[_dps]

I would ask: a waste of money over what time-scale?

I agree that the ROI over the next decade or two seems low. But at some point, if we plan to ever get humans to other planets, we're going to have to do the low ROI slog of figuring out the basics. I don't think we will reach a point where getting people to other planets will suddenly become low-hanging fruit.

So I think the only real options are:

  1) do some low ROI exploratory work to enable higher ROI efforts down the road
  2) never send humans beyond earth orbit (seems short-sighted to me over a 
     century-long timeframe, but who knows)
  3) hope that somehow it will become much cheaper through windfall technology 
     developments in other fields (not impossible, but certainly not one that I 
     would bet on)

[rdl]

It's a waste of tax money, but there are clearly a lot of rich people who would pay for private space tourism.

Going for #3, combined with LEO manned spaceflight on a commercial basis, and then maybe a Mars or Lunar mission privately financed, would be fine with me, even if the same money in government would be more productively spent on aid to the poor or lowering taxes. Let the government spend money on purely scientific missions (with robots or telescopes), and maybe on establishing regulatory frameworks and contracts for specific amounts of space freight to cover government missions.

(If things keep going well technologically, we could have a Mars Direct mission for about 2x the cost of a series of movies about a Mars mission... at that point, it actually becomes worthwhile for private financiers to do it for the media rights.)

[ansible]

I think we're looking at option 3.

With advanced technology, we can modify humans to more easily survive in space. With sufficiently advanced technology, we can just upload them into robot bodies. That will make space missions as cheap as they are now, and without the risk. Because instead of sending up bags of meat that have to be protected from vacuum, radiation, freezing, boiling and dehydration, we can send up AIs or uploaded humans running on rad-hardened processors.

It goes back to the discussions about terra-forming. Is it better to adapt an entire planet (which is big, by the way) to human needs, or is it better to adapt humans to just live in that environment as-is?

Oh, and this sufficiently advanced technology gives you some other side benefits, including practical immortality, so that is worth pursuing by itself.

[Jach]

While I agree that 3 is the most optimal solution in the sense that "all these other problems are solved given 3", we still don't have a firm time frame on it. It could be 1 year, it could be 50 years. (I wouldn't put it at 100 or above personally, barring global catastrophe.) So we do things in parallel and hedge our bets. Could we get a self-sustaining colony on the Moon (or Mars, or somewhere else) within 50 years if we tried? I think we could. And that instantly protects modern humanity from many existential threats while we continue to work on problem #3.

[ansible]

Time frame is always a tough one. Let's try to bracket it with what we know, and be clear about the goal.

First, if we're talking about running an uploaded human-equivalent AI, we've got the processor power for that now, but it takes up a large server room. So I'd say we need to shrink stuff by at least 2 orders of magnitude to launch that into space. With corresponding gains in efficiency. So for that I think we're looking at 10 years at current rates of progress. Tack on another 5 for radiation hardening, because that estimate was based on commercial-grade hardware, which is almost as fragile as meat.

After you have that, it is a small matter of programming :-)

[schiffern]

>3) hope that somehow it will become much cheaper through windfall technology developments in other fields (not impossible, but certainly not one that I would bet on)

Brain uploading. I don't know if Kurzweil's "$1000 computer by 2035" prediction is right, but we'll certainly have it by the end of the century.

Accelerando features a good exploration of this. Your interstellar spaceship is a laser-propelled computer the size of a soda can, with everyone's brains simply uploaded into it.