Vestiges of the Early Solar System in Ryugu Asteroid

Samples returned to Earth from the asteroid Ryugu, analyzed in part at the Advanced Light Source (ALS), revealed that the building blocks of life formed 4.6 billions years ago in the extreme cold of space, followed by reaction with water.

The dark, coal-like organic matter in the carbonaceous asteroid could have contributed to the formation of habitable planetary environments.

In 2014, the Japan Aerospace Exploration Agency (JAXA) launched the Hayabusa2 spacecraft. Its mission: to collect and return samples from the near-Earth asteroid, Ryugu. Asteroids are excellent time capsules, preserving material sourced from the early solar system in pristine condition. With such samples, scientists aim to learn more about how extraterrestrial organic compounds were formed and modified, and whether this material could have eventually seeded life on Earth. Although meteorites can provide valuable information along these lines, they are subject to terrestrial weathering and other contamination from a planet teeming with life.

Hayabusa2 returned to Earth in 2020 to drop off a capsule containing about 5 grams of extraterrestrial material. The spacecraft then left Earth orbit for an extended mission to a smaller asteroid, called 1998 KY26. The samples it left behind were carefully curated and distributed to teams around the world for study.

In the portion of the sample analysis described here, an international team of 130 researchers, led by Hikaru Yabuta at Hiroshima University, received a share of the irreplaceable Ryugu particles for studies of their organic (carbon-based) content. They examined intact Ryugu grains and insoluble carbonaceous residues isolated by acid treatment.

At ALS Beamline, the researchers used scanning transmission x-ray microscopy (STXM) to identify discrete grains of organic material (about 200 nm in size) for further examination by x-ray absorption near-edge structure (XANES) spectroscopy. The beamline enables the acquisition of elemental maps and functional group compositions in submicron-sized sample areas with a spatial resolution below 30 nm.

Read more on the ALS website

Image: Artwork showing the Hayabusa2 spacecraft retrieving a sample from the surface of asteroid Ryugu

Credit: Akihiro Ikeshita

Ancient asteroid grains provide insight into the evolution of our solar system

The UK’s national synchrotron facility, Diamond Light Source, was used by a large, international collaboration to study grains collected from a near-Earth asteroid to further our understanding of the evolution of our solar system.

Researchers from the University of Leicester brought a fragment of the Ryugu asteroid to Diamond’s Nanoprobe beamline I14 where a special technique called X-ray Absorption Near Edge Spectroscopy (XANES) was used to map out the chemical states of the elements within the asteroid material, to examine its composition in fine detail. The team also studied the asteroid grains using an electron microscope at Diamond’s electron Physical Science Imaging Centre (ePSIC).

Julia Parker is the Principal Beamline Scientist for I14 at Diamond. She said:

The X-ray Nanoprobe allows scientists to examine the chemical structure of their samples at micron to nano lengthscales, which is complemented by the nano to atomic resolution of the imaging at ePSIC. It’s very exciting to be able to contribute to the understanding of these unique samples, and to work with the team at Leicester to demonstrate how the techniques at the beamline, and correlatively at ePSIC, can benefit future sample return missions.

The data collected at Diamond contributed to a wider study of the space weathering signatures on the asteroid. The pristine asteroid samples enabled the collaborators to explore how space weathering can alter the physical and chemical composition of the surface of carbonaceous asteroids like Ryugu.

The researchers discovered that the surface of Ryugu is dehydrated and that it is likely that space weathering is responsible. The findings of the study, published today in Nature Astronomy, have led the authors to conclude that asteroids that appear dry on the surface may be water-rich, potentially requiring revision of our understanding of the abundances of asteroid types and the formation history of the asteroid belt.

Read more on the Diamond website

Image: Image taken at E01 ePSIC of Ryugu serpentine and Fe oxide minerals.

Credit: ePSIC/University of Leicester.

