Our neighbor in space, the planet Mars, has been the subject of humanity’s fascination over many years. In our solar system, this red planet is the fourth one nearest to the sun and our planet’s second closest neighbor after the terrestrial planet Venus. But aside from its proximity to our own planet and its beautiful reddish appearance, our interest in unraveling the mysteries of Mars really stems from the similarities it shares with our own planet and the potential for its habitability. It is believed by many scientists that this terrestrial planet was once more habitable than it is today. Some have speculated that there may have been life on Mars billions of years ago while others are not ruling out the likelihood that life may still exist there right now.
In recent years, experts in astrobiology, equipped with their ever-increasing knowledge about the planet and the advanced technology to study it, have become more determined than ever to find proof of life on Mars or, at the very least, some form of verification that it was once habitable. Today, there are various environmental factors being considered to predict the habitability of our neighbor planet but scientists have placed a particularly heavy emphasis in finding evidence on one of them – that is, the presence of liquid water.
THEORIZED PRESENCE OF UNDERGROUND WATER ON MARS
The surface of Mars currently has an extremely cold climate and is deemed to be too dry for any presence of life to be possible. However, experts believe that there is enough evidence to suggest that the Red Planet was once home to several bodies of water like oceans and lakes. As for how Mars virtually lost its liquid water billions of years ago, the exact answer remains a mystery but it is speculated by some that a cataclysmic event may have been the root cause of it all. The planet is assumed to have lost its magnetic field around 3.8 billion years ago and extreme solar radiation resulted to the evaporation of liquid water in the Marian atmosphere and the escape of water’s hydrogen molecules into space.
The theory that Mars may have been very similar to Earth due to the supposed presence of liquid water on the planet in its distant past gave rise to speculations that life might have also evolved on our neighbor planet during this ancient period. And though its surface may be completely devoid of liquid water today, this doesn’t mean that Mars doesn’t have any water at all. Aside from the abundant volume of water ice found in its two polar ice caps, scientists also believe that liquid water is still present on Mars albeit buried in subterranean aquifers. Aquifers are permeable rocks found underground that bear groundwater. On Earth, water stored underground manages to find its way to the surface through natural springs or by pumping. And so, in the case of Mars, scientists believe that should life still exist there today, the chance to unravel this mystery lies in finding where these hidden reservoirs are located now.
All this talk of searching for life and water on planet Mars has gone one for many, many years, but how are we actually faring in finding evidence that supports such theories? Have our unmanned space expeditions to the Red Planet yielded any promising results? Have we detected compelling data to say that there was indeed an ancient ocean on Mars? Are we any closer to finding the underground water supply of Mars now more than we were a decade ago?
To answer these questions, let’s talk about some of the Mars-related studies published in recent years.
2012 FINDINGS OF EUROPEAN SPACE AGENCY’S MARS EXPRESS
In 2012, the European Space Agency revealed that their spacecraft which orbited Mars called Mars Express detected sedimentary deposits on the planets northern plains. To the European researchers, the fact that the Mars Express’s radar detected low-density materials and ice in this region is indicative that this area may have once been an ocean. The agency’s findings using subsurface radar are not surprising but they have added to the existing data gathered from images, atmospheric measurements and mineralogical study of the planet which already previously pinpointed the northern plains to be the site of ancient Martian shorelines.
2012 STUDY ON MARTIAN METEORITES BY MCCUBBIN ET AL.
Within that same year, planetary scientist Francis McCubbin of the University Of New Mexico in Albuquerque and his colleagues published a study on Martian meteorites containing hydrated minerals which allowed them to estimate how much water exists today in the Martian mantle. The authors of the study determined that Mars has enough water in its mantle to submerge the planet for as deep as 200 to 1000 meters. This means the planet is currently shrouding around 70 to 300 parts per million of liquid water somewhere beneath its surface.
