The MMX probe will land on Phobos to collect samples that may include grains blasted off Mars. Finding water or organic compounds would offer key insights.
An artist's rendering of the MMX spacecraft near Mars. (Courtesy of JAXA)
The Martian Moons eXploration (MMX) spacecraft, launched on October 20, aims to carry out the world's first sample-return mission from a Martian moon. It is scheduled to enter orbit around Mars around August next year.
If successful, this will mark Japan's first full-scale exploration of the Martian system. Over roughly three years, the spacecraft will gather a wealth of detailed data on Mars and its moons.
Exploring Phobos
Phobos, one of Mars's two moons, orbits about 6,000 kilometers above the planet's surface. It measures roughly 20 to 30 kilometers across, is potato-shaped, and has extremely weak gravity—about one two-thousandth that of Earth.
After entering orbit around Mars, MMX will observe Phobos from above. It will then deploy a small rover, jointly developed by France and Germany, to survey the moon's surface in detail. The findings will help determine where MMX should land.
The spacecraft plans to land on Phobos twice, at two different locations, spending about two to three hours at each site. Its goal is to drive a cylindrical sampling device about eight centimeters into the surface and collect at least 10 grams of material.
Choosing the landing sites will be crucial, as sampling would be difficult if the device encountered solid bedrock.
In addition to the cylindrical sampler, MMX will carry a device provided by NASA. The device blows gas onto the surface and captures sand particles kicked up into the air, making it easier to collect samples even from rocky terrain.
The main advantage of bringing samples back to Earth is that they can be analyzed in great detail. If water or organic compounds are found, scientists may gain insights into the origins of life. The samples could also reveal other potentially useful resources.
Phobos is also believed to contain Martian sand that was blasted into space when meteorites struck Mars. Researchers estimate that if the mission collects 10,000 grains of sand, around 10 to 100 may have originated on Mars itself.
The spacecraft will also carry 8K and 4K Super Hi-Vision cameras jointly developed by Japan's public broadcaster, NHK, and the Japan Aerospace Exploration Agency (JAXA). These cameras will transmit high-resolution images of Mars, Phobos, and other targets back to Earth.
Preparing for Future Missions
MMX will also help Japan develop the technologies needed for round trips between Earth and Mars. Slowing the spacecraft down to enter orbit around Mars places considerable strain on the vehicle, while returning to Earth will require sufficient thrust to escape Mars's gravity. The knowledge gained will also support future crewed missions to Mars.
Japan's previous sample-return mission from another celestial body was Hayabusa2, an asteroid explorer that returned to Earth in 2020.
Hideaki Miyamoto, a professor at the University of Tokyo who has been involved in MMX since its early planning stages, emphasizes the mission's importance: "Bringing samples back to Earth allows us to conduct research with dramatically greater certainty. We are bound to discover something unexpected, which makes this mission extremely significant."
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Author: Shinji Ono, The Sankei Shimbun