Dyna-Soar went through many dozens of iterations of lifting bodies.
You seem to be mistaking pretty pictures (many of them) for actual flight articles tested suborbitally (6) or re-entering from orbital velocity (zero).
Go back to steam engines, stirling engines? If your power source is light, why bother with electrical engines?
In fact, Mike Fischer's Fischer28 team did use a Stirling engine centered in a reflector, with the reciprocating piston's motion captured by a mechanism that clamped the tether at the top of each up-stroke, "hand over hand" style. It didn't work out this year, but it was an interesting alternative to the conversion losses of photovoltaics and roller drives.
Contests are run because there are often folks who overvalue them, so they are sometimes a cheap way to get things done at the expense of others.
So? Several participants told me that they were attracted by the design challenge and the pleasure of tinkering, and perhaps a bit of fame, more than by the prospect of prize money or by an interest in space technology. The advice you offer your students is fine as career guidance, but I don't see its relevance to the "hobbyist" domain.
Like the X Prize (and the Orteig prize won by Lindbergh), the Centennial Challenges are quite consciously aimed at that kind of leverage -- enlisting a total volunteer investment greater than the value of the prize. As a taxpayer, I approve.
Conductivity of nanotubes (doped and un-doped) is quite a big area, there are half a dozen research groups around the world working on it.
Last spring NASA awarded Smalley's group at Rice a contract to develop a sample of nanotube wire for prospective use in the CEV. Not superconducting by any means, but significantly lighter "per ampere" -- which matters a lot, given that early designs suggest the CEV would be >20% wiring by mass using copper or aluminum.
If that line of development pans out, there's a huge potential market in replacing aluminum high-tension lines with lighter (and ideally stronger) CNT cable -- fewer towers, less sag between towers, lower transmission losses to eddy/hysteresis, and the ability to put power plants farther from NIMBY power consumers.
NASA didn't offer enough money to get any remotely reasonable solution to the problem. Fifty thousand dollars is chump change to the kind of money needed to develop any of this technology.
The Centennial Challenges are intended to yield design ideas, not development. Most of the "cost" of this year's climbers was surely the participants' volunteered time.
It's silly to expect NASA or anyone else to put serious bucks into space elevators until CNT materials get a lot stronger. And to the extent that happens, it is (and will be for some time) paid for primarily by companies interested in stronger materials for engineering and construction use here on earth. If a 100+ GPa bulk material is in fact possible, there are markets many times bigger than all of space activity.
In a space-elevator scenario, you can use the energy of the descending cars to assist in powering the ascending cars.
Eventually, maybe -- but the hardware for that "recycling" adds mass to the climbers and/or the ribbon, which would push a first-generation SE farther into the future. Along with carbon nanotubes, what has given the idea some credibility over the last few years -- and what distinguishes Brad Edwards' version from the science-fiction treatments of Clarke, Sheffield, and Robinnson -- is that Edwards stripped it down to a bare minimum, with a starting mass we could deploy using existing technology.
No asteroid counterweight, no maglev trains, no 20-km base tower, and very likely no energy recycling -- in fact, until there's a need for lots of cargo coming down, it may well make more economic sense to have an up-only elevator and use the climbers for parts in space or simply discard them. Recycling energy would be cool, but sometimes the best is the enemy of the good.
Space Elevator proponents seem to miss the fact that the energy for the elevator isn't free. You still have to expend at least the minimum amount of energy required to move an object into LEO.
To take it one step farther, the potential energy (of altitude) gained isn't free; the kinetic energy (of orbital motion) is free, stolen from the angular momentum of the earth-elevator-counterweight system. At LEO, kinetic energy is the larger portion of the total needed -- and the ribbon at LEO is way below orbital velocity there, so a cargo detached there would still need a lot of delta-v to attain orbit. Potential energy dominates the total needed for GEO -- but there the climber is in orbit.
c) Ability to expend the power [umm -- energy] over a long period of time vs. in a huge controlled explosion
This helps -- you're not dealing with the high temperature and pressure of rocket engines -- but the crucial advantage is that all the energy is going into lifting the climber and cargo. Most of the energy released by orbital rockets goes into lifting and accelerating the propellant they'll be using moments later (that's why propellant is typically >90% of mass at liftoff). The efficiency of beamed energy is far less than that of a rocket engine, but that's outweighed by the advantage of not carrying propellant.
You're quite right about the time scale, of course. Aside from research on carbon nanotubes (the great bulk of which is being done for uses other than space), what's happening now is mostly volunteer or under-paid work on climber design and other technologies, so they'll be farther along when and if the ribbon material comes within reach. Note also that NASA has other, non-elevator uses for both beamed power and strong tether materials -- so these Centennial Challenge prizes don't imply their commitment to the elevator idea.
