Visions of aliens danced in a lot of heads last December, when NASA held a press conference, promising an "astrobiology finding that will impact the search for evidence of extraterrestrial life."
What scientists disclosed was the discovery of a bacteria, pulled from California's Mono Lake, that added deadly arsenic to the list of six basic elements believed needed for life — carbon, hydrogen, nitrogen, oxygen, sulfur and phosphorus. The idea that a microbe could bring poisonous arsenic into its DNA and thrive threw the conventions of biology on its head.
NASA was interested because even skeptical scientists such as Steven Benner of the Foundation for Applied Molecular Evolution, (who served as the token critic on the space agency panel presenting the results) pointed out that if life on Earth could thrive on something as nasty as arsenic, the opportunities for life on other worlds seemed much more expansive.
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