10 Things You Should Know About Life On Mars
From time immemorial Mars has exerted a fascination on people of all races. This is reflected in the many names, familiar to all who read sci-fi/terraforming novels including Al-Qahira (the Arabs), Huo Hsing (the Chinese), Mangala (the Indians), Nirgal (the Babylonians), Kasei ( the Japanese), Ares (the Greeks) or our own word Mars which comes from the Roman name for the planet, associated with the god of war. From the earliest times our ancestors tracked the movements of the planet in the heavens and even by the time of Aristotle people had worked out that it was a lot further away than our own moon. As early as the 5th Century, Indian astronomers had managed to calculate the diameter of the planet. In the west the planet is traditionally associated with the god of war while in the east it is associated with the element of fire. Both arose because of the distinctive red appearance of the planet.
The famous ‘heretical’ astronomer Galileo was the first to view Mars through a telescope but it was not until the 19th Century that the quality of the instruments had improved enough to make detailed observation possible. From that moment interest in the planet increased exponentially. The planet looked so like our own Earth, with changing seasons and melting and expanding icecaps that the possibility of intelligent life on our ‘sister world’ seemed high. Schiaparelli and others such as Lowell, dedicated their time to taking detailed observations of the planet and saw long canals (optical illusions sadly) that looked as though they had been manufactured by intelligent beings. For a time people even believed that there might be open water and vegetation on the surface of the planet.
Of course these days, high powered telescopes and remote exploration have proved to us that that is not the case. Nevertheless there remains the possibility that Mars may have harbored life in the past and even that some form of basic life might remain hidden on the planet to this day. This makes the exploration of Mars one of the highest priorities for space exploration.
10The Possibility Of Life On Mars Has Proved Fertile Ground For Science Fiction Writers
While we now know that intelligent life is unlikely to have evolved on Mars, 150-100 years ago Mars fever, fueled by Schiaparelli’s observations of canals led to many people believing that life on Mars was not only possible but probable. Of these the original and most frightening (even today) was H.G. Wells’ The War Of The Worlds’; a powerful novel depicting a race of warlike Martians whose own planet was dying and left them intent on invading and subjugating Earth as their new home.
Wells’ writing was compelling (the chapter depicting the end of the Thunderchild is some of the most evocative writing in the English language) and his science ahead of its time in many ways. As the book progresses we watch suburban England destroyed and humans struggling to survive. The Earth, and humanity, is only saved because the Martians do not have immunity to terrestrial microbes.
Many other writers followed suit, including Ray Bradbury with his Martian Chronicles, C.S. Lewis and his Out of the Silent Planet and many more. Today depictions of Martian civilizations tend towards the comic such as the excellent film Mars Attacks and Martian fiction is based more on the potential for human colonization and terraformation. Whether those books will prove to be prophetic or every bit as fictional as their predecessors, only time will tell.
9Even 40 Years Ago People Believed That Martian Civilizations Were A Possibility
Some ideas are so seductive that they take a long time to die, even in the face of overwhelming evidence to the contrary and so it was with the concept of Martian Civilizations. Starting with the Soviet probes in the 1960s data on Mars started pouring in. By the 1970s technology was sufficiently advanced to permit the US Viking probes to return detailed images of the Martian surface.
Prior to landing the Viking probes took orbital images of the Cydonia region of Mars, two of these images, taken at different times of the day, show a surface feature that looks like a giant humanoid face. Even at the time NASA dismissed the face as an optical illusion created by shadows but this did not stop conspiracy theorists claiming that it was evidence of a long lost civilization. Chief amongst these was Richard Hoagland who is a prolific conspiracy theorist convinced that NASA is engaged in a gigantic cover up of the existence of evidence of an previously advanced civilization on Mars of which the ‘face’ and nearby ‘pyramids’ are evidence.
The feature has been photographed by later missions including the Mars Global Surveyor and the Mars Reconnaissance Orbiter and these photographs show nothing more than an ordinary, if spectacular, mesa similar to the landforms seen across the American West. These pictures prove that the face is nothing more than an optical illusion, a trick of the light playing on the rocks of Mars.
8The Thin Martian Atmosphere Was Once Much Thicker
Mars, like Earth, has an atmosphere although with 96% Carbon Dioxide, 1.9% Nitrogen and only traces of oxygen it has a very different composition to that of Earth. It is also a lot thinner than our own atmosphere, only about 1% as thick.
We know that oceans of liquid water used to exist on Mars (see below) and for that to be the case the atmosphere would have had to be a lot thicker in the past. These days the Martian atmosphere is known to leak into space in much the same way as a tire with a slow puncture loses air. That leak, however, is not large enough to explain what happened to the atmosphere. Recent explorations have shown that Mars, which has a very weak magnetic field, is vulnerable to solar storms. These storms strip the atmosphere away at a much faster rate. Such storms are much less common now than they were 4 billion years ago when most of the atmosphere was lost.
The loss of the atmosphere would have proved extremely problematic for any life that existed on Mars at the time.
