Artifacts are items that appear on terrain over time; some start there at the beginning of the game, and others spawn during various events. These artifacts provide no benefit on their own but allow explorers to perform an expedition, which uses the artifact to provide a bonus. The explorer loses an expedition module once the expedition action is completed. If an explorer has no expedition modules remaining, they will no longer be able to perform expeditions until they visit a city that their player controls.
Beware! Working on expeditions while surrounded by miasma can be fatal to an explorer. Make sure that you have enough time to complete your expedition before your health is going to run out. If that's not possible, get a worker over there to remove the miasma before you begin your expedition (workers learn how to remove miasma once you master Alien Biology).
There are four types of artifacts: derelict settlement, crashed satellite, alien skeleton, and Progenitor ruins. Each provides one of several possible benefits, ranging from xenomorph units placed under your control, a one-time boost of Culture, Energy or affinity points, or progress toward a specific Technology.
Alien Skeletons and Caves
Alien skeletons are the remains of colossal xenomorphs. Once an expedition is completed on a tile containing this, the player might receive a large affinity increase or gain an alien unit under their control. Destroying alien nests has a tendency to create caves.
Progenitor Ruins
Progenitor ruins are the remains of structures left behind by a nigh-mythical alien race. Once an expedition is completed on a tile containing this, the player will receive either an affinity level increase or progress toward an advanced Technology.
Crashed Satellites
Crashed satellites are the remains of orbitals that have deorbited and crashed back to the planet. Once an expedition is completed on a tile containing this, the player might receive a large Science or Production increase. Sometimes, these sites are formed when orbitals deorbit.
Derelict Settlements
Derelict settlements are the remains of earlier failed human colonies. Once an expedition is completed on a tile containing this, the player could receive a large Culture increase or gain extra population in their nearest city. Destroying stations sometimes causes them to become derelict settlements.