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You could have said the same thing about air travel if you were in the 1930s. Ultimately the limiting factor is energy. If we can transition Earth's power syst

by api 5y ago

You could have said the same thing about air travel if you were in the 1930s. Ultimately the limiting factor is energy. If we can transition Earth's power systems to renewable and nuclear power our remaining fossil fuels (mostly gas) will become cheap and can be used for space flight. In space nuclear fission is much less problematic than it is down here inside a biosphere. If we crack fusion we are done and eventually nobody else in the galaxy will be wondering about a Fermi paradox.

giantrobot 5y ago
> You could have said the same thing about air travel if you were in the 1930s. Space travel and air travel are not comparable in the way you're implying. For instance the Taylor Cub (predecessor of the Piper Cub) came out in 1930. A little 500lb plane could carry two people ~200 miles. It could do this because the atmosphere does a lot of the work lifting the plane and the crew doesn't need to bring their own life support system everywhere they go. A tear in their jacket wouldn't cause them to suffocate. Space travel has much higher minimum requirements to simply keep a human alive. Humans need their life support systems, power for the same, and ample supplies of everything because there's none wherever they're going. > Ultimately the limiting factor is energy. That is the first of several problems. > In space nuclear fission is much less problematic than it is down here inside a biosphere. Fission has its own problems in space. Reactor design is more complicated due to lack of gravity, the non-trivial challenges of excess heat, and no ready sources of a working fluid for turbines. > If we crack fusion we are done and eventually nobody else in the galaxy will be wondering about a Fermi paradox. Marginally better than fission but has several of the same problems. Heat is an even bigger issue to deal with because some sort of fusion engine is always wanting to melt itself. Space travel is hard. It's not at all safe to assume it can ever be "cheap" or democratized. Air travel is just not a good comparison. The atmosphere does a lot of the work involved in flying. In space there's no medium to work in. You've got to take everything with you everywhere you go.

by api 5y ago

giantrobot 5y ago

> You could have said the same thing about air travel if you were in the 1930s. Space travel and air travel are not comparable in the way you're implying. For instance the Taylor Cub (predecessor of the Piper Cub) came out in 1930. A little 500lb plane could carry two people ~200 miles. It could do this because the atmosphere does a lot of the work lifting the plane and the crew doesn't need to bring their own life support system everywhere they go. A tear in their jacket wouldn't cause them to suffocate. Space travel has much higher minimum requirements to simply keep a human alive. Humans need their life support systems, power for the same, and ample supplies of everything because there's none wherever they're going. > Ultimately the limiting factor is energy. That is the first of several problems. > In space nuclear fission is much less problematic than it is down here inside a biosphere. Fission has its own problems in space. Reactor design is more complicated due to lack of gravity, the non-trivial challenges of excess heat, and no ready sources of a working fluid for turbines. > If we crack fusion we are done and eventually nobody else in the galaxy will be wondering about a Fermi paradox. Marginally better than fission but has several of the same problems. Heat is an even bigger issue to deal with because some sort of fusion engine is always wanting to melt itself. Space travel is hard. It's not at all safe to assume it can ever be "cheap" or democratized. Air travel is just not a good comparison. The atmosphere does a lot of the work involved in flying. In space there's no medium to work in. You've got to take everything with you everywhere you go.