Japan has launched the Martian Moons eXploration mission, known as MMX, on an H3 rocket from the Tanegashima Space Center. Liftoff came at 4:41 a.m. Japan Standard Time on October 20, beginning a five year programme to study the moons of Mars and return the first physical samples from the Martian system to Earth.
The spacecraft is due to reach Mars in 2027 and enter a quasi satellite orbit around Phobos, the larger of the planet’s two moons, at about 22 kilometres across. It is planned to spend about three years on observations, surveying the surface and choosing sampling sites, and to collect at least 10 grams of material through two landing operations. A small rover, Idefix, built by the French and German space agencies CNES and DLR, is part of the surface programme. The return capsule is due to land in Australia in 2031.
The central scientific question is origin. Nobody knows whether Phobos and Deimos are asteroids captured by Mars gravity or debris thrown off the planet by a giant impact early in its history. Material analysed in Earth laboratories should distinguish the two, and with it say something about how water and organic compounds moved around the early solar system.
MMX extends Japan’s Hayabusa and Hayabusa2 asteroid sample return record into the Mars system, farther than any previous sample return has operated. Partners include NASA, the European Space Agency, CNES, DLR and Spain’s INTA, with ESA providing deep space communications.