Basic Spacer Modification in 2500

 Basic spacer cybernetics and modification. 

1) inner ear modification - for spin grav and free fall orientation, as well as inertia compass. 

2) Second heart aka 0G heart - an addon circulatory system that balances pressures around the head in low to zero grav. Crucial for EVA as well as helping prevent Passing out in high G. 

3) bowel and urinary enhancements - helps go and hold when the need arises. 

4) Skin micro-biome - skin bacteria to help regulate health, in an environment with little bathing, long hours in suits, the "plant life" that the spacers cultivate have come in many engineered scents from herbs, flowers, spices, and various exotica that change depending on the diet of the spacer. 

there are more expensive ones like 

1) bone mass regulators - similar to coral regrowth - branching microfilaments that vine around the bones to trigger osteo genisis  - can be used in performance enhancement for soldiers. 

2)  the "fresher" is going to be a very different concept. Its probably going to be a diaper so people can go in their bed capsul. 

3) Its hard to plan for humans - humans can't stand the gravity 24 hours. Thus sleeping pods are in the core of the ship. While Exercise and Physical Therapy and Med Bays are in Spin Gravity habitats. 

Work and Sleep is 0G. Therapy is in Gravity. Work is 4 hours x2, Recovery is 2hr x4, and Rest is 4hrs x2.