Asteroid Ryugu from a distance of about 40 kilometers. Details of the asteroid surface are now clear, giving food for thought about the best locations for surface operations. Credit: JAXA, University of Tokyo & collaborators.

Japan’s Haybusa2 is imaging asteroid Ryugu – and revealing a host of engineering challenges ahead for spacecraft operations.

“The shape of Ryugu is now revealed,” explains Hayabusa2 Project Manager, Yuichi Tsuda for the Japan Aerospace Exploration Agency (JAXA).

Japan’s Hayabusa2 is pulling up to Ryugu – a C-type asteroid – for detailed study.
Artwork: Akihiro Ikeshita

“From a distance, Ryugu initially appeared round, then gradually turned into a square before becoming a beautiful shape similar to fluorite [known as the ‘firefly stone’ in Japanese]. Now, craters are visible, rocks are visible and the geographical features are seen to vary from place to place. This form of Ryugu is scientifically surprising and also poses a few engineering challenges,” Tsuda adds.

Rotation axis

According to Tsuda, first of all, the rotation axis of the asteroid is perpendicular to the orbit. This fact increases the degrees of freedom for landing and the rover decent operations.

On the other hand, there is a peak in the vicinity of the equator and a number of large craters, which makes the selection of the landing points both interesting and difficult, Tsuda points out.

Formulate plans

“Globally, the asteroid also has a shape like fluorite (or maybe an abacus bead?). This means we expect the direction of the gravitational force on the wide areas of the asteroid surface to not point directly down. We therefore need a detailed investigation of these properties to formulate our future operation plans,” Tsuda explains in a Hayabusa2 posting.

“The Project Team is fascinated by the appearance of Ryugu and morale is rising at the prospect of this challenge,” Tsuda notes. “Together with all of you, we have become the first eyewitnesses to see asteroid Ryugu. I feel this amazing honor as we proceed with the mission operations.”

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