7Mars Is Blasted By Radiation Which Would Make It Hard For Life To Establish Itself
As we have seen, Mars lost its atmosphere approximately 4 billion years ago. Unlike the Earth which has a semi-molten core, an inner dynamo which creates a magnetic field that deflects solar storms the Martian dynamo shut down billions of years ago (it was probably this which precipitated the catastrophic loss of atmosphere) meaning that Mars has no internal movement at all. Evidence of the once active dynamo still remain; portions of the Martian crust are very heavily magnetized which has led to the creation of small, local magnetic fields. Therefore although the planet in general is vulnerable to solar radiation certain pockets of the surface are protected. Interestingly the magnetized sections of Mars are almost exclusively in the southern hemisphere leading to speculation as to whether the dynamo magnetized only the southern half of the planet or whether an impact demagnetized the north and kick-started the loss of atmosphere.
Once the global magnetic field was lost, the harsh effects of solar radiation would have made it almost impossible for any life that existed to survive unless it moved underground to areas protected by remaining local magnetospheres. It would also make it almost impossible for life to evolve further. Given the catastrophic nature of the loss it is probably a relief that we have not found evidence of intelligent or even animal life having existed on Mars.
6Mars Used To Have A Lot Of Water
Water is one of the key elements for life (as we know it) and Mars once had an awful lot of the stuff. Scientists from NASA have used instruments to compare the ratios of water to heavy water on Mars today to similar ratios from a Martian Meteorite from 4.5 Billion years ago. These measurements show that Mars was once home to 5 million cubic miles of water! Most of that water would have been concentrated in the relatively flat northern hemisphere and is likely to have reached up to a mile in depth in some places. This research is backed up with orbital observations which show some coastline features in the Northern Hemisphere.
As recently as May 2016 scientists have found evidence of two massive, ancient tsunamis caused by meteorite impacts in the giant northern ocean. The first, which occurred about 3.4 billion years ago, was a liquid water tsunami, the water washed over the surface then channeled its way back to the ocean. Over time the climate changed and the oceans started to freeze. A second meteorite impact millions of years later created huge lobes of ice which stayed in place as opposed to returning to their original location. These lobes of ice were probably salty meaning they could possibly have harbored reservoirs of liquid water underneath. As a result the locations of these long lost lobes of ice could be fertile hunting ground for possible signs of past life.
5There Is Water Ice On Mars
Mars is still home to a lot of water, some of which even exists as water vapor in the thin Martian atmosphere. Russian scientists have tracked the seasonal variations of water vapor over many years and estimate that the densities reach as much as 60-70 microns in the northern hemisphere during the summer period and significantly smaller volumes in the southern hemisphere summer. If these numbers sound impressive don’t be fooled, the amount of water vapor present in the Martian atmosphere is less than one-thousandth of that in Earth’s atmosphere.
New discoveries, announced in November 2016, have shown a significant amount of water frozen in an underground reservoir in the Utopia Planitia region of the northern hemisphere. The deposit is spread around an area larger than New Mexico and is estimated to hold more water than Lake Superior. It is thought that the deposit of water, which represents only 1% of the available water on Mars, is the remnant of an ancient ice sheet. It is possible that similar deposits are buried elsewhere on Mars.
Because of the extreme temperatures most of the water on the planet exists in the form of ice held in the Polar Ice Caps where it is mixed with deposits of Carbon Dioxide ice. It turns out that there is far more water ice than originally thought. In the early years of Mars exploration scientists believed that the polar caps, the southern in particular, were mostly Carbon Dioxide ice. It turns out that while each cap is covered with a layer of such ice there are significant water ice deposits underneath the Carbon Dioxide which sublimates away each summer only to freeze again in the winters. Each polar cap is estimated to hold 1.6 million cubic kilometers of ice.
4Free Water Flows On The Surface Of Mars
For many years we believed that water could only exist on Mars in the form of ice and atmospheric water vapor. All that changed in 2015 when NASA announced that it had clear evidence of surface water flows. The Mars Reconnaissance Orbiter, one of the most sophisticated pieces of equipment ever sent to observe the Red Planet carries an imaging spectrometer capable of detecting hydrated minerals. They used the instrument to look at features known as Recurring Slope Lineae, dark streaks which are known to ebb and flow over the surface of slopes in the summer seasons. When these dark streaks were wide and at their most extensive the spectrometer found evidence of hydrated minerals. When the streaks were narrower there was no evidence of hydration. The chemical signatures are consistent with a type of hydrated salt known as perchlorate which, on earth, is capable of keeping liquids from freezing even in very low temperatures.
So, while the water may not be fresh or potable (perchlorates are used as rocket fuel) the fact remains that we now have evidence that water flows on the surface of Mars; liquid water means that life on Mars, current not ancient life, is a possibility.
