That NASA and Amurrican flag on the space elevator fantasy picture ... most ridiculous.
Next: The Imperial Seal of the Holy Roman Empire on the Space Shuttle.
We recently suggested that even the most advanced rocket currently slipping the surly bonds of Earth is nothing more than glorified V2, over 70 years since Hitler's Vergeltungswaffe 2 first lifted off the pad at Peenemünde. Today, we'll have a look at some technologies that may one day allow us to escape V2 designer Wernher …
Including Cyprus, Greece, etc ? LOL.
More seriously, most of this sci-fi is so far in the future that it's more likely to be places like Brasil or the Philippines or somewhere in Africa taking up the slack. China and Europe will be full of the retired elderly by then. The future belongs to those with birth rates above 2.3 per lady.
You misunderstand I think....
I was pointing out that it was the fact we gave them our research that allowed them to solve a big stability issue they had been having (tails...), and then they didn't share theirs back....
I am all for sharing research, I just feel the US in general was a bit of a one way sponge for research in the past..
They are much better now.. just look at NIF & that HiPER will be able to build upon its research, shows that they are sharing...
Sorry, some explanation required there. Why do you think it's bullshit.
I mean, I could just as easily say you are made entirely of bullshit. I've produced just as much evidence.
So common, rather than blurting stuff out, let's have a reasoned argument about why you think it's bullshit.
It's worth pointing out the cost figures for Skylon are expected to be around 10 million dollars per launch with one Skylon having a lifespan of at least 200 flights.
15 tonnes lifted to LEO for only 10 mil? And the 1st prototype is expected to fly in 2018? Point out anything the Americans have coming down the pipeline within the next 20 years that'll match that.
Space elevators are, unfortunately, still firmly in the land of science fiction. The elevator has to have a counterweight beyond GEO, and GEO is really, really far away. Like, really far. Super far. So far it's amazing we can even put satellites there far. The idea of tethering an asteroid or whatever beyond that, and then stringing a near infinitely strong, thirty thousand+ mile long column of carbon nanotubes between the equator and it is, frankly, absurd.
If you've got the materials and knowledge to engineer a space elevator, there are far more reasonable (and safe) options, like the space fountain, which combines magnetic acceleration and space elevator concepts to find a happy medium.
Some might point out that space elevators could be useful on lower-mass objects like Mars, the Moon or big asteroids. The problem there is that their GEO orbits are still proportionally far away - if GEO is close enough to use a space elevator, gravity is weak enough to use a simple maglev launch sled.
That's the satellite with giant rotating arms which scoops a balloon out of the atmosphere and deposits it into space. Thanks to Charles Stross "Saturn's Children" for introducing me to this idea. It's probably even more hairy than a space elevator as an engineering project, but doesn't require quite such strong materials.
Well for me I'd include space fountains and launch loops in with space elevators as it is really just a different way to build a physical link with space and you ride in an elevator ;-)
but for the next 100 years we need skylon or bigger versions of it..
Every other tech uses multiple components, meaning more points of failure..
With skylon you have two engines, can run it from an almost normal runway basically, and so far the tech has been proven, nothing about it is radical any more...
Maybe they say 200 launches each, but who's to say that can't be extended with a damn good refurbishment after 200...
Some might point out that space elevators could be useful on lower-mass objects like Mars, the Moon or big asteroids. The problem there is that their GEO orbits are still proportionally far away - if GEO is close enough to use a space elevator, gravity is weak enough to use a simple maglev launch sled.
I had not heard of a space fountain before; I had always assumed the elevator portion of the space elevator would use magnetic lifting rather than mechanical. Also, setting up a space elevator on the moon might make sense in as much as it provides a lower bar to get over in developing the technology for use on(ish) Earth - plus, you get a nifty moon base as part of the package. Of course there would be other problems not covered by this model (e.g. wind sheer), and it would require getting there with all of the materials needed to build it or starting a mining operation locally...
The difference between a very big Eifel tower and a space elevator is, that the tower is rigid. And we need rigid because the speed of an object on the surface of the earth is much slower than the speed of an object at GEO. So going up the tower, we have a vertical component, and the horizontal component we take from the earths rotation around its axis.
Not so with the space ribbon. This means with every object we send up, the counterweight will start to lag. Energy is taken from the counterweight to speed up payload, so it will lag and it's orbit will decay. And this will get worse with every payload we send up.
