Humans have been sending spacecraft toward Phobos for decades, with mixed results. The Soviet Phobos 2 mission reached Mars in 1989 and returned observations of Phobos before contact with the spacecraft was lost. Russia’s Fobos-Grunt mission, launched in 2011 with the ambitious goal of returning material from Phobos, became stranded in Earth orbit.
NASA has considered its own dedicated missions. The proposed Aladdin sample-return mission wasn’t selected in 1998, while a later concept called PADME was designed around multiple flybys of Phobos and Deimos.
Now Japan is preparing for a much closer look. The Japan Aerospace Exploration Agency’s Martian Moons eXploration mission, better known as MMX, is scheduled to launch in Japan’s 2026 fiscal year. The spacecraft will travel to the Mars system, study both moons and collect material directly from Phobos.
JAXA plans to gather more than 10 grams of material from the moon before sending the samples back to Earth, with return currently expected around fiscal year 2031. Researchers could examine those fragments in laboratories with instruments far more powerful than anything practical to carry aboard a spacecraft.
The payoff could reach well beyond two potato-shaped satellites. If Phobos and Deimos are captured objects, their material could preserve clues about asteroids and the early solar system. If they formed from material ejected by a collision with Mars, their fragments could instead carry information about the young planet.
Either answer would help explain how planets acquire small moons — and why Mars ended up with two of the strangest satellites in our corner of space.
We created this article in conjunction with AI technology, then made sure it was fact-checked and edited by a HowStuffWorks editor.