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Climate of Mars

Climate of Mars Changed dramatically 400,000 years ago

China’s Zhurong Mars rover has made an intriguing discovery about the climate of Mars on the Red Planet. It has found dark ridges atop bright dunes in the Utopia Planitia region, indicating a significant change in Mars’ temperature around 400,000 years ago.

What did the team of National Astronomical Observations do?

A team of scientists from the National Astronomical Observatories of the Chinese Academy of Sciences, led by Li Chunlai, utilized the rover’s equipment and high-resolution images from China’s Tianwen-1 Mars orbiter. It was done to conduct a closer examination of the giant dunes near Zhurong’s landing site in May 2021 and to observe the climate of Mars.

Over hundreds of thousands of years, these dunes have gradually eroded into crescent shapes. On top of the dune fields, long dark ridges called transverse aeolian crests (TARs) have formed. Interestingly, the TARs appear to be oriented at a different angle compared to the wind-blown dunes influencing the climate of Mars. While TARs have been observed across Mars at lower mid-latitudes, global air circulation models have struggled to explain how these features could have originated—until now.

Prof. QIN said;

“According to the measured meteorological data by Zhurong and other Mars rovers, we inferred that these dune surface characteristics were related to the involvement of liquid saline water formed by the subsequent melting of frost/snow falling on the salt-containing dune surfaces when cooling occurs,” 

How did the dunes influence the climate of Mars?

By investigating the dunes, Zhurong discovered that the crescent-shaped bodies are composed of lighter material, while the TARs are made of darker material. From its orbital perspective, Tianwen-1 identified 2,262 bright dunes on Mars that influence the climate of Mars. The researchers estimate that these dunes formed between 2.1 million and 400,000 years ago, based on the number of craters on their surfaces. Consequently, the dark TARs must have developed within the past 400,000 years, superimposed on the dunes.

Climate of Mars img 2
How Mars’ winds changed as the ice age came to an end, forming long ridges at a different angle to the dunes. (Image credit: CAS)

These time frames align with the beginning and end of Mars’ previous primary ice age. The fact that the TARs formed at a different angle than the dunes suggests a change in wind direction in the lower mid-latitudes as the ice age concluded.

What were the consequences of changing climate of Mars?

Changes in the climate of Mars and its axial tilt, influenced by Milankovitch cycles caused by the gravitational effects of the sun, Jupiter, and other planets, along with the planet’s orbit shape and precession, precipitated the start and conclusion of the ice age. These cycles are driven by alterations in both the climate of Mars as well as on the Earth. Between 2.1 million and 400,000 years ago, Mars’ obliquity, or the angle of its spin, shifted from 15 to 35 degrees, resulting in significant temperature disturbances. Currently, Mars has a tilt of approximately 25 degrees.

Interestingly, the climate of Mars and its ice ages differ from those on Earth. During Martian ice ages, temperatures at the poles are usually warmer, causing water vapor and dust to migrate towards the middle latitudes where they become trapped. In the last ice age, this water and dust mixture formed a layer several meters thick that remains beneath the surface in some areas below 60 degrees latitude and near the surface above 60 degrees.

Based on impact cratering rates, the present geological age on Mars, the Amazonian epoch, began between 3.55 billion and 1.88 billion years ago.

Li stated,

“Understanding the Amazonian is important to explain the current Martian landscape, volatile matter reservoirs, and state of the atmosphere, and to connect current observations and active processes to models of the climate of Mars in the past.” 

What will the data on changing Mars’s climate do?

This knowledge will aid in refining our understanding of the climate of Mars and landscape evolution and may even lead to new insights.

During extended northern winter in the Mars climate, the Zhurong rover has entered a dormant state, and its future activities remain uncertain.

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