Author Topic: Are we reaching the limit of space technology?  (Read 33982 times)

Online sdsds

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Re: Are we reaching the limit of space technology?
« Reply #20 on: 11/01/2014 04:51 am »
If e.g. closed loop life support is a "space technology" then we are nowhere near the end limit.
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Offline Burninate

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Re: Are we reaching the limit of space technology?
« Reply #21 on: 11/01/2014 05:40 am »
The issue is, spaceflight is fundamentally an expensive technology, and it only gets cheaper per X as you scale up the number of X's (increasing overall spaceflight expenditures).  A $500,000 ticket to Mars is probably not out of the bounds of possibility, but say it requires a million passengers a year to drive prices that low...  How does that fit into your schema?

Here's what NASA's technology development budget looks like for experimental research:
"From February 1998 to 2007, NIAC received a total of 1,309 proposals and awarded 126 Phase I grants and 42 Phase II contracts for a total value of $27.3 million.[3]"

Nobody's gotten $500,000 to develop an entire *foundational exploratory technology for advanced spaceflight*.  The tech isn't moving forward because we've decided we don't want it to.

Getting technology down on paper, from paper to the lab, from the lab to mass production - there are plenty of techs that have been stuck at one of these stages for *decades*, because we (our political leadership) are simply not collectively interested in anything that enables greater overall spaceflight expenditure.  Some of them, like modular standardized spaceframes and ion thrusters, are stuck on the last stage at NASA long after they became ubiquitous in the commercial market...  because NASA is hobbled by a corrupt political leadership which is largely disinterested in spaceflight.

It doesn't make *any sense whatsoever* to do things like develop Orion and SLS without also building a Deep Space Habitat / Lunar Lander / Mars Lander / mission module.  Not having those things, is going to prevent any meaningful missions from going forward.  But at some point, we decided we had the money for one, but not the other, and the one was too heavily invested in political corruption to cancel.  Then we decided that the one we couldn't cancel was too expensive, so we *extended its schedule* and *scaled down its flight rate*, because that fit into budget numbers, sabotaging human spaceflight for years.

I will say: *Interstellar* spaceflight, versus plain old interplanetary spaceflight, is largely underappreciated in terms of just how much more difficult it is.  This is by design - it's difficult to sell science fiction about a universe where interstellar spaceflight is realistically difficult according to the laws of physics as we understand them.  An interstellar journey using human beings is far beyond our present human civilizational output, and the fraction of that dedicated to spaceflight at this moment is in the hundreds of parts per million.
« Last Edit: 11/01/2014 05:58 am by Burninate »

Offline savuporo

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Re: Are we reaching the limit of space technology?
« Reply #22 on: 11/01/2014 05:46 am »
Only a very small fraction of what people have thought of has even made it past that very first step of "How about some funding for this?".
concur with the assessment that we have only started to scratch the surface. however the question should go the other way around : good idea, if i could make this work how would it make any money?
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Offline Burninate

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Re: Are we reaching the limit of space technology?
« Reply #23 on: 11/01/2014 06:06 am »
Only a very small fraction of what people have thought of has even made it past that very first step of "How about some funding for this?".
concur with the assessment that we have only started to scratch the surface. however the question should go the other way around : good idea, if i could make this work how would it make any money?

This is the post-cynicism answer, but the unfortunate truth is, ways to make money from space on the scale of even our present expenditures on space, are just not there - we haven't thought of any in the near-term.

Oh, there are precious metals, but the price of those will crash as soon as they're not precious anymore - they're largely speculative investments & hedges against economic collapse: As soon as you *announce* a credible mission that significantly impacts eg the platinum market, it's no longer profitable because you've crashed the price.  There's helium-3, but economic usage requires *both* that we be a trillion dollars away (hundreds of missions) from where we are now on a Lunar colony, *and* that we are around a trillion dollars away from where we are now on fusion technology.  Optimistically.

We're *hoping* you can piecemeal-develop human space tourism, but the market clearly doesn't believe that this is an obvious conclusion, or Robert Bigelow & Elon Musk wouldn't be basically funding it out of pocket.
« Last Edit: 11/01/2014 06:23 am by Burninate »

Offline pagheca

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Re: Are we reaching the limit of space technology?
« Reply #24 on: 11/01/2014 07:33 am »
Only a very small fraction of what people have thought of has even made it past that very first step of "How about some funding for this?".
concur with the assessment that we have only started to scratch the surface. however the question should go the other way around : good idea, if i could make this work how would it make any money?

