Satellite images show where water flowed on Mars billions of years ago
Where water flowed on Mars billions of years ago: Stunning satellite images show the valleys and trenches carved by ancient rivers on the red planet
- Images from ESA’s Mars Express satellite show a region near the Huygens crater with dried up river valleys
- Topography suggests water once flowed from north to south to carve 2 km-wide (1.2 miles) valleys in the area
- Southern highlands, where many of these valleys can be seen, is estimated to be about 3.5-4 billion years old
Stunning images captured by the European Space Agency’s Mars Express Satellite have revealed a glimpse into the red planet’s warm, watery past.
In the midst of innumerable impact craters that speckle the surface of Mars, the satellite images show branching systems of trenches and valleys – features likely carved by flowing water that existed long ago.
One particular region highlighted in the latest batch of satellite photos shows ‘clear signs of past water activity,’ according to ESA, with evidence of water that flowed north to south to create valleys that extend hundreds of meters deep.
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Stunning images captured by the European Space Agency’s Mars Express Satellite have revealed a glimpse into the red planet’s warm, watery past. The perspective view above illustrates an ancient river valley network on Mars
A region that sits just east of Mars’ famous Huygens impact crater in the southern highlands is carved by ancient valleys and other evidence of water that go against our current view of the Martian climate.
‘We see Mars as a cold, dry world, but plenty of evidence suggests that this was not always the case,’ ESA explains.
‘Research in past years instead increasingly indicates that the planet once had a thicker, denser atmosphere that was able to lock in far greater amounts of warmth, and therefore facilitate and support the flow of liquid water on the surface below.’
The southern highlands is an area estimated to be 3.5 to four billion years old, providing a glimpse at some of the oldest features on the red planet.
Here, the topography suggests water once flowed from north to south to carve 2-kilometer-wide valleys as deep as 200 meters, according to ESA.
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In the midst of innumerable impact craters that speckle the surface of Mars, the satellite images show branching systems of trenches and valleys – features likely carved by flowing water that existed long ago. A dried up network of rivers can be seen above
One particular region highlighted in the latest batch of satellite photos shows ‘clear signs of past water activity,’ according to ESA. The region (circled above) that sits just east of Mars’ famous Huygens impact crater in the southern highlands is carved by ancient valleys and other evidence of water that go against our current view of the Martian climate
Despite many years of erosion, these valleys remain visible in the satellite images today, though fragmented and smoothed down in many places.
The branching patterns make up what’s known as a dendritic system, with numerous channels in a given system, ESA says.
‘This kind of dendritic structure is also seen in drainage systems on Earth,’ ESA says.
‘A particularly good example is that of the Yarlung Tsangpo river, which snakes its way from its source in western Tibet down through China, India, and Bangladesh.
‘We see Mars as a cold, dry world, but plenty of evidence suggests that this was not always the case,’ ESA explains. River systems that have since long dried up, such as that shown above (center) are signs of flowing water that once existed on the surface
‘In the case of this image of Mars, these branching channels were likely formed by surface water runoff from a once-strong river flow, combined with extensive rainfall.
‘This flow is thought to have cut through existing terrain on Mars, forging new paths and carving a new landscape.’
Though the evidence is there for Mars’ ancient water, just what the source was remains a mystery. Mars’ flowing water may have come from rainfall, groundwater, or even melting glaciers, ESA says.
All of this will be investigated by the upcoming ExoMars mission, set to launch in 2020.
WHAT PROOF HAS BEEN FOUND OF LIQUID WATER ON MARS?
How important is the presence of liquid water?
It is now widely believed that Mars holds a reasonably large volume of water.
However, the surface of the planet is so cold, this water exists only as ice.
In order for life to exist on a planet, many scientists believe it is essential for the world to possess liquid water.
Ever since technology has enabled mankind to gaze at Mars in detail, humans have been looking for indications that there was water on the red planet.
Did water used to flow on the surface of Mars?
The Mariner 9 mission revealed clues of water erosion in river beds and canyons, as well as evidence of weather fronts and fogs on Mars in 1971.
Later missions from the Viking orbiters, which first launched in 1975, revealed yet more details about how water flowed on the surface and carved valleys.
Several studies investigated the presence of liquid water for decades. In 2000, the first proof of liquid water on Mars was discovered.
It was claimed the gullies seen on the surface of the planet had to have been formed by flowing water.
Scientists cited the debris and mud deposits left behind as evidence for moving water existing at some point in the history of the red planet.
However, the formation of these gullies has been hotly debated throughout the ensuing years.
Proof of ice in geological samples from Mars
Spirit and Opportunity, the twin rovers, found evidence of the presence of water enclosed in rock in 2007, when one of Spirit’s wheels broke and gorged a piece of stone.
Analysis of the silica-rich layer discovered in the scratch suggested it formed in the presence of liquid water.
In 2008, the Phoenix lander was gathering geological samples, and they disappeared after a few days.
Scientists thought these were pieces of ice. This assessment was confirmed when the lander later detected water vapour in a sample.
In 2012, Curiosity was meandering over an ancient martian seabed when it examined a number of rocks that were exposed to liquid water billions of years ago.
In 2012, Curiosity (pictured) was meandering over an ancient martian seabed when it examined a number of rocks that were exposed to liquid water billions of years ago
Recurring slope lineae and debate causes it
Features known as recurring slope lineae (RSL) were first identified in 2011.
These dark streaks populate the areas of Mars with a sharp incline.
Researchers speculated that these may have been caused by the intermittent flow of liquid water down steep banks on the planet.
In June 2013, Curiosity found powerful evidence that water good enough to drink once flowed on Mars. In September of the same year, the first scoop of soil analysed by Curiosity revealed that fine materials on the surface of the planet contain two per cent water by weight.
In 2015, Nasa claimed to have discovered the first evidence of liquid water on Mars in the present day.
The space agency said that its Mars Reconnaissance Orbiter (MRO) provided the strongest evidence yet that liquid water flows intermittently on present-day Mars.
In 2017, Nasa issued another statement rebuking its initial findings.
Features known as recurring slope lineae (RSL) were first identified in 2011 (pictured). These dark streaks populate the areas of Mars with a sharp incline. Researchers speculated that these may have been caused by the intermittent flow of liquid water
It said the dark features that run down steep inclines on the red planet were actually granular flows, where grains of sand and dust slip downhill to make dark streaks, rather than the ground being darkened by seeping water.
Images from the MRO revealed the streaks only exist on slopes steep enough for dry grains to descend the way they do on faces of active dunes.
Also in 2017, scientists provided the best estimates for water on Mars, claiming it once had more liquid H2O than the Arctic Ocean – and the planet kept these oceans for more than 1.5 billion years.
The findings suggest there was ample time and water for life on Mars to thrive, but over the last 3.7 billion years the red planet has lost 87 per cent of its water – leaving the surface barren and dry.
A subterranean lake
In a study published in the journal Science, ESO researchers have now discovered the first concrete evidence for liquid water on Mars.
Using radar imagery from the Mars Express probe, the ESO team have found a 12-mile long underground lake filled with liquid water.
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