Been thinking a lot about colonizing Mars lately, with the publicity of Mars One in the news, and started off reading through the MIT analysis, which came to the not-too-surprising conclusion that 50m2 of plant space (in racks) would be insufficient to feed 4 people. What did surprise me was that this conclusion was based on the inadequate CO2 production by the crew to induce sufficient plant growth, and that supplementing the CO2 from the Martian atmosphere would result in flammable levels of O2. The obvious solution to me is that the mission should consider animals to supplement both the food supply and the CO2 production. Were it up to me, I would add the following:

• red worms- to break down compost from human waste and dead plant matter, possibly for processing Martian soil, and for feeding tilapia and quail
• BSF larvae- also for composting and feeding tilapia and quail
• tilapia- for adding protein to human diet and nutrients to grow beds
• quail- mostly for eggs and occasionally meat
• rabbits- add protein to diet and process vegetable waste

None of these take up a great deal of room. The invertebrates can be kept dormant for the trip there, simply by temperature. The tilapia will incur the greatest weight penalty just due to the water weight.

The study utilized the Modified Energy Cascade (MEC) for modeling plant growth. The limited data set in this study inspired me to look further into the topic to see if there was a way to open crowd source the methodology to expand the body of knowledge to a much wider plant set. I'm still looking into that, more to come as I do so.

This topic has me also waxing philosophical about the life cycle of an EcoArk. As somewhat of a CELSS purist, I've long considered the metric of good habitat strictly to be its stability measured in years it is capable of surviving in a completely closed status. However, the process of starting an Eco Ark may start from nearly scratch, from a very limited "seed" of parts and biomass, such as one would take to another planet. A habitat cannot be winked into existence, it must be grown, built, evolved. At the same time, nothing lasts forever, so ultimately CELSS must be able to reproduce, if they are to provide humanity any long lasting benefit. For the growth and meiosis stages of a habitat life cycle, there MUST be a transfer of matter, thus violating the definition of a closed system. However, the catch is that a CELSS cannot exist without considering both the beginning and end processes.

A few additional measures of success for a CELSS habitat come to mind, besides the first one:
1. How long a mature closed habitat can remain stable.
2. The transmissibility of seeds- cost of assembling transporting a seed package.
3. Seed viability- how quickly a habitat can be grown to maturity from a seed

For 2 and 3, intake of outside resource must be considered. No living thing can grow without consuming resources, and also no living thing can birth progeny without sacrificing part of itself. Indeed, it would be sad existence for humans if we could not go travel out of our habitat on an occasional EVA to explore the surroundings in search of resources or to visit other CELSS and exchange genes, companionship and ideas. The ultimately successful CELSS must be able therefore to support both ISRU and EVA.

In the course of analyzing the Mars One study, I came across the NASA Baseline Values and Assumptions Document, which I think gets NASA much farther in the direction they need to go. I will be gradually integrating this paper into the CELSS site as I find time over the coming months, and as I continue also looking for the methodology behind MEC plant data (for which I've already created a wiki page).