Advanced ECLSS: closed loops, quality and degraded modes
This course develops a capability that was still missing from the core curriculum. It starts from concepts and units, builds the necessary calculations, then connects each method to real Mars engineering decisions.
Mastery objectives
- explain quantities, units and assumptions
- repeat at least one calculation by hand
- identify uncertainty, limits and failure modes
- turn the result into a decision for a Mars architecture
1. Closing a loop does not mean 100 percent recovery
Life-support systems recover a fraction of water, oxygen or nutrients. Even small losses accumulate and must be replaced by storage or local production.
Efficiency only becomes meaningful when linked to daily flow and mission duration.
Engineering reflex. Identify what is measured, assumed and calculated, then state what would change the decision.
2. Water has multiple streams and quality requirements
Urine, humidity condensate, hygiene water and process streams contain different contaminants. Keeping them separate can simplify treatment.
High throughput is not success unless product water meets quality requirements.
Engineering reflex. Identify what is measured, assumed and calculated, then state what would change the decision.
3. Air combines oxygen, CO₂ removal and trace contaminants
Atmospheric control requires oxygen supply, carbon dioxide removal, ventilation, filtration and trace-contaminant monitoring.
A safe cabin average can hide a dangerous local pocket if ventilation is poor.
Engineering reflex. Identify what is measured, assumed and calculated, then state what would change the decision.
4. Degraded modes and reserves
A robust ECLSS defines what happens when a water processor, sorbent bed or electrolyser is unavailable. Reserves buy time but do not replace repair.
Time-to-criticality after a failure is as important as nominal efficiency.
Engineering reflex. Identify what is measured, assumed and calculated, then state what would change the decision.
5. From ISS to Mars autonomy
ISS can receive logistics far more frequently than Mars. A Mars base needs deeper diagnostics, spares, cleaning and refurbishment capability.
Closed-loop design is ultimately about slowing residual dependence enough to survive between transport windows.
Engineering reflex. Identify what is measured, assumed and calculated, then state what would change the decision.
Worked example step by step
Build a nominal case and a degraded variant. Write every input with units, convert to one coherent system, perform the calculation, then translate the result into a sentence. Finally vary the most uncertain parameter by ±20% and check whether the decision changes.
Progressive exercise
- Choose a Mars subsystem and list five inputs.
- Classify each input: measured, sourced, assumed or calculated.
- Calculate the nominal case.
- Inject uncertainty or a failure.
- Decide: continue, degrade, stop or reconfigure.
Reasoned solution
A good solution shows units, reasoning, sensitivity and the decision. A numerical result without physical interpretation is not a complete solution.
Validation mini-project
Produce a three-to-five-page engineering note with need, assumptions, diagram, calculation, uncertainty, injected failure, decision criterion and at least three primary sources.