These X-ray computed tomography (XCT) scans released on March 17, 2026, give us a glimpse inside asteroid Bennu. They show the most common types of crack networks observed in Bennu samples; these networks solved a mystery that baffled NASA for years.
When NASA’s OSIRIS-REx spacecraft first approached asteroid Bennu in 2018, scientists expected to see smooth, sandy beach-like surfaces. Instead, they found a celestial body covered in boulders. Observations made in 2007 by NASA’s Spitzer Space Telescope measured low thermal inertia, indicative of an asteroid whose surface heats up and cools down rapidly as it rotates into and out of sunlight, like a sandy beach on Earth. This was at odds with the many large boulders that OSIRIS-REx found upon arrival, which should act more like blocks of concrete, shedding heat long after the Sun has set.
Data collected by the OSIRIS-REx spacecraft during its survey campaign at the asteroid suggested a possible explanation: the boulders could be much more porous than expected. Once the samples were delivered to Earth, researchers were able to investigate this further.
Asteroid Bennu’s Rugged Surface Baffled NASA, We Finally Know Why
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Asteroid Bennu’s Rugged Surface Baffled NASA, We Finally Know Why
These are X-ray computed tomography (XCT) scans of particles from asteroid Bennu. They show the most common types of crack networks observed in Bennu samples.
Credits: NASA/Scott Eckley
In one of the biggest surprises of NASA’s OSIRIS-REx mission, its target asteroid, Bennu, turned out to be a jagged, rugged world covered in large boulders, with few of the smooth patches that earlier observations from Earth-based instruments had indicated.
“When OSIRIS-REx got to Bennu in 2018, we were surprised by what we saw,” said Andrew Ryan, a scientist with the University of Arizona’s Lunar and Planetary Laboratory in Tucson, who led the mission’s sample physical and thermal analysis working group. “We expected some boulders, but we anticipated at least some large regions with smoother, finer regolith that would be easy to collect. Instead, it looked like it was all boulders, and we were scratching our heads for a while.”
Particularly puzzling were observations made in 2007 by NASA’s Spitzer Space Telescope, which measured low thermal inertia, indicative of an asteroid whose surface heats up and cools down rapidly as it rotates into and out of sunlight, like a sandy beach on Earth. This was at odds with the many large boulders that OSIRIS-REx found upon arrival, which should act more like blocks of concrete, shedding heat long after the Sun has set.
Data collected by the OSIRIS-REx spacecraft during its survey campaign at the asteroid suggested a possible explanation: the boulders could be much more porous than expected. Once the samples were delivered to Earth, researchers were able to investigate this further.
Scott Eckley, X-ray scientist within NASA Johnson Space Center’s Astromaterials Research and Exploration Science (ARES), demonstrates the process for placing a container holding a piece of asteroid material in an X-ray Computed Tomography (XCT) machine. XCT scans let researchers image particles through airtight containers and visualize a rock’s shape and internal structure without damaging the sample. Credits: NASA/Robert Markowitz
Ryan’s team scrutinized rock particles collected from Bennu’s surface using a variety of laboratory analysis techniques. In a study published in Nature Communications the authors reported that the boulders are indeed porous enough to account for some of the observed heat loss, but not all of it. Rather, many of the rocks turned out to be riddled with extensive networks of cracks.
To test whether the cracks could be the reason for the asteroid’s surface losing heat, a team at Nagoya University in Japan analyzed Bennu sample material using lock-in thermography. This laser-based technique allows researchers to hit a tiny spot on the surface of the sample and measure how the heat diffuses through it, similar to how ripples move across a pond.
“That’s when things became really interesting,” Ryan said. “The thermal inertia measured in the lab samples turned out to be much higher than what the spacecraft’s instruments had recorded, echoing similar findings obtained by the team of OSIRIS-REx’s partner mission, JAXA’s (Japan Aerospace Exploration Agency) Hayabusa-2.”
To make meaningful predictions about how the material would behave in the large boulders on the asteroid, the team had to find a way to scale up the measurements obtained with the small sample particles.
Using a glove box, team members at NASA’s Johnson Space Center in Houston sealed sample particles in air-tight containers under a protective nitrogen atmosphere, then transferred them to a lab where they could perform X-ray computed tomography, or XCT scans. Once a particle was scanned, it went back into the glove box.
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These are X-ray computed tomography (XCT) scans of particles from asteroid Bennu. They show the most common types of crack networks observed in Bennu samples. One has an extensive and connect framework of curved cracks, whereas the other has sparse, straight, and flat fractures.
These are X-ray computed tomography (XCT) scans of particles from asteroid Bennu. They show the most common types of crack networks observed in Bennu samples. One has an extensive and connect framework of curved cracks, whereas the other has sparse, straight, and flat fractures.
These are X-ray computed tomography (XCT) scans of particles from asteroid Bennu. They show the most common types of crack networks observed in Bennu samples. One has an extensive and connect framework of curved cracks, whereas the other has sparse, straight, and flat fractures.
