★ Hayabusa2 status (the week of 2018.11.26) ★
To guarantee the safety of the mission during the period of solar conjunction, the spacecraft was inserted into a “conjunction trajectory” last week on 2018.11.23. Hayabusa2 will reach its maximum distance of 110km from Ryugu on 2018.12.11 and return to the home position at an altitude of 20km on 2018.12.29. Since even small errors from the designated trajectory may result in an undesired close approach or —in the worst case— a collision with Ryugu, we have carefully measured and evaluated the spacecraft's trajectory after insertion. On 2018.11.30, Hayabusa2 reached a distance of around 75km from Ryugu and the first Trajectory Control Manoeuvre (TCM01) was performed. TCM01 was a ΔV of 3.8 mm/s given along the z-direction (towards Earth). The effect of the solar corona made the resultant ΔV difficult to assess with the two-way doppler measurement compared with past operations. Despite this difficulty, we could confirm the actual ΔV was successfully given with an estimated value of 3.77 mm/s (99.21% of the designated ΔV). Next orbital manoeuvre is scheduled after the end of the deep conjunction phase on Christmas Day (2018.12.25). During deep conjunction, only attitude manoeuvres are scheduled — one every few days— to ensure the Earth is tracked. Although it will be difficult to obtain telemetry data from the spacecraft during deep conjunction, we will take the chance to gain and accumulate valuable experience from the conjunction operation by performing radio science and communication tests. We will utilize the Ka-band capability as well as introduce “Beacon Operations” to obtain the needed minimum amount of spacecraft data on the ground.
2018.12.03 Y.T.2 & S.S.
★ Hayabusa2 status (the week of 2018.11.19) ★
Hayabusa2 has entered the conjunction period where the spacecraft is very close to the Sun as seen from Earth. In preparation for conjunction in the first half of this week, range and DDOR (Delta Differential One-way Range) measurements were performed for the orbital determination, and attitude control was also done. After rotating the spacecraft attitude by 180 degrees on the z-axis, Ryugu seen with the onboard ONC turned upside down. On Labor Thanksgiving Day (23rd) thrusters were used to put the spacecraft safely into the orbit planned for conjunction. We conducted further range and DDOR measurements and we will verify the precision of the orbit and make fine adjustments. Next week, the angle between Hayabusa2 and the Sun will decrease further and telemetry data can no longer be transmitted.
★ Hayabusa2 status (the week of 2018.11.12) ★
This week, Hayabusa2 performed the necessary range measurements and ΔV adjustments to maintain an altitude of 20km from the asteroid while preparing for the approaching solar conjunction operation next week. We also conducted science observations with the ONC, TIR and NIRS3, downloaded the acquired data and checked the health of the spacecraft bus equipment. In particular, the RCS (chemical propulsion system), TCS (temperature control system) and AOCS (altitude control system) were checked for use during the operation preparation phase next week. Since the spacecraft will take observations during the period when communication with Japan's Usuda ground station is not possible, the data download will be performed by the overseas groundstations at midnight. As the spacecraft is now in the same direction as the Sun, Hayabusa2 will be followed by the dayside country on Earth. This is like the poem by Shuntaro Tanikawa, entitled “Morning Relay”:
“We are relaying morning, from longitude to longitude, taking turns protecting the spacecraft”.
2018.11.20 S.H. & M.A.
★ Hayabusa2 status (the week of 2018.11.05) ★
After completing important operations such as TD1-R3 and BOX-C2, the spacecraft returned to the home position at an altitude of 20km. This week, we performed a health check for the optical navigation cameras (ONC), the thermal infrared imager (TIR) and the near infrared spectrometer (NIRS3). Although we normally image Ryugu, for these tests we changed the spacecraft attitude to intentionally remove the asteroid from the field of view and image deep space (a so-called ‘dark observation’). Observing dark deep space allows us to investigate the level of noise in the observation equipment. This will be the third dark observation after arriving at Ryugu.
