The origin of Phobos, Mars' innermost moon, continues to divide planetary scientists. The core question is whether it is a captured asteroid or formed from debris after a giant impact struck the Martian surface.
The debate has persisted for decades because Phobos' composition and internal structure remain poorly understood. This missing data prevents definitive classification, leaving it a 'known unknown' in the field.
According to Phys.org, the key to solving the mystery rests with a better understanding of Phobos' internal structure. Without it, both theories remain plausible but unproven.
Future missions, such as JAXA's Martian Moons eXploration (MMX), aim to collect samples and return them to Earth. Those samples could finally reveal the moon's true origins.
Until then, the scientific community must rely on remote sensing and modeling. The answer may reshape theories about solar system formation.