by Douglas Messier
On May 21, a Japanese H-IIB rocket roared off the launch pad with the ninth and final H-II Transfer Vehicle (HTV) (Kounotori) resupply ship to the International Space Station (ISS).
But, the launch was not the end of the line for Japanese cargo delivery. The Japan Aerospace Exploration Agency (JAXA) is developing an improved variant known as HTV-X to supply the space station and possibly the lunar Gateway.
HTV-X’s lighter weight will allow it to carry heavier cargo. Unlike it’s predecessor, the new cargo ship will have exterior space where unpressurized cargo will be carried, freeing up room inside the pressurized module.
“With regard to pressurized cargo, a shelf structure that allows more efficient use of space has been adopted, so that more pressurized cargo can be mounted than the Kounotori,” JAXA said on its website.
“The HTV-X supports cargo that requires power, such as freezers and small animal breeding cages, that could not be stored with the Kounotori,” JAXA added. “For example, we support scientific experiments on the space station by transporting experimental samples that need to be kept cool during transport, such as the cryogenic courier service we use on the ground.”
HTV-X will have a side hatch that will allow for the late loading of cargo such as fresh foods and experiments. The current HTV does not such a hatch.
JAXA plans to launch the first HTV-X in 2022 aboard the nation’s new H3 booster. The new rocket is designed to be a more affordable alternative to the H-IIA and H-IIB launch vehicles.
JAXA will use HTV-X to conduct experiments and test advanced technologies in Earth orbit for up to 18 months after the vehicle completes delivering cargo and departs the space station.
The Japanese space agency is also considering adapting HTV-X to delivery cargo to the lunar Gateway. The Gateway will be a human-tended station placed in orbit around the moon that will serve as a staging base for astronauts visiting the lunar surface.