The history of one of the oldest objects in the Solar system unveiled

An international team of scientists have unveiled details of the history of the asteroid Ryugu, a truly ancient object in the Solar system, after the Hayabusa2 mission brought samples from this asteroid back to Earth. The ESRF was one of the institutes involved in sample characterization, on ID15A. The results are published in Science.

The asteroid Ryugu, located at 200 million kilometres from the Earth, is one of the most primitive objects of the solar system. The Japanese spacecraft Hayabusa2 explored it from 2018 until it came back to Earth two years later with minuscule multiple samples from the asteroid.

Two years later, and thanks to the international collaboration of institutes led by the Japan Aerospace Exploration Agency (JAXA), the first results on the analysis of the samples shed light on the history of Ryugu, from its formation to its collisional destruction.

Researchers used cosmochemical and physical methods at universities and institutes, including the ESRF and four other synchrotron radiation facilities in Japan, United States, and Europe.

The results combined with computer simulation have allowed scientists to picture the origins of Ryugu:  the Ryugu parent body accumulated about 2 million years after the formation of the solar system, and then heated up to about 50°C over the next 3 million years, resulting in chemical reactions between water and rock. The size of the impactor that destroyed the Ryugu parent body, which is about 100 km in diameter, is at most 10 km in diameter, and that the present-day Ryugu is composed of material from a region far from the impact point.

What the data explain

In particular, the seventeen Ryugu samples analysed contain particles (such as Ca- and Al-rich inclusions) that were formed in high-temperature environments (>1000°C). These high-temperature particles are thought to have formed near the Sun and then migrated to the outer solar system, where Ryugu was formed. This indicates that large-scale mixing of materials occurred between the inner and outer solar system at the time of its birth.

Based on the detection of the magnetic field left in the Ryugu samples, it is highly likely that the original asteroid from which the current Ryugu descended (Ryugu’s parent body) was born in the darkness of nebular gas, far from the Sun, where sunlight cannot reach.

The scientists also discovered liquid water trapped in a crystal in a sample. This water was carbonated water containing salts and organic matter, which was once present in the Ryugu parent body. Crystals shaped as coral reefs grew from the liquid water that existed inside Ryugu’s parent body. Rocks that were deeper underground contained more water than those in the surface.

Read more on the ESRF website

Image: A coloured view of the C-type asteroid 162173 Ryugu, seen by the ONC-T camera on board of Hayabusa2.

Credit: JAXA Hayabusa 2

From Antarctica to the beamline, #weekendusers

A Belgian team is trying to find out about the origin of the Solar System by studying micrometeorites from Antarctica on the Dutch-Belgian beamline (DUBBLE).

Sør Rondane Mountains, Antarctica, 2013. Steven Goderis, from the Analytical Environmental and Geochemistry (AMGC) research group in the Vrije Universiteit Brussel (Belgium), is part of a Japanese-Belgian expedition looking for meteorites preserved in the cold and dry environment of the South Pole. And they hit the jackpot: they found 635 fragments of micrometeorites. After coming back with the precious load, similar meteorite recovery expeditions and field campaigns focusing on micrometeorites continued in the following years, all equally successful. To date, they have found hundreds of pieces of meteorites and thousands of pieces of micrometeorites.

So what is the point of micrometeorites? Of all the material reaching Earth from space only a small part will survive the heating and shock experienced upon entry in the atmosphere. The large majority of this material, the micrometeorites, will rain on Earth as extraterrestrial particles of less than 2mm in size. Although meteorites in general provide us with essential information on the origin and evolution of the planets and the Solar System, micrometeorites, mostly originating from the most primitive objects still remaining in the Solar System, raise an even higher scientific interest. “Any information we can get from micrometeorites will complement the knowledge we have of meteorites, so it is really important to study them. We have a wide array of samples so that we can get the best possible picture of these materials”, explains Bastien Soens, who is doing his PhD on this subject.

>Read more on the European Synchrotron website

Image: The team on the beamline. From left to right: Niels de Winter, Bastien Soens, Dip Banerjee, Stephen Bauers and Niels Collyns.
Credits: C. Argoud.