Let's hear your cheap launch strategies

[Jimbo07]

Several people have voted for the space elevator option and I've got to wonder how anyone can know it's going to be cheap. Too many breakthroughs required to estimate a cost.

Well, of course, that's what Elevator2010 is all about... trying to draw a bound around those breakthroughs and costs. Should those breakthroughs occur, NASA will have gotten them for a song.

Even before the cost of the currently speculative materials required, construction costs running above 10 billion dollars are frequently cited for an elevator that can launch 10 tons to geo every two weeks. Those number don't really suggest low cost or high volume. They work out to about $2,000 dollars per pound just to recover the capital cost.

Current projections for the ISS put it over $100 billion. Even if estimates for the S.E. are out by 100%, it's still cheap by comparison to the current method of doing things.

This would be my first option. And I'd add "built in countries with low labor costs".

So... you don't know about S.E. development costs, but you advocate development of new rockets?

 

[Rasmus]

Even before the cost of the currently speculative materials required,

What is required besides the cable that would need an actual breakthrough?

I know several things would have to be build and developed, but they all seem doable.

construction costs running above 10 billion dollars are frequently cited for an elevator that can launch 10 tons to geo every two weeks. Those number don't really suggest low cost or high volume. They work out to about $2,000 dollars per pound just to recover the capital cost.

I didn't find many examples - but the "Rockot" has a price tag of roughly 13 million $US per launch and can carry just under 2 tons. I make that to be 3250 $US per pound. I am not sure how often they could launch one of these - but there have been 12 launches or attempted launches since 1990, none closer than 3 month to each other.

I am not sure how you reached your numbers, btw. The building cost of the space elevator is a one-time investment. There will also be running costs, but those would be much, much lower.

 

[jimbob]

Jimbob, a captive rocket sled is still likely much cheaper to build and maintain than a huge Linac like that. People who think such a thing would be easy have never worked at a particle accelerator lab.

-Ben

True, but similar problems would begin to be explored with maglev trains, only about 100x slower...

I was also wondering what effect that the Earth's curvature would have on something like that.

 

[RecoveringYuppy]

Okay, that was all just stupid fun. But seriously, I don't know all that much about the space elevator idea, but could one be built that didn't extend all the way to the ground?

If you Google "tethers" you'll find lots of ideas for "partial elevators" in varous orbits.

 

[RecoveringYuppy]

Well, of course, that's what Elevator2010 is all about... trying to draw a bound around those breakthroughs and costs. Should those breakthroughs occur, NASA will have gotten them for a song.

Uhh, how can you know that without knowing what the cost is going to be?

Current projections for the ISS put it over $100 billion. Even if estimates for the S.E. are out by 100%, it's still cheap by comparison to the current method of doing things.

Well, the current projections about the SE are complete fantasy so who knows how off they may be. But I don't see the point of your apples and orange comparison of a station to a transport mechanism. And, as I pointed out in the post you are replying to, the cost and capacity and cited don't make me think it's going to be cheaper than what we're doing now. And since we can't build an elevator now comparing it to what we can do now is a spurious comparison.

So... you don't know about S.E. development costs, but you advocate development of new rockets?

Can you tell me something about SE development costs? Not only can we not build an SE we can barely guess at it's cost. Advocating an SE is about like advocating building the Time Tunnel. Until some of the necessary breakthroughs occur it's pointless to "advocate" it.

When I compare current rocket prices against projected future costs and capacities for the imaginary space elevator I find that we've already built rockets that are close to those imaginary future prices. Seems to me that if we need more cheaper access to space the reliable way to get is to mass produce some current rocket design on an assembly line.

The number I calculated for SE costs based on the wiki article has already been matched by rockets. And that number assumed the SE had no operational costs.

 

[RecoveringYuppy]

I am not sure how you reached your numbers, btw. The building cost of the space elevator is a one-time investment. There will also be running costs, but those would be much, much lower.

I took a proejected cost and divided it by a projected capacity over an assumed lifetime. If you'd like me to repeat the exercise with numbers you prefer please provide the numbers.

How do you know the SE will be a one time investment? It will never need to be replaced? The first one will have all the capacity we will ever need?

How do you know what the operational costs will be?

If I said "No, elevator operational costs will be much higher" how could you dispute me?

Here's a link on launch costs. I'm on a slow connection and haven't checked multiple sources though.

http://cost.jsc.nasa.gov/ELV_INTL.html

 

[Rasmus]

I took a proejected cost and divided it by a projected capacity over an assumed lifetime. If you'd like me to repeat the exercise with numbers you prefer please provide the numbers.

I was just curious what numbers you used. E.g. what is the life time you assumed for the space elevator?

