Life on Mars?
LIFE ON MARS?
 
The debate concerning life on Mars has been in progress now for some 300 years. For many years, the only life considered was that of intelligent aliens, and whether or not they were hostile. When spacecraft missions revealed just how inhospitable Mars really is, the debate switched to whether or not there used to be a Martian civilisation, and why it had died out.
 
History
The discussion concerning Martian life originated in two observations : the ebb and flow of the polar caps coincidental with planet-wide colour changes, and reports from astronomers that Mars was covered with a network of canals. The polar caps of Mars would grow and shrink as Mars passed through its seasons. Simultaneously subtle colour changes were observed in the dark surface markings. Many observers reported that not only did the features become darker during the Martian summer, but that they also became greener. This was obviously caused by the fresh growth of vegetation triggered by the abundance of water from the ice cap. The seasonal changes apparent in the ice caps also helped make sense of the network of trans-planet canals.
 
The great canal argument started in 1877, and was caused by the mistranslation of one word. Observers, like Pietro Angelo Secchi in 1869, had used the Italian word "canali" (channels) to describe faint linear markings seen on the surface of Mars. Giovanni Virginio Schiaparelli, director of the Milan Observatory, also saw channels, and duly reported "canali". The word "canali" was mistranslated into "canals".
 
If a respected professional astronomer had reported seeing canals, then there must be canals. If there are canals, there must be intelligent Martians. It quickly became a popular belief that the Martians were building canals in order to save their dying world. In 1938 Orson Welles produced a radio play based on H.G. Wells' book "War of the Worlds", in which Martians invaded Earth. Although the radio station announced many times that it was just a play, over a million American listeners believed Earth really had been invaded. The belief in canals persisted for many years, until 1965 when Mariner 4 flew past Mars and took the first high-resolution pictures. The pictures showed not canals, vegetation, or any other artificial structures, but a cratered and dead Moon-like surface. Overnight all Martians disappeared.
 
The search for life today
The search for life on Mars is not concerned with a search for large animals roaming the planet. The hunt is on for microscopic organisms. Consider our own planet - on Earth, microscopic organisms are far more common than large ones. A single handful of soil contains millions more microscopic organisms than Europe contains people. Microscopic organisms are also very hardy and versatile, and can adapt to many different environments; for example, in the worst Antarctica environment. If life exists on Mars, it will probably be microscopic.
 
Viking Lander site 1976
 
Viking samples - success
The Viking Landers arrived at Mars in 1976, and one of their tasks was to perform experiments to search for the signs of life. Each Lander was equipped with a scoop, with which it collected a sample of Martian soil, as seen in the images here. The Martian soil was loaded into a small on-board laboratory, and a set of experiments were performed. The soil was cooked in an oven in order to boil off any gases. The composition of the gases was then analysed using a gas chromatograph-mass spectrometer (GCMS), an instrument capable of detecting organic chemicals. Organic chemicals can be one of the signatures of life, and are easier to detect than the life itself. A duplicate Viking GCMS was used on Earth to perform the same experiment on soil from Antarctica, such soil containing very few organisms.
 

Viking lander


Viking lander
 
The GCMS results shown here are very simple: absolutely no organic chemicals were detected. These negative results were obtained by both Landers on all samples. A sample was even obtained from under a rock, in the hope that some form of life might be sheltering from the Sun's harmful ultraviolet light. This experiment was more chemical than biological, and so three biological experiments also took place inside the Lander. It was assumed that Martian life, like all life on Earth, likes to eat, drink, and breathe. The biological tests were designed to look for evidence of this
 

Viking soil analysis.
 

A gas exchange (GEX) experiment was performed, as shown here. The Martian soil sample was given water, and again a gas chromatograph-mass spectrometer (GCMS) was used to monitor any gases given off by the soil. If Martian life was present in the soil, it should "drink" the water giving off either hydrogen or oxygen in the process. The GEX experiment detected oxygen given off by the soil.
 
 
The labelled release (LR) experiment looked for signs of feeding. This was achieved by supplying the soil sample with a nutrient (food), and radioactive carbon monoxide and carbon dioxide gases. The gases supplied were the same mixture as found in the Martian atmosphere. Should any micro-organisms be breathing, they would give off carbon dioxide and methane, but the output gases would also be radioactive and therefore detectable. There was a dramatic increase in the amount of radioactive carbon dioxide given off by the soil, seeming evidence that something in the soil was feeding. A further supply of nutrient produced no additional output of radioactive gas.
 
 
Finally, a pyrolitic release (PR) experiment was tried. This was similar to the LR experiment, in that it used radioactive gases. However, no food or water was supplied, just light designed to match Martian sunlight. Yet again, there was a positive result - something in the soil appeared to be breathing.
 
Viking samples - failure
All three Viking biological experiments had given positive results, and yet it was soon determined that life had not been detected. The soil was behaving in a non-biological manner.
 

