Martian life is awfully cryptic — that is a scientific term; it means life that is out of sight, below the surface, burrowed into ecological niches not easily scrutinized by robotic sentinels from the planet Earth. Or perhaps it is not anywhere. Mars may be dead as dead can be.
Going back to the 19th century, a persistent feature of hypothetical Martian life has been the way it has bewitched and teased earthlings but then refused to materialize. Time and again, scientists have detected signatures of Martian life, only to discover that they were written in vanishing ink. Most notorious were the canals on Mars, promulgated in the 1890s by the great astronomer Percival Lowell, who saw them as evidence of an ancient civilization struggling to survive on a desert world. They were purely an optical illusion.
Extraterrestrial life is one of the greatest unknowns in all of science, and many scientists are sure it has to be out there, somewhere, with Mars an obvious place to look. However, it is proving to be elusive. The latest buzz kill came Thursday when scientists announced that NASA's Curiosity rover had not detected methane in the atmosphere. Atmospheric methane is often a byproduct of living organisms.
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