How do you know the SE will be a one time investment? It will never need to be replaced? The first one will have all the capacity we will ever need?

I wasn't precise enough. The space elevator is believed to have relatively high building costs and relatively low operational costs after that. AFAIK most rockets or at least major parts thereof aren't reusable.

How do you know what the operational costs will be?

I don't. But it is a fair assumption to make that running a cabin up and down a piece of string will be cheaper than throwing it up and down sans the string.

If I said "No, elevator operational costs will be much higher" how could you dispute me?

I would have to remember a lot i forgot about maths, then compare how much energy each system would need to bring one pound of material into orbit. I could find out how much additional fuel a conventional rocket would have to bring partially into orbit.

It would, of course, still be possible that for some unknown reason the space elevator would have to operate far, far from an assumed ideal energy input - but i doubt that would be a reasonable assumption to make.

Here's a link on launch costs. I'm on a slow connection and haven't checked multiple sources though.

http://cost.jsc.nasa.gov/ELV_INTL.html

Cool, thanks.

 

[Jimbo07]

Uhh, how can you know that without knowing what the cost is going to be?

It's called protoyping. NASA has committed to a maximum payout of $4 MM by 2010, across both tether and climber competitions. Assuming the breakthroughs are made for sufficient prototyping, one can probably put +/- 100% bounds on costs, perhaps better. That's the goal of Elevator2010, basically... payout $4 MM so that preliminary cost estimates can be cobbled together.

Well, the current projections about the SE are complete fantasy so who knows how off they may be.

They're not complete fantasy. You'll have to do some follow-up reading on methodologies. Refer specifically to Brad Edwards's work, as he was the one who did the initial work for NIAC. Some of the estimates were done by analogy, but several come from known technologies. "Out there" maybe, but not complete fantasy. Again, refer back to Elevator2010 for movement toward better estimates.

But I don't see the point of your apples and orange comparison of a station to a transport mechanism. And, as I pointed out in the post you are replying to, the cost and capacity and cited don't make me think it's going to be cheaper than what we're doing now. And since we can't build an elevator now comparing it to what we can do now is a spurious comparison.

Actually, there are several comparison points. Is it the railroad, or necessary railroad towns/watering towers/facilities/etc. Both projects are infrastructure (although the utility of the ISS as infrastructure has become more limited through design revisions). Moreover, there is an apt scale comparison for large 'space engineering' projects.

Can you tell me something about SE development costs? Not only can we not build an SE we can barely guess at it's cost. Advocating an SE is about like advocating building the Time Tunnel. Until some of the necessary breakthroughs occur it's pointless to "advocate" it.

What breakthroughs are you referring to, exactly?

The number I calculated for SE costs based on the wiki article has already been matched by rockets. And that number assumed the SE had no operational costs.

All of your operational costs have to be divided over the number of launches. A space shuttle flies five times a year at the best of times. All of those salaries have to be distributed over that timeframe. If you could average those over fifty launches a year, you'd realize an order-of-magnitude savings/kg right there. The salaries example holds whether you're talking S.E.s or more rockets, however, you're not building a new S.E. climber every time.

I took a proejected cost and divided it by a projected capacity over an assumed lifetime. If you'd like me to repeat the exercise with numbers you prefer please provide the numbers.

How do you know the SE will be a one time investment? It will never need to be replaced? The first one will have all the capacity we will ever need?

No. In fact, your best savings are realized once you start using the first S.E. to start seeding others! That's an economy of scale!

How do you know what the operational costs will be?

Nobody does, but megaprojects have been done before. In my current industry, estimating takes data from pilot plants. Prototyping, of a sort...

If I said "No, elevator operational costs will be much higher" how could you dispute me?

We'd have to then go to how we've each come up with our estimates.

I wasn't precise enough. The space elevator is believed to have relatively high building costs and relatively low operational costs after that. AFAIK most rockets or at least major parts thereof aren't reusable.

Right. Moreover, those rockets which have reusable parts have not been as cheap as some would have liked.

I don't. But it is a fair assumption to make that running a cabin up and down a piece of string will be cheaper than throwing it up and down sans the string.

For many reasons.

It would, of course, still be possible that for some unknown reason the space elevator would have to operate far, far from an assumed ideal energy input - but i doubt that would be a reasonable assumption to make.

Many things tend to not operate at a preliminary ideal. However, the laser to PV system is providing interesting results!



Cool, thanks.[/QUOTE]

 

[Dr. Trintignant]

The tangential velocity at the equator is ~0.44km/sec and escape velocity is 11.2km/sec, so launching eastward from the equator save you a whopping 0.15% of the energy (100% * (0.44/11.2)^2).

If the difference is so minimal, why does everyone with a space program build as close to the equator as is practical?

