Kounotori 8 (こうのとり8号機), also known as HTV-8 was the 8th flight of the H-II Transfer Vehicle, a robotic cargo spacecraft to resupply the International Space Station. It was launched on 24 September 2019, 16:05:05 UTC.[8]

Kounotori 8

H-II Transfer Vehicle (HTV-8) being grappled by the Canadarm2 on 1 November 2019.
Mission type	ISS resupply
Operator	JAXA
COSPAR ID	2019-062A
SATCAT no.	44546
Mission duration	40 days
Spacecraft properties
Spacecraft	Kounotori 8
Spacecraft type	HTV
Manufacturer	Mitsubishi Heavy Industries
Launch mass	15800 kg [1]
Dry mass	10500 kg
Payload mass	5300 kg
Dimensions	9.8 metre of long, 4.4 metre of diameter
Start of mission
Launch date	24 September 2019, 16:05:05 UTC[2]
Rocket	H-IIB No. 8
Launch site	Tanegashima, Yoshinobu-2
Contractor	Mitsubishi Heavy Industries
End of mission
Disposal	Deorbited
Decay date	3 November 2019
Orbital parameters
Reference system	Geocentric orbit
Regime	Low Earth orbit
Inclination	51.66°
Berthing at ISS
Berthing port	Harmony nadir
RMS capture	28 September 2019, 11:12 UTC [3]
Berthing date	28 September 2019, 14:09 UTC [4]
Unberthing date	1 November 2019, 13:45 UTC [5]
RMS release	1 November 2019, 17:21 UTC [6][7]
Time berthed	34 days
Cargo
Mass	5300 kg
Pressurised	3400 kg
Unpressurised	1900 kg
HTV ISS Resupply ← Kounotori 7 Kounotori 9 →

Spacecraft

Major changes from previous Kounotori are:[9]

• Replacement of Earth sensor with star tracker for spacecraft attitude control
• New cargo racks developed for HTV-X which allows 30% more Cargo Transfer Bags (CTB) to be carried in the Pressurized Logistics Carrier (PLC). (316 CTBs for Kounotori 8, compared to 248 CTBs of Kounotori 6)

Cargo

Kounotori 8 carries about 5300 kg of cargo, consisting of 3400 kg in the pressurized compartment and 1900 kg in the unpressurized compartment.[9]

Cargo in the Pressurized Logistics Carrier (PLC) include:[9]

• JAXA experiment Cell Biology Experiment Facility-Left (CBEF-L)
• JAXA experiment Sony Optical Link for ISS (SOLISS), a satellite optical communication demonstration co-developed with Sony Computer Science Laboratories [ja]
• JAXA experiment Hourglass, which will investigate the behavior of soil and rock particles under low gravity conditions[10]
• Gas bottle for JAXA experiment
• Experiment materials for Electrostatic Levitation Furnace (ELF)
• CubeSats to be deployed from ISS: NARSSCube-1, AQT-D, RWASAT-1
• NASA system supply cargo: new water tank for Water Storage System (WSS)
• NASA system supply cargo: tank for Nitrogen Oxygen Recharge System (NORS)

In the Unpressurized Logistics Carrier (ULC), Kounotori 8 carries six lithium-ion batteries Orbital Replacement Units (ORUs) for replacing the ISS's existing nickel-hydrogen batteries. The transportation of replacement batteries is a continuation from the previous Kounotori 6 and 7, and will continue through to Kounotori 9.[9]

Operation

Launch

The H-IIB launch vehicle carrying Kounotori 8 was initially scheduled to be launched at 21:33:29 UTC, 10 September 2019.[11][12] During launch preparation, a fire broke out at the launch pad at around 18:05 UTC (T minus 3.5 hours), and the launch was called off.[13] The cause of fire was attributed to the static electricity on the heat resistant material under the mixture of liquid oxygen and gas oxygen for the engine pre-cooling.[14]

After the modification to the mobile launch platform to suppress static electricity, a new launch was scheduled at 23 September 2019, 16:30 UTC,[14] but the collision avoidance check revealed that the 2nd stage of the launch vehicle might approach near the Soyuz MS-15 which was scheduled to be launched on 25 September 2019. A revised launch schedule was set for 16:05 UTC, 24 September 2019.[15] On 24 September 2019, 16:05:05 UTC, the Kounotori 8 aboard H-IIB was launched successfully.[8]

Operation while berthed to the ISS

Kounotori 8 was captured by the Space Station Remote Manipulator System (SSRMS) at 23:13 UTC, on 27 September 2019,[16] and berthed at Harmony's nadir Common Berthing Mechanism (CBM) by 17:55 UTC, on 28 September 2019.[17]

The External Palette (EP8), which carries the lithium-ion battery Orbital Replacement Units (ORU), was extracted from the Kounotori 8's Unpressurized Logistics Carrier (ULC) by the SSRMS (Canadarm2) on 29 September 2019.[18]

The External Palette of Kounotori 7 (EP7) was placed in the Kounotori 8's ULC.[19] EP7 was left on the ISS after the departure of Kounotori 7 due to the schedule change of extravehicular activity after the launch failure of Soyuz MS-10.

Departure and reentry to the Earth atmosphere

On 1 November 2019, Kounotori 8 was detached from Harmony's CBM by the SSRMS (Canadarm2), and it was released into orbit at 17:20 UTC.[20]

It was disposed by the destructive reentry to the Earth atmosphere at around 02:09 UTC, on 3 November 2019.[21]

References

External links

• JAXA HTV page