Japan prepares MMX mission to return samples from Martian moon

Japan is preparing to launch its MMX spacecraft from Tanegashima Space Center to collect material from Phobos, a moon of Mars, and return it to Earth. The BBC reports a departure scheduled for 0441 local time on 20 October 2026; the Associated Press says the spacecraft will fly aboard an H3 rocket.¹²

Journey to Phobos

The launch accounts differ on timing. While the BBC specifies 20 October, The New York Times describes a Monday departure in its report published on 19 October. Both describe a mission bound for Phobos, with the prospect of returning the first samples collected from the Martian system.¹³

Led by the Japanese Space Agency, according to the BBC, MMX is expected to reach Phobos in August 2027. AP gives the same month for arrival at Mars and describes a spacecraft built with three modules. The BBC says MMX will study Deimos before concentrating on Phobos.¹²

The BBC reports that the mission will send a small rover onto Phobos to explore and help identify a landing site. The spacecraft is then intended to gather material with a robotic arm and two samplers. AP says the agency's coring technique will reach roughly two centimetres beneath the surface.¹²

The target is to return 10 grams of material, according to the BBC. Its account places the sample capsule's return in 2031, with a landing in the Woomera desert in South Australia. Sara Russell, a Natural History Museum professor and the mission's deputy for sample analysis, said: "There hasn't yet been a successful mission to go to Phobos and bring a bit back to Earth."¹

Testing the moons' origins

The samples could help resolve two explanations for how Mars acquired its moons, the BBC reports. One proposes that an impact on Mars produced debris that formed the moons. The other suggests Phobos and Deimos were asteroids from the outer Solar System that Mars captured.¹

The BBC says the material's chemistry and minerals could distinguish those possibilities. It describes Phobos as about 20 kilometres across and Deimos as about 10 kilometres across. The returned material could also include grains from Mars because of Phobos's proximity to the planet, according to the report.¹

Other sample-return plans provide a separate backdrop. The BBC reports that the NASA–ESA Mars Sample Return mission has been effectively cancelled following a halt in funding by the US Congress. That project was intended to retrieve samples stored by Perseverance. China plans to launch a Mars sampling mission in 2028 and return material in 2031, the BBC says.¹