Zero Gravity
Source GM Core pg. 99
Environments such as outer space and some small satellites have zero gravity (also referred to as zero-g). Creatures in zero-g have the clumsy 1, off-guard, and untethered conditions. A creature in a zero gravity environment can lift and carry 10 times their normal amount and multiplies the ranges of thrown weapons by 10.
Movement in Zero Gravity
Source GM Core pg. 99
Creatures in a zero-g environment float aimlessly without a method of propulsion, cosmic flight, or nearby objects to Push Off of. Creatures with a natural fly Speed can't use their fly Speed in zero-g unless they have the cosmic trait. Creatures flying via propulsion, such as jetpacks, starship thrusters, and spells like fly or void vessel, are unaffected. Unless a creature has a means of moving in zero-g, it gains the untethered condition.