The third touchdown rehearsal will be performed between October 23 – 25. The purpose of this rehearsal is to use the measured value recorded by the LRF (Laser Range Finder), that performs the altitude measurement at short distances, to control the spacecraft. If this is successful, we will also separate one of the target markers (TM) and attempt to track the detached TM. These operations will allow us to confirm the accuracy of the navigation guidance control at low altitudes of about 20m.
Main schedule for the TD1-R3 operation
|Date & Time（UTC）||Date & Time（JST）||Spacecraft speed (cm/s)||HP altitude (m)||Near-point altitude (m)||Event|
|10/22 23:30||10/23 08:30||0||20,000||Communication via Usuda Deep Space Center begins|
|10/23 08:20||10/23 17:20||Communication via Madrid DSN begins|
|10/23 16:00||10/24 01:00||Comm. via Goldstone DSN begins|
|10/23 23:00||10/24 08:00||Comm, via Usuda begins|
|10/23 23:40||10/24 08:40||Preparation for descent begins|
|10/24 03:40||10/24 12:40||-40||20,000||Begin descent|
|10/24 06:40||10/24 15:40||Comm. via Canberra begins|
|10/24 08:20||10/24 17:20||Comm. via Madrid begins|
|10/24 08:30||10/24 17:30||13,000|
|10/24 14:00||10/24 23:00||-10||5,000||Decelerate descent speed ΔV|
|10/24 16:10||10/25 01:10||Comm. via Goldstone begins|
|10/24 22:40||10/25 07:40||1,500|
|10/24 23:00||10/25 08:00||Comm, via Usuda begins|
|10/25 01:20||10/25 10:20||500|
|10/25 02:00||10/25 11:00||250|
|10/25 02:30||10/25 11:30||0||20||Target Marker (TM) release|
|10/25 02:50||10/25 11:50||50||20||Ascent ΔV|
|10/25 03:20||10/25 12:20||900|
|10/25 04:10||10/25 13:10||2,600|
|10/25 06:40||10/25 15:40||Comm. via Canberra begins|
|10/25 08:20||10/25 17:20||Comm. via Madrid begins|
- Time: Approximate schedule time (in 10 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.
Schematic of the TD1-R3 operation
Fig.1 Schematic of the TD1-R3 operation
TD1-R3 low altitude sequence
Fig.2 TD1-R3 low altitude sequence
Note : Target Marker
Fig.3 Note : Target Marker