JAXA teams are now analyzing the marker’s location to make sure it will be still be visible to Hayabusa2 when the spacecraft gets down to 5 meters from Ryugu during the sample collection attempt. If the analysis shows the marker might be obscured, mission managers can schedule another touchdown rehearsal and drop a second target marker.

The target marker is the fourth object Hayabusa2 has deposited on Ryugu. In September, the spacecraft deployed two hopping rovers, followed by a lander named MASCOT in October.

Another rover named MINERVA-II2 built by a consortium of Japanese universities is scheduled to be deployed next year, but JAXA officials now say a pre-launch check of the rover revealed potential problems.

"Communication between the rover and spacecraft was fine, but the CPU did not respond," Tasker said. The mission team is now considering various options, including deploying the rover anyway with just a "small possibility" of data being returned.

Hayabusa2 operations for solar conjunction will begin 23 November, when the spacecraft will leave its home position 20 kilometers above Ryugu and embark on a 36-day loop that will carry it away from and back to the asteroid. JAXA press materials show Hayabusa2 will travel about 90 kilometers away from the home position in the direction of the Sun, in a funnel-shaped orbit that returns to Ryugu on 29 December.