Japan Plans Space Test of Hypersonic Missile-Tracking Technology

Japan is preparing to test its hypersonic missile-tracking technology in space, marking a major step in its defense modernization efforts as threats from China, North Korea, and Russia continue to grow. The technology demonstration will take place after the country’s new HTV-X cargo spacecraft completes its resupply mission at the International Space Station (ISS) — a mission that also symbolizes Japan’s dual-use approach to space and security.

The HTV-X, built by Mitsubishi Heavy Industries (MHI) for the Japan Aerospace Exploration Agency (JAXA), was launched from the Tanegashima Space Centre on Sunday aboard an H3 rocket. The spacecraft successfully arrived at the ISS on Thursday, where it was captured by the station’s robotic arm and docked. Onboard are 4.4 tonnes of cargo, including food, scientific materials, and research equipment for the station’s crew.

A Dual-Purpose Space Mission

While officially serving as a resupply mission, the HTV-X will later be used as a flying experimental platform in low-Earth orbit for up to 18 months, according to JAXA. Once its initial three-month ISS mission concludes, it will detach and begin a series of defense-oriented experiments — the most significant being the hypersonic missile-tracking trial.

The Japanese Ministry of Defence has installed infrared sensors aboard the spacecraft, designed to detect and track the heat signatures of hypersonic glide vehicles (HGVs) — weapons that can travel at over Mach 5 (five times the speed of sound) and maneuver unpredictably, making them extremely difficult to intercept.

Japan’s 2023 defense budget allocated 3.8 billion yen (approximately US$24.7 million) for this initiative. The ministry stated that the experiment aims to “utilize space experimental platforms” like the HTV-X to evaluate real-time detection and tracking capabilities against simulated hypersonic threats.

According to Japanese media, a projectile mimicking the flight characteristics of a hypersonic missile will be launched near Japan to assess the performance of the HTV-X’s sensors. If successful, the system could be scaled up for deployment on dedicated satellites, enabling a continuous hypersonic detection network in orbit.

Responding to Regional Hypersonic Advancements

Japan’s latest test comes amid a rapid escalation in hypersonic weapons development across Asia. China has operationalized the DF-17 hypersonic missile system, while Russia’s Avangard glide vehicle is already deployed on intercontinental ballistic missiles (ICBMs). North Korea, too, has claimed successful tests of its Hwasong-8 and Hwasong-16B HGV missiles.

These developments have alarmed Tokyo, as traditional radar-based early warning systems may be insufficient to detect hypersonic weapons in time to respond. Hypersonic missiles fly at low altitudes and unpredictable trajectories, slipping through radar blind spots and reducing reaction time to mere minutes.

Japan’s move toward space-based monitoring reflects a strategic shift to counter this threat. By using infrared sensors in orbit, Japan hopes to track high-speed objects in their glide phase, improving response time for allied missile defense systems — particularly those operated jointly with the United States.

Advancing Domestic Hypersonic Capabilities

In parallel with its tracking initiatives, Japan is also developing its own hypersonic glide weapon, known as the Hyper-Velocity Gliding Projectile (HVGP). Designed primarily for island defense, particularly in the context of tensions around the Senkaku/Diaoyu Islands, the HVGP has been in development since 2018. The weapon aims to strike moving or heavily defended targets with precision at extremely high speeds, reinforcing Japan’s deterrence posture.

HTV-X: A New Generation of Japanese Spacecraft

The HTV-X represents a significant technological evolution from its predecessor, the H-II Transfer Vehicle (HTV) — also known as Kounotori, meaning “White Stork.” Between 2009 and 2020, the original HTV series conducted nine successful resupply missions to the ISS.

The new spacecraft maintains a similar launch weight of about 16 tonnes, including 6 tonnes of cargo capacity in low-Earth orbit, but features extended operational capability. Unlike the HTV, which re-entered the atmosphere shortly after its missions, the HTV-X can remain active in orbit for up to one and a half years, allowing for a range of post-mission experiments in space technology, communications, and defense.

Step Toward the Space Defense

For Japan, this mission underscores a broader national strategy that integrates civilian space innovation with defense preparedness. As Tokyo faces an increasingly volatile regional security environment, the ability to detect, track, and ultimately counter hypersonic threats could redefine its defense posture within the U.S.-Japan security alliance.

If the HTV-X proves successful in tracking hypersonic projectiles, Japan could play a pivotal role in developing a multinational early-warning network — one that extends beyond the atmosphere and into the new frontier of space-based defense.

In a region where the race for hypersonic dominance is accelerating, Japan’s latest experiment signals that it intends not just to keep pace — but to take the lead in space-enabled security technologies for the Indo-Pacific.