Long ago kings and empires often signaled their power via impressive buildings, such as temples, cathedrals, and pyramids. Today, cities and corporations often similarly signal via big skyscrapers, bridges, and ships. But for nations, the fraction of wealth spent on a single showy construction has dramatically decreased. Space programs serve a similar function, but don’t leave such huge monuments to admire.
As a chemist, I see a serious flaw in this proposal. Mainly, it requires a lot of helium. Since Earth’s gravity doesn’t capture helium, we have a very limited quantity available on Earth.
We can harvest some helium from the Sun. Yes, it's quite hot, but we'd go there at night time.
Such launch devices will pay their way in reducing existential risk if they can reduce the cost of global warming mitigation strategies like the Angel fleet.
As a chemist, I see a serious flaw in this proposal. Mainly, it requires a lot of helium. Since Earth's gravity doesn't capture helium, we have a very limited quantity available on Earth. Helium also diffuses rather quickly through many materials (you may have noticed that helium balloons tend to shrink in a few days), so constant replenishment would be needed. I haven't done the math (and couldn't, without estimates of the surface area, thickness, and relevant helium diffusion constants of the materials of choice), but I seriously doubt that this is a practical proposal.
>What likely risks can you think of that space colonies would be safe against, but sealed deep mines on Earth wouldn’t?
That's a good point. I suppose that sealed deep mines could use geothermal energy. But you might be stuck in the mine for a while in the event of a catastrophe.
Do you know of anyone working on the problem of surviving a long time in a sealed deep mine?
>We aren’t remotely close enough to a low enough cost of getting into space to kick off a substantial space economy. So the best way to get to that point is to simply grow the world economy; investments now in space activities that don’t pay their way hinders that goal.
OK, I'll tentatively take your word for this because you're an economist. But I've got a question: does the sector of the economy matter? If video game sales go up does that help spaceflight?
It seems to me that this question is quite complicated. Another aspect of things is how reasonable the assumption that man-hours convert into research results at a constant rate is.
> We aren’t remotely close enough to a low enough cost of getting into space to kick off a substantial space economy. So the best way to get to that point is to simply grow the world economy; investments now in space activities that don’t pay their way hinders that goal.
What $ per kilogram to orbit do you think we need to get to?
We aren't remotely close enough to a low enough cost of getting into space to kick off a substantial space economy. So the best way to get to that point is to simply grow the world economy; investments now in space activities that don't pay their way hinders that goal.
"Consider a highly simplified scenario where a single stage-to-orbit rocket is launched to a typical circular orbital height of 120 km. … Comparing initial to final rocket-mass ratios, the elevator launch at 20 km is shown to be 26% more efficient than the equivalent ground launch."
- right, this is not a sufficiently compelling difference.
However I should add that a 20km space tower doesn't make it much cheaper to get into space. I'm no expert, but I expect that the only good application would be in conjuction with a Tether propulsion system
> John, no space tech fielded anytime soon will have any effect on our number of baskets, since humanity isn’t remotely capable of living independently of Earth.
Let us define the time at which the human race stands a 50% chance of survival given the total destruction of the planet earth as t_survival. If no technological singularity occurs, it wouldn't be unreasonable to say t_survival will be in more than 40 years but less than 300 years.
Really cheap access to space via a space tower would make it economically viable for companies to do various things in space and for an entire space economy to develop. This would accelerate the development of a multitude of effective strategies for surviving and thriving in space, and for doing it cheaply. This process is likely to be auto-catalytic - space access costs will come down further as more people want to go there (economies of scale). Furthermore, a *community* of space enthusiasts - people who are prepared to take huge risks to live in space, but who feel compensated for those risks by the psychological benefit it gives them - may develop.
t_survival is thus likely to come forward if we make "mass space" come sooner.
How much is advancing t_survival by one year worth? By my standards, rather a lot; I'm not sure how to put a dollar figure on the future of the entire universe.
