Asteroid samples fetched by NASA hold not only the pristine building blocks for life but also the salty remains of an ancient water world, scientists reported Wednesday. The findings provide the strongest evidence yet that asteroids may have planted the seeds of life on Earth and that these ingredients were mingling with water almost right from the start, reports the AP. "That's the kind of environment that could have been essential to the steps that lead from elements to life," said the Smithsonian Institution's Tim McCoy, one of the lead study authors. NASA's Osiris-Rex spacecraft returned 4 ounces of dust and pebbles from the near-Earth asteroid Bennu, in the biggest cosmic haul from beyond the moon. The two previous asteroid sample missions, by Japan, yielded considerably less material.
Small amounts of Bennu's precious black grains—leftovers from the solar system's formation 4.5 billion years ago—were doled out to two research teams whose studies appeared in the journals Nature and Nature Astronomy. But it was more than enough to tease out the sodium-rich minerals and confirm the presence of amino acids, nitrogen in the form of ammonia, and even parts of the genetic code. Some if not all of the delicate salts found at Bennu—similar to what's in the dry lakebeds of California's Mojave Desert and Africa's Sahara—would be stripped away if present in falling meteorites. "This discovery was only possible by analyzing samples that were collected directly from the asteroid, then carefully preserved back on Earth," said the Institute of Science Tokyo's Yasuhito Sekine, who was not involved in the studies.
Combining the ingredients of life with an environment of sodium-rich salt water, or brines, "that's really the pathway to life," said McCoy, the National Museum of Natural History's curator of meteorites. "These processes probably occurred much earlier and were much more widespread than we had thought before." Bennu—a rubble pile just one-third of a mile across—was originally part of a much larger asteroid that got clobbered by other space rocks. The latest results suggest this parent body had an extensive underground network of lakes or even oceans, and that the water evaporated away, leaving behind the salty clues. "Are we alone?" McCoy asked. "That's one of the questions we're trying to answer."
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