Japan Launches Mars Moon Sample Return Mission

The Japan Aerospace Exploration Agency is launching the MMX spacecraft Tuesday. Its goal is the first sample return from Phobos, a moon of Mars.

• 10 grams of soil minimum is the target, from two landings.
• 13 instruments fly aboard, including a French-German rover named Idefix.
• 5 tons is the craft's weight, split across three modules.
• 2031 is the planned return, with a capsule landing in Australia.

Why it matters: Dozens of missions have gone to Mars since the 1960s, but its moons remain largely unstudied. Several Russian attempts to land on Phobos failed, including one in 2011.

• Scientists debate whether the moons are impact debris or captured asteroids.
• About 0.1% of collected material should originate from Mars, JAXA says.
• Project manager Yasuhiro Kawakatsu says the data could inform a Phobos base.

How 29 sources split on this story

What’s next: After arriving near Mars, MMX will spend three years studying Phobos and gathering samples. Idefix is set to land first, around 2029, for a 100-day survey.

• Landing is the hardest step: Phobos has 1/2,000th of Earth's gravity.
• The mission will also fly by Deimos to collect observations.
• Will the samples settle whether Phobos formed from Mars impact debris or a captured asteroid?
• Will the samples contain any traces of past microbial life from Mars?