Organic Chemistry Across the Universe
Extraterrestrial Transformation



Is There Really Something Out There?

The expanse of space between the stars was once thought to be a barren desert, just as the word space conjures up images of emptiness. This darkness mirroring nothingness is called the interstellar medium. It was assumed that the existence of organic molecules in the galaxy was confined to the atoms, radicals and ions present in stars. These were observed through electronic transitions as they interacted with radiation emitted from the stars(12). More complex molecules were invisible to us and so unknown until advances in the technology of microwave spectroscopy. Now the energy emitted by a molecule as it tumbles and spins around its centre of gravity can be intercepted. Signals are detected escaping from the centres of vast clouds in the interstellar medium. Inside these clouds the density of matter is much higher than the majority of the volume contained within the interstellar medium, which has a low density true to the description of space as a vacuum. How can molecules be created in these clouds? Conditions in space are harsh with extremes of temperature ranging from the unknown heat of the fires of the sun to less than 50 Kelvin, approaching absolute zero for the interstellar medium(7). Destructive radiation fills the galaxy like oxygen fills the Earth's atmosphere. For a long time it was thought that any molecules that may form under interstellar conditions would be executed so rapidly by radiation that we would never know of their fleeting existence(13). Clouds act like a protective shield absorbing cosmic radiation like suncream forming a protective layer over the skin. The lower energy radiation that penetrates the cloud can instead of destroying molecules give them enough energy to react with each other. The cloud will also prolong the life of the product molecule and we are able to detect it. A cloud's nurturing property increases the relative density of organic molecules in that volume of space, which can increase the probability of a gas phase reaction. Gas phase reactions are always temperamental, especially at low concentration because the likelihood of two molecules colliding is small. Clouds posses another route to reaction through interstellar grains. A grain is a mixture of silicate and graphite particles which bond together to form a solid compound(16). In the interstellar medium they are like grains of sand on a beach but in a much lower concentration. These grains have a surface area, which on collision with a gas phase molecule adsorbs the molecule onto the surface. The molecules stick to the surface like candles in a cake, bringing them into close proximity with each other, creating a greater chance that two molecules will be in the same place for reaction to occur. Increasing the odds as catalysts would do on earth.

Why are we interested which organic molecules inhabit the galaxy?

The galaxy is old and does not age in the same time frame as a human. The conditions in the interstellar medium are thought to be the same as they were when the Earth was born. Organic molecules could have been present on the Earth from the very beginning when it was formed out of swirling debris from the interstellar medium that contracted under the pressure to form a planet. But on formation temperatures could have been as high as to destroy all organic molecules that were present. Molecules could have contaminated the earth by hitching a lift inside meteorites or comets formed from the interstellar medium as they crash to earth from space. But on impact or while breaking through the atmosphere these delicate molecules could also have been destroyed. The conditions on the early earth could have been the same as conditions in the interstellar medium. The reactions taking place there now can be the same ones that took place on the young earth. The question is how did life begin and so how did organic molecules arrive on the earth? 'Some scientists have recently moved the soup pot to the seafloor, where they say murky clouds of minerals spewing from hot springs may have generated life's precursor molecules' writes Bernstein et al(9). The heavens though may also hold the answers to the begining of the sequence of life. It starts with the organic molecules needed to produce amino acids and their partner DNA, which codes for proteins, and ends with the evolution of humans.

Start Contents Abstract Introduction Sugar in space
Spectroscopy Polyatomic Aromatic Hydrocarbon Simulating Space Conclusion
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