Ok but one could ask why in other business the market didn't take so long to take the lead? Do you think that the development of aviation or car is still driven (not just supported) by public funding?

You sure that the statement "it took so long because there is not enough funding" is based on evidence?

Please note I have not a final opinion about which of the (4) options listed is the right one. I'm just trying to understand behind some wishful thinking, and would appreciate facts or references, but also examples and reasoning proving one or the others.
« Last Edit: 11/01/2014 07:37 am by pagheca »

Offline R7

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Re: Are we reaching the limit of space technology?
« Reply #25 on: 11/01/2014 01:36 pm »
Knowing whether or not we are reaching the limit is limited by our knowledge about the absolute limits.

Chemical propulsion utilizing the common propellants is probably close to its performance limits. For it do radically improve would require some sort of breakthrough chemistry. Does not mean there's no room for improvement especially in reliability and cost.

Engine size does not necessarily equate progress. Automobile industry could build 2000hp passenger cars but those would be impractical.

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Offline Nilof

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Re: Are we reaching the limit of space technology?
« Reply #26 on: 11/01/2014 03:57 pm »
We are pretty close the the limits of chemical propulsion technology. But "space technology" is much more than that, and reaching the limits of the field is more or less impossible.
For a variable Isp spacecraft running at constant power and constant acceleration, the mass ratio is linear in delta-v.   Δv = ve0(MR-1). Or equivalently: Δv = vef PMF. Also, this is energy-optimal for a fixed delta-v and mass ratio.

Offline Robotbeat

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Re: Are we reaching the limit of space technology?
« Reply #27 on: 11/01/2014 05:20 pm »
There are huge improvements still possible in structures, talking order of magnitude higher strength to weight ratios for materials. Same for electrical conductivity, and especially the two orders of magnitude improvement possible for specific power for solar arrays and electric thrusters, etc.

Chemical rocketry could improve significantly in Isp, too, if we went to full flow staged combustion in lighter hydrocarbons.

But there's a bunch of advancements still possible: even exotic propellants with metal-loading or sub-cooling (slush, even) to improve specific density and even exotic propellants like fluorine, lithium, hydrogen tripropellant rockets. We haven't even built a launch vehicle with even a supersonic (let alone hypersonic) air-breathing first stage, even though such an endeavor is most certainly possible. Aerospike or other altitude-compensating schemes are possible. Nuclear rockets can allow much higher ISPs, still. Big rail-launch-assist structures could enable you to get supersonic with just electricity. All these things are possible, but almost anything in this paragraph isn't going to be justifiable on economics for the next few years.

The big thing is high launch rate reusability. That technology can be done largely with existing engine and structure technology. TPS systems have already been developed that could work for this. RLVs will make a heck of a lot more difference than a NTR in-space stage or a fluorine/hydrogen upper stage. But as is the case with any of these advancements, demand must be there or we have to just bite the bullet and do it anyway.


Even more advanced, interstellar flight can be done with beamed dust propulsion, in combination with a mag-sail brake and perhaps a fission fragment rocket.

There is SO much we can do. We don't have technical limits, we have economic ones. Hopefully we don't end up like the Romans who forgot how to build aquaducts.
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Offline Robotbeat

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Re: Are we reaching the limit of space technology?
« Reply #28 on: 11/01/2014 05:33 pm »
A two-stage fully reusable RLV capable of flying thousands of times is possible. Imagine using such a vehicle to put propellant into LEO, with completely automated launch, docking, quick propellant transfer, de orbit, flyback to launch site, being picked up be an automatic crane, red tacked, refueled, and flying the airframe that way 10 times a day. A single, very small launch vehicle like that (with a capacity of, say, just a couple tons) could put up enough propellant in LEO to fly thousands of people to Mars every synod.

The main things required for that are just high levels of automation, something we're getting increasingly good at and which is subject to continuous improvements due to Moore's Law and algorithms.
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Offline floss

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Re: Are we reaching the limit of space technology?
« Reply #29 on: 11/01/2014 05:35 pm »
In answer to the first post we as in humanity are nowhere near any limit:

You can build a car that runs for years with todays technology.

