Why did Japan's Hayabusa2 spacecraft shoot asteroid Ryugu with a cannonball?

JAXA used its Hayabusa2 spacecraft to fire a cannonball at the potentially hazardous asteroid named Ryugu

The Japan Aerospace Exploration Agency's (JAXA) Hayabusa2 spacecraft recently conducted an experiment that involved shooting the asteroid Ryugu with a small cannonball. The experiment was conducted to understand the composition of the asteroid.

Ryugu, which measures almost a kilometer wide, is regarded as a potentially hazardous near-Earth asteroid. It is the main focus of Japan's Hayabusa2 mission, which has been closely monitoring the asteroid since 2018.

The Hayabusa-2--JAXA and DLR have collaborated on the mission to study asteroid
The Hayabusa-2--JAXA and DLR have collaborated on the mission to study asteroid Ryugu DLR CC-BY 3.0

Hayabusa2's Experiment On Ryugu

Recently, Hayabusa2 carried out an experiment to learn more about the composition of Ryugu. Details of the experiment were presented in two different studies published in the journals Science and Nature.

The experiment involved firing a copper cannonball into the asteroid. The cannonball, known as the Small Carry-on Impactor (SCI), was about as big as a tennis ball and weighed around two kilograms. It hit Ryugu with an impact velocity of about 4,475 miles per hour.

Effect Of SCI Impact On Ryugu

As the SCI collided with Ryugu, Hayabusa2 monitored the clouds of plume generated by the impact using its cameras. After the cloud of debris cleared, JAXA discovered that the impactor created a crater with an elevated rim on the asteroid that's about 47 feet wide. Within the crater is a conical pit about 10 feet wide and two feet deep.

Given the size of the SCI, JAXA's scientists were surprised that it was able to create such a large crater on the surface of Ryugu. They explained that the growth of the crater as well as the plume was limited by the asteroid's gravity and not by its surface strength. This suggests that Ryugu has a weak surface that's similar to loose sand.

asteroid collision
Asteroid collision NASA

Findings From SCI's Impact

This characteristic coincides with the features of other C-type asteroids, which is the most common type of space rock in the solar system. C-Type or carbonaceous asteroids are remnants of the early stages of the Solar System. They came from the same materials that formed the Sun and other planets 4.6 billion years ago.

"Fragile, highly porous asteroids like Ryugu are probably the link in the evolution of cosmic dust into massive celestial bodies," Matthias Grott, the lead author of the study published in Nature told CNN. "This closes a gap in our understanding of planetary formation, as we have hardly ever been able to detect such material in meteorites found on Earth."

Related topics : Asteroid