[rictic]

It only counts as a redundancy site if the colony could survive without Earth. What's the minimum Martian colony size that's self sufficient? Self sufficient doesn't just mean the ability to create sufficient food, water, air, shelter, sewage, etc but the ability to recreate all of the necessary machinery starting only from your initial supplies and undeveloped Martian natural resources.

So many of the industrial processes that we've developed assume a huge interconnected network of supplies. To make Mars self sufficient you'd have to reinvent a huge chunk of the modern industrial system while also trying to keep your small population of colonists from dying. It's a monumental challenge with today's technology.

[saiya-jin]

I agree with you, but this isn't about creating fully working self-sufficient backup in a single go. There needs to be a first step, and then another, and so on. We will learn great deal from it, be it IT technology, materials, physics but also about us - psychology, physiology etc.