Concord was a victim of a Boeing pr blitz.

As for human spaceflight we have only barely scratched the surface.


Offline Jim

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Re: Are we reaching the limit of space technology?
« Reply #30 on: 11/01/2014 07:30 pm »
Concord was a victim of a Boeing pr blitz.


Unsupported balderdash.  It was an economical failure.
And the post is irrelevant to this subject.
« Last Edit: 11/01/2014 07:30 pm by Jim »

Offline high road

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Re: Are we reaching the limit of space technology?
« Reply #31 on: 11/01/2014 10:23 pm »
Only a very small fraction of what people have thought of has even made it past that very first step of "How about some funding for this?".
concur with the assessment that we have only started to scratch the surface. however the question should go the other way around : good idea, if i could make this work how would it make any money?

Ok but one could ask why in other business the market didn't take so long to take the lead? Do you think that the development of aviation or car is still driven (not just supported) by public funding?

You sure that the statement "it took so long because there is not enough funding" is based on evidence?

didn't take so long? Space tech was top secret until the 90s. Cars and planes took more than 20 years to be widespread commercial successes. Planes had the advantage of enormous military funding that rapidly matured their technology during two world and one cold war, while cars only started losing their image of being smelly, dangerous, ugly, uncomfortable and otherwise utterly useless things when rich people started to race with them.

Apples and steak (oranges would be too similar). But it shows why things have slowed down. There's no military benefit beyond LEO. But any success story might kick off a rush in new capabilities

Offline sanman

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Re: Are we reaching the limit of space technology?
« Reply #32 on: 11/01/2014 11:21 pm »
It's also probably the tremendous expense of spaceflight. There's no way that the Wright Brothers could have done a manned space launch successfully. Spaceflight is so much harder than aviation and automotive transport. Supersonic commercial aviation was only undertaken by multi-nation collaborations like Concorde (I think it was also proposed under Kennedy, but proved to be too costly).

It seems like SpaceX is only now able to attempt commercial spaceflight because other underpinning technologies like computing, etc have had enough time to come down in price.


Offline pagheca

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Re: Are we reaching the limit of space technology?
« Reply #33 on: 11/02/2014 09:52 am »
I think any comparison between automotive, aviation and SF is biased also because they did not proceed in parallel, but each technology built up on the previous one. Each of those field development lie on the shoulders of the other (more or less - don't slice my words too much please!). The question is how high is the ceiling?

ST is an intrinsically risky business. Astronauts work in an alien, deadly environment. Energy density in rocket engines is orders of magnitude higher than in aviation and in cars. Speeds and energies involved are huge.

[pessimistic mode ON]
It's good for me to see so much optimism among you but I suspect most of it is not based on evidence but on wishful thinking. Again, I'm not fully convinced about which of the four options I wrote is the most likely, just pondering and mumbling. But I cannot read in your comments any evidence or convincing fact that the actual margins here are very wide. As a person very passionate about ST - like any of you - and being involved in leading edge science projects I really hope in the unknown unknown and in the well known inability of our species of telling the future, but I'm beginning to suspect, 45 years after the amazing success of the Apollo Project and the incredibly quick ramping up in ST, that the failure of so many new technologies and approaches in the field suggests there are intrinsic limitations in what we will be actually able to do in space at any time. Musk or not Musk.
 
I really hope I will laugh of my own naivety soon or later, but perspectives IMHO are narrowing day after day.
[pessimistic mode OFF]

Thanks everyone for your past and future comments on this thread.
« Last Edit: 11/02/2014 02:45 pm by pagheca »

Online laszlo

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Re: Are we reaching the limit of space technology?
« Reply #34 on: 11/02/2014 04:39 pm »
Excerpt from NavalSeaFaring (NSF) forum in 1806:


OP:

Are we reaching the limit of seagoing technology? Just look at ship designs over the last 200 years. Sure, the hulls are shaped a little better, the rigging is more sophisticated and the sailplans are more efficient, but it's still the same wooden ships being blown across the ocean. There may be some incremental improvements, such as better anti-fouling bottoms to keep the weed from robbing the ship of energy, the structural use of metals for improved hull stiffness and rot resistance and maybe one day a non-stretch sailcloth, but there are no big breakthroughs on the horizon that will enable us to get to the New World in, say, less than a month. Have we plateaued, or hit a wall?

