Our search for life on Mars

By JAEMIE BENNETT | September 13, 2018

Those funny-looking, little green Martians have captivated human imagination since their first appearance in print in 1877. And maybe the intelligent version of Mars-based life doesn’t exist, but we’ve recently come closer to finding their long-lost cousins, microbes.

In July of 2018, Italian scientists working at the European Space Agency’s Mars Express mission detected a possible 12-mile-wide pool of liquid near Mars’ south pole. 

This is a huge step forward to finally concluding if Mars has or had held life, since liquid — specifically water — is a primary need for life to arise. So important, in fact, that the National Aeronautics and Space Administration’s (NASA) strategy with Mars used to be “Follow the Water.” However, our prospects of Mars were very different when we first made contact with the Red Planet.

Initially, pictures of Mars from the Viking and Mariner missions showed a dry, sandy planet, dashing hopes of a planet that could sustain life. Little by little, subsequent missions proved Mars used to have a very different environment.

The Mars Global Surveyor was launched in 1996. While in orbit, it spotted dry gullies on the Martian surface that could have been created by moving water. It also found hematite, a compound that forms in water.

The 1997 Mars Pathfinder mission included the Sojourner, the very first Mars rover. In its landing site, Sojourner found rounded, or conglomerate, pebbles that indicated the area used to be a flooding site.

Roaming since 2001, the Mars Odyssey is the longest serving piece of machinery to work on Mars. 

The rover reported large amounts of ice under the surface, as well as salt deposits that NASA scientists agreed could have been formed by stagnant liquid water. The Odyssey also found caves dubbed the Seven Sisters that are a promising place to find life. In 2017, it was announced that a hydrogen signature near the equator could indicate liquid water.

The year 2003 saw the launch of both the Spirit and Opportunity rovers, whose focus was on researching areas with evidence of once having water. The compiled evidence showed Mars has a rich history with water, which was once abundant on the planet and could have supported life.

The 2007 Mars lander, Phoenix, dug near the poles of Mars to confirm the underground ice found by Odyssey as well as outlined a history of weather on Mars, which includes snow and different types of ice deposits.

In 2011, scientists found what they thought was evidence of water on Mars. Along a slope, streaks would form in the hotter months and disappear in the colder months, and molecules formed from salty water would be detected only when the streaks appeared. This lead scientists to believe the streaks were from the slope being stained by liquid water.

However, in 2017, the theory was mostly debunked. The dark streaks were found to be more consistent with the movement of sand down a hill than with water, again putting us back to an age with little evidence for liquid water on Mars in the present.

The Mars Science Laboratory and its partner, the Curiosity rover, started work on Mars in 2012, during the transition of NASA’s strategy from “Follow the Water to “Seek Signs of Life.” 

Curiosity drilled into the Martian surface, finding molecular evidence of sulfur, nitrogen, oxygen, phosphorus and carbon, all important organic molecules. A spike in methane levels was detected at the beginning of 2014, an important finding since methane is a byproduct of organic reactions; however, it can also be indicative of geological processes. 

Curiosity also made the first affirmation of organics on Mars, which are considered building blocks of life but could also be created through non-biological interactions.

In 2018, the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument aboard the European Mars Express spacecraft, which is partially under the managements of NASA, detected a “bright spot” about a mile below the surface of an ice cap on Mars. This recent finding is the best evidence we have so far of large pools of liquid water still existing on Mars, increasing the possibility of the existence of modern extraterrestrial life on Mars.

All the evidence points to an ancient Mars that used to look much like modern day Earth — abundant with water and a warmer atmosphere, conditions that allowed life to emerge here on Earth. 

Although the earthen and Martian environments have greatly diverged from each other, does that mean life once colonized Mars? If it did, could it still be there, hiding underground, deep in this new liquid water deposit or miles under some cave system? Perhaps more importantly, could it host life again — specifically, human life?

The Mars Science Laboratory and its partner, the Curiosity Rover, starting work on Mars in 2012, during the transition of NASAs strategy from “Follow the Water to “Seek Signs of Life.” 

Curiosity drilled into the Martian surface, finding molecular evidence of sulfur, nitrogen, oxygen, phosphorus, and carbon, all important organic molecules. A spike in methane levels was detected at the beginning of 2014, an important finding since methane is a byproduct of organic reactions; however, it can also be indicative of geological processes. 

Curiosity also made the first affirmation of organics on Mars, which are considered building blocks of life but could also be created through non-biological interactions.

In 2018, the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument aboard the European Mars Express spacecraft, which is partially under the managements of NASA, detected a “bright spot” about a mile below the surface of an ice cap on Mars. This recent finding is the best evidence we have so far of large pools of liquid water still existing on Mars, increasing the possibility of the existence of modern extra-terrestrial life on Mars.

All the evidence points to an ancient Mars that used to look much like modern day Earth – abundant with water and a warmer atmosphere, conditions that allowed life to emerge here on Earth. 

Although the Earth and Martian environments have greatly diverged from each other, does that mean life once colonized Mars? If it did, could it still be there, hiding underground, deep in this new liquid water deposit, or miles under some cave system? Perhaps more importantly, could it host life again – specifically, human life?

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