Evidences of Life on Mars

Here I want to talk about the possible evidences of life on Mars. Rocks from space constantly bombard our planet. A few of these visitors make it through the atmosphere without burning up, which are called meteorites. Of the thousands of meteorites that have been collected on the Earth surface, only a precious 2 dozen or so are known to have come from Mars. These chunks of rocks don’t look rare or valuable, but in the 1980’s, clever chemists deduced the origin of these rocks by analyzing their composition.

You might wonder how a chunk of Mars can find its way to Earth. The impact of giant asteroids on Mars is inevitable. Any such collision is going to throw rocks away from the planet and into an orbit around the sun. The sun and Jupiter would sweep most of those rocks because they are the two most massive objects in our solar system, and hence have the strongest gravitational pull. Eventually, however, after millions of years of collisions, a tiny fraction of Mars would inevitably find its way to Earth.

One in every thousand or so meteorites that hit Earth comes from the red planet. It is amazing to think that a piece of Mars has been transferred to us. Just imagine the implications if that piece of rock holds Martian microbes and that they could stand the long journey through space. Many scientists think some microbes could. If so, Earth could have been infected by Martian life.

Indeed, Mars was probably habitable hundreds of millions of years earlier than Earth. If life emerged on Mars first, and it was transferred to Earth, then that might be how life began here. We all may be Martians.

This idea sounds odd but highly respected scientists are given this proposal very serious thought.

The great majority of Martian meteorites that fall to Earth are never found. About three quarters of all meteorites land on the ocean and fall to the bottom. Even the ones that fall on land look so much like ordinary Earth rocks that you could kick one aside without noticing. So, we need to find a place where meteorites stand out as alien objects. For that there is no better place than a flat white sheet of ice.

The deserts of Antarctica are the world’s most productive grounds for meteorites. In these clean regions, dark colored meteorites stand out starkly. Scientists can collects hundreds of meteorites in one short season.

With the discovery of Martian meteorites, scientists could for the first time investigate actual pieces of another planet, and actually find evidences of life on Mars. Conventional wisdom would suggest that such meteorites should be utterly devoid of life.

One Mars meteorite, however, proves to be strikingly different from the others. This meteorite was collected in 1984. It has the scientific designation ALH84001. This meteorite is much older than the other Mars rocks: at least 4 billion years old. It also holds minerals that suggest the possibility of ancient interactions with liquid water. A team of biologists, planetary scientists and meteorite experts, led by NASA’s geologist David McKay, subjected pieces of that four pound rock to a battery of rigorous tests.

They probed the mineral with x-rays, lasers, gamma-rays, beams of electrons. No one in the NASA team ever expected to find evidences of life on Mars in the meteorite. All they really hoped for was a hint of freely flowing water. Yet, gradually, as more and more data piled up, David McKay and his colleagues began to see anomalies that could not easily be explained by normal mineral processes. They were, however, plausible evidences of life on Mars.

The group came to believe that this meteorite indeed had convincing evidences of life on Mars. After a lot of internal debate and cautious evaluation of the data, in 1996, they decided to go public. The NASA wrote up the results and sent the paper to the premier journal Science. It was accepted in short order and scheduled for publication in mid August.

NASA called a hasted news conference several days earlier. Naturally, with a discovery of this magnitude, the highest levels of government, including the White House, were alerted. It turns out that President Clinton’s chief political advisor learned the story and then bragged about the NASA discovery to a prostitute. The prostitute had been selling his secrets to a weekly tabloid, so by early August, NASA’s news was out.

In August 7, McKay’s team publicly claimed the discovery of tiny elongated objects that were once living Martian microbes. Headlines of newspapers screamed “Evidence of Life on Mars!!” The tabloid Weekly World News showed a large photo of an insect with the headline “New Photo of the Life on Mars NASA didn’t want the world to see”.

Meanwhile, Science published the NASA’s team results. This discovery was a huge deal for NASA. They were flooded by news conferences, scientific meetings, etc. President Clinton even got into the act by holding a national press conference during he reflected on the glory of NASA’s triumph.

So, what was the basis of McKay’s claim? Did they find convincing evidences of life on Mars? We’ll analyze their claims in my next post.

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