A Japanese spacecraft has blasted off into space on an ambitious journey to Mars. The mission, called Martian Moons Exploration (MMX), will try to land on Phobos, one of the two small moons orbiting Mars, collect a handful of rock and dust, and bring it back to Earth. If it succeeds, it will be the first mission in history to return samples from a moon of Mars.
The spacecraft lifted off on an H3 rocket from Tanegashima Space Centre in southwest Japan and is scheduled to reach Mars in August 2027. Landing on Phobos will be a major challenge because the potato-shaped moon is only about 20 kilometers wide and has very weak gravity. Before the main lander touches down, the spacecraft will drop a small rover named Idefix. Because gravity on Phobos is just one-thousandth of Earth's, the rover is expected to bounce across the surface for several minutes before it can come to a halt and search for a safe landing area.
After the rover scouts the ground, the main lander will touch down for about two hours. It will use robotic tools to collect at least 10 grams of soil and dust before flying back into space. The material will be packed into a small capsule and sent back across the solar system, with a planned return to Earth in 2031.
Scientists hope these tiny grains will answer a long-standing mystery: where did the moons of Mars come from? Researchers currently disagree on whether Phobos formed from debris after a giant space rock crashed into Mars, or whether it is an asteroid captured by the planet's gravity. Testing the rocks in laboratories on Earth should reveal how the moon formed, and the samples may even contain ancient grains blasted off Mars itself.