Japan's MMX Mission to Target Mars Moon Phobos for Soil Samples

Japan's Martian Moons Exploration (MMX) mission is preparing for launch, with its primary objective being to collect soil samples from Phobos, the larger of Mars's two small moons. The mission will not land on Mars itself, focusing instead on unraveling the origins of the Martian moons and examining the wider evolution of Mars and its local space environment, according to Phys.org.

The MMX mission is scheduled to lift off on Monday, October 19, at 20:41 BST on an H3 rocket from the Tanegashima Space Center in southern Japan. This launch marks the beginning of a five-year mission, during which the spacecraft will orbit and explore Phobos, deploy a lander, touch down, and collect soil and small pebbles. These samples are intended to be delivered to Earth for laboratory study, a process described as a world first.

Led by the Japanese Aerospace Exploration Agency (Jaxa), MMX is a collaborative effort involving the US, France, Germany, and the European Space Agency (Esa). Scientists aim to determine Phobos's chemical composition, which could help differentiate between theories regarding the moons' formation, such as captured asteroids or material coalesced after an asteroid collision with Mars.

Grabbing samples from Phobos presents significant challenges, as evidenced by Russia's failed Phobos Grunt mission in 2011, which did not fire its engines towards Mars after reaching low Earth orbit. Jaxa, however, has a proven track record, having successfully returned samples from asteroids with its Hayabusa missions (2003-2010 and 2018-2020).

MMX will trial sophisticated sampling techniques designed for Phobos's low gravity, which is about 0.1% of Earth's gravitational pull. The mission will also test communication between the spacecraft and a newly developed ground station. The spacecraft is expected to reach Mars in August 2027, taking a year to travel, before orbiting Phobos approximately a month later.

The spacecraft comprises three modules: a propulsion module for orbital maneuvers, an exploration module equipped for landing and sample collection, and a return module to transport samples to Earth. It will utilize 13 science instruments, including high-resolution cameras Tengoo and Orochi for surface mapping, a laser altimeter (Lidar) for contour mapping, an infrared spectrograph MIRS for mineral surveys, and a gamma ray and neutron detector Megane for elemental composition. Data will also be gathered on Mars's smaller moon, Deimos.

In early 2029, the MMX exploration module will deploy Idefix, a microwave oven-sized rover developed jointly by Jaxa, the French space agency Cnes, and the German Aerospace Center (DLR). Idefix will descend onto Phobos's surface from an altitude of 40 to 100 meters and operate for about 100 days, using sensors like a Raman spectrometer and radiometer to inform the exploration module's landing site decision.

The exploration module is slated to land on Phobos in 2030, remaining on the surface for about 2.5 hours. It plans to extract samples once, or possibly twice by landing at a different location, to gather at least 10 grams of material. Sampling options include the C-sampler, which drills a core up to 2cm deep to collect material unaltered by solar radiation, and the P-sampler, a backup that uses nitrogen gas to blast soil into a collection chamber.

After sample collection, the spacecraft will leave Phobos, separating from its landing gear, and travel back to Earth, arriving in 2031. Upon approach, it will eject its sample probe, which will descend via parachutes in Australia for recovery and transport to Japan. A potential side-benefit of the mission is the possibility of finding material from Mars within the Phobos samples.

What to watch: The mission's journey to Mars and its complex sampling operations.

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