Original title: OSIRIS-REx Returned a Pristine Sample of Asteroid Bennu: Takeaways from the Mission's Contamination Control and Knowledge Program
Jason P. Dworkin, Scott A. Sandford, Nicole G. Lunning, Kevin Righter +80 · September 2026
When spacecraft collect samples from space, foreign dust or Earth materials can taint them. NASA sent the OSIRIS-REx mission to bring back a pristineTotally free of any material from Earth or the spacecraft. sample from asteroid Bennu, meaning it had no foreign materials that could disrupt measurements. Scientists investigated suspected contaminants found on the returned regolithLoose rock and dust on the surface of an asteroid or planet., which is loose surface rock. They checked whether foreign materials came from the spacecraft, curation, or test labs. They found most suspected contaminants were not from the spacecraft or curation. Some entered during lab testing, while items like phosphate and sodium fluoride actually came from Bennu itself. Overall, the returned sample meets the pristine standard, except for an isolated 1.24% by mass that escaped its container and collected spacecraft particles.
You spend hours making a perfect chocolate cake from scratch, careful not to mix in any other ingredients. Then when you serve it, a single slice drops onto the counter and picks up some crumbs from earlier baking. Here, the cake is the asteroid sample, the counter crumbs represent spacecraft particulates, and the dropped slice is the 1.24% that escaped the sample container.
Future missions to return samples from other worlds can learn from OSIRIS-REx's contamination tracking. This study shows that careful checking prevents false discoveries and ensures the sample's scientific value. Procedural blanks and sharing samples across labs are key to avoiding contamination.
The abstract only documents contaminants encountered during this mission's analysis phase, not all possible contamination sources. It does not establish the long-term stability of sample purity. The findings are specific to the OSIRIS-REx mission and may not generalize to other sample types or spacecraft designs.
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OSIRIS-REx Returned a Pristine Sample of Asteroid Bennu: Takeaways from the Mission's Contamination Control and Knowledge Program — Jason P. Dworkin, Scott A. Sandford, Nicole G. Lunning et al.
Abstract licence: CC0
Explanation generated by Synthesis from the abstract — it is not the original paper. This is a preprint, so it hasn't necessarily been peer reviewed.