The ancient asteroid samples Hayabusa2 are the purest of all. Why is this such a big deal

What is happening

The Japan Space Agency has conducted a preliminary analysis of samples from the 4.6 billion-year-old asteroid Ryugu.

why does it matter

The samples are some of the most primitive materials ever recovered from space and will help us understand the earliest era of our solar system.

When the Japanese spacecraft Hayabusa2 She dropped her treasure trove of asteroid samples toward Earth in December 2020, the scientists and engineers directing the samples home erupted into a round of applause. after, after Eight-year mission to 4.6 billion-year-old asteroid Ryuguthe old pieces of rock were finally on their way to the ground.

Now, about eighteen months later, the Box opened Its treasures were subjected to a whole series of scientific analyzes. Japan’s space agency, JAXA, had the idea that the precious materials inside the Hayabusa2 sample capsule would be of great scientific value β€” and preliminary chemical analysis shows just how amazing the agency’s samples are.

In a study published in Science on June 9, JAXA scientists provide the first in-depth evaluation of samples recovered from Ryugu since they were returned to Earth.

“We found Ryugu to be the most recent of all CI chondrites,” said Shugo Tachibana, JAXA’s chief scientist in the initial sample analysis.

What this means is that the materials recovered from Ryugu are the most primitive humans have been able to analyze on Earth. They provide a gateway to the early days of the solar system, when the sun was just a budding star and the planets were just beginning to form. Although the study released Thursday is a major milestone in understanding Ryugu, it is only a first step in understanding the solar system and our place in it.

Here’s why it matters.

Napping rocks from the Hayabusa2 sample capsule is a precision process.

JAXA

Journey to the Dragon Palace

Japan’s Hayabusa 2 mission began in 2014 with a journey to recover samples from the asteroid Ryugu, named “Dragon Palace”. In a famous Japanese folk tale. The asteroid belongs to the most common class in our solar system, Type C, and is shaped like a rotating top. Its orbit around the sun is outside the planet Mars. Some scientists believe that these types of asteroids delivered the raw materials needed for life to Earth, which is why JAXA wanted to investigate Ryugu and steal some rocks from its surface.

After a four-year journey, Hayabusa2 met the space rock, and then, in 2019, the spacecraft made two short landings on the asteroid, collecting samples and storing them in a specialized sample capsule. This model capsule landed in the Australian outback in 2020 and its precious cargo has been carefully managed ever since.

The two landings on Ryugu grabbed 5.4 grams of material from the asteroid’s surface and under its surface. The material takes the form of small pebbles and boulders, about 0.4 inches in size. The study, released on June 9, took a very small amount of the sample – about 2% of the total – to examine the chemistry and structure of the asteroid and draw some conclusions about how it formed and changed during its lifetime. Doing so requires powerful electron microscopes and the use of spectrophotometers, which can provide details of the chemicals in an object based on how the object reflects light.

Scientists have concluded that Ryugu most likely formed after another rocky body collided with a massive rocky body in the early Solar System (the early Solar System was very cold, so this was a bit of a hit). Eventually, the material ejected during the impact fused to form the asteroid with a rotating surface we know as Ryugu due to gravity. This effect, according to the analysis, likely occurred about 2 million to 4 million years after the formation of the solar system. Based on the way the samples were altered by the water, scientists believe they date back about 5 million years after the formation of the solar system.

β€œIt all happened so early [in regard to] shaping the solar system,” says Tachibana.

Since then, the asteroid has been in hibernation, with little change in its composition. What does all this mean?

Why are meteorites important

To understand the significance of the samples, it is best to look at the pieces of rock that have fallen to the ground. Scientists call these “meteorites.”

Meteorites can be classified into distinct groups based on their composition and chemistry. The rarest type of meteorite that scientists have seen are known as “CI chrondrites” – since the 19th century, we’ve only seen five meteorites of this class fall to Earth. One of the most famous of these is the fall of the Urgell which occurred in France in 1864, and the other is the Ivona which was discovered in Tanzania.

Part of Ryugu’s database model.

JAXA / ISAS / Ryugu . database

“[U]Unlike other meteorite groups, the chemistry of CI chondrites has not evolved or been modified, and can tell us about the initial formation of the Solar System,” says Ashley King, a scientist who leads the Department of Mineralogy and Planetary Sciences at the Natural History Museum in the UK.

In short, CI chondrites are the most primitive rocks we have ever found. They come from a time when the solar system was just beginning to form. But the rocks that reach the Earth are changed by the action of the atmosphere and the journey back to Earth. When they hit the atmosphere, they heat up and form new minerals and chemicals, and then, when they fall, they change due to moisture and interactions with water.

When analyzing CI chondrites, you might ask “What is naturally present in these rocks when they are in space and what has formed since arriving on Earth?” This has been a puzzle for meteorites, scientists who study meteorites, because – even Ryugu – we didn’t really have the ability to know the chemical composition of an asteroid in space.

This has all changed with JAXA analysis, and it has pushed some meteorite scientists away.

“I read the paper and my first reaction was ‘holy**!'” said Gretchen Benedix, a planetary scientist at Curtin University in Western Australia. ”

“I’m basically stuck in awe of this study at the moment and have a hard time translating into ordinary words how interesting and important it is to have the source of this type of meteorite available for future study,” Bendix noted.

To sum it up, scientists can now get to the closest epoch to our solar system, and the implications for future study are profound. Think of it this way: JAXA scientists have discovered a meteorite that never reached Earth, and therefore never changed due to conditions on our planet. This is a huge result.

“The Ryugu samples are the most chemically primitive extraterrestrial material currently available for study and will lead to new breakthroughs in our understanding of the origin and evolution of planetary systems,” King says.

What now?

This first paper is just the beginning for JAXA scholars. Over the next few months, more details are expected to be revealed about samples from Ryugu, unveiling details about the rocks’ magnetism, how they were affected by weather in space and their exposure to solar winds and cosmic rays.

But it’s not just JAXA that is interested in Ryugu. NASA acquired 10% of the samples returned in December 2021 and will conduct its own analysis of the samples, looking to compare the discovery to their asteroid sample return mission, Osiris-Rex, which visited asteroid Bennu in 2020. This mission is It is expected to return samples to Earth in September next year.

What are scientists waiting to discover? The possibilities are endless. Just this week, reports indicated that JAXA has also discovered amino acids – “the building blocks of life” – in Ryugu. A full scientific report on Ryugu’s amino acids is yet to come, but this discovery adds to the idea that organic compounds may have reached Earth from outer space.

As scientists around the world study the rock grains of Ryugu and Bennu, our murky understanding of the first time in the history of the solar system will gradually come into focus. Possibly, he might even reveal a location we comes from. When we study ancient space rocks, we can find space rocks things This makes us we It was probably delivered on a rock billions of years ago.

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