What a fascinating discussion. I won't go on my materials and energy density improvements rant again.
We already use propellants that are provide around the limit of practical performance of chemical propulsion, and we already use materials that do their job relatively well.
Even the adoption of high-strength materials such as carbon nanotube composites would not suddenly revolutionise everything, though they would improve existing technology greatly (for example a much lighter structure would aid in the construction of an SSTO, but would not solve cost and maintainance issues).
Beyond that, when regarding unknown technologies, speculation is pointless, as we know nothing of the attributes and limitations of things that we... know nothing about, and there is nothing from preventing the suggestion of "super magic metal that transforms into rocketfuel and Makes You A Cup Of Tea Too!"
Hence why some people believe that NASA human spaceflight has been just a glorified jobs programme since Apollo ended. Shuttle was a way to keep the army of engineers and aerospace workers busy.
Exactly.
It's obviously easy to criticize it from the hindsight, but there were some clear thinking people even back then who knew where the programme was heading. Too bad nobody listened to them.
I don't blame them, considering what position they were in.
But this is interesting:
Years later he developed a reputation for rather esoteric interests that might best be described as “new age,” such as a belief in unusual energy sources.
Hmm...
Orgone energy IN SPACE?
I feel like I am moving in circles here. For the last time - the launch price is the root of the problem. When a kilo-to-LEO costs $10,000, it has an immense effect on everything else. Satellites need to be overdesigned to last for a long time with no maintenance, which drives up cost. Reusability is discouraged. Low demand for space station modules and other components of the space "infrastructure" are not mass produced at all, which makes every piece a (very costly) prototype. And so on, and so forth.
Once you find a way to get things up cheaper, prices will fall across the board and the market will grow correspondingly. Positive feedback loop.
And you want to design satellites to last for years with no maintainance anyway, because maintainance is expensive (even with superlow launch rates). Drop launch rates and it now makes sense to cut the service life of a satellite from 20 years to 5, and just launch a new satellite every five years... you still have to deal with the dead satellites though.
The market will grow according to demand. The problem is, the demand doesn't exist for the kind of growth you are talking about.
And... yes... there are low production rates for spaceflight components and such. For good reason; the production rates don't
need to be high. The ISS is the ISS, and even if you had $100/kg, it wouldn't make sense spending the money on making 20 Columbus modules, when you would only need one.
That said, you could construct a station far more efficiently. There are parts on the ISS that could arguably have more commonality than they do in reality, for example you could build a station out of near-identical modules and outfit them all differently. But there is some commonality between the station modules, and for good reason- no purpose in totally redesigning everything when you don't have to.
Christ The whole point of my showing the potential capabilities of a Skylon-like vehicle was to explain WHY and HOW will other business activities in space become interesting. If your short-term memory can't handle that, than I am wasting my time here.
You do not build a truck to drive into the desert, you build a town in the desert for the truck to drive to.
You explained the truck, but the town in the desert is still nowhere to be seen.
So far, you've debunked nothing. You see this "chicken-or-egg" as unsolvable and apply an extremely pessimistic outlook to every challenge. I respect that as a statement of your scepticism, not as a refutation of anything that I wrote.
I could also say that, say that you discount problems and approach the situation with unrestrained optimisim... but such accusations are pointless here.
So? As I said, ISS is a completely new system, one of its kind. Even so, it could have been built much quicker and much cheaper, if politics didn't interfere so much. In the final bill (that's the 100 billion figure that is floating around), the actual cost of the hardware will be one of the smaller items. Launch costs including both the assembly and ressuply flights, as well as the cost of the non-reusable supply ships, will likely overshadow everything else.
I claimed that hardware costs would be high, you claimed that they would be low... it is a debate settled only by concrete numbers.
And the ISS... uses Russian station modules, American shuttle-derived technology. First of its kind, yes, but brand new technology? Not strictly.
So is FTL travel, the difference is that if you actually have models of the final product that work at least in laboratory conditions, you're halfway there. That can't be said about anti-matter drives, which exist only on paper
But! We have electron microscopes, and particle accelerators, and penning traps... they all exist, it is just a matter of combining that technical knowledge into an antimatter spacecraft. :lol:
Except for the hybrid jet-rocket engines and active cooling (which on Skylon isn't as complicated as it seems), everything else has been used in space for decades! Woo, I am excited too
Seriously, I think that if something is going to kill Skylon, it's the aerodynamic properties of its airframe. I really hope they've modelled that right.
I am sure the turbine engines on the A380 are not as complicated as they 'seem', either.
And the fact that everything else on Skylon has been used in spaceflight technology for decades does not help, because as we know spaceflight technology is extremely costly.
Aerodynamics are probably the last thing you'd forget about or mess up. But cost and maintainance issues could be a different story.
