Outer Space
Source GM Core pg. 96
Outer space holds countless stars, planets, and other cosmic bodies. Most characters will venture into space during their adventuring career. Shuttling between planets, visiting an orbiting space station, or traveling to a distant star system are examples of common travel that require a journey through outer space. Most travelers embark on such trips aboard a starship, which protects them from outer space's environmental dangers.
Cosmic Radiation
Source GM Core pg. 96
Stars and other powerful cosmic bodies are radioactive. Most habitable planets have atmospheres that repel their emissions, allowing only a negligible amount of cosmic radiation in occasional bursts. Usually, creatures on a planet with no atmosphere are constantly exposed to mild to severe radiation.
Drift Beacons
Source GM Core pg. 96
Drift beacons are satellites tethered to the Drift, the plane used for rapid interstellar transportation by many civilizations across the galaxy. Drift beacons act as landmarks for Drift travel and relay long-range communications through outer space. Most Drift beacons are artificially constructed and maintained by the Church of Triune, but their designs can vary significantly, ranging from simple industrial buoys to extradimensional pagodas.
Solar Flares
Source GM Core pg. 96
Sometimes a star releases bursts of intense energy that are visible as flares of roiling plasma arcing out from its surface. Creatures and objects on or near a star's surface take massive fire damage and major persistent electrical damage from a solar flare. Solar flares disrupt technology up to millions of miles away from the star. A solar flare causes electronics and radio communications to gain the glitching condition or stop working for up to 1d6 hours.
Vacuum
Source GM Core pg. 96
Space is a vacuum, meaning it contains no breathable air and has zero gravity. Creatures in a vacuum are at risk of suffocation and take minor bludgeoning damage each minute. In addition, they are untethered and require special propulsion to move. Space has no effective temperature, and a creature retains its body heat for several hours in a vacuum. Sound doesn't travel in a vacuum, meaning most sonic effects don't function. Creatures with the cosmic trait are immune to many of the effects of a vacuum.
Decompression
Source GM Core pg. 97
Decompression occurs when a creature suddenly transitions from a pressurized environment to a vacuum, such as by getting shoved out of an airlock or being inside a starship that sustains heavy damage. Such a creature takes moderate bludgeoning damage and immediately begins suffocating (they can't hold their breath). Decompression can also apply to characters in underwater environments.