Dear mr "Destroy All Monsters", if that is your real name. Could you please calculate for me how much reaction mass would be required to give the counterweight "a bit of a boost"? Then compare that to the reaction mass required using a conventional rocket? Of course you can't, because you're calling other people pointing out the bleeding obvious "nerds" you have no clue of the real world around you.
But I can.
This means with every object we send up, the counterweight will start to lag. Energy is taken from the counterweight to speed up payload, so it will lag and it's orbit will decay. And this will get worse with every payload we send up.
No orbital decay. The energy to reach escape velocity comes from Earth's rotation, all you need is fuel to lift the car to the required altitude.
Sorry, forgot the rest:
The lag incurred by lifting the car is compensated by keeping the elevator cable under sufficient tension. When the car stops, the centrifugal force will straighten out the lag.
NASA put money into this. You think they'd have done that if it required the same amount of fuel as conventional reaction thrusters?
I say use the Project Orion system to get a 5000+ ton platform with all the nano tube cables you could ever want into orbit and then you can start to work on it.
I'm sure with modern computer blast modelling we could make cheap powerful enough atomic charges with a radiation half-life of say just a few days/weeks so the environmental risk would be much much lower.
If we could get a few thousand tons of materials into space it really would start the way.
Just one Orion launch is maybe all that's ever needed.
Space elevators will never not work.
Or in other words, space elevators will always work.
It's very amusing how morons have an awful propensity to say the exact opposite of what they wanted to, because they are not intelligent enough to understand the meanings of the words they are trying to use.
Trying to span the depth of the Earth's gravity well with a single structure is terribly non-optimal from an engineering standpoint for a number of reasons. Smaller elevators, however, are quite feasible with off the shelf carbon fiber.
Imagine a rotating cable with a tip velocity of 2400 m/s, and a comfortable 1 gravity at the tip. The radius then works out to 587 km. You don't want the tip to enter the atmosphere, so you set the orbit of the center to 750 km, and the lowest point is then 163 km. The center then orbits at 7.48 km/s, and the tip is moving 2.4 km/s less or 5.08 km/s. Subract the Earth's rotation and you have a velocity of 4.61 km/s relative to the ground.
Your launch vehicle now has a much less challenging job than getting all the way to orbit by itself. It merely needs to reach a landing platform at the tip of the cable. To return to Earth, it has much less velocity to dissipate, so the re-entry heating is much less. Cargo heading to higher orbit merely rides for half a rotation, then lets go. It now is moving at 2.4 km/s above orbit velocity, which puts you in a high transfer orbit.
The load on the cable varies linearly from center to tips, therefore is equal to a cable under 1 g half the length, or 293 km. Good carbon fiber has a breaking length at 1 gravity of 360 km. We want a decent margin of safety, so only load the cable to 40% of ultimate strength. This requires tapering the cable from center to tip, as each point has to support the payload + cable outside that radius, but the taper ratio is not severe, about 7:1 in area.
Because this design is 40 times shorter, it is much less exposed to meteor and debris damage, but they still are a risk. Therefore you build the cable out of something like 21 strands, of which 7 are spares, and cross-connect them every 5 km. So when the inevitable impact happens, you only have to replace the one 5 km segment, which is 0.02% of the total structure. The "single cable" illustrations like the one in this article are just terribly unrealistic from a safety standpoint.
This type of rotating space elevator is called a Rotovator, and can start being useful while under construction, so you don't have to build it all at once. As the length increases, and tip velocity goes up, the launch vehicle needs less velocity, and can therefore carry more payload. If some of the payload is more cable for the Rotovator, the increased cargo on later flights "pays back" the payload spent on launching the cable. This payback time in cargo mass can be relatively short.
You can build a second Rotovator in high orbit, which captures payload sent up by the first one in low orbit, and forwards them to interplanetary trajectories. Since kinetic energy is not free, you need onboard electric thrusters to maintain the Rotovator orbits, but those have ten times higher efficiency than conventional rockets, so you still come out very much ahead on net cargo.
You clearly don't understand orbital mechanics. Of course grabbing a sub-orbital cargo and accelerating it to higher orbit will lower the Rotovator orbit. That I why I mentioned on-board propulsion to make up the kinetic energy lost.
That allows you to substitute low efficiency rocket (on an unassisted rocket) for high efficiency electric thrusters (on the Rotovator), saving you 90% of the propellant consumption, which turns into more payload.