Every new commercial airliner is a new system, but there is something called flight testing. AFAIK REL wants to do literally hundreds of flights before Skylon starts being sold to the customers. These flights should reveal all major problems with the spaceplane before it enters the market.
Airliners are flight tested, I wonder why they still crash... :uhh:
REL's intention to do "hundreds of test flights before making a sale" will be a clear indicator of the success of the program: if they fail to have a high enough flight rate and a low enough cost to perform such testing, then it is clear that Skylon is not viable as a "super-low launch cost" vehicle.
Well, obviously, although as I understand it, the G forces and temperature ranges Skylon will experience during the flight are pretty benign compared to contemporary spacecraft. I think the maximum G-forces are below 3 G during the ascent phase and below 2 G during re-entry.
Modern passenger aircraft undergo atmospheric reentry and endure 2-3G regularly? They are made of superlightweight airframes that contain cryogenic liquids? They are attached to rocket engines?
This I did not know. :shifty:
Again, as I understand it, Skylon should be able to return to the base in case of a non-critical failure (which is infinitely better than what current expendable systems can do). Of course if one of its SABRE engines blows up, then it's over and Skylon goes down - though the same can be said about contemporary twin-engine airliners.
Contemporary twin-engine airliners are still capable of flight on one engine.
Granted, vehicles like STS and the Saturn V had engine-out capacity, I'm not sure about Skylon... but if one of those engines has a catastrophic failure, and it shoots debris through the airframe and into the propellant tank... ouch.
And even if you did have an engine-out, the engines on Skylon are so far apart, that countering the torque from the engine with thrust vectoring might lead to such a degredation of performance that it leaves the vehicle unable to reach orbit- maybe, anyway.
And if there is any failure that leads to the damage of the TPS, or even the active cooling system... then you could encounter bad problems. For all its fragility, at least the TPS on STS is passive. What if a pump, or a coolant radiator, or something else in the active cooling system fails?
Anyway, you're using red herring tactics here. Skylon is not supposed to be as safe as commercial airliners, that would indeed be impossible to achieve. It's supposed to be much safer than contemporary space launch systems. It's been said that the STS is 73,000 times less reliable than commercial airliners based on its accident rate per number of flights. According to Mark Hempsell, the probability of loss of life on Skylon (if it it carries crew) should be roughly 1/10,000 initially, 1/100,000 later. That's still two orders of magnitude or more worse than what's acceptable in commercial aviation, but more than 100 or 1000 times better than STS.
So, what complacency about safety are you talking about? If the stated aim of the company is to make Skylon so much safer than STS and they still think it is possible, you can't really complain. Whether they can achieve these levels of reliabilit, that's obviously impossible for us to determine. I am slightly optimistic, you're not, let's leave it at that.
I never said "as safe as commercial airliners", you seemed to imply that Skylon would have a reliability closer to that of airliners than launch vehicles.
Safer than STS... I don't see the problem with that, but when you're suddenly coming up with failure rates 1-2 orders of magnitude lower than most other launch vehicles, then something is odd. The conspiracy theory slant can't be used here, because
nobody wants a launch failure, and if it is so easily possible, one wonders why it is never seen.
:facepalm:
:suicide:
I was thinking about repeating (again) why you're wrong about these statements, but seeing that you're missing the point on purpose, I realized I'd be wasting my time.
No really, please do explain. I'm completely clueless about why you think my arguments are nonsense, as from where I stand, they make 100% total sense.
I am by no means "missing the point on purpose", I just think you are incorrect.
10 years is optimistic, 20 is more realistic. Your estimates (hundreds or thousands of years) are not even pessimistic, they're insane.
I am basing my estimates on the fact that space is incredibly hostile and can support life only with intensive and costly technology, and there is no reason to move huge amounts of people to such a location, there is no profit to be gained from mass-scale human expansion, and the fact that automation can and will replace at least almost all human functions aboard a spacecraft or space based facility, and such systems are easier to use in space than human workers.
Space is now far more important to us that it was 20 years ago, and we're using it just for telecommunications and navigation. It's hard to imagine a scenario where space isn't even more important for everyday life on Earth 20 years in the future, or 50 years in the future, or 100 years in the future.
Yes, telecommunications and navigation are extremely important to us now, but they're an example of why explosive human expansion into space
doesn't make sense. For one, growth is based on demand (the only reason space should become so hugely incredibly important to us in 50-100 that I can see, is because you
think it will be). There is demand for navigation and telecommunications, but no demand for people living and working on Mars, since it does not affect those of us back home, and it is only a way of spending money.
As for your "manifest destiny" - humanity can either sit on Earth and wait until it dies off for one reason or another, or expand and exploit the opportunities space offers us. I am saying that the second option will become feasible within the next 50 years. You're either in favour of the first option, or you think it will take hundreds of years to even get to Mars. I think that's preposterous and in clear conflict with the observable trends in technology, economy and general human outlook.
