Washington,Planetary scientists have claimed that comets or "dirty snowballs" may have deposited the building blocks of life on Earth billions of years ago. A team at the Bay Area Environmental Research Institute NASA/Ames Research Centre in California says its research has shown that comets bombarding Earth some billions of years ago deposited key ingredients for life to spring up on the planet. Jennifer G Blank, who led the team, described experiments that recreated with powerful laboratory "guns" and computer models the conditions that existed inside comets when these celestial objects hit Earth's atmosphere at almost 25,000 miles per hour and crashed down upon the surface. The research is part of a broader scientific effort to understand how amino acids and other ingredients for the first living things appeared on a planet that billions of years ago was barren and desolate, say the planetary scientists. Amino acids make up proteins, which are the workhorses of all forms of life, ranging from microbes to people. "Our research shows that the building blocks of life could, indeed, have remained intact despite the tremendous shock wave and other violent conditions in a comet impact," Blank said in a release by the American Chemical Society. "Comets really would have been the ideal packages for delivering ingredients for the chemical evolution thought to have resulted in life. We like the comet delivery scenario because it includes all of the ingredients for life – amino acids, water and energy," she added. Comets are chunks of frozen gases, water, ice, dust and rock. These orbit the sun in a belt located far beyond the most distant planets in the solar system. Periodically, comets break loose and hurtle inward, where they may become visible. In their research, Blank and colleagues set out to check whether amino acids could remain intact after a comet's descent through Earth's atmosphere. In one set of experiments, they used gas guns to simulate the enormous temperatures and powerful shock waves that amino acids in comets would experience on upon entering the Earth's atmosphere. The gas guns, devices that weigh thousands of pounds, hit objects with high-pressure blasts of gas moving at supersonic speeds. They shot the gas at capsules filled with amino acids, water and other materials. The amino acids did not break down due to the heat and shock of the simulated crash. Indeed, they began forming the so-called "peptide bonds" that link amino acids together into proteins. The pressure from the impact of the crash apparently offset the intense heat and also supplied the energy needed to create the peptides, she explained. In other experiments, Blank's team used sophisticated computer models to simulate conditions as comets collided with Earth. The scientists suggested that there may well have been multiple deliveries of seedlings of life through the years from comets, asteroids and meteorites.
Source: Indian Express