I spent a career in Boeing's space systems division, and am writing a book on the subject ( http://en.wikibooks.org/wiki/Space_Transport_and_Engineering_Methods ) so please credit me with having a clue what I am talking about.
I haven't ignored it. For a Rotovator design, you hook on and ride half a rotation and then let go. The forces are purely radial in that case. If you are climbing from the tip of rotation to the center, you do see a Coriolis effect, but let's look at the numbers.
Assume you have a maglev-type track that lifts a payload from the tip to center in 3 hours (200 km/s for a ~600 km radius), and the tip velocity is 2400 m/s. Therefore you much transfer 0.22 m/s angular velocity to the structure. The radial tension in the structure is 9.8 m/s at the tip, so you produce 2.2% deflection from purely radial while climbing. This is a manageable deflection of the cable structure.
So... According to Wikipedia - http://en.wikipedia.org/wiki/Space_elevator - Tsiolkovsky's original idea was a tower, which would be in compression. Current thinking resolves around a cable, in tension. Is there a feasible midpoint, which is neither in compression nor tension?
Get ONE thread up, in whole or in part, then get up a counter weight - a very small one, enough to allow a second thread to be pulled up.
Then add more threads, more counter weight, etc., etc., etc...
1000Km sections, glue on the overlapping joints.... easy.
Once the thread is strong enough, and the counter weight is enough to take it from a goat track into a single lane highway.....
Away we go.
10 metric ton loads.....
Space Elevator concepts often include laser beam system to beam energy from the ground up to the crawler. I think that's a stupid approach.
Instead just use a pulley at the top end, on the counterweight. The carbon nanotube string obviously needs to be twice as long. At the bottom end is a simple motor. The crawler is rolled out, clamped to the string, fire up the motor and off you go.
Efficiency might be improved if there was another one coming down on the opposite side of the loop at the same time. They might want to slow down to pass, or use winglets to assure separation.
Critics of this Pulley amendment to the Space Elevator concept will claim that "it's completely impractical" to add a pulley and make the string twice as long. I guess they forgot that we're discussing the gol-damn SPACE ELEVATOR concept - itself completely impractical to the point of insanity.
So the basic rocket used in the 1940s is little different from the ones in use today - 50+ years later. Quel suprise!
Government agencies have little reason to pursue developments - they're expensive, they don't always work and even if you do make a thingy work better, all you get is a pat on the back and a memo of thanks.
Compare that with the (commercially driven) aircraft industry. Coming out of WW1, in 1918 aircraft were still made from wood, with 1 or 2 piston engines and room for one or two "lucky" drivers (though some of the "latest" bombers could carry 6 people). And they were about as reliable as Windows 3.1 However there were lots of civil aviation companies - all competing for government contracts and commercial uptake. Hence, 50 years and a few more wars later we had Jumbo jets.
That is a summary of liquid propellant research (the good, the bad and the insane). They tried everything at least twice (US Navy or Army funding). I cannot imagine work like that being repeated today for at least three reasons. Governments are out of money. When they do spend money, they are useless at asking for what they need and even if they get that right, they ask companies that are experts at taking the money, delivering nothing and getting another contract to do the same thing again.
After reading about it, I can see why 50's tech is so enduring. (Spacex Falcon 9 is kerosene/LOX.)
Yes, but cars still have four wheels an engine and a steering wheel.
But wait, they were saved by the government a couple of years ago, perhaps that's why?
But seriously, get of you "company good / government bad" horse. It's limping. Badly. It needs to be put down.
Cars were saved by government?????
And really, the only thing that needs putting down is excessive government (What is excessive? Everything beyond a government managing the receptions of other government's diplomats: select the restaurants and all that) . Hell, we could have done a lot more with a few world wars less, for starters.
until we invent / discover a better source of power, a 'vacuum propeller' and we all work together, we are going to be stuck in the local area.
Mind you, given that it looks like something / someone a while back was re-fueling at our sun, do we really want to get to far out there.... now where is my tin-foil hat.
ka-boom, cos thats all we can manage at the moment - firework on a stick :D
"ka-boom, cos thats all we can manage at the moment - firework on a stick"
Yeah, but, then again, our cars all basicly run on fireworks in a can (ok, cans), so it's a valid power source if not the most efficient.
That said, I sure would like to get off this rock. Would someone fix that please?!
