A Nearby Asteroid Harbors Material To Seed Life

"The organic building blocks required to seed life have been found on an asteroid for the first time.

Planetary scientists discovered the material within the coal-black dust and rock retrieved from the asteroid known as Bennu, the target of a pioneering NASA probe that scraped its surface and brought the resulting sample back to Earth.

The finding supports the theory that so-called near-Earth asteroids, like Bennu, were the source of life on Earth.

Researchers found 14 of the 20 amino acids that make up proteins and all five molecules that comprise DNA and RNA in mineral deposits of salty brine left on Bennu's surface, according to two papers published on Wednesday.

The finding also means that such building blocks could have come from the far reaches of our solar system and then landed on any hospitable planet or moon, said Tim McCoy, curator of meteorites at the Smithsonian Institution's Museum of Natural History, who examined the sample and is first author of the paper published in the journal Nature.

"We're talking about the earliest steps that lead towards life," McCoy said.

Life didn't arise on Bennu itself because the chemical ingredients and environment didn't have a chance to develop before becoming inert. "In addition to having the environment and the ingredients, you also need time and probably temperature, and we probably didn't have those for long enough or hot enough for this to happen on an asteroid," McCoy said.

The Bennu sample was retrieved by OSIRIS-REx, a robotic spacecraft that the National Aeronautics and Space Administration launched in 2016. After grabbing a soap-bar-sized scoop of rock and dust from the asteroid's surface in 2020, the spacecraft swung past Earth three years later and dropped a sealed capsule containing the material in the Utah desert.

Bennu is a pile of rubble about 1,600 feet across that formed 4.5 billion years ago from an original asteroid that broke apart and then reformed. It passes by Earth every six years about 186,000 miles away, closer than the Moon.

Bennu's parent asteroid contained pockets of liquid water that evaporated, leaving behind brines of various minerals that resemble the salty crusts of dry lakebeds on Earth. The minerals are the base from which the amino acids and other organic material formed.

At NASA's Goddard Space Flight Center in Greenbelt, Md., researchers ground tiny chips of asteroid into a fine powder, then made a "Bennu tea" by boiling it in water. That allowed them to extract and identify the organic compounds, according to Jason Dworkin, an astrobiologist at NASA Goddard and an author of the paper published in Nature Astronomy.

There are still many questions remaining, including why life didn't evolve on Bennu's parent asteroid and whether similar conditions might be present today in other parts of the solar system, such as Saturn's moon Enceladus, Jupiter's moon Europa, or Ceres, a dwarf planet in the asteroid belt between Mars and Jupiter.

More research is being conducted on the Bennu sample.

"This gives us a firsthand report of a negative control for life," Dworkin said. "A place that had all the stuff, but life didn't get going."" [1]

1. REVIEW --- Science Shorts: A Nearby Asteroid Harbors Material To Seed Life. Niiler, Eric.  Wall Street Journal, Eastern edition; New York, N.Y.. 01 Feb 2025: C3.