NASA's asteroid sample just revealed new clues to life's origins

NASA's asteroid sample has revealed new chemical evidence that scientists say sharpens the picture of how the solar system formed and how the ingredients for life spread through space.

Three studies published Tuesday in Nature Geoscience and Nature Astronomy examine pristine material the OSIRIS-Rex mission collected from the near-Earth asteroid Bennu and delivered to Earth in 2023. Researchers report finding important sugars for biology, a previously unknown gum-like substance, and large amounts of dust that were once forged in supernova explosions.

In one study, a team led by Yoshihiro Furukawa of Tohoku University in Japan found six types of sugars, including ribose, which forms the backbone of RNA — a crucial molecule for life — and glucose, a critical energy source for living creatures. It's the first time glucose has been detected in pristine asteroid material. 

Earlier, scientists had already found amino acids — the building blocks of proteins — and nucleobases, which help store genetic information. The discovery of sugars completes the set of key components needed to make proteins and genetic material.

"What this means is that these building blocks of life were distributed from the outer solar system all the way into the inner solar system," said Danny Glavin, an astrobiologist leading the sample organics analysis, in a NASA video. "They were everywhere, ubiquitous, which really makes me more optimistic that not only could these building blocks have enabled life on Earth, but potentially elsewhere — Mars, Europa, the outer solar system."

But what the researchers didn't find might be even more enlightening. Notably absent in the sample was deoxyribose, the sugar used to build DNA. That finding adds credibility to the so-called "RNA world" hypothesis, which proposes that the earliest living things relied on RNA alone to store genetic information and drive basic chemical reactions, before DNA and proteins came about.

"This discovery of ribose, in fact, is really important," Glavin said. "Maybe the origin of life was just a single strand of RNA."

NASA's $800 million OSIRIS-Rex mission, short for Origins, Spectral Interpretation, Resource Identification, and Security Regolith Explorer, launched in 2016. The robotic spacecraft completed its 4 billion-mile trip when it dropped the capsule from 63,000 miles above Earth onto a patch of Utah desert. It's the first U.S. mission to grab a sample of an asteroid. 

These are the most precious space souvenirs NASA has scored since the Apollo moon rocks, gathered between 1969 and 1972. The mission succeeded in collecting about a half-cup of crushed Bennu rocks and dirt. Though that might not sound like much, scientists expect the material to drive profound discoveries for decades to come. 

A second study uncovered an unexpected organic substance unlike anything previously seen in space rocks. The material, now hardened with age, likely had a gummy consistency when it formed, made of polymer-like chains of nitrogen and oxygen. These complex molecules may have provided the scaffolding to assemble the smaller organic ingredients necessary for life on Earth.

The substance likely formed before Bennu broke off from a larger asteroid that existed at the dawn of the solar system. 

"Looking at its chemical makeup, we see the same kinds of chemical groups that occur in polyurethane on Earth, making this material from Bennu something akin to a 'space plastic,'" said Scott Sandford, a NASA astrophysicist who led one of the Nature Astronomy papers. 

The Bennu rocks are the most precious space souvenirs NASA has obtained since the Apollo moon rocks. Credit: Robert Markowitz

The third study focused on so-called "presolar grains," specks of dust that formed around ancient stars before the birth of the solar system and later got incorporated into asteroids and planets. A team led by NASA's Ann Nguyen, a planetary scientist, found that the Bennu sample contains six times more dust from supernovas than has been measured in any other extraterrestrial material.

That high concentration suggests that Bennu’s parent body formed in a region chock full of debris from dying stars. Though fluids later altered much of the asteroid’s rock, the researchers also discovered relatively unchanged pockets, preserving organic material and fragile presolar grains from water damage.

Scientists say these discoveries bolster the idea that the raw ingredients for life were common, widely distributed and delivered to early Earth by asteroids similar to Bennu, helping lay the groundwork for biology long before the planet became habitable.

"I'm becoming much more optimistic that we may be able to find life beyond Earth, even in our own solar system," Glavin said.