The general trend in technology, economy, and general human outlook, is that we've picked most of the low-hanging fruit. What remains is the difficult stuff. Space is one of those things. Space is not the New World, space is not the West. Space is space. Space is a place where there is radiation and vacuum and temperature gradients and hypervelocity particles. It isn't to be taken lightly.
Now, I never suggested that humans would never move off of Earth. If we establish a human colony on Mars in 300 years, this would be a tiny amount of time in geological scales, and even a small amount of time on human scales (consider that agriculture has existed for ~10 000 years, into which you could fit a 300 year time period over 30 times).
If we establish a huge presence in the solar system in 3000 years, this is still a tiny timeframe.
My point is, that we could very well be on the way to "Manifest Destiny IN SPACE", but there's no reason for it to take, 10, 20 years, or even 50 or 100 years. We could expand into space at a snail's pace for us, but at a blinding pace for the Earth.
Now here's the problem with space:
- It's difficult to get to. Even if you slash your launch costs, it is still difficult to get to.
- It's difficult to survive in. There is a vacuum, there is radiation, there are temperature extremes, there is microgravity, etc.
- There's very little out there. Empty space is empty. The Moon is low in volatiles, the asteroids and Mars less so, but it isn't like they're teeming with life or fertiliser, or valuable materials- Earth's hydrosphere and biosphere have put us in a pretty good position, resource wise, compared to the rest of the system.
- The first two conspire to make spaceflight dangerous, more so than air travel, and expensive, more so than air travel. This is undeniable fact based on simple physics and engineering constraints that can never be removed from the situation.
- The first four mean that it makes little sense to access resources in space for use on Earth, and there is little incentive for people to move to environments that are
poorer than the environment they're already in.
- Most things that humans can do in space, automated systems can do for less mass, less complexity, less cost, and less risk.
Now the space enthusiast/advocate comes along, and says "Man Shall Conquer Space Soon!" The only reason for the existence of that whole idea,
is from an outmoded era when the reality of spaceflight was not fully understood. The space enthusiast will adhere painfully to optimisim and put forth any number of dubious reasons for massive space exploitation, regardless of the harsh reality of the general uselessness of space.
And because the space enthusiast is... enthusiastic, has been studying the wonders of space for years, or even decades, and has probably gotten pretty annoyed with people who might well think the Earth was flat, they'll stick to this idea and defend it no matter what, because they well and truely believe that this is the
destiny of humanity and the best
possible future for our civilisation, and disregard and defend against any arguments otherwise.
I thought you inferred it.
According to Zubrin and the article I linked in one of my previous posts, X-33/VentureStar was killed on purpose. Zubrin explicitly states that the new management of L-M (or was it just Martin-Marietta back then? I don't remember) which came after Augustine was opposed to X-33 exactly because it threatened their existing expendable launcher business. For this reason, the project didn't get the funding the company initially promised. The politicians delivered the coup-de-grace when they insisted on using a composite hydrogen tank that simply didn't work. As a result, the whole project collapsed and was cancelled.
Boeing might have had an interest in developing such a vehicle, but since its merger with McDonnell-Douglas and the beginning of its partnership with Lockheed-Martin under the United Launch Alliance, any incentive to develop a working SSTO has evaporated.
It's a pretty interesting fact that all major work on SSTO designs in the US stopped after the wave of mergers in the aerospace industry two decades ago. I wonder why is that
Conspiracy! :blink:
Yet the Americans allowed a similar situation to develop in the space launch industry with dire consequences - even with current technology, space launchers shouldn't be as expensive as they are.
You say that, doesn't mean it is the objective reality.
I completely fail to see how 95% of the cost of a modern launch vehicle is totally unecessary.
Perhaps we need to determine what behaviors it would take to eliminate money and politics. I don't care how how entrenched that crap is in day-to-day living. I don't really give a a hoot how stupid and far-fetched a world with minimal politics and financial constraints is. Politics and finances only serve to stymie creative talent. A lot of that is excess baggage and needs to go. Because with that baggage bogging you down you end up right where we are..
A world with minimal politics and financial constraints is pretty much impossible, after all such things are human nature and engrained into our society by millions of years of evolution.
Even when you remove politics, there will always be economic concerns. It's a system, it doesn't even have to be capitalist, or communist, or whatever. It has parallels with an ecology for example. It doesn't make sense to spend a huge amount of,
effort, if not anything else, on things that do not provide any gains.
I'm really interested in the details of that positive feedback stuff.
I'm still trying to figure out if
any sort of positive feedback has
any validity here, considering the nature of the destination.
IMO there's too much assumption that manned spaceflight is highly important.
