Japan’s Kounotori H-II cargo ship has completed its eighth mission to the International Space Station, foreign media reported. The cargo ship can carry cargo and be used on International Space Station (ISS) resupply missions. Together with Russia’s Progress cargo ship, the U.S. Dragon and The Swan, as well as the former European Automated Cargo (ATV), it can deliver supplies, equipment and experiments to astronauts on the space station.
The Kounotori 8 (HTV-8) mission is the penultimate flight of HTV and will be replaced by the enhanced HTV-X around 2020.
Japan’s contribution to the International Space Station program is managed by JAXA, the Japanese space agency. The launch is JAXA’s eighth resupply mission, coinciding with the 10th anniversary of the first HTV launch. Launched on 11 September 2009, the Kounotori 1 (hTV-1) spacecraft stayed on the International Space Station for six weeks before ending its mission with a planned destructive re-entry on 1 November.
The Kounotori 1 mission also marked the first flight of the H-IIB rocket and the first use of the second launch pad of the Gissendea launch complex at the Seed Island Space Center.
The HTV manufactured by Mitsubishi Electric is about 10 meters long and 4.4 meters in diameter. It weighs up to 16,500 kg (36,400 lb) and includes 4,100 kg (9,000 lb) of pressurized cargo and 1,900 kg (4,200 lb) of unpressurized cargo.
HTV is designed to fly freely for 5 days during a 45-day stay on the International Space Station and can hover in orbit for up to seven days if it encounters problems during an initial berthing attempt.
The main thrusters for HTV are supplied by four IHI Corporation HBT-5 thrusters, which are fueled by a mixture of methylaxoni and nitrogen oxides (MON-3, a mixture of nitrous oxide and 97% nitrous oxide), while twenty-eight anti-acting thrusters are used for attitude control and manipulation. Solar cells are installed on the surface of the spacecraft to generate electricity for its system.
Kounotori was designed to transport pressurized and unpressurized cargo through two compartments to the space station. The pressurized logistics carrier (PLC) is located at the front of the spacecraft and has a universal berthing mechanism for securing it to the station. After berthing, the astronauts will enter the PLC and take their cargo.
Behind this, the non-pressurized logistics carrier (ULC) contains an exposed pallet with other cargo available from outside the space station. For the Kounotori 8 mission, type III exposed pallets will be used, which are designed to be used in conjunction with the mobile base system in the U.S. orbital section. Instead, another type of pallet Type I is designed to be installed on the exposure facility of the Japanese Kibo module.
The station’s robotic arm, the Canad Arm2 and its Dextre accessories, are used to remove pallets from Kounotori and reinstall them before departure.
The exposed palletist is equipped with six track replacement units (ORUs) for the installation of batteries on the station’s integrated truss structure (ITS). These are made up of lithium-ion batteries that will replace the nickel-hydrogen batteries originally fired from the truss segment.
Once these installations are completed, including a series of spacewalks, three-quarters of the truss batteries will be replaced with the last batch, replacing six each, and will be launched next year on the next Kounotori mission. The old batteries will be loaded into the Kounotori 8 for disposal and burned with the spacecraft when they re-enter the atmosphere after the mission. The spacewalk will be completed next year.
The pressurized logistics carrier adopts a new shelf system developed for the next generation of HTV-X spacecraft, which increases the number of cargo transport bags that can be carried from 248 to 316. Each transport bag measures 50.2 x 42.5 x 24.8 cm and provides a volume of approximately 50 litres. The cargo includes food for the station’s crew and experiments to be conducted in Kibo, the station’s Japanese experimental module (JEM).
The Left Cell Biology Laboratory (CBEF-L) contains a centrifuge to support biological and other experiments that require artificial gravity. CBEF-L will join the existing Cell Biology Laboratory (CBEF) to provide new capabilities to simulate a wider range of gravity conditions and facilitate experiments in larger animals than mice.
The hourglass experiment is a materialresearch project that will use CBEF centrifuges to study the behavior of powders and granular materials in microgravity and low-gravity environments. Samples will be tested in cylindrical and hourglass containers to better understand the behavior of surface dust or sand particles on planets and satellites.
The International Space Station’s Small Optical Link (SOLISS) will test optical communications using laser and receiver components with universal dimensions, as well as engineering cameras, which will be installed on the outside of the space station on the IVA Replaceable Small Exposure Experimental Platform (i-SEEP). SOLISS is a partnership between JAXA and Sony to send and receive laser communications on the ground via a 1550nm beam. Although the main purpose of the engineering camera is to observe the operation of the universal frame, its images can also be transmitted to the ground as part of the experiment.
Kounotori 8 also carries three small satellites, which will be deployed from the International Space Station through the JEM Small Satellite Orbiter (J-SSOD). The spacecraft, manufactured under cubeSat standards, will be released from the Kibo module’s airlock later this year.
The AQT-D demo at the University of Tokyo is a three-unit CubeSat that will test the Aquarius-1U in orbit. This will spew water vapor from the satellite to generate pulses that will adjust the satellite’s orbit. The water propulsion system is designed to extend the life of small satellites deployed from the space station without carrying traditional propellants that endanger crew stoics or the station’s base. AQT-D will attempt to verify this in space. The satellite also carries a UHF communications payload.
