OSIRIS-REx sample
NASA/Erica Blumenfeld & Joseph Ebersold
Crucial components required for the emergence of life as we recognize it have been found in asteroid Bennu samples. This discovery suggests that Bennu might have transported the vital elements for life to Earth and potentially to other locations.
In 2020, NASA’s OSIRIS-REx mission gathered samples from Bennu, an asteroid that travels hundreds of millions of kilometers through space, situated between Mars and Jupiter. The mission successfully returned these samples to Earth in 2023. Since then, the 121 grams collected have been distributed to laboratories worldwide for examination, enabling scientists to start identifying various biological compounds.
Preliminary investigations uncovered the existence of water, carbon, and several organic molecules. Subsequently, they identified amino acids, formaldehyde, and all five nucleobases found in RNA and DNA, along with phosphates. However, these findings do not suffice for constructing molecules that encode genetic information, as the crucial sugars—ribose for RNA and deoxyribose for DNA—were not detected in the initial analysis of the Bennu samples.
Recently, Yoshihiro Furukawa and his team from Tohoku University in Japan ground some of the sample and mixed it with acid and water. They then utilized gas chromatography-mass spectrometry to separate and identify the mixture’s components.
This process confirmed the presence of ribose, alongside other sugars like lyxose, xylose, arabinose, glucose, and galactose, but notably lacked deoxyribose.
“This is a groundbreaking find, showing that sugars exist in extraterrestrial materials,” Furukawa remarked, noting that nearly all life relies on glucose for metabolic processes.
“This is a significant achievement of the OSIRIS-REx mission,” says Sara Russell, from the Natural History Museum in London. Although not part of Furukawa’s team, she also works with Bennu samples. “Previously, the only component missing was sugar, which has now been identified, confirming that all essential elements of RNA were present in this primitive asteroid.”
Furukawa and his colleagues propose that Bennu’s parent asteroid generated sugars from saltwater rich in formaldehyde, suggesting the asteroid was saturated with liquid and exhibited numerous chemical reactions.
“Earlier this year, we reported salt findings in the returned samples, indicating that Bennu’s parent body likely housed a saltwater pool,” Russell stated. “Such conditions would provide an optimal environment for synthesizing the complex organic materials found in Bennu.”
Evidence of saline water on Saturn’s moon Enceladus and the dwarf planet Ceres points towards the possibility that fundamental life ingredients might be plentiful throughout the solar system, according to Russell.
Furukawa’s research includes prior discoveries of ribose and other sugars in meteorites, but he emphasized concerns about potential contamination once these compounds reached Earth. “The presence of these sugars in the Bennu sample affirms the legitimacy of these results,” he stated.
The new findings suggest that the asteroid could indeed have supplied all the requisite components for life to other celestial bodies within the solar system, including Earth and Mars, according to Furukawa. The discovery of ribose but not deoxyribose further supports the RNA world hypothesis concerning life’s origins.
This hypothesis posits that, well before the advent of cellular life or DNA-based organisms, Earth’s earliest life forms were RNA molecules capable of carrying genetic information and self-replication.
topic:
Source: www.newscientist.com
