BIOL 1101 Chapter 3: Chapter 3
5 Oct 2016
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Document Summary
In 1984, a group of scientists in the antarctic discovered a 1. 9 kg meteorite that they cataloged as alh84001. Initial studies of it showed it was about 4. 5 billion years old, which is about the same age as the solar system. Its chemical composition indicated that it came from mars and had impacted earth approximately 13 thousand years ago. The meteorite garnered headlines around the world in 1996 when an article was published claiming that this meteorite shows evidence that at one time, life existed on mars. Chemical analysis showed that when on mars, it had one time been fractured and subsequently infiltrated by water. Using scanning electron microscopy, the coauthors of the article observed very small tubular structures in the fractured surfaces that look similar to fossilized prokaryotic cells. Furthermore, the scientists found microscopic mineral globules which bear strong resemblance to mineral alterations caused by primitive cells on earth. The analysis of meteorites for microfossils continues and remains controversial.
