Life Outside the Earth - Term Paper Example

Life outside Earth Number Introduction Is there life on other planets and moons of the solar system apart from the earth? This has been an age old question, and one that has troubled the minds of many, including scientists, philosophers, teachers, politicians and even the curious young child staring at the bright sky in the starry night. Life on earth is possible as a result of special conditions such temperatures, presence of water, and other essential gases and elements, that permit a wide and diverse range of biological life. The question thus remains as to whether life as we know it is possible in any other planet (or moon) outside of ours. Could an organism from earth, inhabit the other planets of the solar system. Well, this essay attempts to answer this lingering question by looking at the key conditions in selected solar system planets and moons with a view of determining whether life is permissible in the highlighted conditions. Planets Mercury Mercury (the closest planet to the sun) is one of the brightest planets in the solar system, alongside Venus, with its surface solar intensities 5-10 times higher than the solar constant. The temperatures in mercury range from 100-700 Kelvin, with quite large extremes between the equator and the poles. Although evidence suggests the presence of water vapor, liquid water is impossible in these temperature extremes). Moreover, because of its small size and high temperatures, the gravity of the planet is unable to hold any atmosphere. This absence of atmosphere hinders the presence of essential gases such as oxygen and hydrogen that are vital for life processes. In as far as the slow rotation of this planet is ideal for ‘normal’ life, the other conditions, on the other hand, are too extreme to allow for the survival of an earthly organism (even the most tolerant kinds). For one, resources are scarce or inexistent meaning an organism would be ‘starved’ to death. Furthermore, extremes in temperature do not allow for the existence of liquid water that is of utmost importance in the survival of both plants and animals. Also, apart from the loss of vision in such high light intensities that would make it hard for organisms to search for food or seek shelter, the absence of an atmosphere allows for free penetration of radiations that would be cancerous or portend a plethora of other deadly effects such as total desiccation. These conditions ensure that even the most extreme/ hardy earth organisms cannot survive the conditions of mercury (Trammel, 2010). Venus Venus is the hottest of all the solar system planets, with temperatures averaging 462 degrees Celsius. Much of its atmosphere is composed of carbon dioxide with nitrogen present in small amounts. It is this presence of nitrogen, carbon dioxide and other gases that causes a greenhouse effect which ensures these scorching temperatures. Because the planet has a very dense atmosphere, pressure on the surface of the planet ranges close to those of the earth’s ocean floors. Hydrogen and oxygen gases rise above the other denser gases (Jortner, 2006). Again, as with mercury, life on Venus seems impossible. If an organism is equipped with the right enzymes and thick coverings that allow it withstand the heat, for example, it would still have to contend with the absence of oxygen (which is scantily available on the upper part of the atmosphere) and liquid water (due to the high temperatures). Life on the surface would also be made difficult due to the high atmospheric pressures that are suitable only for organisms that can generate equally high internal pressures to avoid bursting and associated consequences, but then again, there is no water for life to be supported. It would seem an organism has more chances of survival in the upper part of the atmosphere that has lower pressures and more oxygen than on the surface. However, such as free floating, buoyant/ feathery organism that has heat tolerance and does not need liquid water at all does not exist on earth, or is yet to be discovered. Mars Mars is the fourth planet in the solar system after earth. To some scientists, conditions of mars resemble those of early lifeless earth. Mars barely has an atmosphere. Its atmosphere is 200 times smaller than earth’s. 95% of this thin atmosphere is carbon dioxide. Average temperatures on the planet are -50 degrees Celsius, with the weather characterized by dust storms and strong winds. All these conditions ensure that life on mars is impossible as the temperatures do not for one allow for the existence of liquid water while the thin atmosphere does not offer any protection from lethal radiations. In as much as scientists have recently discovered proteins that could be used to impart tolerance of cold in areas such as mars in organisms (Bova, 2004), this breakthrough will not suffice in realization of stable life in these planets as mars seeing as it only tries to solve the issue of cold temperatures in mars. Jupiter Jupiter is the largest planet in the solar system (with 18 moons orbiting around it). The conditions in Jupiter are characterized by high pressures, strong gravity, and strong winds which range between 225-1000 miles per hour. The strong winds make it difficult for any earth organism to survive in a suitable location that could be discovered. An organism might thus find itself in an uninhabitable region of the planet if such a soft spot that supports life were indeed present. Such an organism would require extensive roots (for plants) or strong adherence structures (for animals), but then the pressures on the surface would not be conducive for life forms, not to mention that the planet lacks any solid surface for such necessary attachments as the organism would be left open to attack by Jupiter’s violent atmosphere of severe storms, lightning, high ultra violet levels and charged particles (Trammel, 2010). In addition, Jupiter has an atmosphere of hydrogen and helium. This absence of oxygen and carbon dioxide makes life on the planet impossible. In addition, the temperatures are not conducive enough to allow for life. Surface temperatures can reach -110 degrees Celsius while the lower atmosphere tends to be extremely hot. The moist conducive part (with regards temperature) would therefore be the upper atmosphere. However, the absence of liquid water, presence of radiation, strong winds, high pressures, no oxygen or carbon