Mars city question

[dangerous_safety]

While completely isolated self sustaining ecosystems may currently be beyond our grasp, it doesn't mean we can't come close. While not fully closed off, vivariums (aquariums, terrariums, etc) can be made to be fairly self reliant in terms of their ecosystems. Techniques from these smaller scale setups could be potentially helpful when designing primitive biospheres for Mars, or even just managing agricultural biota.

Another potential aid in helping to make sustainable ecosystems more viable are the ongoing development of environmental technologies. Again, these are obviously not self contained, but the techniques we learn from those endevours may help in better managing a future Martian biosphere.