Mars, the fourth planet in the solar system, is also the closest to Earth. For generations, man was fascinated by its beauty in the night sky. Red planet, it was called, was attributed to the war god by Romans and even the name Mars is a result of its association with war.
There were many reasons for Mars to become the center of human attention. It was the closest planet to Earth. Other than that, it also shares more similarities with Earth than any other planet. The day is almost similar and so is the tilting. Therefore Mars has four seasons which are twice as long because of the longer year.
With the development of telescopes, man was even more fascinated of its close neighbor. The canal system, made it pretty clear for the early astronomers, that Mars sustained some intelligent life form. It was much later that the canal system was proved wrong. The observational voyages to Mars in the late 20th century made it clear that there is no liquid water on the planet. The atmosphere was so thin that the low pressure is unable to hold liquid water on the planet’s surface. There is no oxygen or water vapor in detectable amounts in the Martian atmosphere. But the scientists were not convinced that it is a total myth that water was once abundant on the planet.
# Evidence of Water in the Past
The presence of polar ice caps in both poles of Mars is a strong evidence for the presence of water. The seasonal change in the thickness of ice caps indicates that there is a large amount of polar ice to this day. And these ice caps are believed to be the remaining of large amounts of water, which once flooded the entire planet.
Viking orbiters found evidence of possible river valleys, signs of erosion and remnants of branch streams in the southern hemisphere. But it was unable to detect any sign of liquid water as expected. These were suggestive evidence that liquid water is no longer available on the Mars’ surface.
# Recent Evidence of Presence of Liquid Water
However, recent images taken by the Mars Global Surveyor (MGS) identified some form of white matter coming out of some recent crates. This white matter was lost over the time (in a matter of months) and this indicated the presence of pure ice beneath the Mars’ surface, which turned to vapor when exposed to the atmosphere. These sites were somewhat away from the poles and this indicated that the ice layer would be far larger than it was previously believed.
Other than the ice coming out of recent crates, there were images of gullies which were of recent origin. These gullies were believed to be made of water coming out from the ice that is believed to be trapped beneath the surface. The gullies clearly showed signs of flowing liquids and this has been a tough point to deny for those who do not believe the existence of water in Mars.
However all these recent evidence are only suggestive of the ice trapped beneath the surface. Scientists around the globe agree on the fact that present Martian atmosphere is too thin to support any form of liquid water on its surface. The temperatures are too low (partly due to its long distance to the sun and partly due to the low carbon dioxide levels in the atmosphere) to keep any water from turning into ice. But there are scientists who still believe in the presence of liquid water, not in the surface, but beneath the ice.
# Did Water Used to Flow on Mars?
So the question still remains. Did water ever flow on the surface of Mars? The likely answer is yes. It is believed that millions of years back, most of the Martian surface was in fact under a large ocean. The entire northern hemisphere was under the ocean while only the high lands of the southern region remained dry. The eroded lines (which were previously named canals) are thought to be the work of large amounts of water that flowed at high speeds across the planet. There are even stones that were shaped by the erosion of waves.
Other than the signs of erosion, there are large amounts of mineral deposits (hematite – a mineral that forms in the presence of water) detected on Mar’s surface. These minerals need large amounts of water to be created and the deposits are scattered around the planet, which is more suggestive of an ocean, which would have taken the minerals by its currents, to different parts of the planet.
# Theories against the Presence of Water
For those scientists who do not agree on the presence of water, the main cause of erosion is seen as the wind. They believe that it was due to the wind that the valleys were formed. They argue that the thin atmosphere was never enough to cause enough temperature on the surface to hold water in the liquid form. They argue that even the faint young sun paradox (a theory which says that the young sun gave more heat compared to its size) is still not enough to believe that the planet was any warmer billions of years back.
So finally if the presence of water is taken as true, then one last question remains. Where did all this water disappear to? Answering this question, scientists believe that most of this water is still trapped in the form of ice and that it could one day be taken in to the surface to use as liquid water by the future humans, who might even go on to colonize the planet.
Even though the planet may not be colonized and the water may not be used for human needs in the near future, finding of liquid water is a great achievement for astronomers. It will lead to the discovery of life beyond Earth and it will expand human knowledge on the evolution of life. After all, water is the main element of life on Earth. Until any other form of life is discovered, people will keep on searching for water, in its quest to find life, beyond Earth.