Thursday, May 21, 2015

Japan to Improve Its HTV Cargo Spacecraft

HTV-4 spacecraft docked to the ISS. Credit: NASA/JAXA

Japan wants to upgrade its homegrown H-II Transfer Vehicle (HTV) also known as Kounotori, an automated cargo spacecraft used to resupply the International Space Station (ISS). On Wednesday, the country’s Education, Culture, Sports, Science and Technology Ministry unveiled the plan to improve the HTV craft at a meeting of a panel of space development experts. The ministry plans to include relevant expenses in its budget estimate for next fiscal year if the plan is approved by the government’s Committee on the National Space Policy.

The spacecraft is four meters across and about 10 meters long, its current weight is 10.5 tons. Manufacturing and maintenance costs will be halved from about $165 million by reducing the spacecraft’s weight by about 30 percent while maintaining its transport capacity of 6 tons.

The development period is still unknown.

HTV is designed to deliver 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 spacecraft with waste material is incinerated when it makes a re-entry into the atmosphere.

The spaceship consists primarily of three parts: 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; an avionics module installed in the center part, with electronic equipment for guidance control, power supply, and telecommunications data processing; and a logistics carrier that stores supplies.

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 the spacecraft 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.

Four HTV spaceships have been launched to space so far. The first craft was launched on Sept. 10, 2009. Five subsequent missions are planned—one each year for 2015–2019.

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