NASA’s 4-year-old mission on Mars via the Curiosity rover keeps finding new clues to the red planet’s history — this time in the form of rock cross-hatched with ridges, which are probably mud cracks.
Once confirmed, this will be the first documented mud cracks, technically referred to as desiccation cracks, and likely evidence of water on Mars.
Diagnosing The Cracks
"Mud cracks are the most likely scenario here," said Curiosity team member and Caltech graduate student Nathan Stein in a statement, leading the probe of the “Old Soaker” on lower Mount Sharp on the planet.
The cracked surface formed more than 3 billion years ago, subsequently buried under layers of sediment that all became stratified rock. Wind erosion removed the layers and exposed the split pieces; materials filling the cracks better resisted erosion than the mudstone surrounding it, resulting in the raised ridges.
Apart from the mysterious cracks that were probably caused by drying, there are other pieces of evidence in the site found by the rover. There is a layering pattern known as cross-bedding, which likely formed where water flowed strong near a lakeshore.
Curiosity witnessed proof of ancient lakes in the older and lower-lying rock layers, as well as in younger mudstone situated above the Old Soaker site.
The cracks’ pattern of four- or five-sided polygons, Stein explained, was not previously seen by Curiosity, likening it to what one would see on the side of the road where mud-laden ground has dried and eventually cracked.
Prospects Of Water On Mars
Examining the materials filling the cracks at Old Soaker, the team saw that there could be different generations of fracturing, namely mud cracks at first, sediments accumulating in them next, and later an episode of fracturing underground and vein formation.
If those are indeed mud cracks, they believe they are evidence of dry spells between what could be considered a history of “long-lived lakes” on that part of Mars, said Curiosity scientist Ashwin Vasavada. The team is now analyzing data on the mud cracks and zeroing in on similar-looking areas.
As water is a critical ingredient for life, the discovery of water ice in different planetary objects — from Ceres to Pluto and Mars — has led scientists to be abuzz over the possibility of life beyond the boundaries of Earth.
The Curiosity rover landed near Mount Sharp back in 2012, investigating how and at what point life-friendly ancient features, such as Martian lakes likely conducive to microbes, transformed into dried, more hostile conditions.
The rover has left the site and is headed toward a future rock-drilling place in an uphill direction. Scientists are currently addressing intermittent issues with the rover’s drill last month.
Curiosity may have also found its third meteorite on Mars, with Jan. 12 images appearing to show an iron-nickel meteorite, only a handful of which are found on the planet.
The meteorite looks quite smooth and shiny, meaning it fell only recently and has not eroded much. Mars, however, does not contain the water and oxygen that would wear away the meteorite's smooth surface, only extending the guessing game as to when the object actually fell.
