Space and PhysicsAstronomy

Returned Samples From Ryugu Match Asteroid’s Surface And What Lies Beneath


Dr. Alfredo Carpineti

Senior Staff Writer & Space Correspondent

clockFeb 10 2022, 19:00 UTC
Image credit: ISAS/JAXA

Asteroid Ryugu in all its glory Image credit: ISAS/JAXA

In 2020, Japanese spacecraft Hayabusa2 collected and carried back to Earth five precious grams (0.2 ounces) of material from Asteroid Ryugu. Now, a new analysis has confirmed that what was brought back is truly representative of the asteroid as a whole.


The analysis, published in the journal Science, looked at the morphology of the grains of space soil from the surface and the subsurface collected by the spacecraft. These grains range from 1 millimeter (0.04 inches) to 1 centimeter (0.4 inches) and studying their shape can already tell us something important.

Are these samples collected from two small areas truly representative of the whole asteroid? Was the collection successful? The findings so far suggest the answers to these questions are a resounding yes. This preliminary discovery is intriguing and there is still so much science being done on them.

“We found that the return samples well represent Ryugu surface particles from a morphological point of view and that there are characteristic flat and elongated particles on the asteroid, which are also present in the returned sample. We also confirmed that the sampler system worked properly to collect and return 5 grams [0.2 ounces] of samples,” lead author Dr Shogo Tachibana, from The University of Tokyo and the Japan Aerospace Exploration Agency (JAXA), told IFLScience.

This initial analysis looked at the hundreds of tiny pebbles in the sample. They found many with cracks. The researchers think is too early to tell if the cracks are an indication that rocks break up on the asteroid due to thermal stress. Such an idea will be explored in future studies. The team is currently busy measuring the physical properties of the sample, among which is mechanical strength.

To collect subsurface material from Ryugu, Hayabusa2 shot a  2.5-kilogram (5.5-pound) copper projectile. The hit excavated a crater 10 meters (33 feet) in diameters, bringing to light pristine material. A few months later, when the dust, quite literally, settled and couldn’t harm the spacecraft any longer, Hayabusa2 flew down and scooped up some of the material.

Just by looking at the shape, researchers can’t see much difference between the material from the surface sample and the material from the subsurface sample. It is unclear if the characteristics will continue to match as more work is done on the two samples.

“Detailed analysis of sample is in progress, but we cannot distinguish subsurface sample from the surface sample only by appearance. So when you look at the grains by naked eyes, the surface and subsurface grains are likely to look similar,” Dr Tachibana told IFLScience.


The asteroid samples from both Hayabusa missions are helping humanity better understand these space rocks. Next year, we will also see the return of the sample collected by NASA’s OSIRIS-REx on asteroid Bennu.

Space and PhysicsAstronomy
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