Image: Allamandola et al. |
Act one in the most common story about life's origins opens in a warm puddle of "primordial soup" somewhere on Earth. But what if that first scene took place in the cold of deep space instead? New findings, published today in a special astrobiology issue of the Proceedings of the National Academy of Sciences, suggest just that. Louis Allamandola and his colleagues at the NASA Ames Research Center have created primitive cells of a sort¿empty, two-layer membranes (see image)¿from elementary chemicals, exposed to conditions like those in interstellar clouds. "Scientists believe the molecules needed to make a cell's membrane, and thus for the origin of life, are all over space," Allamandola says. "This discovery implies that life could be everywhere in the universe."
The team set out to duplicate the chemistry within interstellar clouds in the laboratory. In a vacuum, they first created solid ices containing simple chemicals such as methanol, ammonia and carbon monoxide at temperatures close to absolute zero. Next they blasted the ices with harsh ultraviolet (UV) radiation. In space, the same types of ices are regularly irradiated by the UV emissions from neighboring stars. Among the complex molecules that resulted were solid materials that spontaneously popped open into membranelike structures when put in water. Similar material could have traveled to Earth from space by way of a meteorite and helped pave the way for the beginning of life.
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"We started this work motivated to find the types of compounds that might be in comets, icy planets and moons, providing guidance for future NASA missions," Allamandola adds. "Sure, we expected that ultraviolet radiation would make a few molecules that might have some biological interest, but nothing major. Instead we found that this process transforms some of the simple chemicals that are very common in space into larger molecules which behave in far more complex ways. Ways which many people think are critical for the origin of life, the point in our history when chemistry became biology.
