How did the Mars become a cold, icy planet? IIT scientists have an answer

New Delhi: Why didn't Mars evolve in the same line as Earth even though both planets originated from the same cosmic dust cloud, beginning their planetary lives almost at the same time? Indian scientists now offer an answer.

Researchers from Indian Institute of Technology, Bombay and their collaborators examined the Red Planet with images captured by NASA, European Space Agency and ISRO’s Mars Orbiter Mission and recreated the planet’s history: from the wet and warm past to a cold, icy future.

Earth and Mars were born from the same cosmic system, beginning their planetary lives together approximately 4.5 billion years ago. But their evolutionary paths have diverged dramatically. The Earth is a blue planet teeming with liquid water and life, while Mars is a cold, red desert.

Yet a closer look at the Martian surface reveals geological similarities to the Earth. The complex valley networks, ancient deltas, and sedimentary landforms of the Martian highlands are potential evidence of a time when the Red Planet sustained water flows and glaciers, and even geological activity.

“Both started with similar compositions and atmospheres. So, one of the most pressing questions is, where did all that water go, and why didn't Mars evolve along the same direction as Earth?” said lead scientist Alok Porwal from IIT Bombay.

Porwal, his student Dibyendu Ghosh and collaborators Malcolm Aranha, Sandeepan Dhoundiyal, Guneshwar Thangjam and Ranjan Sarkar from other institutions used high-resolution data from two NASA missions, an ESA probe and Indian Space Research Organisation’s Mars mission to look at Thaumasia Highlands, an ancient region on Mars.

Their study points to a gradual shift in climate from a warm, wet past to an icy future. Using the valley networks as geological thermometers and clocks, they tracked how the region's geology changed with distance from the equator and over time.

“We looked at Mars from a hydrological point of view and analysed features that could have been formed by rivers, glacial and groundwater erosion. We wanted to figure out how the hot and wet planet was transformed,” Parwal told DH.

The study confirms that the majority of the valley networks on Mars were carved predominantly by surface water during the planet's earliest major geological era around 4.1-3.7 billion years ago. But as time progressed, the valley formation processes began to decline.

By around 3.7-3 billion years ago, the processes were further halted with the valleys showing increasing signs of modification by groundwater erosion and glacial impacts.

Such a sequence of evidence suggests a gradual climate change on Mars, starting warm and wet and becoming progressively colder and icier later.

What triggered the change? “Mars being smaller in size, its core was solidified because of which the planet lost its protective magnetic field, exposing the planet to cosmic rays. In contrast the Earth still has its molten core and consequently the magnetic fields,” he explained.

By systematically analysing the transition across different latitudes and geological ages, the IIT research provides a more robust narrative of Mars’ climate shift.

The study has appeared in a recent issue of the journal Advances of Space Research.