The search for water on Mars has been a long and arduous journey, but a very rewarding and fulfilling one. Less than 50 years ago, scientists could only speculate about the presence of water on the Red Planet. These days, scientists have found multiple pieces of evidence that water firstly – did exist on Mars – and secondly – still does exist. The discovery of the polar ice caps was one of the first confirmations of water on the planet, albeit in frozen form. Fast-forward a few years and scientists found evidence of more frozen water below the surface (closer to the equator) and even flowing salty water on the planet’s surface. (Also, excitingly, scientists believe there are channels on Mars where water ten times greater than the average discharge of the Amazon River, the largest on Earth, was discharged.) The search for water on Mars is a worthwhile endeavor, largely because where there’s water, life has the possibility to exist. In search of that, the year 2020 will see a new NASA rover take off from Earth to look for evidence of life formerly existing on the planet. For these and other exciting facts about H20 on Mars, strap on your spacesuit because here are 25 Facts About Water on Mars.
The first credible assumptions of water on Mars
The first assumptions of water on Mars came from photographs sent by Mariner 9, the first spacecraft to orbit another planet, in 1971. The pictures appeared to show dry river beds and canyons, leading scientists of the time to speculate about water on the planet.
The first evidence of liquid water on Mars
For decades, scientists were trying to confirm the current existence of liquid water on Mars. Their breakthrough came in 2000 when gullies appeared which were likely made by liquid water flowing across the planet’s surface.
Mars has likely harbored life
Scientists studying Mars have found that billions of years ago the planet’s climate was rather warm and humid, even partially covered by rivers and oceans.
Water escaped into space
Due to Mars’ thin atmosphere, its weak gravitational force (due to its small size) could not hold all the water on the planet’s surface. As the planet warmed and liquid water evaporated, it was increasingly lost into space.
There is still saltwater on Mars
Scientists have used high resolution images taken by the Mars Reconnaissance Orbiter to identify streaks which change with the seasons. The dark lines have led astronomers to conclude they are made by salty liquid water on the planet’s surface.
"Follow the water"
Since all life on Earth must have water to survive, NASA scientists have made finding water on Mars an even greater priority than finding life, believing that if we find water, we’ll find life. To that aim, all recent spacecrafts and rovers sent to Mars have focused on the search for water.
The biggest flood in the solar system
Despite the current lack of running water, scientists postulate that about 3.5 billion years ago, Mars played host to the largest flood event known in the solar system.
Subsurface water found from space
The European Space Agency’s Mars Express orbiter has been successfully using a powerful ground-penetrating radar to search for evidence of frozen and liquid water below the Martian surface.
Water is trapped as ice on Mars
A massive amount of water is believed to exist on Mars, locked up in the polar ice caps. In summer, the caps shrink as the frozen water passes directly from a solid to gaseous form (sublimation) and in winter, they grow up to halfway between the poles and equator.
Extensive global warming could turn Mars into a massive swimming pool
On average about 2 miles (3 km) thick, if the Martian ice caps melted, the entire planet would be covered by 18 feet (5.6 m) of water.
The composition of the ice caps
The Martian ice caps are complex structures. Stacks of water ice and dust appear to be layered near the bottom, topped by caps of water ice then solid carbon dioxide (dry ice) which resembles freshly fallen snow.
Evidence of an ancient lake
The Curiosity rover found evidence of a shallow ancient lake on Mars. Stretching 30 miles by 3 miles (50 x 5 kms), the lake is estimated to have existed on the planet’s surface for tens of thousands of years, possibly frozen over.
Water is not just frozen in the ice caps
Scientists now think water on Mars may not only be trapped in the polar caps, but also in other subsurface areas around the planet. So far, a massive ice sheet the size of Germany, Sweden, and Japan combined has been found north of the equator. The ice sheet is believed to extend to a depth of 130 feet (40 m).
Evidence for Martian rivers and lakes
On our planet (and presumably all planets with flowing water), the land bordering rivers and lakes is wetter than land further afield. Scientists have found evidence for the same kind of circumstances on Mars. They even found the region around Mount Sharp likely hosted a lake, identifiable by the presence of sediments deposited in the lake bed.
Frequent ice ages affect the amount of available water on Mars
Because Mars lacks a large moon like our own, it does not hold onto a stable axial tilt like Earth’s 23.5° tilt. This has resulted in significant wobbling which frequently takes the planet into an ice age, altering the amount of water available for life to use.
Liquid water can't currently exist on Mars
Mars is currently in the middle of one of these ice ages, making it impossible for liquid water to exist until the planet warms up.
A malfunction leads to a breakthrough
After one of the Spirit rover’s wheels stopped functioning, it dug deep as it plowed across the surface. This malfunction accidentally revealed strong evidence for water on Mars. Dirt turned up by the wheel was rich in silica: the material in quartz and window glass and a material which requires water to form.
A waterflow 100 times greater than the Mississippi River
The Marte Vallis, a massive channel system on the Martian surface, is believed to have seen over 100 times more water pass through it each year than passes through the Mississippi River, the 15th largest river by annual discharge on our planet. Compared to the Amazon River, the largest discharger by far, over 10 times the amount of water passed through the Marte Vallis.
One of the smoothest places in the solar system
Mars is covered in low-lying, mostly flat plains. One of the flattest and smoothest places in our solar system, the lowest of the northern hemisphere’s plains may have been created by vast swaths of water flowing across the Martian surface.
Hot springs may have existed on Mars
This fact about water on Mars is especially exciting. Scientists have found features of possible ancient Martian hot springs that highly match those of hydrothermal springs on our own Blue Planet. Since such springs on Earth (such as in Yellowstone National Park) likely contain the closest relatives of the first living organisms on the planet, the presence of such springs there could mean finding definitive proof of life on Mars.
A rover finds liquid water globules
In 2008, the stationary Phoenix rover was examining the Martian surface and dug up chunks of a bright substance which disappeared over the course of four days. Scientists concluded, also based on two of the spheroids merging together, that the substance was likely liquid water which went on to evaporate.
Snow falls on Mars!
During the 2006-2007 Martian winter, snow fell on Mars, but it’s not exactly what you might be thinking. Carbon dioxide snow clouds noticed above the south pole were depositing carbon dioxide snow onto the surface below, the only place in the solar system where this is known to occur.
Real snow falls on Mars, too!
In an even-more astonishing discovery, also in 2008, the Phoenix rover recorded water-ice snow (the kind we receive on Earth) falling near the Martian north pole.
Examining meteorites from signs of water
Beyond using orbiters and rovers to search for water on Mars, scientists also closely examine Martian rocks which have fallen to Earth, ejected during impacts on the Red Planet. The meteorite Yamato 000593 has furthered scientists’ belief of water (and life) on Mars.
Mars is inhospitable to liquid water
Despite all the water in its many forms we have since found on Mars, the temperature on Mars is still too low and its atmosphere too thin for liquid water to exist on the surface level. Various proposals have been put forth to terraform Mars and warm up the atmosphere to make liquid water possible.