I don't understand why we should start with such an aggressive project. We can use today tethers of far shorter lengths and of current materials in space.
Absolutely correct -- and nobody would "start with such an aggressive project." People are talking about it because it's the sexy, high-profile "end of the rainbow" implementation, just the way people talked about rockets to orbit and beyond for decades while in real life the best they could do was A-3s, V-2s, Vikings, Redstones, etc.
Anybody aiming at a full "skyhook" SE is certainly going to want to test segments of ribbon material in exospheric and space conditions, and those exposure tests might as well be prototype momentum-transfer rotovators or orbital-maneuvering tethers at the same time.
Yes, the Moon and Mars SEs (or rotovators) are less demanding in material strength. OTOH, for the foreseeable future there'll be more demand for moving stuff among various Earth orbits -- and from ground to orbit -- than at the Moon or Mars. In fact, I'd say that if somehow we got to the stage with rockets where a Moon or Mars SE made economic sense, we wouldn't need an Earth SE; we'd have solved the challenge of CATS (cheap access to space) already.
Second, we're ignoring that expendable rockets have a lot of potential left in them. No one is using these rockets properly! By that, I mean no one is launching in volume. You simply can't get effective economies of scale with vehicles that launch at most a couple dozen times a year... We need launch frequencies on the order of several a day not several a year.
IIRC, all civilian and military payloads last year totaled less than 1000 tons -- equivalent to the cargo of one small freighter. And at that, quite a bit of launch capacity went begging; broadly speaking, the launch industry has been in doldrums since it ramped up for the Iridium, Teledesic and Globalstar "constellations" of commsats in the mid/late 1990s, only to be undercut by cheap fiber and the dot.com/comm bust.
Nobody denies in principle that if we built and flew a lot more rockets, we'd get economies of scale. Hell, the same would be true for aircraft carriers, nuclear subs, particle accelerators, and IC fab plants. But unless you know how to generate 10x or 100x or 1000x the current level of demand, that doesn't help much. Many alt.spacers believe that sub-orbital and then orbital tourism will provide that kick of new demand for more and better rockets; we shall see. In the 1980s, quite a few people believed the same thing of SDI.
Belief in the prospect of space elevators is every bit as dependent on faith in "build it and they will come" as belief in the prospect of more/better rockets. The important distinction is that between the "vehicle/ferry" model for rockets and the "railroad/bridge" model for the SE. The latter costs more up front, but offers higher capacity and scalability.
The problem with promoters of this kind of fantasy technology is that they don't understand how engineering really works. For example, the Apollo 11 landing happened more than 40 years after Goddard flew his first liquid fueled rocket.
I'm far from being a promoter, but I find the idea interesting because like many others, I don't believe there's much technical or economic headroom left in chemical rocketry. Your >40-year time scale is appropriate -- and on that time scale, unrealistic ideas such as space elevators, laser launch, nuclear-thermal or nuclear-pulse may turn out to be more realistic than the faith that either NASA or alt.space private enterprise will somehow overcome the rocket equation and the limits of chemical energy.
Your post -- and many others along the same lines -- have a defensive note, as if NASA were about to pour billions into space elevators to the detriment of existing technologies. Get a grip; no one's trying to take your rockets away.
(And to those who think a space elevator is 5, 10, or 15 years away, likewise: get a grip. Simply to establish by 2015 that bulk CNT material of sufficient strength is scientifically possible -- never mind feasible or affordable -- will require blazing progress in materials science. And there's no reason to expect serious investment, public or private, unless and until that happens.)
Did I miss something in the last few years? Did someone come up with a new wrinkle in orbital mechanics that does away with the need for a counterweight in a higher orbit to keep the cable tight?
Yes, you missed something -- and no, no new orbital mechanics required. Edwards' scenario extends the "cable" (a flat ribbon in his version) to 100,000 km/62,000 miles, so that its own mass and momentum beyond GEO provides nearly all the tension. The rest comes from the "spider" climbers used to build the ribbon up from a minimum-mass starter; when their spools are emptied, they're parked at the outer end. Edwards' insight was that
(1) if you can make 23,000 miles of ribbon in the first place, you can certainly make an extra 39,000 miles much more readily than you can either capture an asteroid or orbit Gtons of counterweight from the ground.
(2) the longer the ribbon, the greater the "free" velocity (actually taken from the angular momentum of the earth-ribbon system) available by simply letting your payload "fall" along the ribbon from GEO to the outer end and letting go.
...the Space Race which started ~1957 by 1969 the first mission to the moon began. From basically having little or no technology to do so resulted in Armstrong planting his footsteps on our lunar friend...
Wrong wrongitty wrong. The space race proceeded so fast precisely because the ICBM race from 1953 on -- which cost roughly twice what Apollo did -- had done the hardest, most expensive part in developing large rocket engines, lightweight airframes, guidance and re-entry techniques, and systems engineering. Apollo was mostly a matter of scaling up, adapting and integrating those technologies.