NARSCube-1 is a single unit CubeSat built by the National Authority for Remote Sensing and Space Science (NARSS) of Egypt. The satellite is equipped with a high-resolution miniature camera that will record images of the Earth and transmit them back to the operator, while providing them with experience and demonstration technology ahead of future missions. This was followed by the same NARSScube-2, which was deployed from the U.S. Cygnus spacecraft in August.
The last cube satellite on hTV-8 was the Rwandese Satellite 1 or RWASAT-1. Rwanda’s first satellite, RWASAT-1, carries a communications payload that will collect and forward data from remote surveillance stations on the ground. The satellite also carries two cameras for Earth observation and will act as a technical presenter.
Mitsubishi Heavy Industries’ H-IIB rocket was used to launch the Kounotori spacecraft. The H-IIB is an improved version of Japan’s main H-IIA rocket, with a wider first stage with two LE-7A engines instead of the individual engines used on the H-IIA. The launch, which was used only with HTV, marked the eighth penultimate flight of h-IIB.
JAXA has learned from the lessons of H-IIA and H-IIB to develop the next generation of rocket SH-III, which will reduce the cost of japan’s satellite launch. The H-III is expected to make its first flight in late 2020 or 2021 and will take over the launch of the Enhanced HTV-X.
The launch used the second launch pad of the Gissendlaunch complex at the JAXA Seed Island Space Center. The Gissend complex was built for the original H-II rocket in the 1990s and originally consisted of a launch pad. It was then converted to a mission for H-IIA, and in the early 2000s a near-original backup launch pad was built for the H-IIA.
The H-IIA was never launched from a backup launch pad and was later reused in H-IIB. All H-IIB missions have been launched from the second launch pad, while the H-IIA still flies from its original launch pad. Prior to launch, the H-IIB was integrated on a mobile launch platform 350 meters northwest of the spacecraft assembly building.
Then put the platform on it, the rocket on it, and then lift off. In the hours before launch, the rocket was filled with fuel: the first and second stages of the rocket were filled with low-temperature propellants: liquid hydrogen and liquid oxygen.
About two weeks ago, at this time of the first launch attempt, it accidentally caught fire. It was later discovered that the cause of the fire was an increase in the concentration of liquid oxygen used to cool the H2B rocket engine. Liquid oxygen usually spreads in the wind, but then the wind is weak and the concentration increases, making it easier to ignite.
Further inspections are carried out before a new launch attempt is returned on Tuesday. About three seconds before launch, the first stage of the dual LE-7A engine ignited. During the countdown, four solid rocket engines installed in the first stage were also ignited and the rocket began to rise.
Solids are SRB-A3 motors that provide additional thrust in the early stages of flight. They burned for 108 seconds before running out of propellant. The boosters are then separated.
The flight took three minutes and 38 seconds, and the rocket lifted off about 119 kilometers, with the payload rectifier separated from the H-IIB. The structure is designed to protect it during the Kounotori 8 lift-off and ensure that the rocket has a consistent aerodynamic profile, which is no longer needed once the rocket reaches space and can be discarded to reduce weight. The shroud was split in half and fell off the ship.
The first stage of the H-IIB continues to burn until the duration of the task is 5 minutes and 44 seconds, until the host cutoff (MECO). When the fuel is used up, the two first-stage engines will shut down and the used stages will be separated after eight seconds. After 11 seconds of separation, the second stage of the H-IIB ignited the LE-5B engine and burned for 8 minutes and 11 seconds.
The second stage of combustion sent the Kounotori 8 directly into its initial orbit. JAXA says it will be 200 x 300 km of orbit, although the actual high point may be slightly higher. The orbital inclination is 51.6 degrees, which is commensurate with the inclination of the space station.
After a mission time of 15 minutes and 5 seconds, the HTV-8 was detached from the top of its launch vehicle. Eighty-four minutes after separation, the second stage resumed a brief combustion process, firing about 64 seconds to deorbit itself, ensuring a safe return.
After separation, Kounotori 8 underwent initial activation and inspection, and then performed a series of exercises on the first day of the flight before rendezvous with the International Space Station on the fourth day of the flight. Kounotori moved 10 meters from the space station and, under the control of the astronauts, was captured by the Canad Arm2 Remote Manipulator System (RMS). After capture, the spacecraft is anchored at the lowest point of the Harmony module or at an Earth-facing port.
Kounotori remained on the space station until November 1, when the astronauts unloaded the cargo and replaced it with materials and hardware to be processed. At the end of the stay, canad Arm2 is used to remove kounotori from its berth and release it from the station.
Upon departure, the spacecraft will be destroyed when it re-enters the Pacific Ocean. HTV is not intended for recycling, so this process ensures that it is safely destroyed so that any surviving debris falls harmlessly into no man’s land in the ocean.
The launch was the second in a quiet year for Japan, following the successful deployment of a small Epsilon rocket in January.
By the end of the year, Japan could launch two more rockets – the H-IIA rocket is believed to carry military communications satellites and IGS reconnaissance satellites into orbit – although due to the secret nature of these launches, it is currently unavailable.
The next HTV mission, HTV-9, is currently expected to be launched in May next year, marking the final flight of the current HTV spacecraft and H-IIB rockets.