Japan is preparing to launch the first round-trip mission to Mars’ orbit, targeting the retrieval of physical samples from Phobos, one of the planet’s moons, in a bid to advance understanding of Mars and its potential for life. The mission, known as Martian Moons eXploration (MMX), is set to depart today from the Tanegashima Space Center aboard an H3 rocket, embarking on a five-year journey that includes approximately one year each way for travel and three years dedicated to data collection.
The mission aims to shed light on the origin of Phobos and its smaller companion, Deimos, whose formation remains a major question in planetary science. The moons may either be captured asteroids or debris resulting from a massive collision between Mars and another celestial body. The material gathered could contain vital clues about Mars’ history and its capability to support life. If Phobos is an asteroid, the samples might reveal information about the delivery of water and organic compounds to the inner solar system early in its history. Conversely, if the moons originated from a planetary impact, they may harbor Martian matter potentially linked to ancient life on the red planet.
MMX is a collaborative effort involving Japan’s space agency, JAXA, along with contributions from U.S. and European partners. The spacecraft will deploy a wheeled rover named Idefix, inspired by a dog character from the Astérix comic series, to explore the surface of Phobos. This mission follows Japan’s history of successful sample return efforts, notably the Hayabusa asteroid missions, positioning the country as a leader in this specialized field.
The launch window for the mission is dictated by the alignment of Earth and Mars, which occurs once every 26 months to allow an energy-efficient trajectory. The H3 rocket, which has experienced two failures in nine previous launches, will face intense scrutiny during takeoff. Challenges will also include landing on and departing from Phobos, which has extremely low gravity and an uncertain surface environment.
Scientists see MMX as a pivotal step toward more ambitious Mars exploration, including future crewed missions. While the samples returned from Phobos will not replace the Martian surface samples currently stored by NASA’s Perseverance rover, which awaits a separate retrieval mission, they are expected to complement ongoing research and offer “tantalizing” evidence about Mars’ past habitability.
Experts highlight that the mission will provide valuable insights into the logistics of entering and leaving Mars’ orbit—crucial knowledge for any human expedition. Although it will not address all aspects of landing and ascent from the Martian surface, the MMX mission is considered a groundbreaking effort that will reduce risks for future crewed journeys and deepen scientific understanding of small bodies within the solar system.