What Scientists Saw After Firing a Small Cannonball into a Near-Earth Asteroid

Hyabusa2 — the JAXA spacecraft sent to a near-Earth asteroid — shot a small cannon into Ryugu. The plume unveiled much about its origins.
Brad Bergan
Image formatted to fit. Source: JAXA / University of Tokyo and collaborators

The Japan Aerospace Agency's Hayabusa2 spacecraft shot a copper cannonball — barely larger than a tennis ball — into a near-Earth asteroid called Ryugu to study its composition, and scientists recently published data and images from the ordeal detailed in a new study in the journal Science.


Japan's Hyabusa2 cannon blast

Nearly a year after the cosmic shot, scientists finally had a chance to inspect this first-of-its-kind data — captured by cameras on the spacecraft — to learn about an asteroid roughly 314 million kilometers (195 million miles) away.

Once the Hayabusa2 spacecraft deployed its Small Carry-on Impactor — a nifty piece of technology (packed with explosives) — the device descended and released a blast into the artificial asteroid.

The spacecraft also launched a small camera called DCAM3, to capture the detonation as it happened. The camera witnessed the explosion from roughly 0.8 kilometers (half a mile) away.

JAXA Hayabusa2 Ryugu Surface
An image from the surface of Ryugu. Source: JAXA / University of Tokyo and collaborators

Japan gets the goods on a near-Earth asteroid

The researchers learned that the impact created an almost 10-meter-(33-foot)-wide crater on the asteroid's surface, according to a new study. The impact blew a plume of material upward, which the camera caught in fine detail.

The residual crater looks like a semicircle with an elevated rim, a central pit and an asymmetrical pattern of ejected material, according to the researchers.

Based on the material blown out during the impact, the researchers also think Ryugu possesses material not unlike loose sand on Earth.

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The plume of matter — or ejecta curtain — created during the impact never completely detached from the surface, reports the study. Researchers think the material was held down by gravity.

Ryugu is a dim, spinning-top-like asteroid roughly 914.4 meters (3,000 feet) wide. The asteroid's surface is smothered in boulders, and it's a very dry place.

The researchers also learned how Ryugu likely formed from the photos captured by the spacecraft. The near-Earth asteroid appears to display an even distribution of dark, rough rocks, but also ones that are bright and smooth. Consequently, scientists believe there are two kinds of material on the asteroid collected when it formed from the rubble remains of a parent body.

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