Ancient Ryugu asteroid sample sheds new light on solar system’s creation

Ancient Ryugu asteroid sample sheds new light on solar system’s creation
  • PublishedOctober 8, 2023

A Japanese space capsule that landed in South Australia’s outback 18 months ago is now helping scientists understand more about the creation of the solar system.

Key points:

  • A sample taken from the Ryugu asteroid shows that it was formed about 4.6 billion years ago
  • Scientists say it coincides with the creation of the solar system
  • Months of analysis shows the asteroid is similar to the outer layer of the sun

In December 2020, Hayabusa2 streaked across the desert sky directly over Coober Pedy in the state’s remote far north as it entered the Earth’s atmosphere and plummeted towards its landing site.

It was carrying precious cargo: a canister with samples of dust and pebbles from the ancient asteroid, Ryugu.

Seconds later, it touched down in the Woomera Prohibited Area as NASA scientists flew above in a specialised jet, tracking the capsule’s location.

Until that moment, Hayabusa2 had been travelling through space for six years, covering more than 5.2 billion kilometres to Ryugu and back.

Close up of black dirt and pebbles
The sample taken from two locations on Ryugu were a mix of dark-coloured dust and pebbles.(Supplied: Yada et al, Nature Astronomy)

It had one final leg of its journey to make, a private jet back to the Japanese Aerospace Exploration Agency (JAXA) where scientists carefully opened the capsule.

Now, 18 months on, the experts behind this mission can reveal what they have discovered.

‘Pristine’ asteroid

University of Queensland planetary scientist Trevor Ireland has been working on the Hayabusa mission since 2004 and says the meteorite Ryugu is ancient.

“Really the Ryugu samples may actually be the most pristine example of this very rare type of asteroid,” Professor Ireland said.

“[They] will allow us to look back into what the chemistry of the solar system looked like in the earliest days.”

Months of analysis of the asteroid samples have found that Ryugu is similar to the outer layer of the sun.

The research suggests it was formed around the same time as the solar system: about 4.6 billion years ago.

“When we look back, we find that this actual rock of Ryugu and [its] CI chondrites actually formed about three million years after the earliest inclusions that we can see a meteorite,” he said.

“So this is really pushing back into the earliest times of the solar system.

“Having a sample from that early on is really amazing.”

The surface of the asteroid Ryugu.
The surface of the asteroid Ryugu at an altitude of about 64 metres.(Supplied: JAXA)

This sample shows that Ryugu is very similar to the Ivuna meteorite, which fell to Earth in Tanzania in 1938.

Flinders University space archaeologist Alice Gorman said the findings give scientists a glimpse into the early stages of the solar system.

“What this new research has shown is that Ryugu preserves all of the evidence of this early phase of evolution of the solar system,” Associate Professor Gorman said.

“The more we know about how they came to be, the more we will understand about how life ended up forming on Earth and what our sort of broader place in the cosmos is.

“I think that’s something that is quite critical to know when we are grappling with climate change and we need that bigger context.”


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