensors.
“MEDA is providing high-precision, meteorological measurements enabling Mars’ atmosphere to be characterised, for the first time, from local scales at distances of a few metres, as well as on the global scale of the planet by collecting information on what is happening thousands of kilometres away. All this will lead to a better understanding of the Martian climate and improve the predictive models we use,” concluded Sánchez-Lavega.