Deep canyons and valleys on Mars may have formed as the result of warming periods that stretched for up to 10 million years, melting the glaciers that covered its surface.
The theory could solve the mystery of Mars’ water-carved features, which formed roughly 3.8 billion years ago during a period many believe the planet was frozen.
According to the researchers, a build-up of greenhouse gases in the planet’s thick atmosphere may have spurred dramatic climate cycles, allowing for liquid water to emerge and later refreeze in another ice age.
Gale Crater on surface of Mars was once filled with liquid water for 10,000 to 10 million years, researchers say. A build-up of greenhouse gases in the planet’s atmosphere may have spurred dramatic climate cycles, allowing for liquid water to emerge and later refreeze
Previous studies have suggested that Mars’ warming was brought on by asteroid impacts, creating steam atmospheres that led to rain.
But, these would be much shorter than the time needed to produce enough water.
Instead, the researchers say warming cycles could be responsible.
‘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, a graduate student of astronomy and astrophysics.
According to the researchers, the valleys on Mars are similar in width to the Grand Canyon which is thought to have been carved over 16 million years by the Colorado as it swelled with seasonal snow melts.
Their climate models show that warming periods caused by greenhouse gases may have persisted for up to 10 million years.
These gases slowly built up as they were belched from volcanic eruptions, released by cooling magma, or seeped from the crust.
‘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 co-author Jim Kasting, Evan Pugh Professor of geosciences.
Deep canyons and valleys on Mars may have formed as the result of warming periods that stretched for up to 10 million years, melting the glaciers that covered its surface
‘In terms of water, we need millions of meters of rainfall, and they (previous studies) can get hundreds of meters.’
While rain naturally removes some of these gases from the atmosphere and stores carbon in the ground through chemical weathering, cold temperatures on early Mars meant little rain, and the process could not keep up.
‘Mars is in this precarious position where it’s at the outer edge of the habitable zone,’ said Batalha.
‘It’s receiving less solar flux, so you start at a glaciated state. There is volcanic outgassing, but because you are colder, you don’t get the same deposition of carbon back into the planet’s surface.
‘Instead, you get this atmospheric build-up and your planet slowly starts to rise in temperature.’
Weathering would eventually speed up as the planet warmed, occurring faster than the volcanos could put gases back into the atmosphere.
Frozen beneath a region of cracked and pitted plains on Mars lies about as much water as what’s in Lake Superior, the largest of the Great Lakes, researchers have revealed.
It confirmed huge deposits of ice mixed with dust and larger rock particles in the Utopia Planita region – and experts say the area may once have held life
The name Utopia Planitia translates loosely as the ‘plains of paradise.’
It is a basin with a diameter of about 2,050 miles (3,300 kilometers), resulting from a major impact early in Mars’ history and subsequently filled.
Diagonal striping on this map of a portion of Mars’ Utopia Planitia region indicates the area where a large subsurface deposit rich in water ice was assessed using the Shallow Radar (SHARAD) instrument on NASA’s Mars Reconnaissance Orbiter. The deposit holds about as much water as Lake Superior
NASA sent the Viking 2 Lander to a site near the center of Utopia in 1976.
The portion examined by Stuurman and colleagues lies southwest of that long-silent lander.
The newly surveyed ice deposit spans latitudes from 39 to 49 degrees within the plains.
It represents less than one percent of all known water ice on Mars, but it more than doubles the volume of thick, buried ice sheets known in the northern plains.
Ice deposits close to the surface are being considered as a resource for astronauts.
This would lead to cooling, and another ice age.
Researchers must now determine whether the planet could have produced enough carbon dioxide and hydrogen for this to work.
‘We would be well off if early Mars had plate tectonics just like Earth has today,’ Kasting said.
‘Then it works. But that’s a big debate. A lot of people don’t think Mars ever had it.’
Excess CO2 in the atmosphere would have resulted in acid rain, which in turn would have dissolved carbonate rocks at the surface and deposited them further down.
‘So if the next Mars mission was able to dig down deeper, you might be able to uncover these different carbonates,’ Batalha said.
‘That would be a sort of smoking gun for carbon dioxide.’