Human Factor — Maintenance
The Anti-Decay System
In space, keeping a crew healthy costs real time every single day. It sits on the same line item as oxygen and water.
The Daily Maintenance Budget
Here's what each person has to do every single day just to keep their body from falling apart
Exercise
2.0 hrs
Resistance training and cardio, every day, on the ISS protocol. It slows bone and muscle loss but doesn't stop it.
Setup + Cleanup
0.5 hrs
Getting the equipment ready, cleaning up afterward, dealing with sweat floating everywhere. There are no showers in microgravity, so this takes longer than you'd think.
Medical Monitoring
0.5 hrs
Blood pressure, vision checks, bone density tracking, psychological evaluation. The crew's medical officer needs this data constantly because problems show up quietly.
Meal Prep + Nutrition
0.5-1.0 hrs
Rehydrating food, eating, cleaning up. Eating in microgravity is slow because crumbs and liquids float into everything. You also have to track what you ate for nutritional monitoring.
Total Daily Anti-Decay Budget
3-4 hours / person / day
None of this is mission work. This is just what it costs to keep a human body running.
The Scale Impact
9 crew
27-36 hrs/day
Combined maintenance time. That's like having 3-4 crew members whose entire job is just keeping bodies working.
25 crew
75-100 hrs/day
Now you need schedules for who uses the gym equipment when. Medical staff are spending serious chunks of their day just on check-ups.
100 crew
300-400 hrs/day
You're running a small hospital. Multiple medical staff, gym facility management, the whole thing. That's the operational load of a health department.
What This Means for Getting Anything Done
People are awake about 16 hours a day. 3-4 hours of body maintenance eats 19-25% of that. For a 100-person crew, that's the equivalent of 19-25 full-time people whose only output is keeping human bodies functional.
And that's before sleep (8 hrs), personal time, meals beyond the minimum, and the psychological need for unstructured downtime. The actual window for productive mission work per person may be as low as 6-8 hours per day.
In a closed habitat,
keeping human bodies running is one of the biggest costs
in the entire budget.
Artificial gravity could shrink or eliminate the exercise requirement. Until someone builds it, every person on the crew is also a maintenance load the crew has to carry. Even after months of this daily work, the crew that arrives at Mars will still be weaker than when they left Earth.