If someone without permission had tried to create a spatial passage that passed through the third layer of space, which is also called the crystal shield of the world, they would have failed.
The crystal shield, or the third layer of space, is the most important defense of a world. One would need the permission of the world spirit or be more powerful than the world spirit to pass through the crystal shield.
The mothership had the permission of Ethera, so it was able to pass through the crystal shield with ease. While the mothership didn't have the permission of the world spirit of Aries, the gate was powerful enough to overwhelm the defenses of the world and create a spatial passage that tore through its crystal shield.
This kind of violent entry didn't go unnoticed, though. The sky tore open to reveal a deep darkness. The whole world saw this tear in the sky, so everyone knew that the world was being invaded.
