An ambitious new mission seeks the origin of the moons of Mars

Abstract

Two mysterious moons whirl around Mars. Despite the many missions to the planet, not a single one has focused on its satellites — or, rather, not a single successful one. Three previous Martian moon explorers, launched by Russia or the Soviet Union, all failed. Now Japan is trying its luck with a high-risk venture that aims to grab rocks from the larger Martian moon and bring them to Earth for laboratory analysis. “It’s a very scary mission,” says Tomohiro Usui of the Japan Aerospace Exploration Agency (JAXA) in Sagamihara. The spacecraft’s daunting tasks will include multiple touchdowns on a heavily cratered world. The chief goal is to settle a debate over the origin of the moons (1). Did the Red Planet steal them from the asteroid belt, or did they form after an asteroid smashed into Mars? The answer carries implications for satellites elsewhere and perhaps even for the origin of water on Earth.