By Sabine Stanley, Ph.D., John Hopkins University
Mars has evidence of tsunamis, much greater than the ones on Earth due to its weak gravity, and is covered with craters. Water has left remarkable effects in the minerals on Mars. Can the hydrated minerals also show past life on Mars?
Tsunamis on Mars
Mars used to have lakes, rivers, waterfalls, and a giant ocean covering its northern hemisphere. The shorelines from the ocean are in some areas about 3.8 billion years old. If the whole area inside the shoreline was once filled with water, then 36% of Mars was covered by this ocean. Having such an enormous ocean led to enormous tsunamis, as well.
Evidence suggests at least two mega-tsunamis on Mars. They were most probably created by giant impact events. The wall of water must have been tens to hundreds of meters tall, moving considerable amounts of debris and sediments due to the weak gravity. The moved debris is evidence of the tsunamis.
Boulders covering vast areas of the surface would have been collected and transported by the tsunami wave until they reached the maximum extent of the wave’s penetration onto land. The channels under the boulders would have directed the water back to the ocean.
An area known as the thumbprint terrain was also formed by tsunami waves after the first big one. The curves in this area look like fingerprints and are bright up high and dark down low. There are craters that look big enough to have created the tsunamis.
An impact causing a mega-tsunami would leave a mega crater behind. Lomonosov crater, 150 kilometers wide, fits the description well. Also, a couple of smaller impactors that created 30-kilometer diameter craters a few million years apart could be responsible. Mars’s once water-covered surface is also evident in the rocks.
Learn more about exploring Mars from space and the ground.
Minerals on Mars
When minerals come in contact with liquid water, other minerals are formed, which are, in many cases, hydrated. Getting the hydrogen and oxygen from H2O in the crystals makes them hydrated. There are hydrated minerals on Mars at various locations, showing water was not concentrated in only one area. There are hydrated clay minerals called phyllosilicates in some of the oldest regions of Mars, over 3.5 billion years old. The layered structure shows that volcanic rocks have been in touch with water for a long time.
Hydrated sulfates formed in contact with acidic waters have been found in regions like Valles Marineris and Terra Meridiani, dating back to about three billion years ago. Opal, or hydrated silica, is another mineral found on Mars from about two billion years ago.
Aqueous minerals contain H2O, which means they were formed through reactions with liquid water. The pressure, temperature, chemistry, and even the pH of the water environment can be determined by studying these stones.
Learn more about planets migrated in our early solar system!
Carbonates on Mars
Mars does not have as many carbonates as Earth does. The reason is the missing carbonates problem, whose solution is explained through a few theories. Perhaps, the water was too acidic with a pH below seven, and even six, which is the common acidic level of Earth water.
As a result, Mars’s water reacted with carbon dioxide in the atmosphere to form oxalate, not carbonates. The missions like Viking, Phoenix, and the Mars Science Laboratory all reported the presence of oxalates on Mars.
Mars Global Surveyor found gray hematite signatures in Meridiani Planum. On Earth, gray hematite forms only in hot springs or standing pools of water, indicating that Meridiani Planum was once full of standing water. How was all this evidence collected?
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Robotic Rovers in Search of Water
Even though signs of hydrated and aqueous minerals can be seen from spacecraft orbiting Mars, studying them up close is the best method. NASA sent two robotic rovers to Mars in 2004. They landed three weeks apart at different sides of the planet, searching for water.
The Spirit rover landed first and, after some time, found the rock called Pot of Gold in Gale crater, which contained aqueous mineral hematite. It took Spirit ten months to make its huge discovery: Home Plate, containing magnesium iron carbonate, which forms in neutral-pH waters. Thus, Mars might have been hospitable to life.
Opportunity, Spirit’s twin, landed in Meridiani Planum but bounced and fell into a small crater, only 22 meters across. However, there were numerous signs of past water, including Martian Blueberries – bluish spherules of hematite. They must have formed as concretions that grew in wet environments with dissolved iron.
Other parts of Meridiani Planum also showed footprints of past water, however quite salty. In 2012, Curiosity landed in Mars’s Gale crater. Mount Sharp, in the center, is over five kilometers high and probably formed when sedimentary layers that once filled the craters were eroded.
Further, some parts of Mars fell on Earth. Over 60 rocks from Mars have been found on Earth, some showing evidence of water. Some of them were exposed to water while on Mars as recently as about 620 million years ago. Coincidentally, that would mean exposure to Mars water less than 100 million years before the Cambrian explosion of life on Earth.
So Mars might have had life on it, but we have not found it yet.
Common Questions about Minerals on Mars
Evidence shows that Mars had at least two mega-tsunamis that affected the whole planet. The craters and the hydrated minerals on Mars confirm the existence of water a long time ago.
The tsunamis moved huge amounts of minerals on Mars and created craters and fields of boulders seen today on the dry and cold surface.
There are different types of minerals on Mars, including gray hematite, an iron oxide, that can even be used to make jewelry. However, not all common gemstones on Earth have been found on Mars.
Hydrated minerals on Mars show that there used to be water in large quantities on this planet, perhaps, billions of years ago.