This is an important distinction. People who believe that we developed those crucial technologies "because space was such a compelling, widely shared goal" tend to have much less realistic expectations even today than people who recognize that getting into space was a spin-off from the compelling, widely shared goal of blowing each other up fast from far away.
Sorry folks. Logistics and supply are part and parcel of living in space. Whoever thinks that's boring while doing it in Low-Earth Orbit is just a flat out moron, considering the current state of our technology.
Yeah, I've been trying to understand the widespread "just going around in circles" meme about the ISS. (NB: This is not a defense of the ISS' costs, timing, or "internationalization.") A permanently manned orbital station was a big part of the mainstream space agenda from the 1920s on, with three basic justifications:
1) Observatory for instruments looking up and down, and (post Clarke 1945) comm relay station
2) A place to gain experience and biomedical data on living, working and building in free fall
3) A "dockyard" or staging point for missions beyond
OK, so (1) mostly went away because we got better at autonomous instruments and commsats
(2) The ISS continues to add to what was learned on Skylab and the Mirs; one way or another, that's a base of experience we need.
(3) Here, I think, is the heart of the "going around in circles" riff. If one's focus is on boldly going where no man, etc., and one is frustrated that we haven't, the ISS becomes a lightning rod: If it ain't a dockyard, it ain't ----!
Sorry, but that strikes me as childish. "Firsts" are thrilling, but I want one space activity after another to become routine. That's how I know we're getting good at it.
There are no physical barriers to going to mars that can't be overcome with enough will and funding... this thread is mostly just an indicator of how much America has declined in the last 40 years.
There are no physical barriers to extracting gold from seawater -- or creating it atom-by-atom in an accelerator -- that can't be overcome with enough will and funding. That doesn't make either activity likely or sensible.
Posts about technical ideas to make space activity more affordable can be interesting. Posts about new business models to make space activity more affordable can be interesting.
But posts about how we've lost the Will! the Vision! the Can-Do Spirit of our Ancestors! remain as boring as when they first appeared on Sumerian/.
People who encountered the Internet for the first time thought that they were witnessing a sudden explosion of technology. They had no idea, and evidently no interest in acquiring the idea, that the Internet was the result of gradual development that had gone on for decades before that, right back to Von Neumann if you like.
Excellent post. Apply it to perceptions of "fast" and "slow" progress in space. For the 99% who hadn't been paying attention to missile development from 1935 to 1957, it seemed that the wizards were cranking out frequent miracles during the space race years.
In fact, the hardest parts -- engine development, most avionics, re-entry -- had already been done on military missile budgets bigger than space has ever seen, and what we did from 1957 to 1973 was mostly adapting, integrating and scaling up. Not easy, but not new miracles.
It was when we tried to shift from money's-no-object ICBMs and Apollos to something more affordable and sustainable that we began to encounter the problems we're still living with... and people began wondering "Why has progress become so slow?" NASA bashers and alt.space fanboys notwithstanding, it's hard to get to orbit, and hard to reduce the cost of technology developed in a sky's-the-limit context.
"Look at it this way - the amount of fuel it takes to get to orbit will get you from the US to Australia in a 747. The reason it's cheaper to go to Australia is they don't throw away the plane when you get there (expendables) or take it apart and rebuild it (the shuttle) before the next flight."
I do love this old chestnut: it's perfectly true, and yet so misleading.
Helpful Hint #1: How long does it take to fly the 747 to Australia? What would happen if you took that long getting to orbit?
Helpful Hint #2: What is the difference between energy and power? If two machines release the same total energy, but machine #2 must release it much more quickly with equal or greater precision, which is likely to be more complex and expensive?
god I can't wait for a commercial venture to put nasa in their place
Too bad, because you're going to have to. For quite a while, unless you're among the New Faithful who've convinced themselves that Spaceship One was Apollo redux, but so much cheaper (and cute as a button).
The past two and a half decades have seen NASA throwing billions of dollars at a succession of "high concept", advanced space-plane ideas...could've been spent...in developing a realistic successor to the Shuttle
I admire your unerring gift for knowing in advance whether a given concept is going to turn into a "a realistic successor" or a loser.
The saps at NASA -- and oddly, at every one of the several score technology companies I've worked with -- lack your talent. They often have to spend quite a lot of money to find out which is which, then drop unpromising projects with nothing but experience to show for it.
To me it never made sense to have the shuttle strapped right next to the fuel and solid rockets. I believe it wasn't ever intended to in the original design...
First, there were dozens of "original designs." Tom Heppenheimer explains very well how NASA got to what was actually built, but at two volumes it's kinda long for a/. post. $23 for the pair, used, from Amazon.