These are X-ray computed tomography (XCT) scans of particles from asteroid Bennu. They show the most common types of crack networks observed in Bennu samples. One has an extensive and connect framework of curved cracks, whereas the other has sparse, straight, and flat fractures.
Exterior
Interior
exteriod and interior
X-ray Computed Tomography (XCT) scans of two asteroid Bennu particles
These are X-ray computed tomography (XCT) scans of particles from asteroid Bennu. They show the most common types of crack networks observed in Bennu samples. One has an extensive and connect framework of curved cracks, whereas the other has sparse, straight, and flat fractures.
“The sample goes into its own ‘spacesuit,’ gets a CT scan, and then comes back to its pristine environment, all without having any exposure to the terrestrial environment,” said Nicole Lunning, lead OSIRIS-REx sample curator within the Astromaterials Research and Exploration Science division at NASA Johnson and one of the study’s co-authors. “We can image right through these airtight containers to visualize the shape and internal structure of the rock that’s inside.”
“X-ray computed tomography allows us to look at the inside of an object in three dimensions, without damaging it,” said study co-author and NASA Johnson X-ray scientist Scott Eckley.
It turns out that they’re really cracked too, and that was the missing piece of the puzzle.”
Andrew Ryan
Scientist at University of Arizona’s Lunar and Planetary Laboratory
Once mapped in this way, a permanent 3-dimensional digital archive of a sample particle’s shape and interior is created, and the data are entered into a public database. Ryan’s team used the X-ray CT scan data for computer simulations modeling heat flow and thermal inertia. When scaled up to boulder size, the thermal inertia results fell into agreement with what the spacecraft had measured at the asteroid.
Where scientists once expected the boulders of Bennu to be extremely porous and fluffy, perhaps even spongy, the sample analysis revealed something unexpected.
“It turns out that they’re really cracked too, and that was the missing piece of the puzzle,” Ryan said.
Ron Ballouz, a scientist with the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, and the paper’s second author, said this work transforms how scientists interpret the structure of an asteroid based on its thermal properties seen from Earth.
“We can finally ground our understanding of telescope observations of the thermal properties of an asteroid through analyzing these samples from that very same asteroid,” Ballouz said.
NASA’s Goddard Space Flight Center provided overall mission management, systems engineering, and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator. The university leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space in Littleton, Colorado, built the spacecraft and provided flight operations. Goddard and KinetX Aerospace were responsible for navigating the OSIRIS-REx spacecraft. Curation for OSIRIS-REx takes place at NASA’s Johnson Space Center in Houston. International partnerships on this mission include the OSIRIS-REx Laser Altimeter instrument from CSA (Canadian Space Agency) and asteroid sample science collaboration with JAXA’s (Japan Aerospace Exploration Agency’s) Hayabusa2 mission. OSIRIS-REx is the third mission in NASA’s New Frontiers Program, managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington.
By Daniel Stolte University of Arizona
For more information on the OSIRIS-REx mission, visit:
Hail Yeah! NASA Researchers Use Volunteer Observations for Hail Estimates
The bigger the hailstone, the more damage it can cause. But scientists find that predicting hailstone size can be challenging. How quickly does hail melt as it falls?
Now, you can help tackle this question by joining the SouthEAst REgion CoCoRaHS Hail (SEaRCH) project. This network of backyard weather observers includes volunteers of all ages and backgrounds who work together to measure and report hail in their local communities. SEaRCH is also part of the NASA, National Oceanic and Atmospheric Association (NOAA), and National Science Foundationsupported Community Collaborative Rain, Hail, and Snow (CoCoRaHS) network, whose amateur weather sleuths report rain and snow.. These rain and snow observations are helping scientists better understand local variation in precipitation. CoCoRaHS data is regularly used by the National Weather Service, the Hydrologic Prediction Center, the U.S. Department of Agriculture, the National Drought Mitigation Center, broadcast meteorologists, research scientists, and more.
“I love the project, and I love being able to contribute meaningful data,” says Jeremy Kichler, a CoCoRaHS volunteer.
On June 14, 2023, Kichler witnessed a storm with hailstones ranging from 0.5 inches (12 mm) to two inches (51 mm) in diameter. The hailstones dented cars, damaged roof shingles, and shredded leaves across his neighborhood. After the storm, he submitted a CoCoRaHS hail report to notify the National Weather Service with photos and additional details about the hail.
NASA scientists are now using hail reports from volunteers like Kichler alongside archived satellite overpass data and newly developed hail melt profiles to model how hailstones of different sizes melt, once they fall below the freezing level.
To join volunteers like Jeremy Kichler and make hail reports of your own, all you need is your smartphone and the free CoCoRaHS mobile app. To make rain and snow reports, you’ll need a specific manual gauge approved by the National Weather Service. Find everything you need to get started in the CoCoRaHS and SEaRCH summary on the NASA Citizen Science website.) and the National Science Foundation.
