Phobos is the larger and innermost of Mars' two moons, known for its irregular shape and cratered surface. It orbits incredibly close to Mars, completing a full orbit in just over 7 hours—faster than Mars' rotation. Phobos is slowly spiraling toward the planet and is expected to either crash into Mars or break apart in millions of years. Its surface is covered in dust and loose rocks, making it a fascinating target for future space exploration.