Second, do a thought experiment: put an orbiter with its wings and tail on top of a rocket, where it so obviously belongs according to a lot of cheap hindsight. Now drive it up through the atmosphere, encountering a max Q of about 700 lb/ft^2. Mind you, that's not a nice even pressure as it would be underwater; it's a ferocious buffeting, with dips and spikes all over the place. Might be a few... interesting challenges in maintaining trajectory with a 125-ton weathervane up there, don't you think?
I'll leave the other design consequences -- and there are many -- to your imagination. (Hint: think "tank, SSME fuel, location of")
This complaing of mine is totally off topic, but the politics around NASA pisses me off.
No, politics is very much on topic. We got Apollo not only because St. Jack promised us the moon, but also because LBJ was a stone genius at working the Congress -- from driving the formation of NASA in 1958, as Senate majority leader, right through the artful deployment of NASA facilitie$ and job$ in the "right" districts.
If you think space shouldn't be (maybe shouldn't ever have been) a tax-funded government program, fine. But to have such a program, and then be dismayed that -- shock horror! -- politics plays a big role in it, is childish.
Government spending decisions shaped by politics routinely have life-and-death consequences for soldiers, for people who drive cars, for people who get (or don't get) vaccines, and countless other populations. Are astronauts exempt?
I think next time I'm in Washington DC I will tell everyone that they failed - they were the ones that put the budget restrictions on the initial Shuttle design that effectively "hobbled" it.
I've noted in another post that the most honest of those involved in the STS design acknowledged that there were more serious hurdles than money.
But there's a larger point: as long as you're spending tax money, you'd damn well better view the appropriation you get as just as "legitimate" and "valid" a constraint as the laws of physics. If you don't like that, find another source of funds... or work to elect more space-minded politicians... or shut up.
"Another few billion from that stingy Congress and we could have done it" carries the same information content as "Boy, if kero-LOX had an Isp of 2500, we'd be Slashdotting from Mars today."
When the shuttle first appeared, I remember it being sold as a "space plane", like you'd be able to launch, land later and fuel it up again and take off the next day.
This needs some shading to be accurate. What you describe is the optimistic high end of what STS planners were "selling" circa 1971. Then it got ground down for a decade -- at least as much by engineering realities as by budget constraints, although the Might-Have-Been crowd insists otherwise.
By 1980 (a year before STS-1), a very senior STS design engineer told me: "It seemed so obvious [in 1971] that reusability would lower dollars per pound to orbit. But when you start in a regime where maybe 5% of the mass on the pad gets to orbit... and now that 5% has to include wings and heavier airframe and TPS and landing gear... guess what? Unless you fly the sucker all day every day, the numbers go straight to hell."
That's not making excuses or CYA, that's reality. He and his colleagues (at least the candid ones) acknowledged that even had they had the full budget request at the start, they simply did not know how to pull off much of what they had aimed for, let alone flying "all day every day." We're still not within shouting distance of that for anything that can reach orbit.
If you want to criticize NASA circa 1981 for maintaining an optimistic PR glow appropriate to the hopes of 1971 instead of the hangar queen they had, be my guest. But I've seen many big corporate tehnolology initiatives come in late, over budget, and underperforming, and they're rarely accompanied by a press release saying "It's way less than we planned, but it's the best we could do."
Anyway, that's why Griffin is making the choices he's making. A sizeable faction will, of course, continue to piss & moan that he's not building the cheap, robust, profitable, fully reusable system they Just Know can be done. In fact, they have Powerpoints to prove it could have been done long ago -- no doubt the ones they adapted from overheads in 1986.
It is a totally great thing to have Scaled Composite, Blue Origin, Armadillo, SpaceX, and Sealaunch try new things and give the NASA/Boeing/Lockheed hegemony a little competition. Agreement abounds.
I could bash NASA with the best of them, but in fact I don't think it's more (or less) dysfunctional than other agencies. Specifically, where hardware development and procurement is concerned, for better and worse it looks a lot like (surprise!) DoD.
At the root of a lot of the bashing, I think, is simple frustration at what people perceive as slow progress by comparison with the Apollo years. I think that's because
(1) space is hard and expensive... no matter who pays for it (2) making space activity frequent, sustainable and affordable is a lot harder than a sprint (or seven) to the Moon... no matter who pays for it (3) we want space real bad.
For some people, especially/. libertarians and engineers who think politics and policy exist just to torment them, it's easier to bitch about the Big Bad Bureaucracy that's keeping us from space than to acknowledge (1) and (2).
Slashdot Mirror
Dyna-Soar went through many dozens of iterations of lifting bodies.
You seem to be mistaking pretty pictures (many of them) for actual flight articles tested suborbitally (6) or re-entering from orbital velocity (zero).
Whatever... As others have noted, the second year of the DARPA autonomous-vehicle challenge was strikingly more successful than the first.
