Japan’s Hayabusa2 Mission: Unraveling the Secrets of Asteroid Ryugu
Creating an Artificial Crater
In April 2019, Japan’s Hayabusa2 spacecraft made history by creating an artificial crater on the asteroid Ryugu. The mission aimed to calculate Ryugu’s age and provide insights into its composition.
The spacecraft hurled a four-pound copper ball, known as SCI (small carry-on impactor), towards Ryugu’s surface at an astonishing speed of 4,500 miles per hour. The impact created a crater approximately 47 feet wide, larger than expected.
Calculating Ryugu’s Age
Previous estimates suggested Ryugu’s surface could be millions to hundreds of millions of years old. However, the artificial crater provided a more accurate measurement.
Researchers analyzed the size and shape of the crater, which are influenced by the asteroid’s gravity and the strength of its surface material (regolith). Using this data, they calculated Ryugu’s surface age to be between six and 11 million years old.
Microgravity Crater Formation
The Hayabusa2 mission marked the first time crater formation was observed in a microgravity environment. Unlike Earth, where gravity is strong, Ryugu’s microgravity environment significantly impacted the crater’s characteristics.
The crater’s large size and semicircular shape suggest that Ryugu has a loose top layer covering a denser core. This finding aligns with recent evidence from the Nature journal, indicating that Ryugu is primarily composed of loosely packed sand rather than solid rock.
Asteroid Composition and Evolution
While the surface of Ryugu appears to be relatively young, the asteroid itself may be significantly older. Most asteroids of similar size are estimated to be around 100 million years old.
However, Ryugu’s rapid spin rate could have eroded old craters and reset the surface’s apparent age. Landslides observed by Hayabusa2 indicate that the asteroid may have slowed down from a higher spin rate in the past.
Hayabusa2’s Return and Future Studies
Hayabusa2 left Ryugu in November 2019, carrying samples from the center of the crater. These samples will be analyzed by scientists to gain a deeper understanding of Ryugu’s composition and history.
The Hayabusa2 mission has provided valuable insights into asteroid exploration and the evolution of these celestial bodies. Future studies will continue to unravel the mysteries of Ryugu and other asteroids in our solar system.