We might lastly know why spinning-top asteroid Ryugu has such a bizarre form

Scientists might have lastly solved the mysterious origins of the diamond-shaped asteroid Ryugu: It might be the remnants of a long-dead comet.

The brand new origin theory, taken from findings from Japan’s Hayabusa2 mission, means that the 0.5-mile-wide (0.8 kilometer) asteroid is definitely the rocky stays of a useless comet that, after shedding its ice, was smooshed collectively by its personal gravity.

The brand new suggestion may clarify a set of surprising observations from Hayabusa2. The spacecraft, which launched in 2014 and rendezvoused with Ryugu in 2018, spent a yr surveying the asteroid’s rocky floor earlier than returning to Earth in 2020. That knowledge, when mixed with distant observations, yielded a couple of findings: Ryugu is made up of many small rocks relatively than being one giant boulder, it was deformed into the form of a spinning high from speedy rotation and it’s product of an unusually great amount of natural matter, or matter wealthy in carbon.

Associated: Why are asteroids and comets such weird shapes?

This abundance of natural matter challenges the dominant principle that Ryugu was born from the collision of two bigger asteroids. 

Natural matter — the chemical compounds containing carbon-hydrogen bonds important for all times — is often not discovered on asteroids, however it’s discovered inside comets. It is because comets kind on the outer, colder areas of the solar system, the place clouds of natural matter combine with rocks and ice to create these soiled snowballs. Warmth from the solar slowly melts new comets, which wander into the inside photo voltaic system (bordered by the asteroid belt between Mars and Jupiter). This melting causes the ice to flee the comet in a path that resembles an extended tail. 

It’s this melting course of that created Ryugu — a remnant of gravity-compacted rocks and natural matter left behind after the ice had been vaporized.


Research first writer Hitoshi Miura, an affiliate professor of fabric science at Nagoya Metropolis College in Japan, stated this melting course of might have brought about “the nucleus of the comet to lose mass and shrink, which will increase its pace of rotation.” This speedy spinning might have given the useless comet’s coronary heart “the rotational pace required for the formation of a spinning-top form,” Miura said in a statement.

To additional examine their principle, the researchers constructed a easy mannequin and used it to calculate the time it could take for a once-icy Ryugu to soften and for its rotational pace to subsequently improve. The mannequin concluded that Ryugu had doubtless spent a couple of tens of 1000’s of years as a comet earlier than it moved into the inside asteroid belt, the place it melted and changed into a rubble-pile asteroid.

The researchers want extra proof to know in the event that they’re proper, however that proof may be coming quickly. NASA’s OSIRIS-REx, a van-sized spacecraft, collected a rock pattern from one other diamond-shaped asteroid, Bennu. When it returns to Earth in 2023, indicators of natural matter within the pattern may lend credence to the idea that spinning-top-shaped asteroids had been as soon as comets and provides scientists vital perception into the evolution of the photo voltaic system.

The researchers revealed their findings Jan. 31 in The Astrophysical Journal Letters.

Initially revealed on Dwell Science.


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