Japan is preparing to launch a pioneering space mission to collect and return samples from Phobos, one of the two small moons orbiting Mars. Led by the Japan Aerospace Exploration Agency (JAXA), the Martian Moons eXploration (MMX) mission aims to investigate how Phobos and its smaller sibling, Deimos, formed and what their composition can reveal about the history of the Red Planet.
The mission is expected to take five years, with JAXA planning to launch the spacecraft aboard its H3 rocket on Tuesday, according to an Associated Press report published on 18 October 2026. The spacecraft is expected to reach the Mars region around August 2027 and return samples to Earth in 2031.
Scientists hope that material collected from Phobos could provide clues about the formation of the Martian moons, Mars’ geological history and potentially the origins of life in the solar system. The mission could also help researchers assess whether a Martian moon might serve as a base for future crewed missions to Mars, an objective being pursued by the United States, China and other countries.
Yasuhiro Kawakatsu, project manager for the MMX mission, highlighted the scientific importance of investigating the two moons. “Despite their potential importance, Martian moons have never been fully investigated,” Kawakatsu said. “They are known as the most important unclimbed mountains in the solar system.”
Japan is leading the international effort, with NASA and other national space agencies contributing equipment, sampling technology and communications support.
Scientists seek answers about the origins of Phobos and Deimos
Although dozens of missions have travelled to Mars since the 1960s, its moons remain comparatively unexplored. Several Russian attempts to land on Phobos, including a mission launched in 2011, have failed.
Phobos and Deimos take their names from the Greek mythological personifications of fear and terror, who were the sons of Ares, the Greek god of war. Mars is the Roman counterpart of Ares.
Scientists continue to debate how the moons formed. One theory suggests that they are remnants of debris produced when a large celestial object struck Mars. Another proposes that they are asteroids captured by the planet’s gravitational pull after originating elsewhere in the solar system.
JAXA officials believe that analysing samples collected directly from Phobos could help resolve the debate.
“We can almost certainly come to a conclusion by analysing soil samples,” said Kiyoshi Kuramoto, the mission’s principal investigator.
Phobos was selected as the primary sampling target because it orbits closer to Mars than Deimos and may therefore contain more material originating from the planet. JAXA officials estimate that Martian material could account for approximately 0.1% of the material collected from Phobos.
The moon measures about 27 kilometres (17 miles) across at its widest point and orbits Mars at a distance of approximately 6,000 kilometres (3,700 miles). It completes roughly three orbits around the planet each day.
Samples from Phobos could also help scientists understand Deimos, as the two moons are believed to have similar origins. The MMX spacecraft will therefore conduct observations of Deimos during its mission.
The journey will cover a substantial distance. Although Mars comes within approximately 55 million kilometres of Earth at its closest approach, Kawakatsu estimates that the spacecraft’s actual flight distance will be between 500 million and 600 million kilometres.
International mission faces difficult landing and sample collection
The MMX spacecraft comprises three modules: propulsion, exploration and sample return. Only the third module is designed to return to Earth carrying the collected material.
The spacecraft will carry 13 scientific instruments, including a rover jointly developed by France and Germany, a NASA sampling device, an instrument for measuring gamma rays and a deep-space communications device supplied by the European Space Agency. A Japanese radiation monitor will also collect data relevant to future crewed exploration of Mars.
The French-German rover, Idefix, is scheduled to reach Phobos ahead of the main sampling operation. During a planned 100-day mission around 2029, it will investigate the surface and help identify a suitable landing location for the Japanese spacecraft.
Using topographical information provided by the rover, the MMX team will select a relatively smooth and level area for sampling.
Landing on Phobos presents a significant engineering challenge because the moon has only about one two-thousandth of Earth’s gravity. The spacecraft could bounce off the surface during touchdown, making a controlled landing essential. To reduce this risk, the exploration module has four-legged landing gear equipped with shock-absorbing features.
The rover is also designed to maintain traction in low gravity, recover if it tips over and move slowly across the moon’s uneven terrain.
After landing, JAXA aims to collect at least 10 grams (0.35 ounces) of material through two sampling attempts using Japanese and American techniques. NASA’s sampling device uses pressurised gas to lift surface dust into a collection container, while JAXA’s coring method will retrieve material from a depth of approximately two centimetres (0.8 inches).
During the first attempt, the spacecraft will collect surface and underground material using both devices. A second landing will gather additional underground samples. Scientists believe collecting material from different locations could improve the chances of identifying potential traces of past microbial life originating from Mars.
The samples will be sealed inside a heat-protected capsule designed to withstand the extreme conditions of re-entry into Earth’s atmosphere. The return module is expected to land in Australia before being transported to Japan for detailed analysis. If successful, the MMX mission will deliver the first samples collected directly from a Martian moon.
Read More :