H-IIB already on its way to Tanegashima Space Center

JAXA is continuing arrangements for planned for 30th September 2016 17:16 UTC launching their cargo spacecraft with supplies for International Space Station.

H-IIB F6 rocket started yesterday its journey on boat from Mitsubishi Heavy Industries facility in Tobishima to Tanegashima Space Center. Ship will reach Tanegashima on 1st August, where rocket will be delivered to assembling facility for unpacking, tests and final assembly. HTV was already installed on the top of the second stage of the H-IIB. Mission planned for 30th September is sixth flight of the H-IIB (until now success ratio was 100%). Rocket is strongest version of H-II and is basing on H-IIA version. It is equipped with four SRB-A3 solid fueled (with HTPB) rocket boosters generating total thrust of 9220 kN. Each booster is long for 15 m with diameter of 2.5 m and weight at 306 t. First stage of the rocket is equipped with two LE-7A engines (fueled with LH2/LOX) providing thrust at 2196 kN. It is long for 38 m and its diameter is 5.2 m and weighs 202 t. Second stage is powered with LE-5B engine with thrust at 137 kN. It is shorter and narrower than first stage, with length of 11 m and diameter at 4 m; it weighs 20 t. Total length of the rocket is 56.6 m and mass is  531 t with payload to LEO at 19 t. Payload (HTV) is covered with 5S-H fairing: 15 m long and with 5 m in diameter.

Japanese contribution in resupplying mission for ISS is conducted with the utilization of the H-II Transfer Vehicle Kounotori. It is simple unmanned robotic spacecraft without navigation system, which would make autonomous docking possible. After being launched on atop of H-II rocket, Kounotori is put into desired orbit and is approaching to ISS for about 10 m. Next it is grabbed by Canadarm2 and docked to free port of Harmony module. Spacecraft is able to take up to 6000 kg of payload: 4500 kg in pressurized and 1500 kg in unpressurized section. Spacecraft is long for 9.2 m and its diameter is 4.4 m. After undocking it is performing reentry and burns in atmosphere, due the fact that it is unable to return to Earth.

Last month, HTV Kounotori 6 was packed with supplies for mission planned for 30th September 2016. In spite of food, hardware and water (600 l in 30 soft plastic bags), important spare parts for ISS will be delivered; six lithium ion batteries are remaining inside unpressurized container to serve as replacement for utilized on International Space Station Ni-Mh batteries. Single lithium battery weighs 250 kg and due their high efficiency each one will replace two old Ni-Mh batteries. In spite of higher efficiency they are also lighter and have longer operational life - single old battery weighs 169 kg (104 cm x 94 cm x 48 cm). They will be installed during two EVAs; old batteries will be detached from external platform called Integrated Equipment Assemblies. These delivered by HTV on October, will be used as replacement for old batteries installed in S4 section of Orbital Replacement Units section. Planned EVA assumes utilization of DEXTRE robotic arm for releasing bolts of Flight Releasable Attachment Mechanism (FRAM) which is keeping batteries in place. Both EVAs will be performed during 52 days of HTV-6 mission. It is planned to deliver in future to ISS 24 new batteries during planned HTV missions.

Kounotori will also deliver to ISS KITE experiment. It is Kounotori Integrated Tether Experiment, which will show how electric currents (10 mA) are transmitted on tether without insulation in space. It is based on 700 m long wire, which will be stretched by Kounotori after undocking with one end attached to ISS and with 20 kg mass attached to second end. In spite of measuring electric currents, which will reach 20 kg mass in the end, Kounotori will also use its sensors to monitor dynamic of the weight attached to wire during experiment. Results of both experiments will be useful for Japanese project of Space Tethered Autonomous Robotic Satellite-2, which will use special magnetized steel wire net with length of 10 km for grabbing space debris.

Sources:
http://news.mynavi.jp/articles/2016/07/28/h-iib6_mhi/
http://iss.jaxa.jp/topics/2016/06/htv6_160602.html
http://global.jaxa.jp/press/2016/07/20160726_h2bf6.html