Three years later, this meteorite has become the most intensely studied two kilograms of rock in human history. It has been sectioned, imaged and analyzed. It has accelerated planetary exploration, illuminated the study of exobiology, and caused priests to reluctantly contemplate the idea that life on Earth is not unique. But are we any closer to answering the age old question, “Are we alone in the Universe?” And was the answer here on Earth all along?

Mars on Earth
The search for pieces of Mars on Earth has drawn dedicated researchers to the very limits of Earth’s climatic extremes, with Martian meteorites being found in the rainforests of Brazil, the lush fields of France and recently the sand dunes of the Sahara Desert. But it was a potato-sized rock found in the scarcely inhabited ice cap of Antarctica in 1984 that caught the world’s attention by surprise. Appropriately, it was the first meteorite catalogued in that year; but ironically, its Martian origin was not recognized until nine years later (when its chemistry was shown to match the unique chemistry of Mars as measured by the Viking spacecraft in 1976). By using techniques such as radiometric dating, researchers were then able to unlock clues revealing pieces of the rock’s history and it’s epic journey to our lonely planet.

Remarkably, the rock was shown to be approximately 4.5 billion years old – making it the oldest rock known from any planet. Its origins are traced to magma deposits that became part of the original Martian crust only 100 million years after the planet had formed. Perhaps 3 billion years ago, a meteorite impact shattered the rock, creating fractures into which the controversial traces of life may have ventured and colonized. Eons passed and the rock was peacefully undisturbed, until one day about 16 million years ago, when a massive impact on Mars launched the rock into space, initiating its cosmic journey. The putative Martian microbial inhabitants wandered through the vacuum of space in their meteoric space vehicle for perhaps 16 million years until they encountered Earth. They blazed through its atmosphere and crash-landed into Antarctica, only to be plucked from their destination by a NASA research team 13,000 years later.

The Martian Autopsy:
After a series of dissections, observations and measurements the NASA research team cited four lines of evidence which they believed to strongly suggest the existence of primitive life on Mars:
 

1. A relatively abundant family of organic compounds (called polycyclic aromatic hydrocarbons, or PAHs) was found within the meteorite, and could have been produced by the decomposition of ancient Martian microbial life.
2. Examination of mineral deposits within the meteorite revealed the presence of carbonate globules, which NASA scientists likened to those formed by bacteria as they alter their environment. The larger of these consisted of manganese cores surrounded by concentric rings of iron carbonates and iron sulfides. This implied that the chemical environment changed as the globules were deposited, perhaps as a result of microbial metabolism. 
3. Within the carbonate globules, mineralogical studies revealed the presence of an iron oxide called magnetite, bearing a strong resemblance to minerals used by terrestrial bacteria (bacteria are thought to use the magnetic properties of magnetite to align themselves with the Earth’s magnetic field). Some of this magnetite was in a particular conformation identical to that produced internally by certain strains of terrestrial bacteria; but scientists know of no non-biological source which could have produced it.
4. Perhaps the most provocative evidence for the putative alien microorganisms is the presence of oval and worm-like shapes on the cracked surface of the meteorite, which NASA scientists have interpreted as potential nanofossils of the ancient Martian microbes. 

But for each line of evidence, skeptics have offered a corresponding line of counter-evidence: 
 

1. |PAHs are produced by non-biological reactions in power plants and automobile engines, as well as reactions between simpler carbon compounds in interstellar dust and organic-rich meteorites. And so even if the meteorite’s PAHs are not terrestrial contaminants, their presence does not necessarily infer life.
2. Warm fluids circulating through the Martian crust could have deposited the same sequence of minerals and carbonate globules as observed.
3. Our knowledge of chemistry is incomplete, and therefore we must acknowledge that the magnetite could have been formed inorganically.
4. The so-called “nanofossils” are 100 times smaller than the smallest terrestrial microfossils yet discovered. They might just be narrow ledges of mineral protruding from underlying rock, and masquerading as bacteria under certain viewing conditions.

So there is certainly a degree of doubt to these tentative claims of life, but the original researchers are still confident with their case. As they concluded in Science: “Although there are alternative explanations for each of these phenomenon taken individually, when considered collectively … we conclude that they are evidence for early life on Mars.” But the majority of the scientific community are unimpressed, arguing that the compounding of inconclusive arguments does not make them conclusive.

The NASA Conspiracy:
Some scientists have even suggested that there may have been certain political and financial incentives influencing the announcement. And it is conceivable that a sort of pseudo-conspiracy supporting the existence of extra-terrestrial life could be passively at work within NASA headquarters. If NASA scientists claim they have found suggestive evidence of life elsewhere in the Universe, then the public interest will be so immense as to prompt the American government to inject a generous research grant into future studies and accelerated missions to the red planet. This could act as a sort of survival mechanism for NASA, encouraging its research teams to generously interpret and selectively examine certain experimental data in preference to any evidence to the contrary. 

To fuel this suspicion, under Bill Clinton’s 1997 preliminary budget, NASA’s space science program was planned to drop by $200 million dollars, with the decline in funding continuing for at least five years (under his long-term goal to eliminate national deficit). But after the claim that a meteorite from Mars may bear evidence of ancient life from another planet, the President cancelled this drop. And in his statement regarding the possible discovery, he promised that “the American space program [would] put its full intellectual power and technological prowess behind the search for further evidence of life on Mars”. Perhaps the fact that 1996 was an election year was more than convenient, as the President’s decision to push ahead with the search for life would have been a very effective popularity device.

In the 3 years since the announcement, scientists have published dozens of independent analyses that have both supported and attacked the Martian microbe hypothesis. But admittedly, most of the supporting research has been conducted within NASA, while most of the skeptical research has been conducted by independent Universities. 

The Truth…
Regardless of the political and financial situation, it may be decades before the significance (or insignificance) of the meteorite is finally determined. And if its insignificance is finally proven, then it is destined to quietly fade away with other past hopes of life, due to the selectivity of the popular press against the skeptical media. But independent of the final outcome, there are a number of beneficial effects that shouldn’t be ignored. The meteorite has extended the boundaries of trace chemical measurements, demonstrated the importance of multidisciplinary research, and given a new impetus to the closely related questions of “How did life originate on Earth?” and “Is there life elsewhere in the Universe?” The Martian meteorite is generally considered as one of the main incentives in NASA’s decision to found a new Astrobiology institute, dedicated to the scientific study of life in the Universe.

And to many people, there is no greater scientific discovery imaginable than the discovery of extra-terrestrial life. Such a discovery is critical to establishing our place and purpose in the Universe. It would prove beyond reasonable doubt that no special phenomenon or freak events are required for our civilization to exist as it does. In doing so, the discovery would both vindicate the theory of Darwinian evolution, and enforce the cosmic perspective of our insignificant planet, as a pale blue dot in a vast Universe of planets, stars and galaxies. In particular, it would fuel the origin of life debate with the possibility that terrestrial life originated on Mars, and was transported to Earth by meteorites carrying some very hardy microbes.
 

In Independence Day, the invading aliens appear as human-sized hominids with large black eyes, green slimy skin, and tentacles for dreadlocks. This is in striking contrast to the humble microscopic nanobacteria hinted at within the confines of the Martian meteorite. But regardless of their differing appearances, they both portray a common message – that humankind might not be alone in the Cosmos, and that alternatively we might share time and existence with extra-terrestrial beings in an inhabited Universe with life all over it.