Elizabeth Frank: Testing Our Assumptions About Ancient Life
In nature, there is a certain ratio among the isotopes of an element. When the ratio in a mineral differs from what is expected, it may be indicative of previous life. Such indications are known as biosignatures. Biosignatures occur when organisms, such as bacteria, take compounds from their environment and use them in their metabolic processes, leaving behind elements in a dissimilar isotopic ratio. It is assumed that these biosignatures are stable over geologic time — millions of years. Elizabeth Frank, a junior majoring in interdisciplinary science and minoring in astrobiology, set out to test this assumption. She discovered that although there is a diffusive exchange of the isotopes over long periods of time, the amount of exchange is small enough that the biosignatures can indeed be considered stable. Her project, "Self Diffusion of Sulfur in Pyrite" won first place in the theoretical category of the 2007 Undergraduate Research Forum and Awards. |
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