Surface features of Asteroid Ryugu. Jaumann et al (Science (2019).

“Uncontaminated Extraterrestrial Materials” Revealed in Ancient Asteroid Sample

Samples recovered from the surface of the potentially hazardous asteroid Ryugu contain never-before-seen features. Scientists are saying that the materials they have analyzed are "the most uncontaminated and unfractionated extraterrestrial materials studied so far."

In an important study, researchers report that pebbles taken from an ancient asteroid by a Japanese spacecraft contain crucial clues about how the solar system evolved and how life originated on Earth. They are the most uncontaminated and unfractionated extraterrestrial materials studied so far.

Japanese Hayabusa2 collected the pristine samples during two maneuvers in 2019 that involved shooting projectiles into Ryugu, a half-mile-wide asteroid that may pose a threat to Earth. In 2020, the spacecraft transported back to Earth five grams of surface and subsurface particles from the asteroid.

A study published in Nature Astronomy reveals the “precious alien samples” were “unquestionably among the most uncontaminated Solar System materials available for laboratory study” and provided the best proxy for the bulk composition of the Solar System.” The researcher was headed by Motoo Ito, a cosmochemist at the Japan Agency for Marine-Earth Science Technology.

Kochi’s Phase2 curation team is led by Ito, a team of scientists responsible for analyzing samples with advanced techniques while minimizing exposure to Earth-based terrestrial substances that could contaminate otherworldly materials.

Scientists fould building blocks of life in the soil samples from Ryugu asteroid. Credit: JAXA
Scientists fould building blocks of life in the soil samples from Ryugu asteroid. Credit: JAXA

A new study has now verified that all these precautions paid off, reporting incredible details in the particles, including characteristics that have never been observed before in any other asteroid sample.

Following Japan’s original Hayabusa mission in 2010, which returned grains from the asteroid Itokawa to Earth, Hayabusa2 is the second mission to collect samples from an asteroid and return them to Earth. At least 60 grams of surface samples will be returned by NASA’s OSIRIS-REx spacecraft from asteroid Bennu, another potentially hazardous rock.

Asteroid chunks were originally obtained only from meteorites that randomly fell to Earth prior to these sample-return missions.

Asteroids have been better understood by meteoric material, but these small pieces of space rock become weathered and contaminated by Earth’s atmosphere. Moreover, meteorites are composed of strong rocks that can survive the trip to the ground.

Hayabusa2 landed two times on asteroid Ryugu in 2019 to collect samples and now has returned to Earth successfully. Credit: JAXA
Hayabusa2 landed two times on asteroid Ryugu in 2019 to collect samples and now has returned to Earth successfully. Credit: JAXA

On the other hand, asteroid return missions offer a more direct view of such relics, which are remarkably unchanged since the solar system was born 4.5 billion years ago. Ryugu particles, which are the most uncontaminated samples returned thus far, provide a wealth of new insights and surprises.

As a result, Ito and his colleagues report that observations of Ryugu from orbit suggest that it belongs to a dehydrated rock group called CY-chondrites, whereas actual samples indicate that the rock contains water and is similar to a chemically pristine group that scientists refer to as CI-chondrite.

Ito told Vice that space weather could explain the discrepancy between onboard spectral observations and actual material analysis. There are only a few layers in an asteroid that can be seen with a spectral observation so it may complicate their analysis of the data,”

Future samples may also provide insight into a specific class of carbon-rich organic molecules found inside the Ryugu particles, which haven’t been detected in any other meteorite study yet, Ito asserted.

A picture of Ryugu taken by the station immediately after turning on the engines. Credit: JAXA
A picture of Ryugu taken by the station immediately after turning on the engines. Credit: JAXA

The molecular particles are trapped inside sub-millimeter minerals called phyllosilicates, which may have been in contact with water as well.

Asteroids are believed to have enriched early Earth with water and organic molecules, which are key to life. Thus, these pristine Ryugu particles can provide new insights into our planet’s habitability origins.

Ito explained that coarse-grained phyllosilicates containing organic molecules and water (OH) on primitive asteroids may have served as cradles for organic molecules and water before possibly contributing to the delivery of water and organic material to Earth during the early stages of evolution.

Due to this, Ito is committed to continuing his investigations of organics through the end of next year with the help of colleagues from the Open University and IonToF.

In combination with future sample-return missions to other comets and asteroids, these efforts can reveal the secrets of the early solar system and explain how Earth became so rich in life-sustaining materials.


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Written by Ivan Petricevic

I've been writing passionately about ancient civilizations, history, alien life, and various other subjects for more than eight years. You may have seen me appear on Discovery Channel's What On Earth series, History Channel's Ancient Aliens, and Gaia's Ancient Civilizations among others.

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