CoCoRaHS hail photo submitted by volunteer Jeremy Kichler displaying a hand holding three large and uniquely shaped hailstones.
Credit Jeremy Kichler and CoCoRaHS
Map displaying data from the Special Sensor Microwave Imager/Sounder (SSMIS) satellite. Colors represent the probability of hail being detected (highest probability is dark red, least probability is light grey). Light blue, gray and light green pixels in the image indicate a storm over southern Georgia likely to contain hail. The black dot indicates the location of the hail reported to CoCoRaHS by Jeremy Kichler. The label “plus 10 min” indicates the satellite overpass occurred ten minutes before Jeremy’s observation of hail.
Data from the Special Sensor Microwave Imager/Sounder (SSMIS). Image processing by Sarah Bang.
Though Ireland is known for the many shades of green that grace its grassy pastoral landscapes, there’s one corner of the Emerald Isle where gray reigns supreme. In the Burren region, on the island’s west coast, what geologists describe as limestone pavement covers much of the rocky, treeless landscape.
The OLI (Operational Land Imager) on Landsat 8 captured this view of the Burren on May 16, 2025. The fossil-rich limestone that makes up the gray outcrops was deposited about 325 million years ago during the Carboniferous Period, when what is now Ireland lay near the equator beneath warm, shallow seas. Although the limestone was initially deposited in flat, horizontal layers on the seafloor, it later buckled into gentle arch- and trough-shaped folds as tectonic plates collided during a mountain-building episode known as the Variscan Orogeny.
These folds in the tilted rock layers and differences in their rate of erosion produced the terraced appearance that defines the Burren’s hills, with more erosion-resistant layers of rock persisting as ledges. Glacial activity also played a role in sculpting the landscape, scraping away soil and sediment to expose the limestone pavement and smoothing the region’s hills.
May 16, 2025
Limestone is prone to chemical weathering that produces an irregular terrain known as karst, pockmarked with sinkholes, caves, and fissures called grikes. Many grikes in the Burren collect soil and have become footholds where vegetation grows in the otherwise rocky landscape.
Individual grikes are too small to see in Landsat imagery, but networks of them have aligned along the rock layers, contributing to the concentric vegetation patterns visible in the image. Among the plants that you might find growing in them is the shamrock, the three-leaved clover that has become a symbol of Ireland.
With some luck, Trifolium dubium or Trifolium repens may even be found amidst the shamrock-shaped contours of Moneen Mountain, a 262-meter (860-foot) limestone hill visible in the image above. While there’s hardly consensus about what species is the true inspiration for shamrocks, these two clover species were among the favorites when Irish botanists were surveyed about the topic in the 1880s, according to the Carnegie Museum of Natural History.
NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological Survey.Story by Adam Voiland.
NASA Invites Media to Learn About Upcoming X-59 Test Flights
As its team prepared for second flight, NASA’s X-59 quiet supersonic aircraft underwent engine run testing on Thursday, March 12, 2026, at NASA’s Armstrong Flight Research Center in Edwards, California.
Credit: NASA
NASA will hold a media teleconference at 5:30 p.m. EDT on Thursday, March 19 to highlight plans for its X-59 quiet supersonic aircraft’s upcoming flight tests. The teleconference is set to take place after the X-59 is scheduled to complete its second flight, in California.
For the media call, NASA leadership will join representatives from the Quesst mission and contractor Lockheed Martin Skunk Works. The X-59’s test pilots will be available to answer questions about what it’s like to fly the aircraft and how they prepare for flights.
The news conference will stream on NASA’s YouTube channel. An instant replay will be available online. Learn how to watch NASA content on a variety of platforms, including social media.
Participants include:
Amit Kshatriya, NASA associate administrator
Cathy Bahm, project manager, Low Boom Flight Demonstrator, NASA’s Armstrong Flight Research Center, Edwards, California
Peter Coen, Quesst mission integration manager, NASA’s Langley Research Center, Hampton, Virginia
For second flight, the X-59 will taxi from its hangar at NASA Armstrong, then take off and land at nearby Edwards Air Force Base. The aircraft will fly for roughly an hour, reaching a cruising speed of 230 mph at 12,000 feet before accelerating to 260 mph at 20,000 feet.
This flight will kick off a series of flights known as envelope expansion, during which NASA will gradually take the X-59 faster and higher to ensure the aircraft’s safety and assess its performance. This phase will be followed by flights assessing the X-59’s unique acoustic profile. The X-59 is the centerpiece of NASA’s Quesst mission and was developed to fly supersonic, or faster than the speed of sound, without generating loud sonic booms.
Through Quesst, NASA is working to make commercial supersonic flight over land possible, dramatically reducing travel time in the United States or anywhere in the world.
