Ancient Lake System on Mars was Wet During Two Different Periods

Scientists have learned a bit more about an ancient lake system on Mars. They've completed a new analysis of the lake system that once existed in Jezero Crater, near the planet's equator, and have found that the onslaught of water the filled the crater was one of at least two separate periods of water activity in the region.

"We can say that this one really well-exposed location makes a strong case for at least two periods of water-related activity in Mars' history," said Tim Goudge, one of the researchers, in a news release. "That tells us something really interesting about how early Mars operated."

The ancient lake system was first discovered in 2005. That's when the researchers spotted two channels on the northern and western sides of the Jezero Crater that appeared to have supplied the crater with water. The water eventually overtopped the crater wall on the southern side and flowed out through a third channel. It's not clear how long the system was active, but it appears to have dried out about 3.5 to 3.8 billion years ago.

In 2008, the researchers found that fan deposits in the inlet channels were full of clay minerals, which was a clear sign of alteration by water. But how did the minerals for? In order to find out, the scientists gathered high-resolution orbital images from NASA's CTX instrument and then combined them with data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) aboard NASA's Mars Reconnaissance Orbiter (MRO). With this data, the researchers created a map of the lake system.

The minerals' formation and transportation was separated by a fair amount of time. In fact, the mapping revealed that a younger layer of rock sits on top of hydrated minerals.

"What it implies is that there were actually two periods of water-related activity," said Goudge. "The earlier episode formed the alteration minerals in the watershed, then some time later you had the surface water activity that transported the minerals into the lake. At this site, those two early events appear not to have been genetically related."

The findings reveal a bit more about the early water history of Mars. It appears that the Red Planet had far more water than it does now. Whether it not it had life, though, still remains a mystery.

The findings are published in the Journal of Geophysical Research: Planets.

For more great science stories and general news, please visit our sister site, Headlines and Global News (HNGN).