JAXA has scheduled its Martian Moons eXploration spacecraft to lift off from Tanegashima Space Center aboard an H3 rocket at 4:41:03 a.m. Japan time on October 20. That is 7:41:03 p.m. UTC on October 19, which explains why the mission’s launch date appears differently across regions. NASA also lists the launch as October 19 in the US and October 20 in Japan.
Known as MMX, the spacecraft is designed to study Mars’s two small moons, Phobos and Deimos, before landing on Phobos and collecting material for return to Earth. If the plan succeeds, ESA says it would mark the first landing on Phobos and the first sample brought back from the Mars system.
A five-year round trip
The JAXA-led mission is expected to reach Mars in August 2027 after a cruise of about a year. It will then observe Phobos and Deimos from orbit, deploy the 25-kilogram Idefix rover to survey Phobos’s surface and prepare for the main spacecraft’s landing.
NASA says sample collection is planned for no earlier than December 2028. MMX carries two collection systems: a corer intended to reach about two centimeters below the surface and a pneumatic sampler that uses pressurized gas to move loose material into a container. JAXA’s goal is to return more than 10 grams of Phobos material.
After roughly three years in the Mars system, MMX is scheduled to begin the trip home in 2030. Its return capsule is planned to enter Earth’s atmosphere in 2031 and land in Australia, where the sample would be recovered and transferred to JAXA’s Institute of Space and Astronautical Science for study.
What the sample could resolve
Scientists are still debating how Phobos and Deimos formed. One hypothesis holds that the moons are captured asteroids from the outer solar system. Another proposes that they formed from debris thrown into orbit by a giant impact on young Mars. Remote observations and laboratory analysis of the returned material could help distinguish between those possibilities while revealing more about the early Mars system.
The mission is an international effort. ESA has provided a transponder and power amplifier for deep-space communications, and its Estrack ground stations are expected to help send commands and receive telemetry and science data. NASA’s contributions include the MEGANE gamma-ray and neutron spectrometer, the pneumatic sampler, Deep Space Network communications and navigation support, and support for US scientists on the mission team. France’s CNES and Germany’s DLR jointly developed Idefix.
