A Japanese space mission is about to launch towards Mars. But it will not land on the planet itself. Instead, the Martian Moons Exploration (MMX) mission will focus on Phobos, the bigger of Mars’s two small moons.

The mission will lift off on Monday October 19 at 20:41 BST on an H3 rocket from the Tanegashima Space Center, in the south of Japan.

This will start a five-year mission, during which the spacecraft will orbit and explore Phobos, deploy a lander, touch down and collect soil and small pebbles. In a world first, these samples will be delivered to Earth for study in laboratories.

MMX is led by the Japanese Aerospace Exploration Agency (Jaxa), in collaboration with the US, France, Germany and the European Space Agency (Esa). The overall science objective is to unravel the origins of the two Martian moons, the smaller of which is called Deimos. Mission scientists also want to examine the wider evolution of Mars and its local environment in space.

We still have no clear understanding of how the red planet got its moons. These natural satellites could have been hapless asteroids that were passing by Mars when they got captured by its gravity.

Another possibility is that that they formed when an asteroid collided with Mars, causing rocky material to be thrown out into space. Gradually, this material coalesced into Phobos and Deimos. The MMX mission will give us Phobos’s chemical composition, which could help distinguish between theories.

Grabbing samples from Phobos will be no easy task,........

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