A reply post:

Until they get crew survivabilty under control, we'll be going nowhere. The malnutrition and disease rates are such that crews are essentially expendable. We need to re-use the crews over multiple voyages. If they can ever get that canned food technology worked out, then with reusable crews ocean cruising will be cheap enough for everyone to afford.

A reply post:

Opinion. Where's your sources?

A reply post:

How can you navigate a metal hull? The compass will not work. And, metal may not rot, but it will corrode.

A reply post:

Off topic and conjecture!

A reply post:

What about those multi-hulls the Polynesians use? They can sail faster than the wind is blowing.


In the meantime, in 1807, Robert Fulton invents the steamboat.

« Last Edit: 11/02/2014 04:44 pm by laszlo »

Offline Mark K

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Re: Are we reaching the limit of space technology?
« Reply #35 on: 11/02/2014 05:00 pm »

[pessimistic mode ON]
It's good for me to see so much optimism among you but I suspect most of it is not based on evidence but on wishful thinking. Again, I'm not fully convinced about which of the four options I wrote is the most likely, just pondering and mumbling. But I cannot read in your comments any evidence or convincing fact that the actual margins here are very wide. As a person very passionate about ST - like any of you - and being involved in leading edge science projects I really hope in the unknown unknown and in the well known inability of our species of telling the future, but I'm beginning to suspect, 45 years after the amazing success of the Apollo Project and the incredibly quick ramping up in ST, that the failure of so many new technologies and approaches in the field suggests there are intrinsic limitations in what we will be actually able to do in space at any time. Musk or not Musk.

Thanks everyone for your past and future comments on this thread.

You just changed the goalposts. There is no Technical limit on space travel advancing from where it is now and humans living off planet except for unknowns. In fact we know about enabling technologies that we haven't put any development effort into, but we can see are possible. So your latest post here is equating technical capability with political and economic will and saying that what you perceive as lack of progress due to the one must be due to limits on the other. Not a realistic argument in my mind.

If the current governments of the planet really wanted to, say, colonize Mars, any number of them could spend the resources to seriously attempt it. I don't say succeed because we do not know that there are answers to closed cycle life support and differing gravity and such yet. But there are no technological blockages known that would stop us from doing that. If we had a, say, $100 Billion US per year budget and priority to take risks and expend lives. eg wartime footing I think it would be amazing how fast things would move.

But Space Travel is a complex technological, social enterprise. We may as a set of human societies not succeed in getting humans living off planet, but since it is really the social element that will drive that I think you need to think in terms of decades at the minimum to have the social conditions be aligned. (Will and economics).

We are only now developing technology that will lower the cost point to allow and easier set of social conditions to lead to space. I think this discussion is at least 100 years and probably 200 years too early.


Offline pagheca

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Re: Are we reaching the limit of space technology?
« Reply #36 on: 11/02/2014 05:11 pm »
Excerpt from NavalSeaFaring (NSF) forum in 1806:

Nice quote. Actually there was also a statement by a leading physicist at the end of the XIX century saying - more or less - that everything was done at that time in understanding reality, and the rest would be to just set the initial conditions or so and we would be done with research. Can't remember or find who said that, otherwise I would already have added it to my original post.

We know what happened with the advent of Quantum Physics, Relativity etc...

However, showing that something is true in one situation doesn't necessarily "demonstrate" anything for another situation, as the two fields are not strictly related and there are physical limits. For example, when I was a kid there were a few claim that men could not run the 100 m in less than 10 sec, that is obviously false. However, I bet you would concur that men (at least "no OGM men") will never run the same distance in 5 sec, unless you wait for evolution to radically transform what a man really is.

In the same way most of barely informed people are reasonably sure (note how many "perhaps" I disseminate around here....) we will never overcame the speed of light, or visit the interior of the Sun, or "navigate" into Jupiter. Maybe some of these claims will be quite surprisingly overcome in the future, but most of them will never be, unfortunately.

That's what we can say, I guess.
So: limits exist. The problem is where they are and if we already reached them in this particular field.