The 2015 announcements about free flowing water on the surface of Mars were both exciting and fascinating. Sadly just a year later NASA has cast doubt on its own discovery stating that the Recurring Slope Lineae many not contain free flowing water after all and that the hydration detected might have been sucked from the atmospheric water vapor. An in-depth study of the ground temperatures of Recurring Slope Lineae sites compared with non-Recurring Slope Lineae sites gave an upper limit for the amount of water that could be present in the surface at the at about the same amounts found in the Atacama Desert or Antarctica, the driest places on Earth.
While these latest findings are a blow and may impact on the likelihood of our finding evidence of current life on Mars they do not mean that life did or even does not exist there.
3We May Have Discovered Life On Mars In 2007 And Just Not Noticed!
It sounds pretty far-fetched. Evidence of life on Mars is one of the holy grails of space exploration so surely if we found evidence of it all those years ago it would have been trumpeted from the roof tops, spread around the internet with the same speed as NASA’s announcement of the discovery of free flowing water in 2015.
But, bizarre as it seems, that may have been exactly what happened. In 2007 the Spirit Rover took photographs of some fingerlike formations on rocks near the equator. Because many Martian rock features have parallels on Earth scientists looked to see whether they could find anything like them on Earth. They struck gold when they visited El Tatio in Chile, which has a very similar environment to Mars, and found identical structures called stromatolites. Stromatolites are formed when sediments were trapped on micro-organisms react with calcium carbonate in hot springs and form layers of limestone.
Are the Martian features stromatolites? If so are they evidence of existing microbes or the fossil evidence of past Martian life? It is dangerous to jump to conclusions as the evidence may turn out to be as much an illusion as the Face of Mars. Sadly the theory cannot currently be checked, the Spirit Rover is stuck in sand and the other rovers currently on the surface of the planet are too far away to take samples. The best that can be hoped for is that a future mission will investigate and even, potentially, arrange for samples to be returned to Earth for an in-depth analysis.
2Mars Meteorites Show The Presence Of Organic Compounds
Over the life of the Solar System the Earth has been bombarded with meteorites. Some of these are Martian in origin and scientists have examined them intensively in order to help them understand more about our neighbor in space.
Traces of organic material, the building blocks needed to create life, have been found on almost all of the meteorites examined. Sadly the origin of these organic compounds has been shown to be volcanic rather than biological. The scientific debate is not yet settled, however, and researchers from Switzerland, Japan, China and German dispute these findings. They claim their analysis of the ratios of Carbon 13: Carbon 12 in a Martian meteorite that fell in Morocco in 2011 indicated that the organics had to be biological in origin (on Earth non biological organics such a coal show a higher percentage of Carbon 13 than biological organics which prefer the lighter Carbon 12).
The debate on the origin of these organic compounds is fascinating and the tantalizing possibility that they are biological in origin remains in play.
1Mars Burps Methane
It may sound rude but ‘methane burps’ may be one of the most compelling pieces of evidence for life on Mars because the majority of methane on Earth is produced by living organisms.
In 2014 NASA released findings from their Curiosity Rover which had found evidence of temporary, non-seasonal, tenfold increases in methane in the atmosphere in the vicinity of the Rover. Methane is an organic chemical and while these noticeable spikes may have a non-biological source it is also possible that they indicate the presence of microbes. In addition to the Methane, Curiosity has discovered organic compounds such as carbon, in several rock samples. Whilst there was some initial concern that the samples may have been contaminated by organics from Earth, the scientists responsible feel they can differentiate between the two and can tell which samples are contaminated and which are Martian in origin.
So where does this methane come from? The ‘burps’ could be caused by dead, ancient microbes frozen near the surface, releasing the gas as the rocks they undergo pressure and temperature changes, alternatively they could be caused by modern organisms living deep underground. Of course geological processes such as hot springs and volcanoes also release methane. It is possible for such methane to remain trapped for many millions of years and released in short spurts similar to the burps recorded by Curiosity.
All we know for now is that methane and the presence of the organics shows that the building blocks for life are present and indicate that life, current or extinct may be present.
Is there life on Mars? Sadly we are still a long way from being able to answer this question. If we do find evidence of life it will not be of a complex civilization, our solar cousins, nor will we find mammals, crustaceans or even plants. From the little we know it seems the very best we can hope for is a simple form of microbial life. Nevertheless even that would prove interesting. Firstly it would prove that life on Earth is not unique. If life formed elsewhere in our Solar System, even if it never really got off the ground enough to create language, culture and war then we are not alone. We just got lucky that our planet’s magnetosphere protected our microbial ancestors and our climate remained benign enough for higher forms of life to evolve. If it happened more than once around one star how much more likely is it to have happened elsewhere?
Secondly if life evolved on Mars many billions of years ago it may be responsible for the origin of life on Earth. While the theory is hotly debated some scientists believe that Mars was more hospitable to life earlier in the history of the Solar System than the Earth was. Meteorites from Mars then carried this life, in microbial form, to the Earth where these microbes found a welcoming home. As life on Mars died out life on Earth flourished. Maybe H.G. Wells had it right after all.