Asteroid Material Provides ‘Most Uncontaminated’ Extraterrestrial Samples Ever

The Japanese Space Agency (JAXA) made history in late 2020 when it successfully recovered asteroid samples from the Hayabusa2 mission. Now, research carried out on the precious bits of rock is being published. Researchers from the Japan Agency for Marine-Earth Science Technology confirm that the bits of asteroid Ryugu collected by the probe represent “undoubtedly among the most uncontaminated Solar System materials available for laboratory study.”

Hayabusa2 made history during its mission, and not just at the end. It arrived in orbit of Ryugu in 2018, and soon after deployed a number of small tumbling and stationary robots on the surface. This returned some incredible images and preliminary data on the nature of the asteroid’s surface. It also picked up a few bits of regolith from the surface with the aid of dense tantalum slugs fired at the surface. Later, it deployed the Small Carry-on Impactor (SCI), which launched a shaped HMX explosive charge to create a small crater on the surface, revealing material unaltered by solar radiation.

In total, Hayabusa2 picked up 5.4 grams of material from the asteroid, which was considered a huge success. NASA’s OSIRIS-REx spacecraft, which is still on its way back to Earth, may contain as much as two kilograms of material. In the meantime, the new study published in Nature Astronomy confirms we have a lot to learn from the Hayabusa2 samples, reports Vice.

According to lead author Motoo Ito, the Ryugu material offers the best glimpse yet of the solar system’s “bulk composition.” Before these samples, the best source of information we had were the asteroids that fell to Earth — and plenty do. However, these objects are altered by their trip through the atmosphere and contaminated by contact with Earth’s surface. The Hayabusa2 samples are completely pristine.

The “Phase2” curation team also noted that the samples are rich in water, which is at odds with observations Hayabusa2 made while in orbit of Ryugu. That data suggested the asteroid was of the CY chondrite class, but the presence of water shows that it was most likely CI-chondrite. The team speculates this could be a result of weathering from solar radiation, which could be addressed with different instrumentation on future probes. The samples from OSIRIS-REx could provide additional context to help nail down the discrepancy.

The new study also points to features of the space pebbles that have never been seen on recovered meteoroids, which could expand our knowledge of the solar system. They contain carbon-rich organic molecules compacted in tiny sub-millimeter pockets known as phyllosilicates. This, along with the presence of water, supports the idea that early asteroid bombardment may have given Earth the necessary materials to develop life. The team will conduct more research into the Ryugu organics next year. That’s also when OSIRIS-REx is expected to return home.

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