CAPE CANAVERAL, Fla. — NASA's OSIRIS-REx mission not only returned the largest cache of samples from beyond the Moon but also brought back what scientists describe as the building blocks of life from the asteroid Bennu. These findings, reported by scientists on Wednesday, provide compelling evidence supporting the idea of asteroids being instrumental in planting life on Earth.
Launched in 2016, the OSIRIS-REx spacecraft successfully reached Bennu and collected about 122 grams of pristine material, eventually returning it to Utah's desert on October 2023. This remarkable undertaking caps off the mission's goal of unraveling the secrets held within this ancient space rock, which dates back to the formation of the solar system, approximately 4.5 billion years ago.
The scientific community is abuzz with excitement as preliminary analyses of the Bennu samples have revealed a treasure trove of organic molecules and minerals, including amino acids, sodium-rich salts, and nitrogen compounds like ammonia. Tim McCoy of the Smithsonian Institution, one of the study's lead authors, emphasized the importance of these findings by stating, "That's the kind of environment [in which] the steps leading from elements to life could have occurred."
Several teams analyzed the Bennu samples, publishing their results in reputable journals like Nature and Nature Astronomy. The findings highlight the presence of 14 out of the 20 amino acids used by life on Earth, along with five nucleobases, the fundamental building blocks of genetic materials such as DNA. These results are significant because they suggest conditions favorable for life were likely widespread across the early solar system.
“What we’re seeing is not just evidence of amino acids, but also different types of chemicals involved in forming life as we know it,” said Nicky Fox, head of NASA’s Science Mission Directorate. Intriguing aspects of the samples include the unexpectedly high concentration of ammonia — 100 times greater than found in soils on Earth — which also plays a key role as a life-building element.
Another stunning observation from the analysis was the racemic mixture of amino acids. These samples display equal amounts of left- and right-handed chirality, contrasting with Earth's life forms, which predominantly exhibit left-handed chirality. Danny Glavin of NASA's Goddard Space Flight Center expressed disappointment at this find, saying it seemed to invalidate 20 years of expectations but acknowledged the value of exploration for unexpected results.
The pristine nature of the Bennu samples has been pivotal in affirming their integrity. Unlike materials retrieved from meteorites, which undergo significant alteration upon atmospheric entry, the samples from Bennu remain untainted. Jamie Grunfeld from the Smithsonian noted, “This discovery was only possible by analyzing samples collected directly from the asteroid.”
These revelations have heightened interest among planetary scientists who are eager to explore other celestial bodies. The data gathered not only illuminates the nature of Bennu but fuels discussions about future missions to study other asteroids, such as the dwarf planet Ceres, which may contain substantial amounts of water.
While scientific techniques continue to evolve, NASA is reserving 70 percent of the Bennu samples for future analysis. Some portions are even set aside for study using technologies not yet developed. Dante Lauretta, the mission's chief scientist, explained the importance of this strategy: “The beauty of asteroid sample return missions like this is the ability to study them with new instruments over time.”
Simultaneously, planetary defense remains at the forefront of NASA's focus due to concerns about asteroids posing threats to Earth. Recent reports highlighted the discovery of asteroid 2024 YR4, which has been noted for its potential to collide with our planet. Currently, there is about a one percent chance of impact, with planetary defense experts closely monitoring the situation to gather more observations.
Lindley Johnson, NASA Planetary Defense Officer Emeritus, remarked on the seriousness of the threat posed by Near Earth Objects (NEOs) like 2024 YR4, citing historical impacts like the one responsible for the extinction of the dinosaurs. “An impact on Earth definitely has the potential for massive ramifications,” he stated, underscoring the dual nature of asteroids as both fascinating scientific targets and potential hazards.
Looking forward, researchers are invigorated by the wealth of data from Bennu and will continue to analyze these materials to unravel the history of our solar system and the origins of life. McCoy posed the compelling question, "Are we alone?" as he reflected on the broader significance of the discoveries and the continued quest of science to understand life's beginnings.