NASA’s OSIRIS-REx spacecraft successfully returned samples from near-Earth asteroid Bennu in September 2022, and initial findings from analyzing the material have revealed some puzzling results.
Background on the OSIRIS-REx Mission and Bennu
The Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) launched in 2016 on a mission to visit asteroid Bennu, collect samples, and return them to Earth for analysis. Bennu was chosen because it is a primitive type of asteroid, almost 4.5 billion years old, and scientists hoped studying material from its surface could reveal insights into the early solar system.
In 2018, OSIRIS-REx arrived at Bennu after a two year journey. It spent over two years orbiting and studying the near-Earth asteroid, which is over 1,600 feet wide and has a slightly reddish tint. In 2020, the spacecraft briefly touched down and collected rubble and dust samples from Bennu’s surface before starting its return trip to Earth.
Key OSIRIS-REx Mission Details
| Launch Date | September 8, 2016 |
|---|---|
| Asteroid Arrival | December 3, 2018 |
| Sample Collection | October 20, 2020 |
| Sample Return to Earth | September 24, 2022 |
This material, gathered into a special return capsule, parachuted down over Utah on September 24, 2022. The pristine and uncontaminated samples from Bennu present a rare opportunity for planetary scientists to directly analyze material from the early solar system that may be similar to what formed Earth and other planets.
Initial Sample Analysis Reveals Puzzling Organic Compounds
The sample return capsule brought back about 4.4 pounds of fine sandy material from Bennu’s surface. It has taken scientists time to carefully handle and distribute particles of the precious cargo to different laboratories around the world for analyses using various techniques.
In early December 2023, some initial results were made public from a French lab that performed chemical and isotope analysis on a tiny grain sample from Bennu. They found water-bearing clay minerals and organic compounds containing oxygen and nitrogen atoms.
Quote from planetary scientist:
“We were surprised to find this very unusual organic matter that is rich in oxygen and nitrogen. We don’t fully understand where it came from and how it was formed. It is very different from the organic particles found in primitive meteorites.” – Dr. Laurette Piani, National Center for Scientific Research in Paris
This is surprising because such complex organic (carbon-based) material with so much oxygen has not been definitively found before in material originating from space and predating the planets.
While asteroids like Bennu contain simple amino acids and other organic compounds, the particular molecular structures with oxygen and nitrogen found in this sample were unexpected.
Theories Abound but Questions Remain on Odd Organic Material
There are many open questions and theories from scientists about where these unique organic molecules could have come from.
Some ideas proposed:
- Formed in interstellar space before Bennu formed
- Synthesized inside Bennu from liquid water interactions with rock
- Altered over time by solar radiation or other space weathering processes
Another quote from scientist:
“The make-up of this material is like nothing we’ve ever seen before. It will be incredible to study further and learn more about the conditions and processes in the early solar system that could have produced it” – Dr. Hannah Kaplan, Goddard Space Flight Center
Full understanding will require more research. But early analyses with advanced equipment have shown there is more to uncover about carbon chemistry in space, and possibly about the ingredients that sparked life itself.
What’s Next: More Samples to Analyze with Better Techniques
Additional carbon-rich asteroid samples will be sent to other laboratories over the next year for further analyses, including more precise isotope measurements.
The 4.4 pounds collected from Bennu is the largest sample return from space since the Apollo moon missions, but it is still a tiny fraction of the over 1 million pound asteroid. Future technological advances will allow improved study of these precious specks.
Next Planned Sample-Return Missions
| Mission | Target | Est. Date |
|---|---|---|
| JAXA’s Hayabusa-3 | Asteroid 1998 KY26 | 2031 |
| NASA’s Psyche | Psyche Asteroid | 2030 |
We have only begun to scratch the surface in investigating the building blocks left over from solar system formation. While this first look at material from asteroid Bennu has raised some puzzling questions, it serves as promising motivation for planning even more ambitious sample-return endeavors to asteroids and other destinations across the solar system.
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