Comets May Have Seeded the Earth
However, it seems that besides causing damage and death, the comets might have created life as well. It seems that the comets might have supplied Earth with numerous vital molecules such as water, which might have made it possible for the life to develop on our planet. The scientists hope to find out more about the comets today, when they will perform a flight near Comet Hartley. Currently the belief about the human creation is that Earth was molten when it formed about 4.6 billion years ago, and that it remained in the same state for the first 50 or 100 million years. The heat could explain the reason why the planet was so dry.
Astronomer David Jewitt at the University of California, Los Angeles stated that the people believe that the water was brought on Earth after the creation of the planet, and after it cooled down a bit. As a result, they started looking for things which might have contained water and the most obvious answer were the comets. The comets contain giant pieces of ice, and it is believed that water might have been contained in the ice. The researchers have also discovered the fact that the comets contain lots of compounds on them which might have facilitated the creation of life here on earth.
This conception about Earth and about its creation changed about 15 years ago, according to Jewitt. The scientists observed the fact that both the atoms of deuterium and the ones of hydrogen had a single proton and a single neutron. Jewitt said “The deuterium-to-hydrogen ratios have been observed in four comets now, and these are higher than that seen in Earth’s oceans by a factor of two or three”, which means that the oceans were not created by the comets, because otherwise they would have the same ratios. As a result, the scientists had to look for other sources of water and other life-giving molecules.
They have analyzed the situation and have reached the conclusion that the comets might have come from the steroid belt and not from the Kuiper belt, as it was believed. The Kuiper belt is the place from which all the short-period comets come, which are comets which require less than 200 years in order to complete a full rotation around the sun, and which have higher chances of colliding with the earth. The asteroid belt is located near Mars, whereas the Kuiper one is located near Neptune. The distance is very big, more precisely about 30 to 40 times the distance that Earth is from the sun. Some say that these organic materials would have not been able to resist because of the distance, but there were cases when they were discovered coming from a much farther distance. They have analyzed the deuterium-to-hydrogen ratios in the asteroid belt and they saw that there were a wide range of values, some of them being similar to the ones found in our oceans.
Jewitt stated that the situation is kind of complicated. He believes that the deuterium-to-hydrogen ratios should not have necessarily remained the same, because there could have been lots of geological processes which might have altered with the numbers. He also said that if the comets did actually come from the Kuiper belt, then the ratios for them are unknown. It is also possible that the distance between that place and the Earth to alter the ratio as well. Since the ratios from those comets have not been measured yet, there are some chances that they are similar to the ones found in the oceans, which means that the situation is clear.
He also stated that the Earth might have been wet when it formed, and as a result the water which is present on the planet has been there from the beginning, only that it was trapped inside the rocks. There are many who say that this is not possible, because the rocks could have not trap such large amounts of water. However, what many might not realize is the fact that the water from Earth is only 1 percent of the total mass of the planet. Jewitt stated that his opinion is that water on Earth is a result of all of those three factors: asteroid belts, comets, and the primordial matter. The truth is that the comets have caused more doom than bringing life, and according to Jewitt “Statistically, comets must hit planets.” Luckily in most of the cases the comets explode in the atmosphere and they do not hit the ground with too much of an impact. The reason for that is the fact that they posses large amounts of weak ice.
However, even under these circumstances, they are considered extremely dangerous. For example, the Tunguska explosion which flattened 2,000 square kilometers of Siberian forest is considered to be such a comet impact which never managed to hit the ground. NASA is in the verge of a great discovery, as on November 4, it will go within 698 km of the Comet Hartley 2. It is kind of different than the rest of the comets, because its ice structure is unaffected. Michael A’Hearn, principal investigator for the mission stated that this will give them an opportunity of analyzing the comet more thoroughly, and of finding possible answers for all the questions regarding the origins of water on Earth.
However, the mission might raise even more mysteries, because during the approach, the probe discovered a fivefold surge in the amount of cyanide-laced gas which the comet pumped-out. What makes things interesting is the fact that the comet pumped out dust which is very unusual in such situations. They will try to solve the mystery behind that as well.11