The Search for Life in the Cosmos
Are we alone? For generations, humans have asked this question as they looked to the stars for answers. Never have we been so close to finding an answer, as we are today. In the field of Astrobiology, the search for extraterrestrial life is the top priority, and scientists are going to great lengths to find it, studying life here on Earth to better understand how it might arise in the universe, then scouring the cosmos for any hint of a potentially habitable environment. So what is life? What does life need to survive, and if it does exist outside of our home planet, where might we find it? All of these questions, we will attempt to answer through the research of the most brilliant minds in astronomy and biology. According to Professor Stephen Hawking, “[life is] an ordered system that can sustain and reproduce itself… Living being[s] usually have two elements: genes and metabolism.” (Hawking) From what we have learned about life on Earth, living beings require water to live, and are made of several types of atoms built on chains of carbon. It seems possible that life could potentially be built on a different chemical foundation, but carbon and water appear to be key to the arrival of life. Accordingly, in the great search for E.T., water and carbon are what astrobiologists look for when determining if a planet or moon are habitable. (Randall) Astronomers talk about the small habitable zone of planets around their star, or the “Goldilocks zone”, because it’s not too hot, and not too cold, but just right to support life. But the truth is, life is extremely resilient, and needs little more than a little liquid water, the most basic of resources to not only survive, but to thrive! In recent years, there have been organisms found that live in habitats we never imagined: a microscopic animal that lives completely without oxygen, bacterium that live in the frozen lakes of the arctic, and most interestingly, the tube worms that inhabit the toxic, super-pressurized waters of the boiling-hot hydrothermal vents at the bottom of the ocean. (Moskowitz) There is no sunlight here (at over a mile deep), which means no photosynthesis to produce food for animals. Instead, the bacteria that live inside the stomach of the tubeworms turn the toxic chemicals from the vents into food that the tubeworms can digest, through a process called chemosynthesis. (DiscoveryEducation.com) Now, I know this may seem slightly off-topic (why is he talking about worms and chemical-eating bacteria??). However, it is a crucial detail in observing the way that life works. The bottom line here is: if there is a way, life will find it. And that’s exactly what scientists are hoping for in the case of Mars, as the planet is virtually dead. In fact, they’ve basically given up on searching for active life, and instead have turned their focus to searching for compounds associated with life, such as carbon and methane (given off by bacteria during metabolism). If there is life there now, it is likely beneath the surface of Mars, hidden from the solar radiation that the Martian atmosphere fails to intersect as efficiently as ours. Some scientists suspect that we may one day find fossils of previous life on Mars, as it is theorized that the planet was once covered in Oceans and a thick atmosphere similar to Earth’s. However, its small size and weak gravitational pull allowed Mars’ atmosphere to be literally blown away by the power of the solar wind, and the water eventually evaporated into space as well. (Redd) There have been several unmanned missions to Mars, such as the Viking, NASA’s first Mars lander, which performed an experiment that, years later, is gaining attention as a possible missed discovery of biological activity in the Martian soil. (Waugh) In August of this year, NASA landed its latest Mars lab, Curiosity. While it does not have the tools to find life, Curiosity is teaching us more about the planet itself - its chemical...
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