In this article from the New Scientist, August 17, 2009, it is reported that, for the first time, organic molecules that are the building blocks for more complex biological molecules have been found in comets. Captured on four approximately 1 cm. squares of aluminum foil by an unmanned spacecraft and then returned to earth for analysis, the organic molecules sampled from the comet consisted of "several amino acids", including glycine as well as amines, a functional group of amino acids.
Previously, organic molecules have been found in meteorites which landed on earth, however, this represents the first direct finding of organic molecules in space. Remembering what we learned about the structure of amino acids, one shouldn't be surprised that glycine was one of the amino acids found since it has the simplest structure of all amino acids with it's side chain consisting of just a single hydrogen atom.
This is a significant finding for scientists both investigating the origin of life on earth and searching for life elsewhere in the universe. I think that the article's claim that 'the discovery confirms that some of the building blocks of life were delivered to the early Earth from space" is a bit of an overstatement. These findings provide additional evidence that the spontaneous construction of organic building blocks is a universal happening given favorable conditions (a source of carbon, nitrogen, and hydrogen, a reducing environment, and the lack of oxygen). For people interested in searching for life beyond our own planet, this discovery seems to bolster their cause. However, a number of studies over the last 50 years have made the case that an environment favorable to building organic molecules from inorganic sources also existed on earth in the past. Where the first organic building blocks came from that led to the origin of life on earth - outer space, deep sea vents, or a shallow primordial sea, - remains "unconfirmed".
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Were the organic molecules found in the meteorites on earth the same as the comets found in space, or did the time on earth effect the structure of the earth bound meteorites? The reason behind my questioning is the fact that the meteorites on earth were not considered a direct enough source to varify organic molecules in space. However, the aluminum foil from the spacecraft that came directly from space gave enough evidence to varify the hypothesis that organic molecules in fact exist in space.
ReplyDeletehttp://www.buzzle.com/articles/meteorites-facts.html
ReplyDeleteI researched and found that certain Chrondites meteorites have traces of amino acids and organic molecules in them, however, some of the other types do not. There are two other types of meteorites called Achrondites and Iron, which don't consist of organic molecules. This varified my question about the reason of the comet in space being a more direct source of organic molecules. It is not the fact that the earth changed them, but the fact that there are three different types of meteorites:
Chrondites (86%)
Achrondites (8&)
Iron meteorites (6%).