Go back to steam engines, stirling engines? If your power source is light, why bother with electrical engines?
In fact, Mike Fischer's Fischer28 team did use a Stirling engine centered in a reflector, with the reciprocating piston's motion captured by a mechanism that clamped the tether at the top of each up-stroke, "hand over hand" style. It didn't work out this year, but it was an interesting alternative to the conversion losses of photovoltaics and roller drives.
Contests are run because there are often folks who overvalue them, so they are sometimes a cheap way to get things done at the expense of others.
So? Several participants told me that they were attracted by the design challenge and the pleasure of tinkering, and perhaps a bit of fame, more than by the prospect of prize money or by an interest in space technology. The advice you offer your students is fine as career guidance, but I don't see its relevance to the "hobbyist" domain.
Like the X Prize (and the Orteig prize won by Lindbergh), the Centennial Challenges are quite consciously aimed at that kind of leverage -- enlisting a total volunteer investment greater than the value of the prize. As a taxpayer, I approve.
Conductivity of nanotubes (doped and un-doped) is quite a big area, there are half a dozen research groups around the world working on it.
Last spring NASA awarded Smalley's group at Rice a contract to develop a sample of nanotube wire for prospective use in the CEV. Not superconducting by any means, but significantly lighter "per ampere" -- which matters a lot, given that early designs suggest the CEV would be >20% wiring by mass using copper or aluminum.
If that line of development pans out, there's a huge potential market in replacing aluminum high-tension lines with lighter (and ideally stronger) CNT cable -- fewer towers, less sag between towers, lower transmission losses to eddy/hysteresis, and the ability to put power plants farther from NIMBY power consumers.
NASA didn't offer enough money to get any remotely reasonable solution to the problem. Fifty thousand dollars is chump change to the kind of money needed to develop any of this technology.
The Centennial Challenges are intended to yield design ideas, not development. Most of the "cost" of this year's climbers was surely the participants' volunteered time.
It's silly to expect NASA or anyone else to put serious bucks into space elevators until CNT materials get a lot stronger. And to the extent that happens, it is (and will be for some time) paid for primarily by companies interested in stronger materials for engineering and construction use here on earth. If a 100+ GPa bulk material is in fact possible, there are markets many times bigger than all of space activity.
if you had something at 0 elevation going 13 miles per second it could cut through the atmosphere and get into orbit
I think you meant "...a few surviving incandescent fragments of it might just get into orbit."
Even at Everest altitude, encountering the air at 13 miles per second would destroy any feasible spacecraft very, very quickly.
In a space-elevator scenario, you can use the energy of the descending cars to assist in powering the ascending cars.
Eventually, maybe -- but the hardware for that "recycling" adds mass to the climbers and/or the ribbon, which would push a first-generation SE farther into the future. Along with carbon nanotubes, what has given the idea some credibility over the last few years -- and what distinguishes Brad Edwards' version from the science-fiction treatments of Clarke, Sheffield, and Robinnson -- is that Edwards stripped it down to a bare minimum, with a starting mass we could deploy using existing technology.
No asteroid counterweight, no maglev trains, no 20-km base tower, and very likely no energy recycling -- in fact, until there's a need for lots of cargo coming down, it may well make more economic sense to have an up-only elevator and use the climbers for parts in space or simply discard them. Recycling energy would be cool, but sometimes the best is the enemy of the good.
Space Elevator proponents seem to miss the fact that the energy for the elevator isn't free. You still have to expend at least the minimum amount of energy required to move an object into LEO.
To take it one step farther, the potential energy (of altitude) gained isn't free; the kinetic energy (of orbital motion) is free, stolen from the angular momentum of the earth-elevator-counterweight system. At LEO, kinetic energy is the larger portion of the total needed -- and the ribbon at LEO is way below orbital velocity there, so a cargo detached there would still need a lot of delta-v to attain orbit. Potential energy dominates the total needed for GEO -- but there the climber is in orbit.
c) Ability to expend the power [umm -- energy] over a long period of time vs. in a huge controlled explosion
This helps -- you're not dealing with the high temperature and pressure of rocket engines -- but the crucial advantage is that all the energy is going into lifting the climber and cargo. Most of the energy released by orbital rockets goes into lifting and accelerating the propellant they'll be using moments later (that's why propellant is typically >90% of mass at liftoff). The efficiency of beamed energy is far less than that of a rocket engine, but that's outweighed by the advantage of not carrying propellant.
You're quite right about the time scale, of course. Aside from research on carbon nanotubes (the great bulk of which is being done for uses other than space), what's happening now is mostly volunteer or under-paid work on climber design and other technologies, so they'll be farther along when and if the ribbon material comes within reach. Note also that NASA has other, non-elevator uses for both beamed power and strong tether materials -- so these Centennial Challenge prizes don't imply their commitment to the elevator idea.
