Mars has a layer of molten rock inside
The push for humans on Mars is deeply misguided. The same resources should be used to send many more probes and for far longer durations. After 100 years of deeply mapping all available resources, then <i>maybe</i> send humans if a long-term colony is self-sustainable and necessary for deep space exploration with better propulsion technologies.<p>Edit: Without a self-sustaining colony and next generation propulsion tech, any humans on Mars as a backup plan will die lonely deaths. Surprised people seem confused on the necessary and sufficient conditions. Show me that robots can set up a self-sustaining colony with self-generating resources to get to other worlds, and that’s a legit “backup” plan. Otherwise we’re just arguing about edge cases with no viable solutions. You don’t need humans on Mars to show what’s possible.