How exactly do you know that? The only experiment about creating closed human colonies was deemed complete failures and not to be replicated due to ethical concerns.
And a base on Mars will not be a closed system. It will continuously draw in raw materials from the surrounding environment. Mars is enticing for this because carbon dioxide and water are abundant, giving you the three most important elements for fuel and food production.
We've never done this on any significant scale with success.
Think of it more like a nuclear submarine with a greenhouse full of potatoes attached -- we can most likely do that.
Nobody's going to try to launch an entire mangrove forest on the first go. Biosphere2 is a failure of experimental design, not a failed experiment.
Maybe, but if we want to make Mars economically self sustaining the correct analogy is nuclear submarine that never surfaces and can totally self repair, including building new nuclear reactors and eventually replace all parts in itself.
There was Biosphere 2 experiment few decades ago, but they could not keep the biosphere stable.
There's just a huge psychological difference between knowing that you're in space, millions of miles from Earth or any kind of help and knowing you're in a simulation on Earth.
I suppose it's possible to fool people that they're in the former while actually being in the latter. But the ethical issues surrounding such an experiment would make it out of bounds for NASA. It might make for a fun scifi story, though.
To make the colony self supporting, you need to transfer factories, chemical plants, machine industry, mining industry, etc.
The really cool thing about this is that methane can be used as a feedstock to produce many plastics and the oxygen can be used for humans to breathe.
The MCT is a prototype for a seed factory style Von Neumann probe.
Everyone's keeping quiet about the inevitable role of RTGs or fission reactors in early human Mars exploration.
Solar will come either via an abundance of payloads delivered to Mars as things ramp up, or via panels produced on Mars itself.
Other viable methods for power generation that are amenable to in-situ production include geothermal heat loops and solar concentrators.
Like they said, most of the cost is transportation. Which gets cheaper.
That's pretty much the whole of the economics. People and governments will jump at the chance to send humans to Mars, if there's a way to do it at a reasonable price.
The cost of the things that are necessary on Mars that will have to be shipped from Earth will be rolled into the ticket price. Hence the first few rounds of tickets will probably be quite expensive.