Inner Sphere
Atmosphere: Vacuum
Most of the Sphere is Outer Space; its vastness, emptiness, and inhospitality shape the economics, politics and societies of its inhabitants. The emptiness of space has shaped the Yom Economy a system of common value where goods and resources are exchanged independently of currency. The Vastness of space is the principal challenge interstellar organizations need to surmount. Nothing in the Galaxy has been able to surpass the speed of light. Interstellar craft are only able to beat this limitation by "short-cutting" through Rift Space.
These are hazards of the Inner Sphere visitors will likely encounter when they venture outside the astrospheres of stellar clusters.
Cosmic Radiation: An unprotected being would be battered by the unmitigated energy of the big bang. Unprotected individuals risk Extreme Radiation Sickness. Inadequate Protection or compromised radiation shielding would risk exposure to less intense forms of Radiation Sickness.
Metronomes: By sounding metronome signals navigators Plot Course at a DC 20 Base difficulty to make their way to a known cluster
Vacuum: Unprotected individuals take 2d6 Bludgeoning Damage per round and are at risk of suffocation while exposed to the void.
Decompression: When a creature suddenly transitions from a pressurized environment to the vacuum of space, Such a creature takes 5d6 bludgeoning damage and immediately begins suffocating (they can't hold their breath).