Launches, yes, but landings? Athmosphere is your enemy during launches, but your friend in landing.
Mars has an atmospheric pressure less than one percent of that of earth. That makes losing speed other than with rockets a problem, and that requires bringing lots of fuel.
In addition, the athmosphere that's there can be windy and turbulent. That can directly affect a spacecraft, but also causes dust storms that can make it hard to measure distance to ground.
In other words, I believe that Mars' appeal is a mirage. Musk and company are seeing it as another Earth where people can live like here, with a little terraforming.
I think it would be much more difficult. Of course I could be wrong, or I could be right but, even then, Musk could be modern Columbus.
- Water and free carbon dioxide are hugely more abundant on Mars than on the Moon. These are essential supplies for increasing biomass and making fuel.
- There's a nice, somewhat-protective atmosphere.
- There's a 24.66 hour day.
- Temperatures are relatively moderate.
[1] - http://www.nbcnews.com/id/6908408/ns/technology_and_science-...
If you can get net energy by fusing He3, you can also do it by fusing deuterium, which is easier. And the end product of deuterium fusion is He3! (Half the time directly, the other half producing tritium which decays to He3.) So instead of sifting through millions of tons of dirt on the moon, you can just make He3 on Earth and gain energy in the process.
Deuterium fusion produces neutrons but they're lower energy than D-T neutrons. Fusion startup Helion (funded in part by YCombinator) is working on a hybrid D-D/D-He3 fusion reactor, and says only 6% of the output energy would be as neutron radiation.
That said, I am also doubtful. I don't foresee a trade-hub attracting 1 million people - if there are really a million people who want to go. Who the hell wants to risk their life and net worth just for the privilege of living on a rock less hospitable than Antarctica?