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Comment by beloch | Hacker News Reader

This new launch vehicle has a realistic chance of getting people and materials to Mars in sufficient quantities to build an outpost. I'd like to hear more about how they plan to build a self-sustaining colony on Mars though. There are some pretty big challenges to overcome, such as the relative lack of Nitrogen. A colony is going to have to grow plants but, to do that on Mars, we're going to need a way of fixing Nitrogen for those plants from an Atmosphere where it's just not very plentiful.

Please note that this isn't an argument against going to Mars now. There's a lot we can learn by building an outpost on Mars that is supported heavily by Earth, including how to build a self-supporting Mars colony. I'm just asking what the current state-of-the-art opinion is on the challenges of building a self-supporting Mars colony.

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Mars has plenty of Nitrogen, it's in the atmosphere (2% of it). That may be at low pressure, but once you have a few hundred tonnes of industrial equipment on Mars you can start doing things like fractional distillation of the atmosphere, and then you're just pumping Nitrogen out of the atmosphere and using it for whatever you want.

2% of a very low pressure may not seem like much but in total that's about half a trillion tonnes, or half a million cubic kilometers of Nitrogen. It'll be a very long time before that resource is depleted. Additionally, Mars has nitrates, which can be mined and exploited.

I noticed Musk tentatively mention nuclear - I think that's because it will be the only logical way to generate enough power to support a city in such an inhospitable climate. There is going to be a huge and ongoing energy need just to survive.

Unless we build a battery/solar panel factory there is no way solar is going to cut it.

Sadly - but it just tells you that he is acutely aware of the public opinion aspect of his vision. Nuclear - especially a firm grasp and experience in Thorium reactors - would be a perfect energy solution for all industrial processes on Mars. One can only hope that a massive project as the one he is proposing here will lead to a renaissance in thinking big - colonial in its ambition - and with it in challenging the Unenlightened modern anti-nuclear phobia.

Nitrogen is extremely common. Curiosity rover found nitrogen that can be used in farming:

http://www.nasa.gov/content/goddard/mars-nitrogen/

The problem is more like 96% CO2 in the air. Yes, plants need CO2. But I read that if the CO2 concentration is too high, plants stop being able to perform photosynthesis well.

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