Scientists Find Life-Friendly Molecules In NASA's Asteroid Samples

(MENAFN- The Peninsula) Washington Post

The asteroid Bennu, visited by a NASA robotic probe five years ago, contained many of the basic building blocks for life as we know it, including amino acids, according to long-awaited research published on Wednesday.

Moreover, these organic molecules were once immersed in a brine that could have served as a congenial medium for prebiotic chemistry, creating a "feedstock” of molecules available for the eventual appearance of life on Earth, scientists said. The Bennu samples suggest that the raw materials of life have probably been present in great abundance in the solar system for about 4.5 billion years.

The discoveries are reported in papers published in the journals Nature and Nature Astronomy.

"I think it shows that the early steps toward the path to life were occurring much more widely and much earlier than we had thought before,” said Tim McCoy, a geologist at the Smithsonian National Museum of Natural History and lead author of the paper in Nature.

The analysis of the Bennu samples is the scientific payoff for NASA's OSIRIS-REx mission, which in 2016 launched a probe to the asteroid on a multiyear journey.

The spacecraft jabbed the asteroid in 2020, dug out samples, sealed them in a canister and then flew back to Earth, flinging the precious cargo onto a Utah bombing range in September 2023. The next stop for the material was the NASA Johnson Space Center in Houston, which distributed samples to researchers across the globe.

Ever since, scientists have been fussing over every pebble and grain of dust, studying this remnant of the distant past and trying to discern the chemistry of the early solar system.

At the Natural History Museum, McCoy and his colleagues used a scanning electron microscope to examine a Bennu sample. They detected sodium carbonate compounds like the "soda ash” found on Earth in certain lakes that have evaporated. That was the signature of the presence of liquid water long ago, and liquid water is considered essential to biochemistry on Earth.

The origin of life remains one of science's greatest and most persistent mysteries. Solving it is challenging because life appears to have been present very early in Earth's history, and our planet has reworked its surface so thoroughly that there aren't many very old rocks to be found.

The analysis of Bennu samples is an incremental step toward understanding the solar system as Earth was cooling and becoming potentially more friendly to life. Although the definition of life remains debatable, it is widely considered to be a self-sustaining chemical system capable of Darwinian evolution. But no one knows when, how or where the chemistry became sufficiently complex to develop into something scientists would consider life.

Although meteorites can bring fragments of asteroids directly to the surface of our planet in modern times, scientists wanted to study an asteroid in its natural environment, free of terrestrial contamination.

"What makes the Bennu samples special is they're so pristine,” said Daniel Glavin, an astrobiologist at the NASA Goddard Space Flight Center and lead author of the paper in Nature Astronomy. "We can trust these results. This is extraterrestrial matter and not contamination from Earth.”

This was NASA's first sampling of an asteroid, though not humanity's first effort. Japan's space agency conducted a sampling with its Hayabusa2 mission that in 2020 brought fragments of a larger asteroid called Ryugu to Earth.

OSIRIS-REx obtained a greater quantity of asteroid samples and found some differences, including a significantly higher percentage of ammonia, a building block for amino acids, themselves the building blocks of proteins.

"It's a lot of ammonia. That was a big surprise,” Glavin said. The largeabundance of the volatile molecule (one nitrogen atom, three hydrogen atoms) is a sign that the parent body of Bennu accreted material very far from the sun, beyond Jupiter's current orbit.

Life itself was unlikely to find purchase in the rocks of Bennu. The asteroid, NASA discovered when the spacecraft tagged it, is a rubble pile of loosely aggregated material left over from a largerparent asteroid that formed about 4.5 billion years ago and later collided with another object.

Bennu was chosen as a target for OSIRIS-REx (which stands for Origins, Spectral Interpretation, Resource Identification and Security - Regolith Explorer) in part because it is an Earth-crossing asteroid, meaning its path around the sun could lead it to collide with Earth someday.

If life ever got a foothold on Bennu, it left no trace behind. "We have looked through the Bennu sample at a very fine level,” Sara Russell, a planetary scientist at the Natural History Museum in London, said during a NASA news conference on Wednesday. "We don't see any cellular structures that you might expect if there were fossils in there.”

Calculations of Bennu's orbit show very low risk of such an impact for the next couple of centuries. Still, scientists want to keep an eye on it, and every time it makes a close approach they can refine their projections for where it will be in the foreseeable future (and whether we need to try to do something about it).

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