Washington:
The liquid water on Mars may have carved the surface of the red planet as a result of dramatic climate cycles that were triggered by the greenhouse gases, scientists including one of Indian origin, Ravi Kumar Kopparapu from University of Maryland in the US, have found.
The deep canyons and extensive valley networks are similar to that carved by running water on Earth over millions of years.
It has been a subject of debate among the scientists for long that how these could be formed on Mars some 3.8 billion years ago, a time many believe the planet was frozen.
The researchers say the early Mars, which was covered with glacier, may have experienced long warm periods which lasted up to million years at a time. A thick atmosphere of carbon dioxide and hydrogen caused the long warm periods.
The warming cycles would have lasted long enough, producing enough water to create the changes, the team found.
“With the cycling hypothesis, you get these long periods of warmth that give you sufficient time to form all the different Martian valley networks,” said Natasha Batalha, graduate student at Pennsylvania State University in the US.
According to precious research, asteroid impacts led to the warming up of the planet and created steam atmospheres that led to rain.
However, due to the shorter durations of those warm periods, they couldn’t produce enough water.
“We think Mars had to be warm for millions to tens of millions of years, and the impact hypothesis can keep it warm for thousands of years,” said Jim Kasting, Professor at Penn State.
Kasting said valleys on the Martian surface are similar in width to the Colorado River Canyon.
Scientists estimate it took 16 million years for the Colorado River, swollen seasonally as the snow melts in the Rocky Mountains, to carve the nearby Grand Canyon.
Using climate models, the team showed warming periods - caused when greenhouse gases reached a certain tipping point - lasted millions of years on Mars.
With the right choice of parameters, these warm periods can last up to 10 million years.
According to researchers, greenhouse gases accumulated in the atmosphere gradually, belched by volcanic eruptions, released by cooling magma on the surface or seeping up from the planet’s crust.
Rain naturally removes some of this from the atmosphere when it falls, storing some carbon in the ground through a process called chemical weathering.
However, since early Mars was cold, it rained less and this process couldn’t keep up, the researchers said.
As the planet warmed, chemical weathering would eventually happen faster than volcanoes could return gases into the atmosphere, and the planet would begin to cool, ushering in another ice age.
The study was published in the journal Earth and Planetary Science Letters.
(With inputs from PTI)
