The mission operation to deploy the MINERVA-Ⅱ1 rovers will be conducted from September 19 – 21. On September 19, activities will focus on preparation for the spacecraft to descend towards asteroid Ryugu and on September 20, the actual descent will begin. The scheduled deployment of the MINERVA-Ⅱ1 rovers is on September 21.
The approximate schedule currently planned is shown in the following table. The safety of the spacecraft is a priority in all operations, so the schedule may change depending on the current situation.
MINERVA-Ⅱ1 main schedule for deployment
| Date & Time（UTC） | Date & Time（JST） | Spacecraft speed (cm/s) | HP altitude (m) | Near-point altitude (m) | Event |
|---|---|---|---|---|---|
| 9/19 00:00 | 9/19 09:00 | ０ | 20,000 | Communication via Usuda Deep Space Center begins | |
| 9/19 08:10 | 9/19 17:10 | Communication via Madrid DSN begins | |||
| 9/19 16:00 | 9/20 01:00 | Comm. via Goldstone DSN begins | |||
| 9/20 00:00 | 9/20 09:00 | Comm. via Usuda begins | |||
| 9/20 04:10 | 9/20 13:10 | confirm readiness for descent | |||
| 9/20 05:10 | 9/20 14:10 | -40 | 20,000 | Begin descent | |
| 9/20 07:10 | 9/20 16:10 | Comm. via Canberra DSN begins | |||
| 9/20 08:10 | 9/20 17:10 | Comm. via Madrid DNS begins | |||
| 9/20 10:00 | 9/20 19:00 | 13,000 | |||
| 9/20 15:30 | 9/21 00:30 | -10 | 5,000 | Decelerate descent speed ΔV | |
| 9/20 16:00 | 9/21 01:00 | Comm. via Goldstone DSN begins | |||
| 9/20 18:30 | 9/21 03:30 | 4,000 | |||
| 9/21 00:00 | 9/21 09:00 | Comm. via Usuda begins | |||
| 9/21 00:00 | 9/21 09:00 | 2,000 | |||
| 9/21 00:10 | 9/21 09:10 | 1,500 | |||
| 9/21 03:00 | 9/21 12:00 | 500 | |||
| 9/21 03:40 | 9/21 12:40 | 250 | |||
| 9/21 04:00 -04:30 | 9/21 13:00 -13:30 | ~60 | MINERVA deployment | ||
| 9/21 04:00 -04:30 | 9/21 13:00 -13:30 | +50 | ~60 | Post deployment upward ΔV | |
| 9/21 05:40 | 9/21 14:40 | TBD | Increase ΔV to return to home position | ||
| 9/21 07:20 | 9/21 16:20 | Comm. via Canberra DSN begins | |||
| 9/21 08:10 | 9/21 17:10 | Comm. via Madrid DSN begins | |||
| 9/21 16:00 | 9/22 01:00 | Comm. via Goldstone DSN begins | |||
| 9/22 00:00 | 9/22 09:00 | Comm. via Usuda begins |
- Time: Approximate schedule time (in 10 -minute 5-minute increments). There is a possibility that this may change during operation. The time is the onboard time, so confirmation of the event is the radiowave propagation time of about 18 minutes later.
- Spacecraft speed: This is the speed relative to the asteroid (minus is towards the asteroid, positive is away). Numerical value is displayed only when speed control is performed. After a speed control operation, the speed changes due to the gravitational force of Ryugu and other celestial bodies.
- HP altitude：Distance to the center of Ryugu
- Near point altitude：Distance to the surface of Ryugu.
Operation sequence
-
[open in another window] MINERVA-Ⅱ1 schematic showing the deployment operation sequence (©JAXA)
- dV, ΔV：acceleration of the spacecraft
- free fall：The speed of the spacecraft is not controlled, but falls due to the pull of Ryugu’s gravity.
- GCP-NAV：Ground Control Point Navigation, tool for image guided navigation during the descent operation.
- HP：home position
- LIDAR：laser altimeter
- ONC-T：Optical Navigation Camera Telescopic (installed on the bottom of the spacecraft).
- ONC-W1：Optical Navigation Camera Wide angle (installed on the bottom of the spacecraft).
- ONC-W2: Optical Navigation Camera Wide angle (installed on the side of the spacecraft).
- Attitude scan：change the attitude of the probe to photograph MINERVA-Ⅱ1
- constant descent velocity： the spacecraft descends at a nearly constant speed. At first, this speed is about 40 cm/s. From an altitude of about 5km, the speed is about 10 cm/s.
- Trigger Altitude：when this altitude is reached, the spacecraft’s speed will be controlled.
- Additional free fall for preventing plume contamination: the spacecraft will not use thrusters during the period shown in the figure when MINERVA-II1 is in free fall. This is to avoid thruster gas hitting MINERVA-II1.
Hayabusa2 project
2018.09.20
