China's Zhurong rover discovers Mars' Ice Age ended drastically 400,000 years ago

Scientists have long speculated that the climate on Mars has shifted throughout time. However, obtaining firsthand data from the Martian surface to assess the planet's climatic processes over its history has been difficult. Fortunately, the rover's array of equipment made it possible to directly gather data from the surface of Mars.

The team studied data collected from instruments such as terrain and multispectral cameras, surface composition analyzers, and meteorological measuring devices. Additionally, high-resolution orbital cameras were also used to image the Martian surface.  

According to the study's findings, a change in the tilt of Mars' rotational axis resulted in the planet emerging from its most recent ice period. This climatic shift is evidenced by the stratification of sand dunes in the southern region of Utopia Planitia.

The Amazonian epoch

Mars is currently in the geological era known as the Amazonian epoch, which began somewhere between 3.55 and 1.88 billion years ago. 

And scientists have been making the best use of robotic probes and orbiters to conduct a detailed examination of the Martian ecosystems and weather today and in the past. 

"Understanding the Amazonian climate is essential to explain the current Martian landscape, volatile matter reservoirs, and atmospheric state, and to relate these current observations and active processes to models of the ancient climate of Mars. Observations of the current climate of Mars can help refine physical models of Martian climate and landscape evolution, and even form new paradigms," Prof. Li Chunlai from the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC), principal investigator of the study, said in a statement.

The Zhurong rover landed on the red soil in May 2021. However, its current condition is subject to speculation as it has been in hibernation since May last year. CNSA recently stated that the rover was most likely dead due to heavy dust deposition on its solar panels.

Nevertheless, the data collected in this duration continues to provide valuable insights into Martian climate and geology.

This study was conducted by the NAOC, Institute of Geology and Geophysics, and Institute of Tibetan Plateau Research of the Chinese Academy of Sciences (CAS) in collaboration with scientists from Brown University in the US.

The results are published in the journal Nature. 

Study Abstract:

Orbital observations suggest that Mars underwent a recent ‘ice age’ (roughly 0.4–2.1 million years ago), during which a latitude-dependent ice-dust mantle (LDM) was emplaced. A subsequent decrease in obliquity amplitude resulted in the emergence of an ‘interglacial period’ during which the lowermost latitude LDM ice was etched and removed, returning it to the polar cap. These observations are consistent with polar cap stratigraphy, but lower- to mid-latitude in situ surface observations in support of a glacial–interglacial transition that can be reconciled with mesoscale and global atmospheric circulation models are lacking. Here we present a suite of measurements obtained by the Zhurong rover during its traverse across the southern LDM region in Utopia Planitia, Mars. We find evidence for a stratigraphic sequence involving initial barchan dune formation, indicative of north-easterly winds, cementation of dune sediments, followed by their erosion by north-westerly winds, eroding the barchan dunes and producing distinctive longitudinal dunes, with the transition in wind regime consistent with the end of the ice age. The results are compatible with the Martian polar stratigraphic record and will help improve our understanding of the ancient climate history of Mars.