I thought the V2 ran on hydrogen peroxide and kerosene - not liquid hydrogen for oxidizer, and certainly not ethanol diluted with water as fuel. Some people might seem to use that latter substance as fuel... but there's no need to dilute ethanol with water for safety reasons when using it as fuel.
They may have left some water in with the hydrogen peroxide, though, even if what they used was stronger than hair bleach.
There was actually a problem with tankers for V2s turning up with less fuel on board than they'd started out with.
The percentage of water was down to ease of manufacture and handling in the engine, the fuel was used for cooling the engine chamber before being burned and getting 75% abv probably only needed a single distillation. The V2 did use peroxide, but for driving pumps, not for propulsion.
"I thought the V2 ran on hydrogen peroxide and kerosene - not liquid hydrogen for oxidizer, and certainly not ethanol diluted with water as fuel. "
LOX/Diluted Ethanol for main propellant. Decomomposed Hydrogen Peroxide (Steam and O2) drove the turbo pumps, as it still does for some Russian launchers.
It's readily available information.
Didn't the A4/V2 run on T-Stoff (hydrogen peroxide) and C-Stoff (hydrazine hydrate / methanol / water)? The Germans certainly had hydrazine. Hydrazine is still in use as a propellant.
John D. Clark's book 'Ignition' is a terrific read and is quite amusing at times... and freely available.
Nuke as Nork rockets probably use HTP and hydrazine
LOX/Ethanol. The V-2 engine was not very well cooled, so they had to use dilute alcohol (75%) and low chamber pressure. The Soviets got that back up to 90% ethanol and doubled the thrust of the engine for their R-5 rocket, by doing a lot of tinkering with the cooling. The fuel traveled around a spiral of pipes outside the thick steel walls of the combustion chamber, but that was insufficient. So they borrowed a trick from Goddard (who was actually being spied on by the Germans), and sprayed fuel onto the inside of the chamber.
The V-2 was a fascinating rocket, because it was an order of magnitude bigger than previous ones. You can debate whether rocketry really starts there, because it didn't have any new conceptual ideas. People had build liquid fuel rockets, used gyro stabilization, etc in America, Russia and probably a few other places. Tsiolkovsky in Russia first proposed space rockets using liquid fuel, and Goddard built the first one, Glushko in Russia had the best engines, but they were much smaller than what the V-2 needed.
And the electronic computer of the A-4 is also of mucho interest!
Check this (if you understand german):
A fascinating talk about great ideas meeting full-on retardation of academia and industry (not understanding cybernetics at all) and military (not understanding shit) about the design of the on-board analog computer. Is there an english translation?
"Ich möchte nur erwähnen daß, wenn bei Nyquist von Schwingung gesprochen wird, diese Schwingung nichts unmittelbar mit einer Schwingung zu tun hat, welche die Rakete im Flug ausübt oder nicht ausübt. Ich benutzte daher, abweichend von dem Sprachgebrauch der “klassischen Wurzel-Methode.” das Wort “Phase” und “Phasenschieber.” Einer der Herren der Firma fragte mich, ob ich wüßte, daß das Wort Phase nur Sinn mache, wenn es sich um eine Schwingung handelte. In anderen Worten, “wenn die Rakete keine Schwingung ausübt, kann ja Ihr System gar nicht funktionieren und die Schwingung wollen wir ja gerade vermeiden.” Diejenigen von Ihnen, die sich einmal mit Regelungstechnik befaßt haben, werden jetzt anfangen zu lachen und ich tat das auch bis mir der Ernst der Lage klar wurde. Dies war nämlich für unseren General, der die Sitzung leitete, aber noch weniger davon verstand, so sehr überzeugend, daß er das neue System abdrehte. Die Computersteuerung war kaputt - tot - und die Industrie war beruhigt. Dies blieb so bis Prüfstand Tests zeigten, daß es das einzige System war, das wirklich funktionierte. Es wurde dann das endgültige System für die Rakete. Nicht nur, daß es billiger war, es war auch zuverlässiger und man konnte nun alle Geräte der Steuerung miteinander austauschen und miteinander arbeiten lassen. Z.B. Siemens Richtgeber mit Anschutz Rudermaschine oder stabilisierte Plattform von der Firma Kreiselgeräte mit irgend einer Rudermaschine von einer anderen Firma oder umgekehrt. Ich möchte noch erwähnen, daß auch die Stellungszuortnung der Rudermaschine überflüssig wurde. Wenn Ihnen also jemand ein Steuerungsschaltbild zeigt, welches Wendezeiger enthält, dann war es nicht die V 2 Steuerung sondern der Vorschlag von einem, der es gerne verkauft hätte, wenn es funktioniert hätte."
