Hayabusa2 Set to Land on Asteroid Ryugu on Feb. 22

JAXA Hayabusa2 Mission Status Report
(Week of 2019.1.28)

Hayabusa2 returned to the home position (HP) on 1/31 from the BOX-B operation which observed the north pole of Ryugu. At the HP, we carried our regularly performed observations for one rotation period. The distance of the Sun from Ryugu varies from 0.96au to 1.42au (1 au is the average distance between the Sun and Earth, about 150 million km). The angle formed by the Sun, Ryugu and the Earth (equivalent to the SPE angle) also varies from 0 degrees (at the conjunction time) to a maximum of about 40 degrees.

Depending on the current solar distance and solar angle, the characteristics of the reflected sunlight observed by the ONC and the characteristics of the thermal radiation observed by the TIR vary. We therefore observe Ryugu regularly from the HP because it is helpful to acquire data under different observation conditions. The observations on 1/31 were particularly valuable as the Sun’s distance about 1.42 au (near aphelion: the furthest distance) while the SPE angle was 10.1°.

Due to the relative positions of the Sun, Earth and Ryugu, the operation start time at the Usuda ground station is now so early that it is before the first train in the morning! The person in charge of operations and “Commander-san” who is responsible for sending commands to the spacecraft, are not able to reach the campus in time, so we first started acquiring telemetry data only from the Usuda station. Then in Sagamihara, we began our command operations a little later. We call operations like this “ripuro-nyukan”, which indicates that the telemetry is received automatically at the beginning of the operation. It is helpful for extremely cold mornings…

JAXA Hayabusa2 Mission Status Report
(Week of 2019.1.21)

This week was the tour or “BOX-B” operation. Here, the spacecraft’s altitude is lowered from the Home Position (HP) by about 2km and shifted towards the north pole by about 9km. We moved slowly over several days, arriving on 1/24. In the previous BOX-B operation, we observed the south pole hemisphere of the asteroid, so this time we moved to observe the north pole region from above.

We stayed at that location for about 1 day to make scientific observations, after which a ΔV (acceleration) was performed and we are now returning to the HP (schedule to arrive at HP on 1/31). Observations were made with all scientific instruments; ONC, TIR, NIRS3 and LIDAR. Working with both the Goldstone and Madrid ground stations, as well as Usuda, we were able to acquire the observational data over the weekend. We also gathered additional valuable data, including a health check for the ONC and dark imaging from the TIR during the tour.