The return of a sample of asteroids could help uncover the origins of life and the solar system

What’s your idea of ​​an asteroid? Many people consider them to be potato-shaped, inert and perhaps rather dull and pockmarked objects – very far away in deep space. But in the past decade, two Japanese space missions – Hayabusa and now Hayabusa 2 – have sent that view to the history books. Asteroids are interesting bodies that may be able to explain how life on Earth originated.

The Japanese space agency, JAXA, is returning to Earth samples of the 1km-wide Ryugu asteroid, with a touchdown scheduled for December 6 at a military test site in South Australia. The first Hayabusa aircraft returned samples from the asteroid Itokawa in 2010, which like Ryugu orbits the Sun close to Earth. I am one of the scientists who analyzed the grains and now I can’t wait to investigate Ryugu.

Observations from Hayabusa 2 cameras have already revealed some intriguing features of the asteroid Ryugu (meaning “Dragon Palace”). The asteroid appears to have formed as a heap of rotating rubble from previous generations of several asteroids. Ryugu shows that asteroids have a rich and well-documented history, being bombed by meteorites and blasted by harsh solar wind and cosmic rays.

Many “carbonaceous chondrite meteorites” like Ryugu are rich in aqueous minerals such as clays – they may in fact have brought water to Earth. Curiously, Ryugu’s observations suggest that it is not as rich in water as was expected when it was selected as a target for this mission. It is possible that the water in the asteroids from which it formed has evaporated due to internal heating by radioactive material. In contrast, the asteroid Bennu, which was sampled by NASA’s Osiris Rex mission and will bring back samples in 2023, appears to be rich in hydrated minerals.

Ryugu could tell us a lot about the history of the Solar System. Earth and the other planets formed from small rocky bodies in a disk of gas, ice and dust called the solar nebula. The asteroids are the leftovers from this process. While planets have undergone extensive changes, developing crusts, mantles, and nuclei throughout their lifetimes, asteroids have not. By studying primitive samples of asteroids, we can therefore reveal many secrets about how the solar system was formed.

For example, were the building blocks of life present in that nebula or did they develop later on Earth? If they were present in the nebula, we might be able to see them on Ryugu. Previous research has in fact suggested that reactions with water on asteroids are linked to the production of amino acids, which make up proteins. If we discovered that the building blocks of life were present at the time of the Earth’s birth, this could mean that life may be more common in the universe than one might think. It could also help us understand how organic material spreads across planets, such as Mars and Earth.

One of the benefits of a carefully prepared sample return mission like Hayabusa 2 is that contamination from organic materials on Earth is at an absolute minimum. So if we find amino acids on Ryugu, we can be sure they actually come from there.

Complicated sampling

However, getting the sample wasn’t easy. To obtain a piece from beneath Ryugu’s surface, where the material is protected from meteorite impacts and radiation, the spacecraft had to move to a safe distance from it. There, he fired a bullet at the surface of the asteroid. The small crater that was created was then visited in a short touchdown when the material was collected. JAXA is cautious in saying how much was collected, but hopefully tens of grams.

The same sampling mechanism was used in the Hayabusa 1 mission, but on that occasion the projectors and collection were incorrectly evaluated, causing only a fine cloud of dust to be collected.

However, this also allowed us to understand how Itokawa formed and that it was identical in mineralogy to a type of meteorite called “LL5”. This then helped us to explain how thousands of LL5 meteorites also formed in our Earth collections.

Next steps

Hayabusa 2, who embarked on a six-year mission, departed for Earth in November 2019. There will be live YouTube coverage showing the returning capsule fireball and a radio beacon inside the capsule will aid quick recovery. with drones and helicopters. After the capsule is recovered, it will be taken to Sagamihara Campus near Tokyo, Japan for opening.

Sample return missions require laboratory techniques that can analyze minute samples. We will deploy state-of-the-art methods including organic analysis, electron microscopy, which fires electrons at a sample to provide a highly magnified view, and synchrotrons, huge X-ray-generating accelerators to study matter in minute detail. Much like during the Apollo era of the 1960s and 1970s and the Stardust mission from 2006 onwards, the next generation of sample return missions will advance our analytical capabilities to Earth.

While the return mission is underway, the spacecraft minus its asteroid sample cargo will proceed to the last part of the mission, heading for a tiny asteroid named 1998KY26. It will arrive in 2031 after a series of land flyovers. Could Hayabusa 2 really land on this 30m wide asteroid? It will be a fascinating challenge. It could also help us understand how to deflect an asteroid that may be close to crashing into Earth in the future.