I don't understand why we should start with such an aggressive project. We can use today tethers of far shorter lengths and of current materials in space.
Absolutely correct -- and nobody would "start with such an aggressive project." People are talking about it because it's the sexy, high-profile "end of the rainbow" implementation, just the way people talked about rockets to orbit and beyond for decades while in real life the best they could do was A-3s, V-2s, Vikings, Redstones, etc.
Anybody aiming at a full "skyhook" SE is certainly going to want to test segments of ribbon material in exospheric and space conditions, and those exposure tests might as well be prototype momentum-transfer rotovators or orbital-maneuvering tethers at the same time.
Yes, the Moon and Mars SEs (or rotovators) are less demanding in material strength. OTOH, for the foreseeable future there'll be more demand for moving stuff among various Earth orbits -- and from ground to orbit -- than at the Moon or Mars. In fact, I'd say that if somehow we got to the stage with rockets where a Moon or Mars SE made economic sense, we wouldn't need an Earth SE; we'd have solved the challenge of CATS (cheap access to space) already.
Second, we're ignoring that expendable rockets have a lot of potential left in them. No one is using these rockets properly! By that, I mean no one is launching in volume. You simply can't get effective economies of scale with vehicles that launch at most a couple dozen times a year... We need launch frequencies on the order of several a day not several a year.
IIRC, all civilian and military payloads last year totaled less than 1000 tons -- equivalent to the cargo of one small freighter. And at that, quite a bit of launch capacity went begging; broadly speaking, the launch industry has been in doldrums since it ramped up for the Iridium, Teledesic and Globalstar "constellations" of commsats in the mid/late 1990s, only to be undercut by cheap fiber and the dot.com/comm bust.
Nobody denies in principle that if we built and flew a lot more rockets, we'd get economies of scale. Hell, the same would be true for aircraft carriers, nuclear subs, particle accelerators, and IC fab plants. But unless you know how to generate 10x or 100x or 1000x the current level of demand, that doesn't help much. Many alt.spacers believe that sub-orbital and then orbital tourism will provide that kick of new demand for more and better rockets; we shall see. In the 1980s, quite a few people believed the same thing of SDI.
Belief in the prospect of space elevators is every bit as dependent on faith in "build it and they will come" as belief in the prospect of more/better rockets. The important distinction is that between the "vehicle/ferry" model for rockets and the "railroad/bridge" model for the SE. The latter costs more up front, but offers higher capacity and scalability.
The problem with promoters of this kind of fantasy technology is that they don't understand how engineering really works. For example, the Apollo 11 landing happened more than 40 years after Goddard flew his first liquid fueled rocket.
I'm far from being a promoter, but I find the idea interesting because like many others, I don't believe there's much technical or economic headroom left in chemical rocketry. Your >40-year time scale is appropriate -- and on that time scale, unrealistic ideas such as space elevators, laser launch, nuclear-thermal or nuclear-pulse may turn out to be more realistic than the faith that either NASA or alt.space private enterprise will somehow overcome the rocket equation and the limits of chemical energy.
Your post -- and many others along the same lines -- have a defensive note, as if NASA were about to pour billions into space elevators to the detriment of existing technologies. Get a grip; no one's trying to take your rockets away.
(And to those who think a space elevator is 5, 10, or 15 years away, likewise: get a grip. Simply to establish by 2015 that bulk CNT material of sufficient strength is scientifically possible -- never mind feasible or affordable -- will require blazing progress in materials science. And there's no reason to expect serious investment, public or private, unless and until that happens.)
Did I miss something in the last few years? Did someone come up with a new wrinkle in orbital mechanics that does away with the need for a counterweight in a higher orbit to keep the cable tight?
Yes, you missed something -- and no, no new orbital mechanics required. Edwards' scenario extends the "cable" (a flat ribbon in his version) to 100,000 km/62,000 miles, so that its own mass and momentum beyond GEO provides nearly all the tension. The rest comes from the "spider" climbers used to build the ribbon up from a minimum-mass starter; when their spools are emptied, they're parked at the outer end. Edwards' insight was that
(1) if you can make 23,000 miles of ribbon in the first place, you can certainly make an extra 39,000 miles much more readily than you can either capture an asteroid or orbit Gtons of counterweight from the ground.
(2) the longer the ribbon, the greater the "free" velocity (actually taken from the angular momentum of the earth-ribbon system) available by simply letting your payload "fall" along the ribbon from GEO to the outer end and letting go.
...the Space Race which started ~1957 by 1969 the first mission to the moon began. From basically having little or no technology to do so resulted in Armstrong planting his footsteps on our lunar friend...