There is also the element that alcohol with some water, makes for a GOOD cooler running engine....
This is the difference, when faced with a range of compromises, limitations, and hard fact, that these were a successful rocket, in terms of capability and range.
And given that at the time, these were the state of the art engines... in wartime, with limited resources, time, materials and tooling - with bombs falling on them, and Russians up their arse.
But with MORE research, better materials, more development and testing, etc... the size of the rocket engine reduced by many factors, while the power went up by many factors.
So the difference between the shuttle engines and the V2 engines, were absolutely staggering.
Another possibility - Mitchell Burnside Clapp's 'Black Horse' concept for Single Stage to Orbit. It used mid-air refuelling.
It sounds unlikely, but it's apparently quite practicable. It used standard existing technology as much as possible - and Mitch pointed out that the US Air Force does mid-air refuelling up to hundreds of times a day.
Cine SF afficioadoes will have seen this film, in which mankind escapes from a doomed Earth in a spacecraft which is launched along a track from a mountain peak, down into a valley, and then up the other side.
I've never found out why this idea is unfeasible. The problem with rockets is that you spend most of your fuel getting the rest of your fuel up to mere subsonic velocity. So why not use a maglev track (or even a giant train track) to electrically accelerate your rocket up to maybe 600mph, and only then fire the rocket? The aerodynamics of a supersonic maglev launcher would be far harder, but physically there's no reason why your assist has to stop at subsonic speed. (Might be safer to accelerate only after the liquid-fuel rocket was burning. Throttle up from minimum to maximum after it leaves the track).
Launching from underneath a carrier aircraft is somewhat equivalent, but is limited to the payload that can be lifted by an aircraft. (There's a limit, to do with the bending strength of wings). A track launcher could handle much heavier payloads.
Although the diminishing returns with rockets are awful they aren't quite that bad. http://www.braeunig.us/apollo/SaturnV.pdf has some interesting figures from a moderately detailed simulation of a Saturn V launch:
Dry weight: 242 tonnes
Fuel mass at launch: 2657 tonnes
Fuel mass at mach 1: 1786 tonnes
So getting beyond sub-sonic used 1/3 of the total fuel mass but also got it to 7.9km altitude through the densest part of the atmosphere - even a high altitude maglev track will fall somewhat short of this. It would still be a fantastic saving though.
But perhaps the required increase in lateral strength would be problematic - for a conventional rocket almost all force is transmitted vertically, whereas even a gently curved track will add further sideways acceleration to the standard 1G experienced just by lying on its side.
Mongo, you are also missing the point that it is bad by design, because that is good.
Consider a Saturn 5 engine block. It generates a certain amount of thrust if you pump fuel into it fast enough. Imagine that you have a rocket with only 2/3 of the amount of fuel that NASA actually used. It would weigh substantially less and yet have the same thrust. It would therefore accelerate much faster. So why didn't NASA do it this way? Well, they did. Once you've burnt 2/3 of the fuel in a real Saturn 5, you have exactly the rocket I've just described, except that you are now "launching it" from a platform five miles up traveling at Mach 1.
The optimal launch weight of any rocket is "as much as it can lift". In the case of the Saturn 5, at the moment of launch you have a 3500 ton ballerina balancing just above the launch pad on a downward thrust of exactly the same. (In fact, just to be sure that the launch is truly optimal, I think they overfill it slightly and it doesn't start moving until it has burnt off a little fuel. Fortunately, at 5 tons per second, that doesn't take long.)
"Ultimate goal" of SSTO - well, for some. Other rocket scientists have, apparently, concluded that as long as you are "spending most of your fuel getting the rest of your fuel up to mere subsonic velocity" (nice phrase) multi-stage is the only sensible option.
@Nigel11: errr, cos it's got zero velocity by the time it gets back up the other side?
@Skylon-fans: yes, I have a design for a cost-to-orbit of ten quid per kilo... somewhere round here on a bit of paper....