dioxide, and so on, do not offer any hope of life existing in this region either. Saturn The atmosphere of this ringed planet closely resembles that of Jupiter with violent storms and wind speeds (where those around the equator can clock a staggering 1,800 km/hr, for instance). The atmosphere of the planet is predominantly composed of hydrogen gas (75%) and helium gas (25%) with small traces of methane and water ice (Bova, 2004). The planet also has ammonia clouds but noticeably lacks important gases such as oxygen that support life, sufficient sunlight and has no liquid water. The conditions of high winds, low densities of the surface (0.7 that of water) and high pressures only serve to seal the deal and ensure survival of an earthly organism is not possible in this planet. Selected Solar System Moons Earth’s Moon The earth’s moon has played host to a number of visiting astronauts in recent decades due to its proximity to earth and the more manageable conditions of this moon. These human visits have been made possible because the astronauts carry their own oxygen tanks, food and water, while adorning themselves in special suits (clothing) that help them counteract the light gravity of this satellite. This characteristic light gravity of the earth’s moon implies that a surface organism (or any organism, for that matter) would have to be heavy enough so as not to float away into space. Moreover, this moon lacks air, and more specifically, oxygen and carbon dioxide. This makes survival impossible for animals that respire aerobically and plants that need carbon dioxide to perform the important process of photosynthesis. Apart from these glaring impediments, the earth’s moon further lacks an atmosphere, has no weather and no oceans of water (except for the lunar South Pole that boasts a reserve of water ice). The moon has no liquid water that is important for all life forms. Water makes up approximately 80% of the bodies of living organisms, without which an organism cannot survive. In addition, the moon is largely characterized by extremes of diurnal temperature ranges from day time highs of 123 degrees Celsius to -233 degrees Celsius in the night hours. In as much as these conditions are habitable for certain extreme earth organisms (and indeed there are regions with temperatures that mankind can withstand), life on the moon cannot be accomplished as these organisms would still require different levels of water in liquid form, nutrients and other gases such as oxygen for growth, development and reproduction (Fisher, 2010). Titan Of all the moons of the planet Saturn, Titan is the largest. It is the second largest moon in the solar system, after Jupiter’s Granymede, and is larger than the planet mercury. Many scientists hold that the conditions in this enormous moon resemble those of early earth, and as per the theory of evolution, this moon may somehow experience life forms in future. However, as it is, the conditions in the moon do not permit survival of any organism on earth as we know it. Titan is recognized as the only moon in the solar system with an atmosphere that resembles those of planets, coupled with the presence of clouds. It is a rare moon that shows similarities with the conditions on earth. This is of course, except for the fact that the earth being closer to the sun is suitably warmer allowing life to thrive in all its forms. The temperatures on the surface of the Titan average around -179 degrees Celsius. This range makes it impossible for the existence of liquid water which is vital for all life forms, with water in the Titan reportedly as hard as rock. The pressures of the Titan are almost like those on earth except they are slightly higher than the earth’s. The Titan’s pressure at sea level, for example, is 1.6 bars, compared to the earth’s 1 bar. However, these favorable pressures do not mean much if all the other factors that should favor survival of life are absent. Titan has a dense 600km long, active and complex atmosphere made of nitrogen (95%) and methane (5%). There are also organic molecules composed of hydrogen and carbon, and in some cases, oxygen. However, these are rare and scarce to allow for sustained assimilation by organisms to yield essential compounds such as body water. Likewise, life of plants on this moon is impossible because of the absence of enough sunlight to support photosynthesis (Stetefeldt, n.d.). Rains observed on the planet are only methane rains, with the absence of liquid water yet again ruling out the existence of any life forms on an otherwise promising heavenly body. In line with these findings, evolutionists continue to express hope that it is a question of time before this atmosphere, like the earth’s proto-atmosphere, transforms itself into a form that can support life. However, this transformation and ability to support life may be impossible due to the moon’s position from earth and the insufficient light that reaches its surface. Conclusion A critical analysis of the vital conditions in other heavenly bodies of the solar system, such as the ones discussed above, reveals that it is only on earth that we find a peculiar situation where all life supporting factors/ conditions are all simultaneously present thus permitting life (Horneck, 2002). These important factors considered include the availability of liquid water, temperatures, presence of nutrients (which are replenished through processes such as the nitrogen cycle), energy source, and protection from ultra violet rays and galactic cosmic radiation. Even when man lands on the moon, it does not mean that life is possible on the moon unaided. Astronauts carry with them enough food supplies and water, while wearing protective clothing (Stetefeldt, n.d.). References Bova, B. (2004). Faint echoes, distant stars: The science and politics of finding life beyond Earth. New York: Morrow. Fisher, D. (2010). The solar system. Pasadena, Calif.: Salem Press. Horneck, G. (2002). Astrobiology: The quest for the conditions of life. Berlin: Springer. Jortner, J. (2006). Conditions for the emergence of life on the early Earth: Summary and reflections. Philosophical Transactions of the Royal Society B: Biological Sciences, 1877-1891. Stetefeldt, C. (n.d.). Can Organic Life Exist in the Planetary System Outside of the Earth? Publications of the Astronomical Society of the Pacific, 91-91. Trammel, H. (2010). The solar system. New York: Childrens Press. Read More