The validity of the GEX, LR and PR experiments was tested by heating the soil samples to
175o C for three hours to destroy any micro-organisms. Unfortunately, when the GEX, LR and PR procedures were repeated on the heat-sterilised Martian soil, positive results were again obtained. The experiments were detecting chemistry, not biology. Viking had merely allowed water-reactive chemicals to react with water for the first time. Finally, the complete failure of the gas chromatograph-mass spectrometer to find the simplest organic molecules (not even one in a thousand million) confirms the lack of life. Organic molecules were even found in Moon rocks brought back by Apollo.

 
The Martian soil is dead.
 
The evidence from these experiments leaves only two further possibilities. Life, now extinct, may have existed in the distant past. Alternatively, life exists on Mars, but the Landers were in the wrong places to find it. This second scenario can be ruled out.
 
The two Landers were separated by over 2000 kilometres, and Mars suffers global dust storms. These storms move material around the planet, and any organisms in the material would be distributed planet-wide.
 
The Face
While the Landers were on the ground proving that there was no life, one of the Viking Orbiters appeared to make its own detection of very advanced life. One of the images obtained from orbit shows what looks like a face. As "The Face" is looking up from the planet, could it have been built by Martians in order to be seen by spacecraft? The Orbiter also found that the Face was located near unusual features, which have been interpreted as a Martian city, complete with pyramids, a fortress, and even bomb damage from a war. For a variety of reasons, the Orbiter was not able to take any further Face pictures, but this has been explained as the American government suppressing secret pictures in order to prevent widespread panic.
 

The 'Face'.
'Martian City'
 
 
Aliens in Antarctica?
Meteorites fall onto Earth each year, and many of them end up lying on the surface indistinguishable from other rocks. Antarctica, however, presents an entirely different scenario. Where the landscape consists of pure ice and snow, and in the middle is one small rock, burnt on the outside, it is easy to spot it as a meteorite. The first groups of meteorites in Antarctica were found by a Japanese expedition in 1969, and since then about 14,000 meteorite pieces have been found by American and European expeditions. This is about the same number as all other meteorites that have been found the world over. This does not mean that meteorites tend to fall on Antarctica, rather, it just shows how easy it is to spot them lying in the ice. These meteorites have not been exposed to industrial pollution, and so are chemically "clean", because of their protective covering of ice.
 

Antarctica
 
Amongst the many specimens discovered in Antarctica, one of them, ALH 84001, became famous overnight. ALH 84001 was found in December 1984, and weighed about 1.93 kilograms. It was covered with black glass, or fusion crust, which was created as the meteorite burned its way through the Earth's atmosphere. Scientific analysis shows that its age is about 4.5 thousand million years; the age of the molten lava from which the meteorite first formed.
 

ALH 84001
 
Scientific analysis of the air trapped inside ALH 84001 showed an interesting result - the chemical composition of the meteorite's air matched exactly the chemical composition of Martian air, as determined by the Viking Landers. The inside of ALH 84001 has never been exposed to Earth's air, (having been cut open in a nitrogen-filled cabinet at Johnson Space Center) and so the exact match means that ALH 84001 is in fact a piece of Mars.
 

Analysis.
 
The geological history of ALH 84001 appears to show that the meteorite originally solidified from molten lava, about 4,500 million years ago. About 500 million years later it was subject to two shock events the second of which may have blown ALH 84001 off Mars and into orbit. Once in space, ALH 84001 would have remained orbiting the Sun, being exposed to cosmic rays. It appears that ALH 84001 orbited the Sun for 16 million years. Eventually, gravitational tugs from the other planets, especially massive Jupiter, brought it into an orbit that crossed Earth's orbit. Finally, 13,000 years ago, ALH 84001 crashed into Antarctica.
 
ALH 84001's life story is not unique. The difference is that around 3,600 million years ago, some unknown liquid flowed through ALH 84001, and deposited globules composed of carbonate minerals as seen in this microscope view. As ALH 84001 was at this time still on Mars, the liquid must also have been Martian. There is much evidence to show that at one time there was water on Mars.
 
 
It is the images shown here that ended up in newspapers the world over. When scientists used a scanning electron microscope to investigate the carbonate globules, strange shapes could be seen: biological shapes. According to the scientists, the microscope was revealing fossilised microbes buried deep inside ALH 84001. The evidence that ALH 84001 comes from Mars is very strong indeed, as it has a unique atmospheric fingerprint that places it on the Martian surface. The only doubt that remains is whether or not what appears to be fossilised microbes could have been formed by geological processes. Nevertheless, you may well be looking at aliens from Mars.
 
The Face revisited
In 1988 the Mars Global Surveyor spacecraft obtained a new image of the Cydonia region of Mars, including the Face. This is the first new image of the Face since it was last seen in 1976. However, this time round, the resolution of the image acquired is ten times better than that achieved by the Viking Orbiter. As can be seen here the original symmetry of the Face, which caused so much debate, is now absent. It would seem that the Face is nothing more than a geological feature showing signs of heavy erosion. In spite of this, there are still those who insist that the Face is an artificial monument, that has been subjected to heavy erosion.
 

The face revisited.