Asteroid samples fetched by NASA hold secrets to building blocks for life on Earth

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

Cape Canaveral: 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.
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.

NASA’s Osiris-Rex spacecraft returned 122 grams of dust and pebbles from the near-Earth asteroid Bennu, delivering the sample canister to the Utah desert in 2023 before swooping off after another space rock. It remains the biggest cosmic haul from beyond the moon. The two previous asteroid sample missions, by Japan, yielded considerably less material.

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Small amounts of Bennu’s precious black grains — leftovers from the solar system’s formation 4.5 billion years ago — were doled out to the two separate 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.

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.”

NASA’s Daniel Glavin said one of the biggest surprises was the relatively high abundance of nitrogen, including ammonia. While all of the organic molecules found in the Bennu samples have been identified before in meteorites, Glavin said the ones from Bennu are valid — “real extraterrestrial organic material formed in space and not a result of contamination from Earth.”

Bennu — a rubble pile just one-half of a kilometre 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.