Space Transportation Systems H-II Transfer Vehicle "KOUNOTORI" (HTV)

Operation Completed

About H-II Transfer Vehicle "KOUNOTORI" (HTV)

H-II Transfer Vehicle "KOUNOTORI" (HTV) Key Space Transfer Vehicle

The International Space Station (ISS) represents a global partnership of fifteen nations. The ISS is a versatile research institute and a large observation platform in the unique environment of outer space. In this international project, Japan participates with its first manned space facility, Japanese Experiment Module "KIBO". "KIBO" means "hope" in Japanese.
Since 2009, six astronauts are always living in the ISS. For their prolonged stay there, it is imperative to ship food, clothes, and various experiment devices. To date, cargo transport has been carried out by the American Space Shuttle and the Russian Soyuz and Progress. Lately, the ATV (Automated Transfer Vehicle) of the ESA (European Space Agency) was launched, and a Japanese transporter, the H-II Transfer Vehicle "KOUNOTORI" (HTV),is also going to start playing a transportation role.


The KOUNOTORI is an unmanned cargo transporter to be launched by the H-IIB launch vehicle. It is designed to deliver up to six tons of supplies including food, clothes, and experiment devices to the ISS in orbit at an altitude of about 400 kilometers and return with spent equipment, used clothing, and other waste material.
The KOUNOTORI with waste material is incinerated when it makes a re-entry into the atmosphere. This transport operation involves a rendezvous with and docking to the ISS, in a situation requiring a highly reliable transfer vehicle.

The system was, therefore, being developed based on the rendezvous technical technology accumulated through work on the Engineering Test Satellite VII (ORIHIME/HIKOBOSHI), and with the application of fuselage design techniques accumulated during the development of the H-II and H-IIA launch vehicles, and manned space technology used for the Japanese Experiment Module "KIBO."
The development of the HTV is aimed at the practical use of a low-cost and highly reliable means of transport to the ISS. It is expected that the practical operation of KOUNOTORI will allow Japan to accumulate know-how that can serve as basic technology for its future projects on the Space Flyer Unit and on manned transportation.

Project Topics

May 21, 2020 Updated

Successful Launch of the H-II Transfer Vehicle "KOUNOTORI9" aboard H-IIB Launch Vehicle No. 9

At exactly 31 minutes and 00 seconds past 2 o’clock on the morning of May 21, 2020, the H-II Transfer Vehicle known as "KOUNOTORI9" (HTV9), the cargo transporter to the International Space Station (ISS), was launched aboard H-IIB Launch Vehicle No. 9 (H-IIB F9) from the JAXA Tanegashima Space Center. H-IIB Vehicle light up in blue before its launch ©JAXA Messa...

Characteristics of H-II Transfer Vehicle "KOUNOTORI" (HTV)

KOUNOTORI Components

KOUNOTORI is four meters across and about 10 meters long, a size large enough to accommodate a sightseeing bus.

It consists primarily of three parts:(1) A propulsion module installed at the rear and composed of main engines for orbit change, Reaction Control System (RCS) thrusters for position control, fuel and oxidizing reagent tanks, and high-pressure air tanks; (2) An avionics module installed in the center part, with electronic equipment for guidance control, power supply, and telecommunications data processing; and (3) A logistics carrier that stores supplies.

KOUNOTORI Specifications

Length Approx. 9.8m (including thrusters)
Diameter Approx. 4.4m
Total Mass Approx. 10,500kg
Cargo capacity
(supplies and equipment)
Max. 6,000kg
  -Pressurized cargo: Max. 5,200kg
  -Unpressurized cargo: Max. 1,500kg
Cargo capacity (waste) Approx. 6,000kg
Target orbit to ISS Altitude: 350km to 460km
Inclination: 51.6 degrees
Maximum duration of a mission Rendezvous flight period: about five days
Bearthed with the ISS: about 45 days
On-orbit emergency stand-by: about seven days