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Life Cycle Assessment (LCA) 

I use the current human waste management on the ISS as the LCA benchmark. The condition is defined according to the lunar outpost mission, in which there will be 4 crew members rotating every 6 months.


The human waste management on the International Space Station (ISS)


The evaluation focus on the disposable products which go into the process in a year. However the following variables are excluded since the information is inaccessible or irrelevant to the project:

- Product for air filtration

- Refill Water Pouch

Functional Unit


Waste in human waste process/4 crewmembers-year (lb)

The Current Process 

The Simplified Flow Diagram

LCA process tree - the waste system

LCA process tree - input materials

Impact Matrix

The new process
Comparison of Okala score



The actual input and output from Torrefaction Processing Unit (TPU) and Heat Melt Compactor (HMC) still need more information and study to precisely conduct LCA and Okala score.

*Replaced with related process to roughly measure the scale of the impact since the item is not included in Okala Factor.




The Okala score of the new solution has demonstrated a huge decrease in environmental impact. This improvement resulted from the effective processing of Torrefaction, and the possibility of applying repurposed human waste product in lunar habitat.


The new closed-loop process has eliminate the needs for storage canisters and the trip for destructive re-entry to Earth, which the impact mainly came from.

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