Water on Mars and What it Means for Humanity

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Recent Substantial Evidence of Water Flowing on Mars - 

The Discovery of Water on Mars

When Italian astronomer Giovanni Schiaparelli first announced in 1870 that Mars seemed to have ‘canali’, or channels, indicating there was flowing water on Mars, this inspired American businessman Percival Lowell to found the Lowell Observatory in Flagstaff, Arizona for further observation of the Martian Planet. Lowell’s examinations of the Martian planet led him to believe it had canals that were created by intelligent beings.

The theory that Mars had canals dug by intelligent life became prevalent and popular in the scientific community until 1965, when Mariner 4 flew past Mars, taking the first ever close-up photographs of another planet. It was in 1971 that Mariner 9 became the first spacecraft to orbit another planet, and in 1972, after a months-long planet-wide dust storm, Mariner 9 was finally able to get clear pictures of the Martian surface. These pictures provided the first bit of evidence that liquid water had once flowed on the Martian surface, however they also seemed to confirm that liquid water on Mars was only something of the past.

Phoenix Lander Finds Evidence of Ice on Mars

Topographical Evidence that Liquid Water Existed on Martian Surface

It was NASA’s Viking Program that helped give the world their current understanding of water on Mars and the extent to which it had once covered the Martian planet. Large river valleys, some spanning thousands of kilometers, are clearly visible in photos taken from the Viking Orbiters. The Viking Orbiter also discovered other signs of water on Mars; ocean beds, river valley, and indicators of heavy rainfall are prevalent all over the planet. Other indications of water on Mars include islands, heavily eroded areas, and minerals only found in places water has existed.

Scientists have identified many features that indicate the past presence of liquid water on Mars, some of which appear to have been carved by flowing water with the force of 10,000 Mississippi Rivers.

These photos show branching and intertwining channels (top) that are strong evidence that it once rained on Mars. The labeled photo shows areas that were once flooded by large quantities of water.

Recent Substantial Evidence of Water Flowing on Mars

Outflow Channels

These outflow channels are hypothesized to be the result of a sealed subterranean aquifer being breached by meteorites or volcanic activity. The amount of water discharged to create these outflow channels was exponentially greater than the discharge of any of the largest rivers on Earth.

The Ares Vallis was created by outflow channels

Mars has around 25 outflow channels, which are vast areas of land that have been shaped by water on Mars flowing down slope. They often formed valleys, or vallis, due to the massive amount of water released. Outflow channels are hundreds of kilometers in length and usually greater than 1 kilometer in width. The largest of these valleys is the Kasei Vallis; it is approximately 3500 kilometers long, over 400 kilometers wide, and more than 2.5 kilometers deep.

The age of the outflow channels on Mars vary. Most of the outflow channels have been created since the early Hesperian period (3.7 - 3.0 Billion Years Ago), with some having been formed just in the last tens of millions of years, which is extremely young by Mars standards.

Ravi Vallis was formed by massive flooding 

Ice on the Martian Surface

Water ice is present in large quantities at the Martian poles and mid-latitudes. Until recently, it was thought that ice was only present on the Martian poles, but observation of recent meteorite impacts, as well as samples taken by the Martian lander have led to the discovery that ice exists on much of the Martian surface, This was confirmed by the Phoenix lander on July 31st, 2008 when it took samples of water ice in the mid-latitude Martian soil. From those samples it was determined that the ice was H₂O.

Both the North and South Martian Poles each contain approximately 1.6 million cubic kilometers of ice. If just one of the poles ice caps was completely melted the volume of water would be enough to cover the entire Martian surface to a depth of 11 meters.

Further evidence from the Phoenix lander indicated that at mid-latitudes there are large quantities of water ice just below the Martian surface, with some of it just one centimeter below the surface. The detected water ice ranges anywhere from one centimeter below the surface to 10 meters below the surface. The ice was exposed by meteorite impacts that broke through the Martian soil; the images of the ice were then caught on camera.

This shows the same impact site.
Notice ice is present and sublimates over the period of three months.

This diagram shows the depth at which
 the ice exists at 6 impact sites.

It is theorized that there is also liquid water below the surface that undergoes geothermal heating, thus keeping it at temperatures necessary for it to keep its liquid form. Until such time that we can take subterranean samples we will not know for sure, but the prospect is enticing

Speculation of Underground Water on Mars

The frigid temperature on Mars and its lack of sufficient atmosphere makes it impossible for liquid water to exist on the Martian surface. This is a firm fact of Mars that has been established by multiple satellites and land rovers over the past few decades.

But new findings have suggested that underground reservoirs of liquid water figured prominently in creating the prominent surface features of Mars, most particularly the numerous outflow channels. There are thought to have been large aquifers of water just below the Martian surface, that when ruptured by a meteorite or tectonic shifting released enormous amounts of water, carving the landscape Mars presently has. The exciting part is that these underground reservoirs of liquid water likely still exist on Mars.

If underground reservoirs of water do still exist on Mars they are likely similar to those found underneath the permafrost in the most inhospitable northern regions of Earth. This means that reservoirs of liquid water on Mars are most likely to exist under areas that are known to be water-rich, like glacial ice and salt beds.

These liquid water reservoirs would need to be insulated from the frigid temperature on Mars. Planetary Science Institute's Alexis Palmero Rodriguez, head of the study for subterranean liquid water reservoirs explains:

If you have a few tens of meters of porous, fine-grain sediments, dunes, or alluvial deposits, you can create a thermal anomaly that would produce melting or perhaps stabilize existing water at shallow depths

Four close-up views of a different type of geological
deposits formed with the involvement of water.
All four date from the earliest period of Martian history
 (3.7-4.1 Billion Years Ago), called the Noachian Period.

He goes on to say that there would presently need to be approximately 120 meters of porous sediments in order to create a sufficient environment for liquid water. Rodriguez makes sure to note that 120 meters is considered to be very shallow and accessible to humans.

Because the liquid water would exist below unconsolidated, porous sediments it would be relatively easy and inexpensive to drill deep below the surface.

What Water on Mars Means for Humanity

Whether you think the existence of water on Mars implies that life did, or does exist, it is undeniable that the discovery of ice on the Martian surface and the speculation of underground water reservoirs will help further Manned Exploration of Mars, since, as Rodriguez states, "Water is fundamental to sustaining long-term human settlements on Mars. In addition, hydrogen extracted from water can be used as fuel." These assertions are shared by many in the scientific community and are highly encouraging for the future of space development.

The fact that the ice sampled by NASA's Phoenix Mars Lander was pure H₂O, eliminates the worry that the ice could have been dry ice, composed primarily of carbon dioxide.

The discovery of water on Mars will undoubtedly lead to other developments in the field of Martian exploration and discovery.

"I have tasked the men and women of NASA with an ambitious new mission: to break new boundaries in space exploration, ultimately sending Americans to Mars. I know they are up to the challenge – and I plan to be around to see it."

-President Barack Obama