This rare Martian meteorite, called Nahkla, landed in Egypt in 1911.
Meteorites provide both a glimpse into the past and a window to the future. They represent both birth and death; creation and destruction. Meteorites are important because they were a potential source of life on Earth, have contributed to the development of a life-sustaining environment and have posed a significant threat to that life. Furthermore, scientists are discovering the secrets of the early solar system locked within these space rocks.
Source of Life on Earth
Meteorites are important because they may represent the pathway by which life arrived on Earth. One source of meteorites is the debris field of comets. Many scientists believe it is possible that this debris retains much of its durable organic material. In fact, meteorites have been found to contain amino acids, the building blocks of life. Furthermore, this organic material may undergo unique chemical changes when exposed to the high temperatures of atmospheric entry. How much of this organic material survives to be deposited in the atmosphere and on the surface of the planet is currently being investigated by scientists.
Effects on Earth's Environment
Meteorites are significant because they provide insight into how meteors have affected the earth's environment. Meteors release water and carbon dioxides as they vaporize in the atmosphere. By studying meteorites, scientists have determined that they release up to 12 percent of their mass as water vapor and up to 6 percent as carbon dioxide. While the individual contribution is insignificant, in large numbers the effect becomes substantial. For instance, around 4 billion years ago, a meteor shower known as the Late Heavy Bombardment delivered up to 10-billion tons of each. This release significantly increased the levels of greenhouse gas and water vapor, leading to a more hospitable environment for life.
Threat to Life
Meteorites represent violent collisions that can have a devastating effect on the planet's life forms. By studying meteorites, scientists can better understand past impacts and, therefore, provide better guidance on hazards posed by future ones. This is especially important considering the fact that, as of July 2011, there were 8,155 know near-Earth objects, 1,241 of which have been classified as potentially hazardous. For example, at 112-miles in diameter and 3,000-feet deep, the Chicxulub crater in Mexico is one of the largest meteorite impact craters on the planet. Its significance is demonstrated in the fact that this meteorite, originally an asteroid, was responsible for the elimination of 70 percent of life on earth and, possibly, the extinction of the dinosaurs.
Cosmological Database
Meteorites represent the left-over building materials from the creation of the solar system. They provide important information about the chemical compositions and physical structures that existed at that time. Some meteorites actually come from other planets, the product of comet, asteroid and meteor impacts. These meteorites provide science with important information about planetary geology that would otherwise be unavailable. In fact, meteorites are responsible for a large percentage of all that is known about the solar system, including its age and history.
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