Wrong wrongitty wrong. The space race proceeded so fast precisely because the ICBM race from 1953 on -- which cost roughly twice what Apollo did -- had done the hardest, most expensive part in developing large rocket engines, lightweight airframes, guidance and re-entry techniques, and systems engineering. Apollo was mostly a matter of scaling up, adapting and integrating those technologies.
This is an important distinction. People who believe that we developed those crucial technologies "because space was such a compelling, widely shared goal" tend to have much less realistic expectations even today than people who recognize that getting into space was a spin-off from the compelling, widely shared goal of blowing each other up fast from far away.
The problem is that the exhaust gases from a rocket are moving at the speed of sound
Time to stop reading here. Still, it would be entertaining to watch you "work out the Isp from these new power plants..."
Sorry folks. Logistics and supply are part and parcel of living in space. Whoever thinks that's boring while doing it in Low-Earth Orbit is just a flat out moron, considering the current state of our technology.
Yeah, I've been trying to understand the widespread "just going around in circles" meme about the ISS. (NB: This is not a defense of the ISS' costs, timing, or "internationalization.") A permanently manned orbital station was a big part of the mainstream space agenda from the 1920s on, with three basic justifications:
1) Observatory for instruments looking up and down, and (post Clarke 1945) comm relay station
2) A place to gain experience and biomedical data on living, working and building in free fall
3) A "dockyard" or staging point for missions beyond
OK, so (1) mostly went away because we got better at autonomous instruments and commsats
(2) The ISS continues to add to what was learned on Skylab and the Mirs; one way or another, that's a base of experience we need.
(3) Here, I think, is the heart of the "going around in circles" riff. If one's focus is on boldly going where no man, etc., and one is frustrated that we haven't, the ISS becomes a lightning rod: If it ain't a dockyard, it ain't ----!
Sorry, but that strikes me as childish. "Firsts" are thrilling, but I want one space activity after another to become routine. That's how I know we're getting good at it.
There are no physical barriers to going to mars that can't be overcome with enough will and funding... this thread is mostly just an indicator of how much America has declined in the last 40 years.
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There are no physical barriers to extracting gold from seawater -- or creating it atom-by-atom in an accelerator -- that can't be overcome with enough will and funding. That doesn't make either activity likely or sensible.
Posts about technical ideas to make space activity more affordable can be interesting. Posts about new business models to make space activity more affordable can be interesting.
But posts about how we've lost the Will! the Vision! the Can-Do Spirit of our Ancestors! remain as boring as when they first appeared on Sumerian
People who encountered the Internet for the first time thought that they were witnessing a sudden explosion of technology. They had no idea, and evidently no interest in acquiring the idea, that the Internet was the result of gradual development that had gone on for decades before that, right back to Von Neumann if you like.
Excellent post. Apply it to perceptions of "fast" and "slow" progress in space. For the 99% who hadn't been paying attention to missile development from 1935 to 1957, it seemed that the wizards were cranking out frequent miracles during the space race years.
In fact, the hardest parts -- engine development, most avionics, re-entry -- had already been done on military missile budgets bigger than space has ever seen, and what we did from 1957 to 1973 was mostly adapting, integrating and scaling up. Not easy, but not new miracles.
It was when we tried to shift from money's-no-object ICBMs and Apollos to something more affordable and sustainable that we began to encounter the problems we're still living with... and people began wondering "Why has progress become so slow?" NASA bashers and alt.space fanboys notwithstanding, it's hard to get to orbit, and hard to reduce the cost of technology developed in a sky's-the-limit context.
"Look at it this way - the amount of fuel it takes to get to orbit will get you from the US to Australia in a 747. The reason it's cheaper to go to Australia is they don't throw away the plane when you get there (expendables) or take it apart and rebuild it (the shuttle) before the next flight."
I do love this old chestnut: it's perfectly true, and yet so misleading.
Helpful Hint #1: How long does it take to fly the 747 to Australia? What would happen if you took that long getting to orbit?
Helpful Hint #2: What is the difference between energy and power? If two machines release the same total energy, but machine #2 must release it much more quickly with equal or greater precision, which is likely to be more complex and expensive?
god I can't wait for a commercial venture to put nasa in their place
Too bad, because you're going to have to. For quite a while, unless you're among the New Faithful who've convinced themselves that Spaceship One was Apollo redux, but so much cheaper (and cute as a button).
The past two and a half decades have seen NASA throwing billions of dollars at a succession of "high concept", advanced space-plane ideas...could've been spent...in developing a realistic successor to the Shuttle
I admire your unerring gift for knowing in advance whether a given concept is going to turn into a "a realistic successor" or a loser.
The saps at NASA -- and oddly, at every one of the several score technology companies I've worked with -- lack your talent. They often have to spend quite a lot of money to find out which is which, then drop unpromising projects with nothing but experience to show for it.
They need you, man!
To me it never made sense to have the shuttle strapped right next to the fuel and solid rockets. I believe it wasn't ever intended to in the original design...
