Discovering the Lab Security Code in The Town, will grant you access to the Research Complex. Inside, you'll encounter several hospital beds and evidence of what appears to have been a viral outbreak, as well as research materials and various studies which were being conducted by the Soviets during the 1970s. The research here indicates that a “portal” was discovered sometime during the Cold War era, and that the Soviets used said portal to reach this planet. You'll want to switch on your Flashlight by pressing either (RB) or F, which will help you see in some of the darkest areas here. You'll need to jump over the fence to turn on the power, and once inside the science center you'll need to pick up the Dynamite and place it by the blocked exit (before running a short distance to safety before it detonates). With the doorway cleared, continue down the path to discover glowing green footprints. By following these footprints, you'll come across an old mining operation. Jump up on the side to access where the broken ladder fell, and you'll find yourself an opening to the Chasm.