The study provides new insights into the surface and structure of asteroid Bennu

SwRI-led study provides new insights into the surface, and structure of asteroid Bennu

A research led by SwRI discovered that the regolith of asteroid Bennu is principally free rubble. Photographs taken earlier than and after contact and launch pattern assortment point out floor disturbances of as much as 15 inches. Credit score: NASA/Goddard/College of Arizona

When NASA’s OSIRIS-REx spacecraft collected floor samples from asteroid Bennu in 2020, the forces measured through the interplay supplied scientists with a first-hand check of the poorly understood near-surface bodily properties of cumulus asteroids. Now, a research led by the Southwest Analysis Institute describes the layer beneath the asteroid’s floor as consisting of poorly bonded rock fragments that comprise twice the void space as the general asteroid.

“The low gravity Dr Kevin Walsh of SwRI, lead creator of a paper on this analysis printed within the journal, mentioned: science progress. “We conclude that the low-density, poorly bonded subsurface layer should be a world property of Bennu, not simply native to the focus.”

It’s acceptable to name it a “pile of rubble.” asteroidBennu is a globular assortment of rock and particles fragments 1,700 ft in diameter interconnected by gravity. It’s believed to have fashioned after the impression of a bigger physique of the asteroid belt. The boulders are scattered throughout its closely cratered floor, suggesting that it has had a tough and uneven existence because it liberated From a a lot bigger asteroid a number of million or billion years in the past.






The native floor of Bennu earlier than and after sampling. Flashing between the earlier than and after sampling photos highlights adjustments to the floor, together with the rock apparently fired 12 meters away. Credit score: NASA/Goddard/College of Arizona

The target of the OSIRIS-REx (Origins, Spectral Interpretation, Useful resource Identification, and Safety – Regolith Explorer) mission is to gather and return at the least 60 grams of floor materials from Bennu and ship it to Earth in 2023. Extra sampling actions have been supplied for concepts.

In keeping with Walsh, researchers concerned within the OSIRIS-REx mission thus far have measured Bennu’s thermal and crater properties to estimate the power and porosity of the discrete particles of the asteroids that make up the rubble pile. The set of particles (or regolith) on the floor of an asteroid that instantly management and affect long-term evolution has not been examined but.

Earlier than, throughout, and after the sampling occasion, the OSIRIS-REx Digicam Suite’s Pattern Acquisition Verification Digicam (SamCam) captured photos trying on the robotic arm of the Pattern Acquisition Mechanism (Contact-and-Go) (TAGSAM).

SwRI-led study provides new insights into the surface, and structure of asteroid Bennu

A research led by SwRI discovered that the dominant rocky parts of the floor asteroid Bennu are weakly certain, and present near-zero cohesion, presumably as a result of dimension and low gravity of the small physique. Credit score: NASA/Goddard/College of Arizona

“The SamCam photos in parentheses for the time being of contact present that the contact precipitated a big disturbance on the pattern website,” mentioned Dr. Ron Blose, co-author from the Johns Hopkins College Utilized Physics Laboratory. “Nearly each seen particle is moved or redirected in any respect factors alongside the perimeter of TAGSAM, as much as a radius of 15 inches.”

SamCam photos confirmed that the downward power of TAGSAM lifted a rock roughly 16 inches in dimension. Though robust sufficient to resist breaking, the rock was reoriented and small particles emerged from its floor. The motion of those millimeter-sized particles beneath comparatively weak forces signifies minimal cohesive bonding with the floor of the bigger rock.

SwRI-led study provides new insights into the surface, and structure of asteroid Bennu

A latest research led by SwRI supplied new insights into the floor and construction of asteroid Bennu. Information from NASA’s OSIRIS-REx spacecraft point out twice the empty area close to its floor in comparison with the general physique. Credit score: NASA/Goddard/College of Arizona

Scientists hypothesized that the typical dimension of the regolith particles will increase as the scale of the asteroid decreases, as a result of bigger objects retain smaller materials because of greater floor gravity. The group then in contrast Benno and asteroids resembling a rubble pile.

“We detected a break up between the tough, rock-covered surfaces of Bennu and Ryugu versus Itokawa, which incorporates swimming pools of smaller particles throughout 20% of its floor,” Walsh mentioned. “This might have a number of explanations, together with that the close to floor of the latter has been compressed sufficient to thwart these microparticles seeping inward or maybe the granular sediments are subsurface layers revealed by latest disruptive reorganization of the physique.”

The study provides new insights into the surface and structure of asteroid Bennu

Photographs instantly earlier than and after contact with Bennu present that in about one second that elapsed, the sampling head disturbed an space roughly 3 ft huge and threw particles into the air. Benno supplied minimal resistance to the pattern head being compressed into the asteroid, which will be seen partially from the large-scale turbulence attributable to the contact, and this knowledge helped conclude that the asteroid’s higher layers had been very frivolously filled with massive empty areas. The yellow envelope reveals the actual turbulent area within the post-contact picture, and the picture on the backside proper reveals shadows on the fringe of the sampler head and raised particles that each helped infer floor properties. Credit score: NASA/Goddard/College of Arizona

Companion paper within the journal Sciences, co-authored by Walsh, marked the 30-foot-long elliptical crater drilled by the TAGSAM arm when the pattern was collected. The occasion crowded rock and mud right into a plume of particles, exposing materials that was darker, redder, and extra plentiful in fantastic particles than the unique Floor. The majority density of the displaced subterranean matter is about half that of the asteroid as a complete.


NASA spacecraft screens asteroid rock Bennu “physique armor”


extra data:
Kevin J. Walsh et al, Close to-zero coherence and free packing of Bennu close to the Earth’s inside revealed by spacecraft contact, science progress (2022). DOI: 10.1126 / sciadv.abm6229

DS Lauretta et al, Spacecraft pattern assortment and subsurface drilling of the asteroid (101955) Bennu, Sciences (2022). DOI: 10.1126 / science.abm1018

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