« Last Edit: 11/02/2014 05:17 pm by pagheca »

Offline RanulfC

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Re: Are we reaching the limit of space technology?
« Reply #37 on: 11/03/2014 08:01 pm »
pagheca: Modfied #1 in that:
"(1) ST will progress forever UNLESS "disturbed" by other factors.

Technological and other collaspes happen so it's a "non-zero" possiblity we could in fact turn out back on ST all together for some reason.
"It's just a matter of funding and effort."

Forgot "will" which is an important factor. Lack of, in many cases leads to slow or non-existant progress.

"We will reach Mars, the other parts of the Solar System and then exoplanets in a timely fashion. Space tourism is there and access to space for a multitude of people is just a matter of (a few) decades"

I will remind folks that the "experts" were thinking we'd be lucky to go to Mars within a century of achieving orbit :)

And that also points out a very real factor (also pointed out in the satirical posting post above) that more often than not you can only "guess" at the limits with what you know. Guessing whether or not you've reached the "limits" of a technology assumes that's the only technology that can (or will) solve that particular situation.

We're nowhere near the "limites" of space technology yet. We really haven't put enough time and effort into testing the limits we KNOW about let alone the ones we are 'assuming' are out there once we start operating on a regular basis.

Randy
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British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline IslandPlaya

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Re: Are we reaching the limit of space technology?
« Reply #38 on: 11/03/2014 08:04 pm »
Are we reaching limits?
No.

Offline The Amazing Catstronaut

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Re: Are we reaching the limit of space technology?
« Reply #39 on: 11/03/2014 08:44 pm »
There are limits to technology? In what domains?

Yes, there are optimum limits to what velocities a piston engine driven propellor will afford you. Just as we approached the limits of sustainable airspeeds, the jet engine obsoleted the former in many of its primary applications. Are we approaching the limits of chemical rocketry? Possibly - but the same was doubtless assumed by the timurids amongst other ancient civilisations who utilised them as crude gunpowder weapons. Slush cooling along with other formats of storage, potentially exotic, along with the utility of exotic fuels add further orders of magnitude.

Yes, the magnitudes of energy involved in space travel are enormous, and yes, the distances are theoretically infinite. Why does that present a limiting factor? Arguably, space is one of the most fantastical mediums against which to propel yourself as the level of friction in the thermosphere, exosphere and the interplanetary or even interstellar mediums are so much lower, permitting extremes of travel speeds without suffering aerostresses. Space craft can afford to be flimsier than aircraft; they do not require so much superfluous mass such as wings, or are mandated to form any shape other than one permissive of even mass distribution and heat dissipation. And this is only taking a very linear view at chemical rocketry. Currently people sniffle at the idea of using antiprotons for a chemical rocket - and rightly - but who's to say that in a millennia (or significantly sooner) antimatter is not a viable method for extracting energy from mass? Whatever ensues, we can guarantee that in a hundred years people will sneer at our own primitive accomplishments as much as we sneer at the conquistadors who went around smashing up sundials. Who's to say warp drive, for want of a less, ah, media-fixated phrase, will not be a viable form of stellar transit in the indefinite future?

Pessimism leads to disappointment regardless of the outcome; any accomplishment appears inevitable to the pessimist and is thus rationalised as a failure, or nothing to be proud of. Dreaming leads to captivation with your dream until you suddenly are surprised to find that dream grounded in reality.

Confide with somebody in the seventies that you would, within forty years, be able to carry a library with access to the entire reservoir of human public data in your pocket, accessible from nearly anywhere in the planet, a library which also serves as a flawless, meter accurate map guided by satellite constellations and can track your position in real time, a colour camera capable of capturing (and editing) video and still images, a library which can organise anything for you, from sex to a meeting with your mother in law, a library which can serve as a medium for live video conferencing regardless of where you are, a library that could also serve as a cinema, along with a television with access to hundreds of thousands of channels, readily recordable less you miss an episode, a library which is considered a human necessity by over four billion people, a library capable of recognising the sound of your voice and all within the size of a paperweight, they would have assumed you were delusional. Oh, and the library also works as a phone. Crazy stuff, right? That clearly never happened, either.

Crazier things have happened and happen every day. We're going to space. Sure, we may not live to see any more than a few baby steps of the journey that awaits us all, but damn, are we all going to be proud parents.

Cya' in space.
Resident feline spaceflight expert. Knows nothing of value about human spaceflight.

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