From Halopedia, the Halo wiki
"Michelle" is the name given to one of the modified drones owned and operated by Niko, the technology expert serving aboard the Mariner-class transport ship, Ace of Spades. Michelle is capable of flight in the vacuum of space and is equipped with a camera and a sensor suite. In early 2557, the Ace of Spades followed the coordinates left behind via a log buoy from the UNSC Spirit of Fire in 2531. They led the ship and crew to the debris field of the destroyed Forerunner shield world, Shield World 0459. Upon discovering a large section of the world with its own gravity and a functioning energy barrier holding in atmosphere, Michelle was launched into space and piloted toward this vestige. After crossing the threshold to the interior of the energy field, she picked up faint signs of life beneath the surface. Niko used her to discover a doorway leading into a nearby structure.
List of appearances