@sci-fi-fans - anyone remember the one that had a huge orbiting station that would "scoop up" shuttles lobbed up to orbital altitude and accelerate them to orbital velocity (which is where ~90% of the energy is required) by simultaneously DEcelerating a returning shuttle, i.e. transferring energy from one to the other?
Note on X-15 flights - quite a few pilots got awarded astronaut wings, cos the USAF deems space to begin at 50 miles (80km) up, not 100km. Both are of course arbitrary definitions.
You misunderstand. It's got as much kinetic energy as you can pour into it via the maglev. A U-shaped track is a plausible maximum-length realization in a mountainous region.
There's no particular reason you shouldn't start at the bottom of a mountain and accelerate it to the top, but that would be a shorter run so you'd subject the crew to a higher G force for any particular "launch" velocity. A long horizontal run to get up speed before deviating uphill is also possible, if you can find a mountain that rises from a plain without any foothills. Whichever, you certainly want as much atmosphere as possible below you before "launch", in other words end the track at the top of a high mountain, and for other hopefully obvious reasons a mountain close to the equator.
You want to read Alastair Reynolds' latest book Blue Remembered Earth. He has a maglev launcher launched from under the plains that ascends through the middle of Kilimanjaro before being boosted to orbit with lasers.
Lots of other interesting ideas in it as well as you might expect from an ex astrophysicist.
I like the untethered design space elevator. Basically you balance the (~30km) bit of string so that one end is at say 20km above earth and the other is beyond geo stationary.
It must help solve some big issues. Lots of the friction will happen lower down with air, you can leave it in the shade or sun as you need. I'm thinking that balance would be done with liquids and pumps.
Mines the one with the infinitely strong carbon nano tube in the pocket.
We always seem to invent cool stuff when we actually want to use it to kill our fellow human beings... and by war I mean WAR not an invasion of some barely capable nation with no means to fight back (although amazingly managed to drain our collective coffers considerably, although I suspect that was little to do with the actual "fighting of natives" and more to do with those who were in charge of declaring the actual thing a war)
Don't know what total arseholes in need of having their heads sledgehammered for the good of all us us upvoted this.
How's burning down cities wholescale and killing a few 10⁷ people as well as impoverishing whole nations by destroying capital goods and consumer goods IN ANY WAY helpful in building capital-intensive technologies that will get you into space? Fucking cretins pretending that wars "kickstart the economy" (and whom I would glad dropkick and kerbstomp with no moral qualms whatsoever) never provide an explanation about how this magic is supposed to happen either, so I suppose it doesn't.
In the same vein you could argue that Auschwitz was needed because it relieved population pressure. Sure it did, but there were some problems with the whole show, right?
Nope, wars don't help. In fact, without WWI/WWII and the whole Red Revolution / Cold War bullshit we could pobably already book tourist class to Mars.
It works because, when there's a war on, "we need a better XYZ to win this" overrides planning, budget, political oversight and "elf n safety" concerns. Anyone producing paperwork that obstructs getting the results quickly is given a rifle and sent off somewhere to get shot at.
Same development, just a lot quicker.
Hey, D. A. M. lets take everything to wild extremes instead of using some modicum of rational thought. Typical liberal dipwad thinking ONLY with your heartstrings instead of your brain.
The fact remains that the entire world economy came out of the Great Depression due to WWII and nothing else. Ask anyone over 56 or those in their 80's while they are still here to learn from.
The "Boom Years" that followed in the 50's and 60's are what gave you the standard of living we have enjoyed for 40 years. They could not have occurred if WWII or resulting Cold War did not happen.
SirDigalot, I have to agree but it hasn't always been during an attempt to kill people, more like during the periods when we "think" about how to kill people.
The space race also created a lot of new commercial technology. Velcro, mylar, electronics, etc.
We can thank war for many advancements in material science, plastics, metal alloys, etc, also the entire development of commerical air travel is based on military cargo and troop transport planes that were later redesigned for airlines.
Since they did not have computers then, the design of wings and structures was a crap shoot and the time tested designs from WWII went straight to producing McDonnell Douglas and other commercial airliners
While we are using SciFi as a basis of design, sounds farfetched but what we REALLY need today is an "Independence Day" style common enemy then we will stop thinking about individual countries and start acting in the best interests of all of humanity. Only then will we be able to rise out of the muck and mire and become a truly advanced species.
I'm afraid the evidence is clear - we do develop technology faster during war. Bizarely conflict promotes co-operation - we work together against a common enemy, we take risks, we pay costs that we wouldn't otherwise do.
