Shield World

While the Forerunners were responsible for the creation of the Halo Array—a weapons network which consisted of seven ringworld installations distributed throughout the galaxy—their plan against the Flood included yet another critical component.

“Shields” or “shield worlds” were also created as a shelter against the galactic holocaust unleashed by the firing of the Halo Array. In response to the Flood’s brutal and virulent spread across the galaxy, the Forerunners would activate the Halo Array, placing salvageable life forms within these shield worlds for preservation. Although only two of these installations have ever been historically documented, the differences between the two are distinct and intriguing.

The first was discovered in 2531, when the UNSC Spirit of Fire stumbled upon a remote planet in the uncharted regions of our galaxy. As they traveled toward the world, they found their ship forcefully drawn to an aperture on its surface—an aperture which took them to the planet’s interior. Within it lied the revelation that the entire structure was an artificially-created Micro Dyson Sphere—a shell-like installation with a vast interior surface and a burning sun at its center.

During their exploration of this mysterious shield world, the Spirit’s crew discovered that the Flood had somehow been unleashed on its surface—the same parasite which the installation was ultimately intended to protect against. After engaging Covenant forces within the planet’s interior, the Spirit was forced to destroy the shield world, the Flood outbreak and a dormant Forerunner fleet which the Covenant were frantically seeking to activate.

Twenty years later, a contingent of ONI personnel and Spartans found themselves stranded on the remote and hidden planet known as Onyx. This planet would also be revealed to be a Forerunner shield world—and while its ultimate purpose would be similar, its design would be wholly different.

Within the center of Onyx was a controlled Slipspace rift—a technological concept which far outstripped anything humanity had ever encountered before. Escaping into the rift to evade a Covenant army, these humans found themselves with yet another Micro Dyson Sphere, this one existing outside of normal space. Though its dimensions were astronomical, the environment was completely hidden in Slipspace, safe from the obliterative pulse of Halo.

While these installations were both fascinating and impressive, it remains unknown whether their true purpose was ever successfully realized.