2018.11.13 N. S.
★ Hayabusa2 status (the week of 2018.10.29) ★
Our second “BOX-C” operation began on 10/27, immediately after returning to the 20km altitude home position from the “TD1-R3” operation. This time was a special operation in two steps; BOX-C1 where the spacecraft descended to an altitude of about 5.1km and BOX-C2, with descent to about 2.2 km. Arrival at BOX-C1 occurred as scheduled on 10/30 and we completed observations using the laser altimeter and optical cameras. We arrived at BOX-C2 on 11/1 with the objective of photographing the TM (Target Marker) that was successfully dropped during TD1-R3, and to accurately identify its position. The spacecraft descended over the sub-solar point where the spacecraft, Sun and TM on the surface of Ryugu all line up. The spacecraft captured an image at an altitude of about 2.5km with the Optical Navigation Camera - Telescopic (ONC-T), and then withdrew after descending to an altitude of about 2.2 km. The result was a huge success! The retroreflective material of the TM reflected sunlight and made the TM glow in the image. This is another step forward for the TD1 operation at the beginning of next year. The spacecraft then slowly rose to save fuel and returned to the home position on 11/5.
★ Hayabusa2 status (the week of 2018.10.22) ★
Making maximum use of the data obtained during TD1-R1-A, the TD1-R3 operation ran from October 23 - 25. This was a rehearsal that covered the operation sequence until the point just before touchdown. The spacecraft descended to the same region at TD1-R1-A using the LRF (Laser Range Finder); a short-range laser sensors with four beams that measures the distance to the asteroid surface. Using this measurement, the spacecraft automatically kept the altitude constant and hovered above Ryugu, and then dropped a TM (Target Marker). The spacecraft was able to recognise the image of the TM when lit by the FLA strobe light (FLAsh lamp), moving to just above the TM position and continuing to hover. Finally the spacecraft ascended. This result was a huge success! Everyone is feeling relieved as we move into next year.
★ Hayabusa2 status (the week of 2018.10.15) ★
At midnight on October 15 during the TD1-R1-A operation, the spacecraft reached an altitude of about 20m from the asteroid surface and then rose to return to the home position. With this operation, we were able to confirm the performance of the LRF (Laser Ranger Finder), which is a laser sensor for close range, and were also able to acquire more images of the surface of the asteroid. We are now busy analyzing the data from TD1-R1-A and confirming the procedure again for the next touchdown rehearsal (TD1-R3) in the next week.
★ Hayabusa2 status (the week of 2018.10.08) ★
On October 8, the spacecraft returned to the home position at remained there for this week. Project members made the final preparations for the second touchdown rehearsal (TD1-R1-A). Images taken by MASCOT were released by the MASCOT team and the surface conditions of Ryugu were even more apparent. From October 14, the TD1-R1-A operation began.
★ Hayabusa2 status (the week of 2018.10.01) ★
Preparation for the MASCOT separation operation began on September 30 and descent began around noon JST on October 2. On October 3 at 10:57:20 JST, MASCOT was deployed at an altitude of 51m. MASCOT then landed on the surface of Ryugu and proceeded to operate for about 17 hours. The spacecraft then returned to the home position after staying for about 1 day at an altitude of around 3km. Originally, we planned to reach the home position on October 5, but due to the forecast of a typhoon approaching Japan at the weekend, this was delayed until October 8.
★ Hayabusa2 status (the week of 2018.09.24) ★
This week, the MINERVA-II1 rovers that landed on the asteroid last week sent images from the asteroid surface. No regolith was seen in these images, only a shocking scenery of large and small boulders. On the other hand, the scenes of sunlight on the asteroid and the rover hopping were both very beautiful and dynamic. Next week is the deployment of the MASCOT lander. The descent operation is always a nervous time and we want to deliver the lander steadily and carefully. (Regolith: fine grain sediments).
