Smaller than planets, but every bit as fascinating, there are over a million asteroids orbiting the sun and they come in all shapes and sizes. Vesta, the largest, is around 530 kilometres in diameter, but others are just a few metres across. Somewhere in the middle is the asteroid named ‘Ryugu’.
Measuring around 900 metres in diameter and orbiting the sun in a position between Earth and Mars, Ryugu has been of special interest because it is classified as ‘carbonaceous’ (sometimes called ‘c-type’). This means that it is formed of carbon and other organic compounds and contains large quantities of water – putting it among the oldest types of heavenly bodies. Previous research suggests that c-type asteroids are relics of the early solar system and may hold clues about its birth and the origin of the life that inhabits it. So, it is Ryugu’s advanced age that makes it so important, and why The Japan Aerospace Exploration Agency (JAXA) sent the asteroid exploration spacecraft Hayabusa2 to retrieve samples of materials such as sand, rocks and gases from its surface back in 2014.
Visiting the ‘Dragon Palace’
The name ‘Ryugu’ was given to the asteroid in 2015 by the Minor Planet Centre (the official body for observing and reporting on minor planets, including asteroids) and has a delightful origin. In a Japanese folktale, Ryūgū-jō (or ‘Dragon Palace’) is a magical underwater place, visited by a fisherman called Urashima Tarō, who travels there on the back of a turtle and returns with a mysterious box. However, at the time of Ryugu’s formal naming, the spacecraft Hayabusa2 (which means ‘Peregrine Falcon 2’ In Japanese) had already been in space for a year and the two eventually ‘met’ in 2018. Hayabusa2 surveyed Ryugu over a period of a year and a half, during which time it ejected two rovers and an observation lander onto its surface to collect data, as well as an ‘impactor’ to create an artificial crater on the asteroid, from which samples could be extracted.
Image of Hayabusa2 landing on the asteroid (Image reproduced with kind permission of JAXA)
To return the samples to JAXA for analysis, Hayabusa2 dropped a capsule from about 200 kilometres above Earth’s surface, which hit the ground in Woomera, in the Australian Outback on 6th December 2020. As well as delivering physical specimens, this historical moment was both the first time that gas samples had been retrieved from outer space and only the second largest sample ever recovered from an asteroid.
The contents of the capsule subsequently went through four months of intense analysis and part of this process was undertaken using a quadrupole mass spectrometer (QMS). Manufactured by Canon ANELVA Corporation, who are experts in the field of advanced vacuum technologies, it was installed on the testing device. Utilised by many government agencies and research facilities, a QMS is an instrument that can help identify and examine low-mass gases contained in gas test samples.
Shortly afterwards, JAXA issued a press release to report that “a black sand granular sample believed to be derived from the asteroid Ryugu was confirmed inside the sample container.” And quickly teams across seven universities, JAXA and the Japan Agency for Marine-Earth Science and Technology got to work on unravelling its mysteries. By February 2023, they were able to announce their first fascinating discovery. From this pristine sample, the researchers identified uracil, a molecule that helps carry genetic information in cells, as well as nicotinic acid, otherwise known as vitamin B3. These molecules might have formed on Ryugu or other asteroids, and this supports the idea that they were somehow delivered to early Earth, rather than originated here.
From this pristine sample, the researchers identified uracil, a molecule that helps carry genetic information in cells, as well as nicotinic acid, otherwise known as vitamin B3.”
“Scientists have previously found nucleobases and vitamins in certain carbon-rich meteorites, but there was always the question of contamination by exposure to the Earth’s environment” said Associate Professor Yasuhiro Oba of Hokkaido University, the lead author of the study. “Since the Hayabusa2 spacecraft collected two samples directly from asteroid Ryugu and delivered them to Earth in sealed capsules, contamination can be ruled out.”
More recently, the same sample from Ryugu allowed scientists to study the effects of tiny meteoroids hitting the asteroid’s surface and how it is affected by space weathering (changes to the surface of planetary bodies without an atmosphere). This can help us to understand how planets and other objects in space might have changed over time, but also to explore what might have caused the damage – potentially unlocking new information about other planets. Again, because the samples are free from contamination, the researchers were able to conduct this analysis confidently and gain new insights into the early solar system.
Every new finding adds to the bigger picture of the beginnings of our universe and steadily increases the body of evidence that suggests the building blocks of life as we know it originated in space – and were delivered to Earth billions of years ago by meteorites.
Learn more about JAXA’s Hayabusa2 project and how Canon ANELVA contributes to the development of society through its ultra-high vacuum technology.