First off, your calculation is wrong. You don't square the difference in velocities; you take the difference of the squares. Thus, the difference is proportional to (11.2^2 - (11.2-0.44)^2)/11.2^2, which is more like an 8% savings.

But it gets much better than that. The rocket equation is exponential with velocity, because every extra meter per second you need comes from the beginning, where you're carrying your entire fuel load.

That's why launching at the equator is so important, and why a rail/sled/etc. system would be so effective, even if it only gets you to a few hundred meters per second.

It's also one reason why space elevators are so promising. You don't need to carry your fuel at all--it just gets beamed from the ground. That in addition to no atmospheric or gravitational losses make for a big win.

I will grant that a fast, high altitude aircraft launch can have many of the same benefits as the rail launch, but it's more likely to limit the size of your rockets.

- Dr. Trintignant

 

[R.Mackey]

If the difference is so minimal, why does everyone with a space program build as close to the equator as is practical?

First off, your calculation is wrong. You don't square the difference in velocities; you take the difference of the squares. Thus, the difference is proportional to (11.2^2 - (11.2-0.44)^2)/11.2^2, which is more like an 8% savings.

But it gets much better than that. The rocket equation is exponential with velocity, because every extra meter per second you need comes from the beginning, where you're carrying your entire fuel load.

That's why launching at the equator is so important, and why a rail/sled/etc. system would be so effective, even if it only gets you to a few hundred meters per second.

Correct. In computing the rocket equation, it's momentum or total impulse, and thus delta-V, not energy, that matters.

Launching near the equator helps, but it's not make-or-break. The Kennedy Space Center is not at the southern tip of Florida, nor do we launch from Panama or what have you... The choice of launch site is primarily determined by the orbit you want to hit. Being close to the equator gives you large stretches of open ocean, allowing you to launch into a low inclination orbit without passing over population centers or radically changing your flight path.

But if you want a polar or sun-sync orbit, being equatorial doesn't help. Quite a few launches are from Vandenburg or even Alaska for this reason.

It's also one reason why space elevators are so promising. You don't need to carry your fuel at all--it just gets beamed from the ground. That in addition to no atmospheric or gravitational losses make for a big win.

I will grant that a fast, high altitude aircraft launch can have many of the same benefits as the rail launch, but it's more likely to limit the size of your rockets.

The major drawback to the space elevator is the capital investment cost -- launching the elevator itself is several orders of magnitude beyond any envisioned capability. If we already had one, different problem, but I just don't see it happening.

 

[Dr. Trintignant]

The Kennedy Space Center is not at the southern tip of Florida, nor do we launch from Panama or what have you...

True, and one has to keep in mind practical considerations, such as transportation costs. The latitude of KSC gets you ~88% of the benefit of launching from the equator. Compare to, say, France, which doesn't have such a favorable location (either in latitude or coastline), and launches from French Guiana instead.

But if you want a polar or sun-sync orbit, being equatorial doesn't help. Quite a few launches are from Vandenburg or even Alaska for this reason.

Also very true. My intuition is that these are relatively rare, but I honestly don't know the percentage.

The major drawback to the space elevator is the capital investment cost -- launching the elevator itself is several orders of magnitude beyond any envisioned capability. If we already had one, different problem, but I just don't see it happening.

I suppose the idea is that you can make a starter cable fairly cheaply--say, on the order of a billion dollars. You then increase the capacity by pulling up additional strands/layers. Capacity growth would be slow but exponential, and perhaps within several years could be at a point where you could carry cargo.

Of course, the first step in all this is building long, strong strands of carbon nanotubes. The second step is using them in more Earthly construction (say, a suspension bridge). Maybe then, the idea will be a bit more interesting.

In the meantime, I really, really want someone to build the Sea Dragon.

- Dr. Trintignant

 

[Father Dagon]

This might sound like knee-jerk libertarianism, but I would leave it to the market, seriously.

The dark side of NASA is not the bloated costs per se, but that they set a standard. "Everoyne" can point to the costs and conlcude that space travel is expensive business, something that only the state can pay for.

And the costs isn't high beacuse of evil or some plan, it's in the small steps. It's the same every Christmas. I always buy gifts for some 10-20% more than I first budgeted for. But on the other hand I can lower my expenses in other fields as I usually gets books, clothes and films for Christmas. Leftovers from the Christmas-dinner helps too. Now imagine Christmas-splurging without lowering any costs in any field at all, all around the year on every imaginable department.

 

[RecoveringYuppy]

It's called protoyping. NASA has committed to a maximum payout of $4 MM by 2010, across both tether and climber competitions. Assuming the breakthroughs are made for sufficient prototyping, one can probably put +/- 100% bounds on costs, perhaps better. That's the goal of Elevator2010, basically... payout $4 MM so that preliminary cost estimates can be cobbled together.