★ Hayabusa2 status（the week of 2018.09.17）★
This week was very exciting. On September 19, preparation began for the separation of the MINERVA-II1 rovers. Descent from the home position began at around 14:00 JST on September 20. On September 21 after 13:00 JST, the two MINERVA-II1 rovers, Rover-1A and Rover-1B separated from the spacecraft. After this, the spacecraft rose and returned to the home position at around 15:00 JST on September 22. After separation, we attempted communication with MINERVA-II1. By September 22, images and data confirmed that both rovers had landed on Ryugu and that at least one was hopping and moving. We published a press release on September 22, releasing the situation of MINERVA-II1 and the acquired images. The Project Members were also very impressed by these images sent from MINERVA-II1.
★ Hayabusa2 status（the week of 2018.09.10）★
The first half of the week was devoted to the landing rehearsal operation (TD1-R1). The operation was suspended at an altitude of 600m, and the spacecraft returned to the base camp 20 km home position. Although TD1-R1 was interrupted, we were able to see the response of Hayabusa2 at low altitude and gain a valuable image of the landing candidate area at high resolution. The Project Team feels that we are narrowing down the unexplored areas step by step. Our analysis of this data continues for the upcoming rover separation and landing operation.
★ Hayabusa2 status（the week of 2018.09.03）★
Last week, we started moving from “BOX-B” and returned to the home position for the spacecraft (“BOX-A”) as scheduled. We have continued to observe the asteroid everyday using the onboard cameras, while frantically preparing for the first touchdown rehearsal that will begin from Sept. 11 and the other operations that will follow. This next descent operation will take about two days to complete, but the preparatory work is taking several dozen times that. To get the best results from this preparation, we need to concentrate through this next week.
★ Hayabusa2 status（the week of 2018.8.27）★
Hayabusa2 has completed operation in BOX-B; observing the asteroid while moving laterally up to 9km while remaining at an altitude of about 20km. As the first rehearsal for touchdown is scheduled to start on 09/11, the spacecraft is now returning to the descent start position. In the first touchdown rehearsal, the spacecraft will descend to 30m or less from the asteroid surface to acquire a more detailed image of the primary touchdown candidate point, L08, and the surroundings. The distance to the asteroid will be measured for the first time using the LRF (Laser Range Finder); a short-distance laser sensor that is used for touchdown. This will be the first time the LRF has been used to measure distance since launch.
★ Hayabusa2 status（the week of 2018.8.20）★
The spacecraft is currently operating in BOX-B. On August 23, we announced to the media that the point denoted “L08” near the asteroid equator had been selected as the candidate site for the touchdown of Hayabusa2. However, the surface of Ryugu is covered with boulders, so we need to continue gathering and considering information so that we can touchdown safely. The MINERVA-II-1 and MASCOT lander decided to land at mid-latitude sites, N6 and MA-9. MINERA-II-1 separation is scheduled for September 21, and MASCOT on October 3. We are looking forward to seeing what kind of data these will collect!
★ Hayabusa2 status（the week of 2018.8.13）★
After returning from the Gravity Measurement Operation, Hayabusa2 operated in BOX-A (the home position). Japan experienced very unsettled weather this week, with thunderstorm around the Usuda Deep Space Centre. In addition to this, thunderstorm occurred at US Goldstone ground station when we operated Hayabusa2 from there. Weather at the ground stations is concerning. Also this week was an active discussion on landing locations. On August 17, a large number of international Project Members gathered to engage in this debate. From August 18, BOX-B operations began and the spacecraft starting moving from BOX-A.
★ Hayabusa2 status（the week of 2018.8.6）★
From August 5 - 7 this week we performed the “Gravity Measurement Descent” operation. This was the second operation in which Hayabusa2 descended towards the asteroid using the same technique as for landing. The final altitude was 851m! At this close approach, the gravity of Ryugu could be sufficiently felt to be measured and we were able to take valuable close-up images. Now at ISAS, researchers are gathering from Japan and abroad. Sagamihara is passionate about the scientific debate on this brand-new astronomical object for humanity.
