Kounotori is the Japan Aerospace Exploration Agency’s (JAXA) cargo transportation contribution to the International Space Station (ISS). Conceived in the 1980s, Kounotori began development in the 1990s and first flew on September 2, 2009.

The spacecraft is launched on theH-IIB launch vehicle (hence its HTV designation) and is designed to deliver up to 13,227.7 pounds (6,000 kg) of pressurized and unpressurized cargo to ISS including food, clothes, and experiments. The spacecraft also disposes of spent equipment, used clothing, and other waste material by destructively reentering Earth’s atmosphere.

Kounotori (“White Stork”) was named as a result of a public campaign; the name was chosen because in Japan a white stork carries an image of conveying an important thing (a baby, happiness, and other joyful things); “therefore, it precisely expresses the HTV’s mission to transport essential materials to the ISS.”

The spacecraft incorporates rendezvous technology developed forthe Engineering Test Satellite VII (ETS VII), a pair of satellites (Orihime/Hikoboshi) launched in 1997. The fuselage design incorporates lessons learned during the development of the H-II and H-IIA launch vehicles, and manned space technology used for the “Kibo” Japanese Experiment Module on ISS.

Vehicle Capability/Description

Kounotori resembles the European Automated Transfer Vehicle and Orbital ATK Cygnus spacecraft, in that it has a simple cylindrical design, save that it does not include outrigger solar panels. Instead, the solar panels are attached directly along the exterior of the fuselage. Like Cygnus and Dragon, Kounotori is berthed to ISS using the Station’s robotic arm rather than docking directly under its own power.

The spacecraft is 32.1 feet (9.8 m) long and a diameter of 14.4 feet (4.4 m). It includes a pressurized cargo module forward, which can be accessed once berthed and an unpressurized cargo module amidships, which is accessed via the robotic arm. The aft section of the spacecraft contains the propulsion module.

The interior of the Pressurized Logistic Carrier (PLC) is separated into two bay areas: the first rack bay (Bay #1) located on the hatch side, and the second rack bay (Bay #2) in the rear. Each bay accommodates four racks, accommodating up to eight racks per flight.

Mission Profile

After lifting off aboard the H-II launch vehicle, the payload fairing jettisons, and Kounotori separates from H-II to begin its three-day pursuit of ISS. When the spacecraft comes within 3.1 miles (5 km) of ISS, it drops below the station and approaches from the nadir (Earth) side. At a distance of 984 feet (300 meters), Kounotori rotates 180 degrees in the yaw direction and continues its approach to a parking point 98 feet (30 m) from ISS until all is ready for final approach. When ISS is ready to receive the spacecraft, Kounotori approaches to within 33 feet (10 m) of ISS. The astronauts command the spacecraft’s thrusters to disengage so the robotic arm can grapple Kounotori and berth it to an open node along the Station’s exterior.

Once berthed, the astronauts access pressurized cargo via the using the Common Berthing Mechanism (CBM). Unpressurized cargo is accessed and deployed via the robotic arm. Once all cargo and racks are unloaded from the PLC, trash and other discarded items will then be loaded into the pressurized cargo module.

When fully loaded, Kounotori is unberthed by the robotic arm and released. The spacecraft thrusters and restarted and the spacecraft moves away from the Station in a nadir direction and maneuvers to ensure a destructive reentry over a safe area of the ocean.

Vehicle Status

Kounotori has flown successfully to ISS six times since 2009, with an additional three missions planned on the current NASA manifest.

JAXA has announced plans for an advanced version of Kounotori called HTV-R (HTV-Return), which would include the ability to return hardware and other materials safely from ISS like Dragon or Soyuz. The design would change the forward pressurized module from a cylinder to more of an Apollo-like capsule shape. The pressurized carrier would be 12.5 feet (3.8 m) long and 13.8 feet (4.2 m) in diameter. It would have a total mass of 14,300 pounds (6,500 kg), with a pressurized volume of 590 cubic feet (16.7 m³) and a downmass capability of up to 3,527 pounds (1,600 kg).

Payloads

In addition to launching water, food, clothing, and other necessary equipment for the ISS, Kounotori has been responsible for launching numerous scientific payloads, including Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES), Hyperspectral Imager for the Coastal Ocean (HICO), Remote Atmospheric & Ionospheric Detection System (RAIDS), Space Communications and Navigation (SCAN) Tesbed, samples and other experiments for the Kibo module, Mouse Habitat Unit (MHU), Electrostatic Levitation Furnace (ELF), several CubeSats, and the CALorimetric Electron Telescope (CALET).

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