/. post. $23 for the pair, used, from Amazon.
First, there were dozens of "original designs." Tom Heppenheimer explains very well how NASA got to what was actually built, but at two volumes it's kinda long for a
Second, do a thought experiment: put an orbiter with its wings and tail on top of a rocket, where it so obviously belongs according to a lot of cheap hindsight. Now drive it up through the atmosphere, encountering a max Q of about 700 lb/ft^2. Mind you, that's not a nice even pressure as it would be underwater; it's a ferocious buffeting, with dips and spikes all over the place. Might be a few... interesting challenges in maintaining trajectory with a 125-ton weathervane up there, don't you think?
I'll leave the other design consequences -- and there are many -- to your imagination. (Hint: think "tank, SSME fuel, location of")
This complaing of mine is totally off topic, but the politics around NASA pisses me off.
No, politics is very much on topic. We got Apollo not only because St. Jack promised us the moon, but also because LBJ was a stone genius at working the Congress -- from driving the formation of NASA in 1958, as Senate majority leader, right through the artful deployment of NASA facilitie$ and job$ in the "right" districts.
If you think space shouldn't be (maybe shouldn't ever have been) a tax-funded government program, fine. But to have such a program, and then be dismayed that -- shock horror! -- politics plays a big role in it, is childish.
Government spending decisions shaped by politics routinely have life-and-death consequences for soldiers, for people who drive cars, for people who get (or don't get) vaccines, and countless other populations. Are astronauts exempt?
"Wouldn't it be pretty to think so?"
I think next time I'm in Washington DC I will tell everyone that they failed - they were the ones that put the budget restrictions on the initial Shuttle design that effectively "hobbled" it.
I've noted in another post that the most honest of those involved in the STS design acknowledged that there were more serious hurdles than money.
But there's a larger point: as long as you're spending tax money, you'd damn well better view the appropriation you get as just as "legitimate" and "valid" a constraint as the laws of physics. If you don't like that, find another source of funds... or work to elect more space-minded politicians... or shut up.
"Another few billion from that stingy Congress and we could have done it" carries the same information content as "Boy, if kero-LOX had an Isp of 2500, we'd be Slashdotting from Mars today."
When the shuttle first appeared, I remember it being sold as a "space plane", like you'd be able to launch, land later and fuel it up again and take off the next day.
This needs some shading to be accurate. What you describe is the optimistic high end of what STS planners were "selling" circa 1971. Then it got ground down for a decade -- at least as much by engineering realities as by budget constraints, although the Might-Have-Been crowd insists otherwise.
By 1980 (a year before STS-1), a very senior STS design engineer told me: "It seemed so obvious [in 1971] that reusability would lower dollars per pound to orbit. But when you start in a regime where maybe 5% of the mass on the pad gets to orbit... and now that 5% has to include wings and heavier airframe and TPS and landing gear... guess what? Unless you fly the sucker all day every day, the numbers go straight to hell."
That's not making excuses or CYA, that's reality. He and his colleagues (at least the candid ones) acknowledged that even had they had the full budget request at the start, they simply did not know how to pull off much of what they had aimed for, let alone flying "all day every day." We're still not within shouting distance of that for anything that can reach orbit.
If you want to criticize NASA circa 1981 for maintaining an optimistic PR glow appropriate to the hopes of 1971 instead of the hangar queen they had, be my guest. But I've seen many big corporate tehnolology initiatives come in late, over budget, and underperforming, and they're rarely accompanied by a press release saying "It's way less than we planned, but it's the best we could do."
Anyway, that's why Griffin is making the choices he's making. A sizeable faction will, of course, continue to piss & moan that he's not building the cheap, robust, profitable, fully reusable system they Just Know can be done. In fact, they have Powerpoints to prove it could have been done long ago -- no doubt the ones they adapted from overheads in 1986.
It is a totally great thing to have Scaled Composite, Blue Origin, Armadillo, SpaceX, and Sealaunch try new things and give the NASA/Boeing/Lockheed hegemony a little competition.
/. libertarians and engineers who think politics and policy exist just to torment them, it's easier to bitch about the Big Bad Bureaucracy that's keeping us from space than to acknowledge (1) and (2).
Agreement abounds.
I could bash NASA with the best of them, but in fact I don't think it's more (or less) dysfunctional than other agencies. Specifically, where hardware development and procurement is concerned, for better and worse it looks a lot like (surprise!) DoD.
At the root of a lot of the bashing, I think, is simple frustration at what people perceive as slow progress by comparison with the Apollo years. I think that's because
(1) space is hard and expensive... no matter who pays for it
(2) making space activity frequent, sustainable and affordable is a lot harder than a sprint (or seven) to the Moon... no matter who pays for it
(3) we want space real bad.
For some people, especially