stuff I didn't know but learned as I got into Hard Scifi TRPGs
1) humans need 1 atmosphere of pressure, that space suits are designed to remain flexible as 1 atmosphere of pressure balloons the suit and make it immovable. Without the pressure, suffocation happens (as our lungs which function by creating a pressure differential stops working) and bubbling of nitrogen in our joints causes incredible pain.
2) that the pressure in most Spacesuits is below 1 atmosphere of pressure and that they raise the oxygen content from what is normally 18 to more to compensate. an Electronic spark inside a vacc suit is scary.
3) That in freefall Extra-Vehicular Activity can kill you by simply drifting away - the need for lanyards and jet packs.
4) That gravity is necessary in so many human functions, Air pressure, and blood circulation. The shortened life of an Astronaut staying in long periods in freefall/0G is quite a sacrifice.
5) that Centrifugal Spin Gravity is painful to people who have Motion Sickness - if you can't take a boat ride - try a small spin habitat with a size below 200m Radius (400m diameter).
6) That planets have Radiation Belts - created by the magnetic fields of a planet that has one interacting with the Sun's radiation. The shielding of it is expensive and they can be incredibly powerful.
7) That humans need about 60 cubic meters and up of space as well as about a work out of 1 hour a day and more to compensate for Low gravity or freefall deteriorating effects.
😎 That teams of scientists and mathematicians work on these navigational calculations well in advance and in Scifi game we handwave the number of calculations and Checking - if a gamer is daunted by a simple escape velocity calculation magnitude of complexity need to know where one is and how to get where. Getting these wrong cost lives.
9) Solar Flares, Thermospheric Storms (Particularly in jupiters thermosphere with charged metallic hydrogen), Micro-meteorites, Radiation Belt Fluctuations (as magnetic poles change), Space Manifolds miscalculations, Kessler Syndrome (when particles hit each other that create a cascading failure that makes a debris field that will destroy everything in its path) as well a Human Error are factors that can kill.
it is so deadly - thriving is a miracle. The game might be daunting but with the right people its not just amazing but educational.