Asteroid Anniversary: Looking Back on Johnson’s Year With Bennu Samples

It was a historic moment in U.S. space exploration when the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security – Regolith Explorer) sample return capsule landed in the Utah desert on September 24, 2023. Years in the making, the successful landing may have seemed like the mission’s conclusion, but it signaled the start of an exciting new phase for the curation and mission teams at NASA’s Johnson Space Center in Houston.

The unopened sample canister’s delivery to Johnson on September 25 kicked off the next phase of activities for the engineers, scientists, and processing and handling specialists who comprise the curation team. They worked diligently to disassemble the canister, extract the rock and dust collected from asteroid Bennu, and process and protect the precious sample.

“The OSIRIS-REx curation team’s work has been really exciting,” said Nicole Lunning, OSIRIS-REx curator. “They overcame many hurdles to reach, document, containerize, protect, and begin to distribute these valuable samples.”

One of those hurdles arose early in the team’s methodical disassembly of the sample canister. The bulk of the sample was held within the TAGSAM (Touch-and-Go Sample Acquisition Mechanism) head inside the canister. The TAGSAM head was on the end of a robotic arm that collected rocks and dust from asteroid Bennu’s surface in 2020.

While the team was pleasantly surprised to find an abundance of Bennu material outside of the TAGSAM head, their curation efforts paused when they discovered that two of the 35 fasteners on the TAGSAM head could not be removed with the tools that had been approved for use in the OSIRIS-REx glovebox.

That frustrating development had a silver lining, though.

“One of my favorite moments of the last year was in October 2023 when the curation team was able to scoop about 70 grams of sample out of the TAGSAM head, even though we were having difficulties disassembling this piece of hardware,” Lunning said. “This allowed us to see a lot of bulk sample for the first time – including the largest rock particle – as well as exceeding the 60-gram mission requirement for the returned sample mass.”

Lindsay Keller, OSIRIS-REx Contact Pad Working Group lead, said that was a standout experience for him, as well. “It was incredible seeing the dust all over the interior of the sample return canister and on the avionics deck and knowing that we had successfully sampled Bennu,” he said. “I had been waiting 20 years for that moment since I had first become involved with this incredible mission.”

The curation team worked to design, develop, and test new tools that enabled them to remove the problematic fasteners in January and begin retrieving the rest of the sample. All told, the team extracted over 120 grams of material from the sample canister – more than double the mission’s target amount. 

Another milestone occurred at the end of March, when the team released the first OSIRIS-REx sample catalog detailing the small rocks and dust that scientists around the globe can request for their research. It was the first opportunity for scientists outside of the curation and mission teams to see the Bennu samples in detail. It also kicked off the first round of sample requests, as international research teams began submitting their proposals for scientific analyses.

NASA’s international partners JAXA (Japan Aerospace Exploration Agency) and CSA (Canadian Space Agency) were among the recipients of those samples. A portion of the Bennu sample was permanently transferred to JAXA in August 2024 as part of an asteroid sample exchange. JAXA previously transferred to NASA a portion of the sample retrieved from asteroid Ryugu by its Hayabusa2 spacecraft.

In addition to their curation work, OSIRIS-REx team members conducted the very first analyses of the Bennu samples in the Astromaterials Research and Exploration Science Division’s (ARES) laboratories. Between the sample’s arrival at Johnson in September and mid-October, a ‘Quick Look Team’ comprised of Johnson civil servants and contractors and scientists from universities and museums led an intense effort to collect preliminary data and prepare images and information for release to the public. 

“Since then, we have been analyzing the samples using a coordinated approach where we do the least destructive analyses first and follow those up with more destructive analyses on the same samples – in this way we maximize the science return on these precious materials,” Keller explained. “We have been focusing on understanding the minerals and organic matter that make up the samples, their relationships, their chemical and isotopic compositions, and microstructures, and what these details tell us about the formation and evolution of asteroid Bennu.” Since Bennu is a remnant from the solar system’s tumultuous formation, scientists hope that studying its composition will provide insight into Earth’s own development. They also hope the sample will reveal whether asteroids like Bennu delivered water and other ingredients for life to our planet when they collided with Earth billions of years ago.

Adds Ann Nguyen, deputy lead of the OSIRIS-REx Sample Elements and Isotopes Working Group, “What’s great is that we have a whole suite of powerful, world-class instruments and expertise, all housed in one building. This makes it easier to get as much information out of these samples as possible. Some fragments we have been studying are just millimeter sized.” She said she takes pride in how the team has worked together. “While we each have our own expertise, scientific interests, and instruments that we operate, we are able to work well together to make the most of this phase of sample analysis. Our results are definitely stronger from this collaborative spirit.”

One of the team’s early analyses revealed the surprising presence of magnesium-sodium phosphate in the sample – a mineral not detected by the OSIRIS-REx spacecraft while at Bennu. The finding hints that the asteroid may have splintered off from a long-gone, tiny, primitive ocean world. Nguyen noted that much of the data and figures presented in this inaugural paper came from the labs at Johnson.

The OSIRIS-REx team looks forward to several important milestones in the next year. Keller expects a flurry of analyses to be shared with the scientific community before year end, noting that the team is currently preparing several manuscripts to appear in scientific literature. “We are also anxiously awaiting analyses of the samples from larger stones that were prepared here at Johnson and distributed to laboratories on four continents.” Results from team analyses will be presented at scientific conferences, as well, including the Lunar and Planetary Science Conference, and the annual Meteoritical Society meeting.

Next month, the team plans to release an updated sample catalog that will include additional documentation and data. The team will begin processing samples for and allocations to the broader scientific community in the coming months and will complete sample processing and allocations for the mission sample analysis team in 2025.

“I am incredibly proud of the OSIRIS-REx curation team’s resilience, determination, and problem-solving to keep the returned samples uncontaminated,” Lunning said. “We have achieved an extensively long list of milestones in the last year!”