Maybe that's why politicians are keen to talk up "War on terror", "war on drugs",
I don't think anyone is saying war itself is a good thing - except Orson Wells
http://www.youtube.com/watch?v=5XQ2tPrBA1k about 5:25 on
and I don't think he's representing his own views
Once some joker works out how to mass produce sheets of graphene (unrolled nanotubes if you like) then you will have no more potholes in the roads for a start. As the only ingredient is carbon - which is effectively negative in price with carbon credits -once someone works out how to make continuous crystals of this stuff we're going to be buried in it!
Its one of these world changing developments that would result in a product so cheap its almost not worth doing...
"...negative in price with carbon credits..."
I think "carbon credits" is shorthand for "Avoided or Sequestered Carbon Dioxide Credits". I don't think that pure carbon is negative price. CO2 might be, but you find that reversing the ... -> CO2... reaction takes at least as much energy as the reaction provided in the first place.
I genuinely can't figure out any method of building a launch loop, and they don't seem to have a proposal either.
Even assuming enough of the appropriate materials and budget, it still appears impossible to actually assemble one of those!
I like Space Fountain idea because it's buildable.
Yes, like all infrastructure-to-orbit concepts you still need an unreasonable budget (although less unreasonable materials), but it does have a clear method of building it - and one that we've been doing for a while in bridges and skyscrapers. Build the foundation, build the top and slowly jack it up.
A launch loop seems to need to be complete before it can support itself - so how do you put it together?
With what? A nuke? And nothing would happen. That's the whole idea.
Snapping a tethered cable space elevator near the bottom would do very little - it would simply start to slowly drift, and you'd need to grab it again within a few days or it might go too far away from your 'base' complex.
You'd need to break it much further up to do much damage - but break it far enough up and it'll wrap around the entire globe...
On the other hand, physically snapping the assembly near the base of a Space Fountain or Launch Loop would disintegrate quite spectacularly, as the dynamic stabilisation energy gets dumped into the remains of the base.
Heinlein took this into account with his depiction of a launch loop. A Big-Ass Lake, with enough content to boil away the heat. Of course you wouldn't want it near any kind of population centre (then again you don't want airports near populaton centres, but everytime someone builds an isolated one people start building all arond it)
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By rectangular pieces of paper.
Space elevators. People talk in terms of "Yuris" as a measure of the strength needed. A good design needs materials of about 40 Million Yuris. Current materials are hitting 3.5 Mega Yuris, but it's not clear if you could build such a structure out fo Speltra fibre.
IIRC there is a prize to get materials to about 1 Mega Yuri.
Skylon's Special Sauce (C Lewis Page) is a TSTO payload fraction (3-3.5% of GTOW) in an SSTO. No previous design could offer this. It's important because development budget scales with payload. Previous SSTO' needed to be 3x bigger to give the same payload). However while they have tested the hardest part of the design they are currently building a complete sub scale test engine. Note there are still plenty of hard problems in the design to solve but they are moving forward. I'd love El Reg to get an interview with some of the players.
BTW Skylons development budget is in line with vehicles like the A380 and the Shuttle (with allowance for inflation). It's what big aerospace projects cost.
Arthur gets it. "Prelude to Space" - 1947.
Sled to accelerate, Nuclear ramjet carrier plane with a conventional rocket for the final bit. I reckon that's all the bases covered some years before anyone else noticed that there were bases to be covered.
 Can't remember off the top of my head what powered the sled.
 Air goes in the front end, very hot and somewhat radioactive air comes out the back. Very messy.
But I already spent myself over here:
Short story: with Amsteel Blue as a tether on Ceres a space elevator has some real utility with real stuff we can make right now, and acceptable engineering margins, that we can get out there with our lift capability, and a reason why. There is no other place in the solar system where this is true right now. Ceres has vast quantities of the most precious space mineral there is: water.
/No, I don't work for Samson nor any vendor that sells rope, nor any other relevant thing. I don't know if they can make a 900 km rope. I just like the whole "space elevator" thing, and am jazzed that there is at least one current use of Clarke's dream even if it isn't where he thought it was.
involve lots and lots of alcohol
Even lager seemed to help start the whole shebang!
As for superguns and lots of G - might kill humans but the cheapest way of getting lots of fuel up there for when a man mozies up through duty free for a long trip.
