Japan is preparing to send a spacecraft on a five-year journey to Mars' mysterious moons, and the rocket carrying it will be making a crucial flight of its own.
The Japan Aerospace Exploration Agency is scheduled to launch its Martian Moons eXploration mission aboard the H3 rocket on October 20, with liftoff planned from the Tanegashima Space Centre in Japan.
The mission, which features contributions from NASA and other international partners, aims to study Phobos and Deimos, the two small moons of Mars, and bring samples from Phobos back to Earth in 2031.
The H3 is Japan's next-generation flagship rocket, developed jointly by the space agency and Mitsubishi Heavy Industries to replace the older H-IIA rocket and make satellite launches more affordable and flexible.
Standing up to 63 metres tall depending on its configuration, the H3 can be fitted with varying numbers of engines and solid rocket boosters to accommodate different types of missions.
The development budget for the rocket rose from an initial USD 1.2 billion to over USD 1.5 billion, as the investment is intended to give Japan a dependable domestic launch system and help it compete for commercial satellite-launch contracts.
The primary task of the H3 for this mission is to carry the spacecraft away from Earth and set it on the correct trajectory toward Mars, after which the rocket's role will be complete.
After travelling for roughly a year, the spacecraft is expected to reach the Martian system in 2027 to study both moons, collect at least 10 grams of material from Phobos, and return the samples to Earth in 2031.
The H3 programme has previously faced setbacks, including a failure during its first flight in March 2023 and a subsequent investigation following its eighth flight, making its performance on this upcoming mission particularly important for Japan's broader space ambitions.
Beyond this scientific endeavor, the H3 is intended to launch commercial satellites and other spacecraft, ensuring that Japan maintains independent access to space while remaining competitive in the global launch market.