As a chemist, I see a serious flaw in this proposal. Mainly, it requires a lot of helium. Since Earth’s gravity doesn’t capture helium, we have a very limited quantity available on Earth.
We can harvest some helium from the Sun. Yes, it's quite hot, but we'd go there at night time.
More uncritical coverage:
http://scienceblogs.com/pri...
To reiterate, the idea makes no sense, because of the wind.
Such launch devices will pay their way in reducing existential risk if they can reduce the cost of global warming mitigation strategies like the Angel fleet.
As a chemist, I see a serious flaw in this proposal. Mainly, it requires a lot of helium. Since Earth's gravity doesn't capture helium, we have a very limited quantity available on Earth. Helium also diffuses rather quickly through many materials (you may have noticed that helium balloons tend to shrink in a few days), so constant replenishment would be needed. I haven't done the math (and couldn't, without estimates of the surface area, thickness, and relevant helium diffusion constants of the materials of choice), but I seriously doubt that this is a practical proposal.
>What likely risks can you think of that space colonies would be safe against, but sealed deep mines on Earth wouldn’t?
That's a good point. I suppose that sealed deep mines could use geothermal energy. But you might be stuck in the mine for a while in the event of a catastrophe.
Do you know of anyone working on the problem of surviving a long time in a sealed deep mine?
What likely risks can you think of that space colonies would be safe against, but sealed deep mines on Earth wouldn't?
>We aren’t remotely close enough to a low enough cost of getting into space to kick off a substantial space economy. So the best way to get to that point is to simply grow the world economy; investments now in space activities that don’t pay their way hinders that goal.
OK, I'll tentatively take your word for this because you're an economist. But I've got a question: does the sector of the economy matter? If video game sales go up does that help spaceflight?
It seems to me that this question is quite complicated. Another aspect of things is how reasonable the assumption that man-hours convert into research results at a constant rate is.
I just added to the post.
> We aren’t remotely close enough to a low enough cost of getting into space to kick off a substantial space economy. So the best way to get to that point is to simply grow the world economy; investments now in space activities that don’t pay their way hinders that goal.
What $ per kilogram to orbit do you think we need to get to?
We aren't remotely close enough to a low enough cost of getting into space to kick off a substantial space economy. So the best way to get to that point is to simply grow the world economy; investments now in space activities that don't pay their way hinders that goal.
"Consider a highly simplified scenario where a single stage-to-orbit rocket is launched to a typical circular orbital height of 120 km. … Comparing initial to final rocket-mass ratios, the elevator launch at 20 km is shown to be 26% more efficient than the equivalent ground launch."
- right, this is not a sufficiently compelling difference.
"To stay upright and withstand winds, full-scale structures would require gyroscopes and active stabilisation systems in each module."
Hah! - very funny.
However I should add that a 20km space tower doesn't make it much cheaper to get into space. I'm no expert, but I expect that the only good application would be in conjuction with a Tether propulsion system
> John, no space tech fielded anytime soon will have any effect on our number of baskets, since humanity isn’t remotely capable of living independently of Earth.
Let us define the time at which the human race stands a 50% chance of survival given the total destruction of the planet earth as t_survival. If no technological singularity occurs, it wouldn't be unreasonable to say t_survival will be in more than 40 years but less than 300 years.
Really cheap access to space via a space tower would make it economically viable for companies to do various things in space and for an entire space economy to develop. This would accelerate the development of a multitude of effective strategies for surviving and thriving in space, and for doing it cheaply. This process is likely to be auto-catalytic - space access costs will come down further as more people want to go there (economies of scale). Furthermore, a *community* of space enthusiasts - people who are prepared to take huge risks to live in space, but who feel compensated for those risks by the psychological benefit it gives them - may develop.
t_survival is thus likely to come forward if we make "mass space" come sooner.
How much is advancing t_survival by one year worth? By my standards, rather a lot; I'm not sure how to put a dollar figure on the future of the entire universe.
Those are both good articles.
What's the cost of the tower?