And no silly frames required - just stick a launch pipe up the side of the Andes!!
Dont call me surely but a solar array driving lasers in LEO in itself would be reasonable possibility - more of the power could be accurately directed at the rising missile. Wavelengths could be used that would not fry those on the surface. I dont know if anyone's tried a laser powered directly by sunlight but if you could work out how to cool it you could have a lot of fun!
Always been my problem with that one.
Any mode of transport that relies on setting off thermonuclear warheads under its arse and relying on the bit between you and them to keep all the nastiness on the other side of it has a fundamental problem.
Finding someone daft enough to sit in it.
25% in the long term, compared to the 0% long-term survival probability of the converse that we currently have.
A large asteroid strike is inevitable unless we have the technology to reliably redirect one. That takes routine extra-orbital space travel.
I say our current situation is the converse because over the last decade our politicians have been shoving us into various mapcap schemes to "preserve the planet" that simply don't work anyway because they don't scale anywhere near the size needed for current population, let alone predicted population, and in many cases actually seriously damage the environment!
Large numbers of people will die as a result of those policies - not because climate change is real, but because the methods to "stop" it that the politicians were backing are futile and harmful to people and the environment.
There is some hope - Hinkley C has been given the go-head, which is finally a zero-emissions* generating plant at the scale we need to stop the lights going out and people dying.
It'll be coming on stream too late though.
* Ignoring construction emissions, just like the wind and solar people.
"A large asteroid strike is inevitable unless we have the technology to reliably redirect one"
If by "large" you mean large enough to wipe out the species then the evidence is against you. Our technology already means that we'd be among the most resilient species of large animal and the solar system hasn't whacked the Earth with anything hard enough to knock everything out for many, many millions of years. And even *that* fails to take account of the fact that most of the loose asteroids out there were hoovered up in the first half-billion years, so looking at the surface of the moon is a really bad guide to the current risk level.
It's simply not urgent. At current rates of technological progress, it will be trivial in a thousand years or so whether we prioritise it or not. In fact, since "prioritising" probably means we work less hard in other areas, throwing cash at what might turn out to be the wrong technologies is actually counter-productive.
We know that there aren't any outright planet killers due in the next couple of centuries, and nothing excessively large in the next hundred years.
We don't know if something big enough to effectively destroy our civilisation is going to hit in 150 years - and although I suppose I am conflating "species" with "civilisation" here, I think you'd agree that "civilisation falls" is still an apocalypse worth spending some energy avoiding?
We also don't know whether something big enough to wipe out a major city like London, New York, or Washington DC is going to hit tomorrow. That Russian meteor? Imagine if that had airburst directly over a major city at a lower altitude, instead of 'merely' ~25 km up and ~50 km away.
To really avoid those 'civilisation killers', and to even spot the 'citybusters' in time to simply evacuate, interplanetary space travel needs to be routine. Not the "launch a last-ditch heroic attempt to deflect atop quickly thrown-together rocket" we see in films, it has to be "Oh, that one's coming a bit close in fifty years, better start planning to send something to go deal with."
Even simply getting to an asteroid takes a year or two.
We only have around 100 years of clear time to do that - and given our current rate of progress, we won't make it.
I probably won't live to see it. But I want my kids to go to space - for a holiday, or even permanently.
Encounter With Tiber - John Barnes and Buzz Aldrin, had antimatter suspended in an aerogel for thrust, in addition to the laser for larger ships travelling inter-stellar.
Red Mars - Kim Stanley Robinson - had a space elevator but attached to a captured asteroid and harmonised to avoid moons.
Comparing a modern rocket to a V2 is like comparing a Fort T to a modern car: Both run gasoline-burning piston engines with a transmission shaft and mechanical gears. Even modern electric cars are not fundamentally different from those that were designed 100+ years ago.
The reason is that the basic design works well. The same is true for rockets. And that is why viable alternatives are still stuff of the future.
One idea that hasn't been mentioned is using ionised air as the main propellant: The motor is a linear accelerator that ionises the incoming air, accelerates it and expels it at the other end. The energy could come from a nuclear reactor or (for a slower acceleration) solar panels. A solar powered craft could use traditional propellers for a first stage to lift the craft to high altitude, where the next stage (with smaller wings) uses the linear accelerator motor. Eventually, the air would be too thin, at which point you could switch to air you brought along (e.g, liquid nitrogen).