Japan launches ambitious robotic mission to Martian moon Phobos

Japan launched a spacecraft on Tuesday on a historic mission to explore Mars’ moons and return samples to Earth, marking a major step in planetary science. The Martian Moons eXploration (MMX) probe, carried by Japan’s H3 rocket, lifted off from the Tanegashima Space Center in Kagoshima Prefecture shortly before dawn local time. Officials confirmed the spacecraft had separated from the rocket’s upper stage an hour later, triggering celebrations among flight controllers who erupted into cheers and embraces. The mission aims to investigate the origins of Phobos and Deimos, Mars’ two small, irregularly shaped moons. While NASA has landed multiple probes on Mars, no spacecraft has previously touched down on either of its moons. If successful, the MMX mission could deliver samples from Phobos to Earth by 2031. The spacecraft, weighing nearly 5 tons, is expected to reach Mars by late 2027, where it will enter orbit and conduct detailed studies of Phobos before deploying a French-German rover named Idefix. The probe will synchronize with Phobos’ orbit around Mars and release Idefix, a compact rover roughly the size of a microwave oven. Designed to bounce upon landing due to Phobos’ extremely weak gravity, Idefix will move at a painstaking pace of 1 millimeter per second once its solar panels are deployed. The rover is intended to scout safe areas for the main lander, which will descend to collect samples in late 2028 or 2029. The lander will gather at least 10 grams of material using drills and vacuum systems before returning to Earth. Phobos, the larger of the two moons, measures approximately 22 kilometers in diameter and is thought to be composed of material similar to asteroids. Scientists are eager to determine whether Phobos and Deimos originated from a massive impact with Mars or were captured asteroids. The findings could provide insights into the broader processes shaping the solar system and the conditions necessary for life on terrestrial planets. The MMX mission represents a collaborative effort involving Japan’s space agency, JAXA, along with NASA, the European Space Agency, and other international partners. It follows Japan’s prior successes in retrieving samples from asteroids, including the Hayabusa2 mission to Ryugu. The spacecraft will also conduct flybys of Deimos, the smaller of the two moons, before departing the Martian system in 2030. The mission faces considerable challenges, given the unpredictable nature of Phobos’ surface and the technical complexities of landing on such a small body. Engineers have accounted for potential issues, such as the rover sinking into loose regolith or becoming trapped between rocks. Despite these risks, the mission has generated enthusiasm among scientists and space enthusiasts alike. The H3 rocket used for the launch is a newer generation of Japanese launch vehicles, designed to carry heavier payloads and improve reliability. Its performance during the launch was described as nominal, with both stages firing as planned. The spacecraft is now en route to Mars, where it will begin its orbital phase before executing the complex sequence of maneuvers required to reach Phobos and execute the sample collection. As the probe travels through space, scientists anticipate gathering data that could reshape understanding of Mars’ moons and their role in the evolution of the solar system. The samples, once retrieved, will undergo extensive analysis to determine their composition and geological history. This information could inform future missions aimed at exploring Mars itself, including potential human expeditions.