Astral projection was a psychic power that involved creating an astral body which left the physical body. It could be more clearly thought of as a form of travel in which the soul leaves the body. Humans developed a method of astral projection which allowed for psychically travelling to different planets as opposed to doing so in starships.
The Fendahl had such enormous energies that it was able to project itself from the Fifth Planet to Earth before being trapped in a time loop, possibly ravaging Mars along the way. (TV: Image of the Fendahl)
The Osirians were capable of mentally projecting themselves, which could be thought of as astral projection. They also designed psi-projectors which let them travel through space using only the power of their minds. (TV: Pyramids of Mars, PROSE: The Sands of Time)