The surface of Mars is now cold and dry, but it used to be covered with rivers and lakes, new evidence suggests, according to Space.com. Volcanic eruptions on the Red Planet could have caused a warm up, which would have helped water flow across the cold planet.
The atmosphere of early Mars was too thin to keep it warm and the sun was not as bright, according to Space.com, so Mars would not have had much chance to stay toasty. Scientists do believe, though, at one point, the planet had rivers and lakes.
"The problem of explaining the evidence for liquid water on early Mars has defied attempts to solve it for a very long time," lead study author and planetary geochemist at the Weizmann Institute of Science in Rehovot, Israel, Itay Halevy, told Space.com.
However, now research shows that volcanic activity caused greenhouse gas emissions, providing an insulation to trap heat. Every eruption would have heated Mars for "decades or even centuries," according to Space.com.
Large, powerful volcanos were active on early Mars causing geological features that date back to 3.7 billion years ago. On Earth, volcanic activity leads to cooling because ash and sulfuric acid reflect the sunlight. On Mars, the dusty atmosphere could have coated the ash and sulfuric acid particles, keeping the reflection of the sun's rays at a minimum. Martian volcanoes also produce the greenhouse gas sulfur dioxide, helping the planet heat up.
"The reason that no prior work has seen similar effects is that no prior simulation of Mars' early climate included both dust and sulfuric acid," Halevy told Space.com.
"This model for Mars' early climate is like 'Brigadoon,' the Scottish village that appears for one day every hundred years," Halevy said. "For a few decades every several millennia, an eruption so large goes off that the atmosphere changes, the climate warms, the rivers flow and the lakes fill. Then, as the eruption dies off, things slowly relax back to their cold, icy, sleepy state for a few more millennia until the next biggie."
Scientists compare early Mars' atmosphere to the McMurdo Dry Valleys in Antarctica.
"The average yearly temperature in the Antarctic Dry Valleys is way below freezing, but peak summer daytime temperatures can exceed the melting point of water, forming transient streams, which then refreeze," said study co-author James Head from Brown University in Providence, R.I. "In a similar manner, we find that volcanism can bring the temperature on early Mars above the melting point for decades to centuries, causing episodic periods of stream and lake formation."
"Life in Antarctica, in the form of algal mats, is very resistant to extremely cold and dry conditions and simply waits for the episodic infusion of water to bloom and develop," Head said. "Thus, the ancient and currently dry and barren river and lake floors on Mars may harbor the remnants of similar primitive life if it ever occurred on Mars."
The scientists published their findings on Nov. 17 in the journal "Nature Geoscience."
