Asteroid M has been destroyed and reconstructed by the Master of Magnetism many times since it was first introduced. Each iteration has had several internal levels, including an observation deck, hangar bays and medical facilities. The various facilities have had technology that keep the asteroid concealed from standard detection technology. They have all been positioned in a low geosynchronous orbit. Each asteroid was relatively small yet large enough that it could not be shot down, or destroyed externally, without the risk of massive devastation to Earth.