Japanese mission seeks to unravel the origin of Mars' moons

The Martian Moons eXploration (MMX) mission is about to be launched to explore Phobos, the largest moon of Mars. The probe, developed by the Japan Aerospace Exploration Agency (JAXA), has the main objective of bringing samples from Phobos back to Earth. These samples may finally clarify how Phobos and Deimos, the other Martian moon, formed ¹.

Mission details

The launch of the MMX is scheduled for October 20, 2026, from the Tanegashima Space Center in Japan. The probe is expected to reach Mars in August 2027 and then enter orbit around Phobos to map its surface in detail. During this phase, the surface of Deimos will also be observed ¹.

After the completion of the mapping, the JAXA team will choose an appropriate location for the MMX to land on Phobos. During one or two brief landings, the probe will perform two main tasks: release a small rover called IDEFIX and collect soil samples. The rover will be the first to operate on such a small celestial body, helping to confirm the viability of wheeled rovers in low-gravity environments ¹.

Sample collection is the main focus of the mission. The MMX has two sampling devices: one that uses a gas jet to lift dust and pebbles, and another that drills into the soil to obtain samples up to a few centimeters deep. The collected samples will be stored in the probe, which will then return to Earth, with an expected arrival in 2031 ¹.

The analysis of these samples on Earth should resolve the long-standing debate about the origin of Phobos and Deimos. For over a century, scientists have debated whether these moons are captured asteroids or formed from an impact on Mars, similar to the formation of Earth's moon. Their shapes and surfaces resemble asteroids, but their circular orbits around Mars' equator suggest an impact. The composition of the samples should definitively clarify this issue ¹.

The MMX mission is an international collaboration involving JAXA, NASA, the French space agency (CNES), the German Aerospace Center (DLR), and the European Space Agency (ESA) ².