War of the Worlds by H. G. Wells

H. G. Wells wrote in his book, "War of the Worlds", about Martian invasion toward earth. He mentioned, "No one would have believed, in the last years of the nineteenth century that this world was being watched keenly and closely by intelligences greater than man's and yet as mortal as his own; that as men busied themselves about their various concerns they were scrutinized and studied, perhaps almost as narrowly as man with a microscope might scrutinize the transient creatures that swarm and multiply in a drop of water."

Since then it has now been about 100 years Wells based his well-known story of human's first contact with extraterrestrial life. Now, in the 20th century scientists are starting to believe what was once a fictional story by writers now actually could be real, becoming the stuff of science. In 1994 scientists discovered fragments of meteorites which may in fact prove that signs of early life existed on Mars. Many of these meteorites are found in the Antarctica, extremely cold weathers aid in preserving and fossilizing the fallen meteorites for millions of years. In order for scientists to conclude that the meteorites are from Mars and contain signs of fossilized life or traces of it they must provide sufficient evidence to support their theory.

Today, a meteorite from Mars is being closely scrutinized by earthly intelligences. The famous meteorite to bare significant signs of life is the Allan Hills 84001 (ALH84001), classified as one of the meteorites thought to come from Mars. Due to the atmospheric data taken by the Viking Lander spacecraft sent to Mars in the 1970s. The data make it possible to know that gases trapped inside the rock is identical to the Martian atmosphere. "It is one of only 12 meteorites identified so far that match the unique Martian chemistry measured by the Viking spacecraft that landed on Mars in 1976" Scientist believed that the ALH84001 blasted off from the surface of Mars about 16 million years ago by a comet or asteroid. The rock orbited in the solar system for a few million years and finally reached Earth about 13, 000 years ago.

Investigation into the ALH84001 and the possibilities for containing remains of ancient Martian life was assigned to a team of NASA scientists. Dr. David McKay, Dr. Everett Gibson and Kathie Thomas-Kerpta of Lockhead Martin co-led the team with assistance from a Stanford team led by Professor of Chemistry Dr. Richard Zare. They investigated different features in ALH84001, trying to explain their origin and meaning and if these are evidence for life having once existed on Mars.

The ALH84001 is a rock formed originally from molten lava, containing small rounded carbonate mineral globules within the tiny cracks and fractures inside the rock. Within these carbonate minerals that the possibility of life existed on Mars is found. Water is a necessity in all forms of like. It acts as a solvent and needed for chemical reactions. Therefore, the minerals are believed to have precipitated from a liquid, possibly water, which was percolating through the rock. The key features are "carbonate globules"; contain mineral grains, which are similar to minerals produced by some bacteria on earth. Therefore it is possible that the mineral grains in ALH84001 could have been produced by Martian bacteria and would be further evidence that life once existed on Mars. These carbonates have hot been found in any other Martian meteorites. The ALH84001 weighs about four pounds it was actually much bigger, due to the entrance through Earth's atmosphere the rock burned up to the size it is now.

Researchers claim that 3 to 4 billion years ago water containing carbon dioxide percolated throughout the Martian rock that eventually became ALH84001. This deposited carbonates inside the meteorite as well as organic molecules, minerals, and even the fossil remains of Martian bacteria that once flourished in the water. Within the carbonates, were findings of minerals that could be associated with life. They found iron oxides and sulfides, which can be produced by anaerobic bacteria and other microbes. "The team found unusual compounds--iron sulfides and magnetite--that can be produced buy anaerobic bacteria and other microscopic organisms on Earth" They also found magnetite, which is a form of iron associated with some earthly bacteria. The size, structure and purity of the magnetites which can be produced biologically by bacteria on earth, thus they could have been formed by Martian bacteria. "Impressed by the grains' resemblance in size, shape, and crystalline regularity to magnetite produced within some terrestrial bacteria, the researchers argued that bacteria also produced the meteorite's magnetite-martian bacteria, that is" Such minerals are usually produced as waste products and the grains in ALH84001 are very similar in shape and structure to those produced by earth bacteria. The conditions under which these minerals were formed means they were probably formed through a biological process. Although this evidence is very suggestive of life having once existed on Mars, it is possible that the mineral grains formed by a non-biological process as well. "Some meteorites carry these compounds, presumably made by nonbiological processes" The samples analyzed may have been poor examples and have been interpreted in the wrong way.

Secondly, the scientists identified organic carbon molecules that they believed originated on Mars. The organic carbon molecules called polycyclic aromatic hydrocarbons (PAHs) were found in and on the carbonate globules. They identify these PAHs as decay products of living organisms that flowed in when the carbonates were deposited. PAHs are very common in the earth's atmosphere and occur from a variety of processes.

The PAHs could have formed while the meteorite was in Antarctica and have entered it from the atmosphere. They could have occurred by entering the meteorite before it was found in Antarctica. If so it would be expected that the PAHs would be more common on the outside and become less abundant towards the center of the meteorite. Investigation shows the opposite of this found and PAHs were more abundant towards the center of ALH84001. This would be expected if it was extraterrestrial due to the meteorite burning up upon entry into the earth's atmosphere vaporizing PAHs near the surface. "No PAHs were found in the meteorite's exterior crust, but the concetration of PAHs increased in the meteorite's interior to levels higher that ever found in Antarctica" Also the concentration of PAHs is greater that what would have been in the atmosphere at the time impacted. Again this makes the source more likely to be extraterrestrial.

PAHs that occur in other