Scientists analyze samples NASA returned from an asteroid made a surprising discovery that could mean space rock was once part of a long gone ocean world.
What the team found was water-soluble magnesium-sodium phosphate in the spotted rocks, a mineral that no one expected because it didn’t show up in any of the data collected by the spacecraft when it was at the asteroid Bennu. Phosphate compounds are key to all known life, forming the backbone of DNA.
The new the findings of the studypublished in Meteoritics and Planetary Sciencesare integral to the “rogue asteroid,” so named because it confounds scientists at every step of the way OSIRIS-Rex mission.
“The presence and state of phosphates, along with other elements and compounds on Bennu, suggest a watery past for the asteroid,” said lead researcher Dante Lauretta in a statement.
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This Bennu particle, about a millimeter wide, reveals a bright crust of phosphate under a microscope.
Credit: Lauretta & Connolly et al. (2024) Meteoritics and Planetary Sciences
NASA’s $800 million OSIRIS-Rex mission, short for Provenance, Spectral Interpretation, Resource Identification and Security Regolith Explorer, launched in 2016. The robotic spacecraft completed its 4 billion-mile journey when it dropped the capsule 63,000 miles above Earth onto a patch of Utah desert last year. It is the first US mission to sample from an asteroid. These are the most significant space memorabilia received by NASA since Apollo Moon Rockscollected between 1969 and 1972.
NASA chose Bennu for the mission because it did very little chance of hitting Earth in the following centuries. Learning about the asteroid can be useful for future efforts to redirect it.
But the team also chose Bennu because it is full of carbon, meaning it could contain the chemical origins of life. Some of its mineral fragments may be older than the solar system by 4.5 billion years. These grains of stardust may have come from dying stars or supernovae which eventually led to the formation of the sun and planets.
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NASA has made samples of asteroid Bennu collected during the OSIRIS-Rex mission available for scientists around the world to study.
Credit: NASA / Erica Blumenfeld and Joseph Ebersold
All life forms on Earth have specific chemicals in their composition, such as amino acids and sugars. Scientists know that asteroids contain molecules that are thought to be precursors to these chemicals. This is why many suspect that space rocks were responsible for bringing them to the planet through collisions in ancient cosmic history. By studying the Bennu samples, they hope to gain more insight into how these ingredients might have evolved.
“What I want to know is how do you go from a simple carbon molecule, like methane, which is a natural gas, to something like amino acids, which make our proteins, or nucleic acid, which makes up our genetic material,” Lauretta said last year .
His dream discovery would be evidence of amino acids beginning to link together through chemical bonds to form a chain known as a peptide, signaling the evolution of the protein.
Bennu is teardrop-shaped and made of gravel and boulders barely held together by their own microgravity.
Credit: NASA Goddard Space Flight Center / University of Arizona
The mission managed to bring home approx half a cup of crushed stones and earth. So far, the researchers have not been disappointed with their prize.
The sample is rich in nitrogen and carbon, essential ingredients for life. The team’s early analysis found particularly abundant clay minerals serpentine. This is similar to the type of rock found in Earth’s mid-ocean ridges, where geologists believe the recipe for life on our planet may have begun.
The magnesium-sodium phosphate in the Bennu sample resembles the sodium phosphates Enceladus. This moon of Saturn is encased in a saline ocean beneath ice and is known to shoot huge geysers into space. Similar phosphate-enriched fluids are found in terrestrial soda lakes such as Last Chance and Goodenough in Canada.
The OSIRIS-Rex sample return capsule after it landed on Earth.
Credit: NASA / Keegan Barber
In the new OSIRIS-Rex paper, scientists suggest a “possible connection” between Bennu and Enceladus, but this idea will require more investigation to prove. Examining the sample has only begun to scratch the surface.
“These findings highlight the importance of collecting and studying material from asteroids like Bennu,” Lauretta said, “especially low-density material that would normally burn up (if it entered) Earth’s atmosphere.”
