We Finally Have The First-Ever Analysis of Stardust Retrieved From The Ryugu Asteroid

Cortez Deacetis

It truly is been above a calendar year because the Hayabusa2 probe delivered its precious cargo of dust from an alien place rock, and we’re eventually finding a far more in-depth glimpse of what will make up asteroid Ryugu.


In two papers published today, global teams of researchers have discovered that, in accordance with analyses carried out by the probe although at the asteroid, Ryugu is incredibly darkish, pretty porous, and some of the most primitive Photo voltaic Method product we have ever experienced access to in this article on Earth.

Whilst not unforeseen, the benefits are really awesome. Given that the asteroid has remained far more or less unchanged due to the fact the development of the Photo voltaic Technique 4.5 billion many years back, the sample is a single of our best instruments yet for being familiar with the composition of the dust from which the interior Solar Program objects coalesced.

“The Hayabusa2 returned samples … show up to be among the most primordial materials obtainable in our laboratories,” wrote just one of the groups in their paper. “The samples constitute a uniquely precious selection, which may possibly contribute to revisiting the paradigms of Solar Program origin and evolution.”

Asteroid Ryugu, formerly known as 1999 JU3, is only the next asteroid from which a sample return mission has been executed. The first was Itokawa, whose sample return system failed, ensuing in only a minute volume of dust eventually reaching Earth in 2010.


Ryugu is about a kilometer (.62 miles) across, with a ridge all over its equator it travels an elliptical orbit that carries it just within Earth’s orbital route close to the Solar, then out pretty much as far as Mars’s orbit. The mission to get to the asteroid, touch down on it twice, then return any dust retrieved to Earth took a deeply extraordinary degree of skill and arranging.

But it labored, and 5.4 grams of precious asteroid dust ended up returned and duly analyzed, while Hayabusa2 sailed off for a sequence of rendezvous with other asteroids above the coming many years.

SixRoundVialsWithBlackRocksRyugu samples returned by the Hayabusa2 probe. (Yada et. al., Nat. Astron., 2021)

Dependent on remote sensing and on-asteroid measurements, we by now know Ryugu is what we simply call a C-type asteroid, the most popular type of asteroid in the Solar System. These rocks are prosperous in carbon, which makes them extremely dim they also have lots of unstable elements. 

In the initially paper, led by astronomer Toru Yada of the Japan Aerospace Exploration Company (JAXA), an examination of a Ryugu sample reveals that the asteroid is particularly dark. Usually, C-kind asteroids have an albedo (that is the measure of how a lot solar radiation a system displays) of .03 to .09. Asphalt has an albedo of .04. Ryugu’s albedo is .02. That means it displays just 2 p.c of the solar radiation that hits it.


The asteroid is also, the researchers identified, really porous. According to their measurements, Ryugu has a porosity of 46 p.c. That is extra porous than any carbonaceous meteorite we have ever had the option to research, though we have noticed much more porous asteroids. This is constant with the asteroid’s porosity as calculated by remote thermal imaging, and measurements performed on the asteroid by itself.

In the next paper, a team led by astronomer Cédric Pilorget of the Université Paris-Saclay in France analyzed the composition of the dust. They detected that the asteroid looks to consist of an particularly darkish matrix, potentially dominated by phyllosilicates, or clay-like minerals, even though there was a lack of a obvious hydration signature.

In this matrix, they identified inclusions of other minerals, these types of as carbonates, iron, and unstable compounds.

Both equally of these papers concur that, in porosity and composition, Ryugu appears to be most equivalent to a kind of meteorite classed as “CI chondrites”. That indicates the meteorite is carbonaceous, and related to the Ivuna meteorite. These meteorites have, in contrast to other meteorites, a composition extremely similar to that of the photo voltaic photosphere, suggesting they are the most primitive of all identified house rocks.

Additional in-depth analyses will no question be on the way to attempt to explore much more – not just about Ryugu, but what our Solar Method was like as it was forming from the Sun’s leftover dust.

“Our original observations in the laboratory for the whole established of returned samples display that Hayabusa2 retrieved a agent and unprocessed (albeit somewhat fragmented) sample from Ryugu,” Yada’s team wrote in their paper.

“Our details help and increase distant-sensing observations that suggested that Ryugu is dominated by hydrous carbonaceous chondrite-like resources, identical to CI chondrites, but with a darker, more porous and far more fragile character. This inference really should be additional corroborated by in-depth investigations hereafter by point out-of-the-art analytical techniques with increased resolution and precision.”

The two papers have been published in Nature Astronomy. They can be identified listed here and listed here.


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