Such is the unknown and exclusive GPS system developed by Japan, the QZSS
- Japan wants its QZSS to divorce itself from the US GPS
- Constellation positioned over Japan reaching as far as Oceania
Japan has been operating its own navigation satellite network since November 2018, which it has just expanded by placing another link, the sixth, in space, of its Quasi-Zenith Satellite System, or QZSS. It is a constellation that offers high-precision positioning data to millions of users in the Japanese islands, the Far East and even Australia and parts of New Zealand.
Japan's regional satellite-based navigation, positioning and timing network is unique. It is based on the North American global positioning system (GPS), and is therefore often referred to as ‘the Japanese version of GPS’. It uses the term ‘Quasi-Zenith’ because several of the satellites are positioned almost directly above the Japanese archipelago, which means that their signals reach smartphones and receiving devices with a high degree of quality and precision.
The Tokyo authorities see the QZSS constellation as an initiative of national sovereignty. Proof of this is that the Japanese Aerospace Exploration Agency (JAXA) and the Ministries of Communications; Science and Technology; Economy, Trade and Industry, as well as that of Infrastructure and Transport are all involved in the project. But Japan aspires to achieve full technological autonomy from Washington in the short term, an issue that Prime Minister Shigeru Ishiba, 68, has discussed with Donald Trump during their very recent meeting at the White House.
The meeting of the two leaders took place just five days after a new Japanese H3 launcher fired from the Tanegashima space base put another satellite in the QZSS constellation into orbit. With a mass of 4.9 tonnes, the spacecraft, named Michibiki-6 (which means ‘guide’ in Japanese), has been developed to provide complementary signals and correction data, thereby increasing the degree of accuracy and reliability of the services provided by the North American GPS architecture in the Indo-Pacific region.
Michibiki-6 also carries a military payload, the result of an agreement in 2020 between the Japanese National Space Policy Secretariat and the US Space Force. It is a secret American optical sensor developed by the Lincoln Laboratory of the Massachusetts Institute of Technology (MIT), whose function is recognised by the head of the Indo-Pacific Space Force, General Anthony Mastalir, as being to ‘monitor areas of common strategic interest’. Another similar sensor is installed in the Michibiki-7, which is being built by Mitsubishi Electric Corporation (MELCO) for launch in 2026.
Japan wants its QZSS to divorce itself from the US GPS
The commitment of Prime Minister Shigeru Ishiba - inherited from his predecessors in office: Fumio Kishida (2021-2024), Yoshihide Suga (2020-2021) and Shinzo Abe (2012-2020) is to ‘guarantee easy access to positioning services to an even greater number of users’, details the prime minister's statement released after the success of Michibiki-6. To achieve this, Tokyo needs to increase the number of QZSS network in-flight platforms: first to seven satellites and then to 11.
And the fact is that, according to the so-called Official Cabinet, the prime minister's body responsible for Japan's space policy, the Quasi-Zenith satellite system contributes to ‘strengthening cooperation between Japan and the United States, improving industrial competitiveness, disseminating the Japanese lifestyle and the activities of public organisations’. It also ‘guarantees national security’ by providing navigation and synchronisation capabilities independent of global systems administered by other powers, such as GPS, which is under the control of the Pentagon.
The brains behind the Japanese constellation is Professor Koji Terada, who emphasises that the elliptical orbits of QZSS have been designed so that, when the constellation has seven satellites, it is possible to ensure that ‘at least three or four are positioned over the zenith of the skies over the Japanese archipelago at all times’. In this way, it will be possible to capture and maintain QZSS signals and minimise the interruptions caused by tall buildings and uneven terrain.
By expanding the satellite fleet, we will be able to offer ‘better coverage to the inhabitants of densely populated cities,’ emphasises Koiji Terada, ‘ensuring that the signals are not reflected by large skyscrapers and that they reach users in mountainous areas’ on the different islands of the archipelago. But a minimum of seven satellites is required for the QZSS system to be even more accurate and to operate independently of GPS, which is the aim as soon as possible.
The advisor to the National Space Policy Secretariat of the Cabinet of the Prime Minister of Japan, Air Colonel Shinichiro Tsui, stresses that the QZSS constellation is ‘vital’ for Japan's sovereignty. One example is that, in order to alert the population to serious threats, earthquakes, tsunamis or any type of disaster and emergency, the J-Alert code, which warns of the possible impact of ballistic missiles, began operating in April 2024. And the L-Alert code was instituted to disseminate evacuation instructions. A signal authentication notification was also launched, which verifies whether the message received by the user is reliable and secure.
Constellation positioned over Japan reaching as far as Oceania
The regional QZSS network complements and improves the coverage and accuracy of the GPS constellation, with solutions and applications tailored to the specific needs of the Indo-Pacific countries. To achieve this, the network has four ground verification and tracking stations in Japan and another five outside the country, in Bangalore (India), Bangkok (Thailand), Canberra (Australia) and on the North American islands of Hawaii and Guam, in the Pacific Ocean.
Not all the satellites are in geostationary orbits, that is to say, they do not always occupy the same position in relation to the Earth's surface. Several of them move, tracing a figure-of-eight trajectory in space that covers both Japan and the Far East and a large part of Australia and New Zealand. This arrangement makes it easier for public and private institutions in Japan and other countries in the area to use QZSS signals for multiple applications, including the automatic driving and navigation of autonomous vehicles, transport by road, sea, air, rail and for the movement of robots.
The Japanese rocket that successfully launched Michibiki-6 into the QZSS constellation is the fifth in the H3 series, a launch vehicle with two disposable, i.e. non-reusable, propulsion stages. Its inaugural launch on 7 March 2023 ended in resounding failure just over 14 minutes after take-off. Its loss also led to the destruction of the 3-tonne ALOS-3 radar technology observation satellite that it was taking into space.
Fortunately, after almost a year in dry dock undergoing revisions and improvements, the next three H3 flights throughout 2024 have ended positively. The fifth and final one too: the Michibiki-6 mission on 2 February. So, with four successes in five launches, the H3 developed by the powerful multinational Mitsubishi Heavy Industries (MHI) has become JAXA's new workhorse in space to compete in the global market.
So far, MHI's H3 has already received two major accolades. The first was from the French communications satellite operator Eutelsat, which last September contracted several missions to launch its new generation of OneWeb satellites from 2027. The second was in October, when the Space Agency of the United Arab Emirates announced that in 2028 it would entrust its scientific probe bound for the asteroid belt to the H3. For the remainder of 2025, JAXA has scheduled five H3 missions, one of which is the inaugural flight of the HTV-X unmanned automatic cargo spacecraft to the International Space Station.