Breakthrough Discovery: Asteroid Bennu Holds Clues to Earth’s Origins and Life
Asteroid Bennu, a near-Earth asteroid with significant implications for our understanding of the solar system and the origins of life, has revealed surprising insights. Samples collected by NASA’s OSIRIS-REx spacecraft contain not only the chemical building blocks essential for life but also evidence of a briny, watery parent body.
OSIRIS-REx: A Mission to Return Asteroid Samples
In September 2023, the OSIRIS-REx spacecraft delivered over 120 grams of material collected from asteroid Bennu. This delivery, eagerly awaited by scientists for nearly three years, marks the first time NASA has returned samples from an asteroid for detailed study on Earth.
Asteroid Bennu, as imaged by the OSIRIS-REx spacecraft’s camera. (NASA Goddard)
Collected in October 2020, these samples represent a critical opportunity to study an asteroid’s composition and history directly without the destructive effects of re-entry into Earth’s atmosphere.
Unveiling Bennu’s Surprising Chemistry
Two recent scientific studies detail exciting findings from the Bennu samples. Published in the journals Nature and Nature Astronomy, these papers shed light on previously unknown aspects of Bennu’s composition.
Salt Crystals and Ancient Briny Waters
The first study, published in Nature, identified unexpected salt crystals within the Bennu samples, indicative of briny water that once existed on its parent body. Specifically, sodium carbonate—a common salt found in dried-up salty lakes like Searles Lake in California—was detected.
“We’re seeing minerals in Bennu samples that we have never seen before in a meteorite or any extraterrestrial sample,” commented Tim McCoy, curator of meteorites at the Smithsonian’s National Museum of Natural History and lead author of the research paper.
Salt minerals from the Bennu samples, deposited as a result of brine evaporation from its parent body. The purple needles of hydrated sodium carbonate would likely have been lost if samples had been exposed to water in Earth’s atmosphere. (Rob Wardell/Tim McCoy/Smithsonian Institution/Heather Roper/University of Arizona)
Building Blocks of Life Found in Asteroid Samples
The second study, published in Nature Astronomy, further expanded on the OIRIS-REx findings. This research identified 14 out of 20 essential amino acids needed for proteins, as well as nucleobases fundamental to DNA and RNA, demonstrating the asteroid contains the critical building blocks for life.
“These samples from Bennu are an incredible discovery, showing that the building blocks of life were widespread across the early solar system,” stated Dante Lauretta, a co-author of both studies from the University of Arizona’s Lunar and Planetary Laboratory.
Five nucleotide bases, essential for forming DNA and RNA, were detected in samples from asteroid Bennu. (NASA Goddard/OSIRIS-REx)
Implications for the Origin of Life
These discoveries provide fascinating significantu Bennu provide valuable insights into the conditions necessary for life. The presence of both salty brines and organic compounds suggests that liquid water and the building blocks of life existed in the Bennu’s parent body, hinting at potential life-supporting environments in the early solar system.
By examining how these materials interacted in environments like Bennu and proto-Earth settings, scientists hope to uncover how life could emerge and where to search for it beyond our planet.
OSIRIS-REx’s Journey: From Bennu to Apophis
The OSIRIS-REx mission, launched in September 2016, involved collecting samples from Bennu after months of orbiting the asteroid. Lauding the mission’s success, Jason Dworkin, OSIRIS-REx project scientist, said, “Data from OSIRIS-REx adds major brushstrokes to a picture of a solar system teeming with the potential for life.”
Having fulfilled its primary objective, the OSIRIS-REx spacecraft
