In 2020, the Hayabusa2 spaceship of the Japan Aerospace Exploration Agency (Jaxa) completed its main mission when rehearsals from asteroid Ryugu returned to Earth. In 2023, NASA’s Osiris-Rex also ended its main task by returning samples from asteroid Bennu to Earth. Scientists in laboratories around the world have examined these rehearsals and uncovered some surprises.
The Ryugu sample contained Uracil, one of the four RNA nucleotides that are essential for life as we understand it. This discovery shows that asteroids could have played a role in providing raw materials for life on earth. The Bennu test contained its own surprise. It contained unexpected phosphate compounds that pointed out that it is a splinter of a small, old body with an ocean.
These results show how complex asteroids can be and that they are more than just space rock pieces.
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Asteroids are the fragments of collisions in which planetics are involved. Each is a piece of the puzzle that can help the astronomers uncover the history of our solar system. One of the most important aspirations in asteroid and solar system science is determination of which asteroids have announced the same parent, which can help to illuminate the overall history of the solar system.
New research in the Planetary Science Journal shows that Bennu and Ryugu came from the same parenthood. Research is “JWST spectroscopy of (142) Polana: Connection to Neas (101955) Bennu and (162173) Ryugu”, and the senior author is Dr. Anicia Arredondo from the Southwest Research Institute.
Both come from the Polana collision family in the main seasons girdle (MAB) between Mars and Jupiter. It took more than a laboratory study of the rehearsals to confirm them. The JWST also played an important role by receiving both medium infrared and infected infrared spectra from both asteroids.
“We present JWST near the infrared spectrographer and the mid-infrared instrument spectroscopy of the overarching body of the family (142) Polana and compare with space vehicles and laboratory data from both near-earth seeds,” the authors write. “Spectral features in similar wavelengths in the spectra of Polana and those of Bennu and Ryugu support the hypothesis that both asteroids come from the Polana family.”
This illustration shows the hydrogen content of asteroids, which are determined by various techniques in other research. The polan results are added from this study. Shaded regions show the area of H WT % for carbon -containing chondrites. Polana is similar to Bennu and Ryugu and, in contrast to the CI and CM chondrites. Photo credits: Arredondo et al. 2025. PSJ.
“Very early in the formation of the solar system, we believe that large asteroids collided and broken into pieces to form an” asteroid family “with Polana as the largest remaining body,” said Lead author Arredondo in a press release. “Theories of this collision have not only created Polana, but also Bennu and Ryugu. In order to test this theory, we began to look at spectra of all three bodies and compare them. “
“They are similar enough that we are confident that all three asteroids could come from the same parent,” said Arredondo.
Polana is much larger than Ryugu and Bennu with a diameter of about 55 km. Bennu has only a diameter of around 500 meters and Ryugu has only a diameter of around 850 meters. Polana is very dark, with an albedo of only 0.045 and is a carbonaic asteroid of type F, a subgroup of the more common asteroid from the C type.
The researchers believe that Ryugu and Bennu were pushed out of their orbits near Polana after the collision that they have produced by Jupiter immense gravity. As a result, the two smaller asteroids were changed by their closer proximity to the sun.
“Polana, Bennu and Ryugu all had their own trips through our solar system since the effects they may have formed,” said Dr. Tracy Becker by SWRI, co-author of the paper. “Bennu and Ryugu are now much closer to the sun than Polana, so that their surfaces may be affected by solar radiation and sun particles.
There are some differences between the three, especially the depth and width of the 2.7 μm characteristic. This feature indicates hydrated minerals or water -containing minerals and tells scientists about the history of an asteroid of thermal and watery change. “The differences in the depth and width of the 2.7 μm feature are more pronounced between Polana and Ryugu than between Polana and Bennu. The cause of this difference is uncertain, but could possibly be due to the situation in early planetics or the effects of space loss,” the researchers write.
This figure compares NIRSPEC Polana data with Bennu and Ryugu data. There are differences around the 2.7 micrometer function, which are probably due to loss of space. Photo credits: Arredondo et al. 2025. PSJ.
“Polana may also be older than Bennu and Ryugu and would therefore be exposed to a micrometeoroid effects for longer,” added Becker. “This could also change aspects of its surface, including its composition.”
The differences could also be attributed to differences in the parent.
“The differences in the hydration between Bennu and Ryugu do not necessarily mean that they come from different parent bodies,” the authors explain. “Differences between Bennu and Ryugu in a similar size could be due to partial dehydration of the parent due to the internal warming. If Bennu came from surface material and Ryugu came from inner material, the influence of the parent body would generate different layers of compression that would have different macroporities and levels of hydration.”
In their conclusion, the authors state that despite the differences, they are confident that all three bodies share the same parent. “We find that similarities in the forms and strengths of many of the spectral features in the entire NIR and that, including the prominent OH feature at 2.72 μm, support the hypothesis that Bennu and Ryugu could have arisen in the new Polana family,” they write.
According to the authors, some regions of the spectra require further investigations to understand and explain.
“The analysis of the returned rehearsals of Bennu and Ryugu has continued, and future developments to understand the manifestry of the surface processes in NIR and me spectra will provide additional insights into the interpretation of our Polana spectrum,” they conclude.
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