The cargo transporter Kounotori safely completed its final mission to the International Space Station (ISS) on August 20.
The nine successful Kounotori missions so far have each supported ISS activities, thereby raising Japan’s international profile, and making a strong contribution to manned space technology.
Building on this success, Japan is now looking toward its first manned lunar exploration.
Magnificent Maiden Launch
Kounotori’s maiden launch took place in the early hours of September 11, 2009, from the Tanegashima Space Center in Kagoshima Prefecture.
Shaped like a cylinder, and with a total length of 10 meters and a diameter of 4.4 meters, the Kounotori resembled a sightseeing bus. Attached to a newly developed H2B rocket — the largest rocket made in Japan — the Kounotori shot up into the night sky, painting it orange while making a thunderous noise. The throng of onlookers was dazzled by the experience.
The maiden launch happened just five days before Yukio Hatoyama, leader of the former Democratic Party of Japan (DPJ), became the country’s prime minister. Society was entering a new era with a sense of expectation and excitement, and Japanese space development was taking a new step forward.
As time went by, confidence in the former DPJ dwindled, but Kounotori transport missions continued to take place at a rate of about one per year. Japan gained the trust of countries and regions such as the United States, the European Union, and Russia. The total weight of supplies carried by the Kounotori had reached approximately 50 tons.
A Triumph for ‘Monozukuri’ Japan
The Kounotori development process stretches back to 1994. The U.S. requested that Japan shoulder some of the burden in terms of the transport of supplies — after the latter had chosen to focus on developing its Kibo laboratory instead of paying to take part in the ISS plan.
Around that time, Japan had just launched its first domestically made H2 rocket, and the U.S. did not have full confidence in Japan’s space technology.
“The Americans viewed us in an extremely severe manner, and perfecting the design was a real ordeal. However, that ultimately led to the success of the nine Kounotori missions,” recalled Japan Aerospace Exploration Agency Vice President Hiroshi Sasaki, who was involved in the Kounotori development from the start.
One of the Kounotori’s key features is its temperature-adjusted and pressure-adjusted cargo bay, which enables astronauts to perform tasks in space while wearing casual clothes. This also means that fresh fruit and vegetables can be delivered to astronauts on the ISS, providing a more pleasant experience to those in space.
From a safety perspective, ISS docking is a matter of life and death as there is a risk of crashing, so it is imperative that the Kounotori is reliable.
The Kounotori needs to approach a point that is about 10 meters away from the ISS, connect with the ISS robot arm, and then dock. It also needs to exactly match the direction and speed of the ISS, which travels at about eight kilometers per second.
Nevertheless, after overcoming various issues, the first Kounotori was completed after 15 years of hard work. It safely burned up upon re-entering the Earth’s atmosphere after a transport mission.
In the words of someone involved in the project at the time, the successful mission was a “triumph for ‘monozukuri’ [make things] Japan”.
Expanding the Program to Test New Technology
Initially, it was planned that there would be just seven Kounotori launches, but an extension to the ISS plan resulted in nine launches. The seventh launch in 2018 took on a new twist. The Kounotori transported a small re-entry capsule to the ISS, and collected into it about one kilogram’s worth of test samples from the ISS.
Just before landing in the Pacific Ocean off Minami Torishima (Tokyo), the re-entry capsule injected its engine to soften the impact of landing. This kind of technology is necessary to resist heat upon re-entering the Earth’s atmosphere, and can also be used by manned spacecraft.
The Kounotori has led to a huge improvement in Japanese space technology. The development of cargo bays and re-entry capsules means that manned spacecraft is a realistic goal.
Future Missions to the Moon
In fiscal 2021, it is planned that Kounotori technology will be passed on to Kounotori's successor, the “HTV-X,” which will be launched with a next-generation H3 rocket. A nickname for the successor has yet to be decided.
The load that the successor can carry will be 1.5 times greater. The larger fuel tank and solar panels will mean a longer flight time, with a mission to the moon becoming a possibility.
In the joint exploration declaration signed between the U.S. and Japanese governments in July 2020 — which included details on a maiden Japanese moon landing — there was also text concerning transport of supplies by the Kounotori’s successor to “Gateway,” which will orbit around the moon.
The development of automatic docking technology is now also in demand.
Arguably, the Kounotori missions were the “travel expenses” needed for getting Japanese astronauts closer to the ISS. The Kounotori’s successor — which will deliver supplies to Gateway — could be the key to getting Japanese scientists to the moon.
The technology and legacy of the Kounotori are both vital for Japan’s continued space development.
(Read the article in Japanese at this link.)
Author: Shinji Ono, Science News Department, The Sankei Shimbun