Stickney crater's internal structure could settle debate over Phobos's formation
Researchers are modeling gravity and motion data around Stickney Crater on Mars's moon Phobos to determine whether the moon is a captured asteroid or debris from an ancient Martian impact. The upcoming MMX sample return mission may provide the measurements needed to resolve the moon's origin.
The competing origin theories for Phobos hinge on dramatically different timelines for Stickney Crater's formation. A Martian debris origin would place the impact at roughly 4.2 billion years ago, while a captured asteroid scenario suggests a much younger event around 2.6 billion years ago. These age differences carry profound implications for the moon's internal composition and evolution.
Phobos is believed to have a porous structure that may contain water ice, and the Stickney impact could have compressed material beneath the crater into a denser region. Japan's MMX sample return mission is poised to gather the gravity measurements and physical samples needed to test these models directly, potentially settling a debate that has persisted for decades.
Resolving Phobos's origin could reshape how scientists understand planetary moon formation throughout the solar system, with implications for asteroid dynamics and Mars's geological history. The findings may influence future exploration priorities, particularly as space agencies consider crewed missions to Mars and its vicinity. Public interest in planetary science could grow as the mystery unfolds, though the direct societal impact remains primarily educational and scientific rather than practical in the near term.