The tethers and climbers coming out of 2010 are extremely unlikely to be realistic prototypes of a space elevator. And that 4MM you cite is unlikely to be the final price tab on the breakthroughs required?

They're not complete fantasy. You'll have to do some follow-up reading on methodologies. Refer specifically to Brad Edwards's work, as he was the one who did the initial work for NIAC. Some of the estimates were done by analogy, but several come from known technologies. "Out there" maybe, but not complete fantasy. Again, refer back to Elevator2010 for movement toward better estimates.

I've read all that and still can't past the fact that the crucial bit of technology required can't be produced now and can't reasonably be viewed as scaling up any existing technology.

What breakthroughs are you referring to, exactly?

Power transmission, radiation shielding for the long trip through the VA belts, cable or tether stability of thousands of miles. There are others.

All of your operational costs have to be divided over the number of launches. A space shuttle flies five times a year the best of times. All of those salaries have to be distributed over that timeframe. If you could average those over fifty launches a year, you'd realize an order-of-magnitude savings/kg right there. The salaries example holds whether you're talking S.E.s or more rockets, however, you're not building a new S.E. climber every time.

Well, actually to justify the numbers I gave earlier you would have to build a new climber each time. To be generous to the SE concept, I left out the time it would take for the climber to come back down.

And how long does it take a climber to go up and come down? The first SE certainly isn't going to be taking up payloads weekly.

No. In fact, your best savings are realized once you start using the first S.E. to start seeding others! That's an economy of scale!

Have you heard to old joke about the business man who loses a nickel on every sale but makes it up in volume?

Can you cite some numbers that make bootstrapping or "economies of scale" a plausible idea?

Using the first SE to build a second only makes sense if the SE can lift stuff cheaper than it's competition. And it looks to me (see link I posted earlier) that rockets are already nearing some of the hypothetical costs claimed by SE enthusiasts.

And what economies of scale do you see operating on an SE? Are we ever going to mass produce SEs?

IIRC the lowest launch cost in that link I cited was about $650/pound for a rocket that was custom built only a few times. You were talking about prototyping earlier. That rocket really has been prototyped and flown. So have most (all?) of the rockets on that list. If we need cheap abundant access to space then we should produce one of those rockets on an assembly line.

 

[jimbob]

Jimbob, a captive rocket sled is still likely much cheaper to build and maintain than a huge Linac like that. People who think such a thing would be easy have never worked at a particle accelerator lab.

-Ben

OK, this has given me an idea for an implausible launch strategy.

To get to the stars,why not do a "fantastic voyage" and then fire the resulting scientists out of a synchrotron?

I admit that there are technological hurdles, but hey...

 

[Jimbo07]

The tethers and climbers coming out of 2010 are extremely unlikely to be realistic prototypes of a space elevator.

Care to share why not?

And that 4MM you cite is unlikely to be the final price tab on the breakthroughs required?

Actually, you're exactly right. Altogether, the competing teams will spend more than NASA is paying. I didn't say it was a good financial deal for every team, I was just telling you how I had a guess on what costs are going to be. I also know the dollar amount my team has spent.

Spaceship One cost more than the X-Prize award of $10 MM. Such is life...

...

Anyway, I have to admit that you have me on the ropes. I don't have the resources to give this the rebuttal it deserves. I'm leaving work soon this afternoon, and won't have work access for 5 days, nor home internet access for 2 weeks! Maybe we can take this up later?

 

[RecoveringYuppy]

Sure. I'm on a slow connection due to holiday travel also.

The 2010 conference is unlikely to produce a prototype simply because the breakthroughs required can't be scheduled.

 

[TjW]

Even if you build a space elevator, you're going to need a cheap launch strategy to build the first one.

 

[jimbob]

How many gigatonnes of carbon would be needed for a space elevator, plus the extra to initially launch it into geostationary orbit?

Would you really want someone to steer a carbonaceous asteroid into geostationary orbit?

Of course it worked in "Red Mars"...

 

[RecoveringYuppy]

Presuming the desired material becomes available, most elevator designs are not billions of tons. Thousands of tons, more likely.

 

[BenBurch]

Well, we do have a lot of carbon...

But I think the one think that dooms any beanstalk is space flotsam and jetsam. There is no way that it will not suffer many high speed collisions and that it will be degraded and eventually destroyed by them.

Not only would we have to capture and ground every single satellite now in earth orbit, but every fleck of paint, every explosive bolt cover, etc., but also we would have to look for and deflect small (and large) asteroids, and the bottom end of size of concern would be quite small.