Japan launches probe to collect samples from Mars moon Phobos

Japan will launch a spacecraft on April 18 to visit Phobos, the larger of Mars’s two moons, and bring back the first-ever samples from a Martian satellite. The launch will take place at the Uchinoura Space Center in Kyushu, using an H3 rocket built by Mitsubishi Heavy Industries. The probe, named “Phobos Sample Return Mission,” is part of Japan’s renewed effort to explore the Red Planet after a 28‑year gap since its first Mars probe, Nozomi, failed in 1998.

Phobos is a key target for understanding Mars’s history. Scientists believe it may have formed from debris left over after a giant impact or could be a captured asteroid. Studying its surface composition could reveal whether Mars once had water or how its crust has evolved. Japan’s agency, JAXA, has teamed with the University of Tokyo and the Institute of Space and Astronautical Science to analyse the samples in its own laboratories. The mission follows a decade of Mars orbiter work by JAXA, including the successful Mars Orbiter Mission and the Mars 2020 rover, and reflects a growing global focus on sample‑return missions that can deliver pristine material to Earth.

The spacecraft will launch on a 4‑month trajectory, arriving at Phobos in early 2025. It will use a small lander to touch down on the moon’s regolith and collect rock and dust with a robotic arm. The samples will be sealed in a sterile container and stored in a pressurised chamber. After a brief stay, the lander will lift off and rendezvous with the orbiter, which will return the payload to Earth via a ballistic re‑entry capsule. The mission’s budget is about 3.5 billion yen (roughly 30 million USD), and JAXA plans to keep the capsule in a high‑altitude orbit for several months before re‑entry, allowing a controlled descent over the Pacific Ocean.

If successful, the Phobos sample‑return mission will be the first time any country brings Martian moon material to Earth. The data could help confirm whether Phobos shares a common origin with Mars or is an interplanetary relic, and it will inform future missions that may use Phobos as a stepping stone to Mars. JAXA will release preliminary results in 2026, and the findings could shape the design of the next generation of Mars landers and rovers, as well as international cooperation on deep‑space exploration.