2018.8.13 Y. T.
★ Hayabusa2 status（the week of 2018.7.30）★
From our descent through BOX-C to an altitude of about 6km last week, we made a fleeting return to BOX-A at a 20km altitude. Then this week, we conducted the “Medium Altitude Observation” operation, which is the first critical operation after arrival. Unlike BOX-C, we descended to an altitude of about 5km in 24 hours while performing strict position control, then hovered at the same altitude for 1 asteroid rotation cycle while observing the asteroid. As the first critical operation, it was a tense period but the operation safely succeeded and I think gave momentum for future operations. Next week, we will implement the “Gravity Measurement Operation” which is a second critical operation.
★ Hayabusa2 status（the week of 2018.7.23）★
This week, we returned from the 6km altitude “BOX-C” to “BOX-A”, staying at an altitude of 20km±1km while images taken at BOX-C were downloaded. The images released on July 25 showed a detailed view of the unevenness of Ryugu’s surface. Meanwhile, we conducted a test on the laser distance measurer, LIDAR, in preparation for the “Middle Altitude Observation Operation”, in which the spacecraft will descend to hover at a 5km altitude and then perform the “Gravity Measurement Descent Operation” which decreases the altitude to just 1km. We are ready!
★ Hayabusa2 status（the week of 2018.7.16) ★
Last week we performed short-term operations at an altitude of about 6 km. This allowed closer observations of Ryugu in more detail and the data downlink is happening now. While usual operations are “BOX-A”, these operations at a different maintenance altitude are called “BOX-C” operations. While we did not keep the order, we will do “BOX-B” operations. Do look forward to these!
★ Hayabusa2 status（the week of 2018.7.9) ★
Operations continue at the Home Position (an altitude of about 20km). Overseas stations as well as the Usuda Deep Space Observatory have also been used for the Ka band downlink and uplink transfer. The ONC-T, LIDAR, NIRS3 and TIR have performed BOX-A (20km altitude) observations, continuing our steady data acquisition.
★ Hayabusa2 status（the week of 2018.7.2) ★
The first week after arriving at Ryugu has gone by in a flash. Monitoring the landscape of a brand-new astronomical object for humanity while continuing spacecraft operations is a wonderful and amazing experience.
The two main activities this week were:
・Establishing the procedure needed to accurately hover 20km above the asteroid.
・An operation check of the observational instruments when directed towards Ryugu.
The outcome of both activities was good. The LIDAR (Laser altimeter) measured the altitude of the asteroid’s facing surface and the Ka-band communication equipment started sending high speed data through the NASA Deep Space Network. From the Doppler shift of the radio waves sent from Hayabusa2, we could tell that the spacecraft is feeling the gravity of the asteroid. Hayabusa2’s exploration of Ryugu in this first week has been a smooth start.
We have carried out the second optical navigation trajectory correction manoeuvre (TCM02)
On June 11, 2018 at around09:30 - 10:40 JST, the thrusters were fired several times to give an acceleration of 13 cm/s (x-direction), 1 cm/s (-y-direction), 26 cm/s (z-direction). The distance from the spacecraft to the asteroid during the manoeuvre was about 1320km and their relative speed after TCM02 was about 2.1m/s. Until now, Hayabusa2 was approaching Ryugu from the side. But with TCM02, the asteroid is now directly in front of the spacecraft, along the direction of travel.
Downlink Test Using Ka-band
Today (June 29, 2016), we made a downlink test using Ka-band,and the result was successful. The antenna of DSS26 in Goldstone, DSN (Deep Space Network) of NASA was used and the calibration for the ground station was done today.
We made the first test of Ka-band in the beginning of January 2015, and the test of today was the second time. The distance between the Earth and the spacecraft is about 50 million km, which is about four times larger than the distance at the first test. We are using the X-band (8 GHz) for the daily operation, and we will use the Ka-band (32 GHx) when the spacecraft arrives at Asteroid Ryugu and send the data of Ryugu to us.