2014 ICARUS STUDY ON ARAM CHAOS
Then there’s also the study published by the international journal Icarus in 2014 which revealed that a team of geologists found evidence of a vast ancient underground ocean located beneath the surface of Aram Chaos, one of the impact craters on Mars. Around 2.5 billion years ago, about 93,000 cubic kilometers of water supposedly broke through and flooded the surface after the lake ice – which was concealed underground – melted and its ceiling suddenly collapsed.
Here’s an idea how much water reached the Martian surface at the time: they say it is equivalent to around 80% of the free-flowing fresh water that exists on our own planet today.
2015 ATMOSPHERIC MAPS OF MARS BY NASA
In 2015, researchers at the NASA Goddard Space Flight Center in Maryland, led by planetary scientist Geronimo Villanueva, developed infrared maps of water isotopes on Mars which showed the distribution of atmospheric water on the planet - H2O and its deuterated form, HDO. In doing so, they were able to estimate how much liquid water Mars used to have. According to their findings, Mars may have once had enough water to cover up to 20 percent or about a fifth of the planet more than 4 billion years ago. They also suggested that the planet could still contain some subterranean water reservoirs and that the key to finding them lies in refining the infrared maps they had developed.
2015 DISCOVERY OF LIQUID BRINE ON MARS
That same year, another study revealed that NASA’s Curiosity rover – which landed on Mars’s Gale Crater back in 2012 – managed to measure estimates of the concentration of subterranean water on the planet. The new measurements suggested that the soil in Mars is moist with liquid brine. The presence of this liquid brine is supposedly caused by the perchlorate salts found in the soil as it is known to reduce the freezing point of water. The salt is the one responsible for absorbing the water vapor from the atmosphere which then precipitated under the surface. The researchers considered this find as an indirect evidence of transient liquid water on the planet though they insist that the presence of liquid brine is not enough to deem Mars equipped to support terrestrial organisms.
A similar finding was reached that same year by examining the data and images gathered from NASA’s Mars Reconnaissance Orbiter or MRO. At the time, the researchers believed that the dark streaks found on Martian craters is actually Martian soil being dampened by briny water, which may have been enough to allow microbial life to thrive on the planet. However, authors of a later study argued against the hypothesis that there is liquid water on the Martina surface, suggesting instead that the dark streaks captured by the MRO’s powerful camera were just grains of sand and dust that occasionally slipped downhill.
2016 DISCOVERY OF MASSIVE UNDERGROUND ICE DEPOSIT ON MARS
An underground layer of water ice was also detected within the planet’s Utopia Planitia region. Researchers used the Mars Reconnaissance Orbiter again, particularly its ground-penetrating Shallow Radar instrument, which is also referred to as SHARAD. After they analyzed the data provided by the high-powered radar, they discovered a massive deposit of water ice in the area that is much bigger than the State of Mexico. This subterranean ice deposit runs deep – between an estimated thickness of 260 feet to around 560 feet. Fifty to eight-five percent of the deposit is made of ice while the rest is made up of dust and rock particles.
The water ice deposit in Utopia Planitia managed to elude the danger of being vaporized by the planet’s hostile atmosphere because of the thick soil that successfully separated the two. Estimates of the soil’s thickness in this region range between 3 to 33 feet.
2017 DISCOVERY OF WATER ICE NEAR MARTIAN EQUATOR
Another compelling evidence that supports the theory that an ancient underground ocean is hidden beneath the Red Planet’s surface comes from the reanalyzed data from NASA’s Odyssey spacecraft which has been orbiting the planet since 2001. Researchers found patches of water ice in regions at surprisingly lower latitudes. Should this equatorial ice eventually melt and reach the surface, it is presumed that it would very likely result to the formation of a more accommodating environment that could be perfect for the survival and growth of microbial life.
Despite the vast amount of research that has gone into finding water and life on Mars, many of the missing pieces needed to complete the entire picture of what happened to this unique Red Planet and what remains there now have yet to be found. However, it is safe to say that we know more about our neighbor planet now more than we did before, and most of the information we have learned about Mars has only strengthened our scientific community’s conviction that liquid water once filled a sizeable portion of the planet’s surface and may still be lurking beneath its porous subterranean rocks.