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Getting back is actually much easier, and we won't send anyone until there's a return ship ready for them on the ground. Mars escape velocity is ~5 km/s compar

Getting back is actually much easier, and we won't send anyone until there's a return ship ready for them on the ground. Mars escape velocity is ~5 km/s compared to 11 km/s for Earth, so right off the bat it takes half as much delta-v to get off Mars. The numbers get even more attractive when you consider that Mars's atmosphere is so thin you can use vacuum-optimized engines on the surface. It's a near-certainty that the second stage of ITS will be able to launch fully fueled from the Martian surface and return to Earth orbit, and possibly Earth's surface, without any refueling on the way.

bsdetector 10y ago
What I meant is, until Mars is self-sustaining and eventually capable of recolonizing Earth. Colonists rocketing back to a nuclear wasteland or planet infected with super-viruses won't protect us from extinction. And it's much easier and cheaper just to have underground bunkers than to bring a few people back from Mars on a rocket right after some disaster.
- nickparker 10y ago
  Civilization isn't the human species, it's a higher level and far more fragile thing. If a small fraction of civilization survived a global disaster in bunkers, it's very possible they would regress during the aftermath and never achieve a global society like ours again. A self sustaining civilization on Mars guarantees not just our survival in the Darwin sense, but our continued technological advancement and expansion.
- InclinedPlane 10y ago
  This is a limited line of thinking. Eventually humans who are capable of living in a self-sustained colony on Mars will also be able to live anywhere. In space using asteroidal/cometary resources, for example. On the moons of Jupiter and Saturn, etc. The jump between being able to live on Earth and then Mars is actually much greater than the jump between being able to live on Mars and anywhere. At that point humanity no longer would be planet bound. We'll be building cities that house billions of people in, say, the Earth-Sun L4/L5 lagrange points, or wherever we feel like it.

bsdetector 10y ago

What I meant is, until Mars is self-sustaining and eventually capable of recolonizing Earth. Colonists rocketing back to a nuclear wasteland or planet infected with super-viruses won't protect us from extinction. And it's much easier and cheaper just to have underground bunkers than to bring a few people back from Mars on a rocket right after some disaster.

nickparker 10y ago
Civilization isn't the human species, it's a higher level and far more fragile thing. If a small fraction of civilization survived a global disaster in bunkers, it's very possible they would regress during the aftermath and never achieve a global society like ours again. A self sustaining civilization on Mars guarantees not just our survival in the Darwin sense, but our continued technological advancement and expansion.
InclinedPlane 10y ago
This is a limited line of thinking. Eventually humans who are capable of living in a self-sustained colony on Mars will also be able to live anywhere. In space using asteroidal/cometary resources, for example. On the moons of Jupiter and Saturn, etc. The jump between being able to live on Earth and then Mars is actually much greater than the jump between being able to live on Mars and anywhere. At that point humanity no longer would be planet bound. We'll be building cities that house billions of people in, say, the Earth-Sun L4/L5 lagrange points, or wherever we feel like it.