Author Topic: Are we reaching the limit of space technology?  (Read 32500 times)

Offline sanman

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Re: Are we reaching the limit of space technology?
« Reply #40 on: 11/04/2014 09:30 pm »
It seems like energy/power density is the most constraining factor -- and that too mainly for Earth-to-Orbit. Once you actually get to space, it seems like there's enough energy available to sustain all sorts of missions, at least in the inner Solar System.

If some sort of breakthrough were achieved in energy/power density for propulsive purposes, then it would open up the floodgates for a lot to happen.

Offline aceshigh

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Re: Are we reaching the limit of space technology?
« Reply #41 on: 11/05/2014 01:14 am »
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.

not sure...

check out this NASA paper about propulsion techs... there are some chemical propulsion techs that are considered TRL<3

http://www.nasa.gov/pdf/501329main_TA02-InSpaceProp-DRAFT-Nov2010-A.pdf

HIGH ENERGY DENSITY MATERIALS
- Metallic Hydrogen
- Atomic Boron/Carbon/Hydrogen
- High Nitrogen Compounds (N4+, N5+)



there are tons of different propulsion techs described in the paper above (it doesnt even consider warp, wormhole, propellantless, etc, until the end (just a single paragraph for all of them).


fact is, we are far from reaching the limits of space tech.

Offline Robotbeat

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Re: Are we reaching the limit of space technology?
« Reply #42 on: 11/05/2014 01:32 am »
With the exception of really good TPS, I don't think we NEED amazingly good or exotic space technology to make utilization of space inexpensive. What we NEED is demand and just good engineering and implementation. And, primarily, reusability.
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Offline pagheca

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Re: Are we reaching the limit of space technology?
« Reply #43 on: 11/05/2014 01:03 pm »
a library which can organise anything for you, from sex to a meeting with your mother in law,

how did you get the best and the worst of the internet in the same sentence?

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Offline The Amazing Catstronaut

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Re: Are we reaching the limit of space technology?
« Reply #44 on: 11/05/2014 01:23 pm »
a library which can organise anything for you, from sex to a meeting with your mother in law,

how did you get the best and the worst of the internet in the same sentence?

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Offline p51

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Re: Are we reaching the limit of space technology?
« Reply #45 on: 11/06/2014 04:39 pm »
Technology comes in spurts. For example, let's discuss weapons...
The crossbow was a primary weapon in warfare for an amazing amount of time, multiple generations used them with nothing better until gunpowder became common.
Artillery was stagnant from the late 1600s until the invention of rifeling, over 200 years later.
Nobody's been able to come up with anything better than Eugene Stoner's design for the M-16, over 50 years after he designed it. The M1911 pistol's design is over a century old and still being used a lot (the military actually went back to the slightly-tweaked design for limited use)
A lot of what we're using right now is simple tweaking of existing technology.
It's silly to think we'll see a continuous progression of technology like we did from the 1940s to the 1980s, for example. There's going to come a time when we've gotten to the current limits of what we can do until another quantum leap occurs. With space technology, there's an argument to be made that we're there right now.
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Offline Star One

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Are we reaching the limit of space technology?
« Reply #46 on: 11/06/2014 05:52 pm »
With the exception of really good TPS, I don't think we NEED amazingly good or exotic space technology to make utilization of space inexpensive. What we NEED is demand and just good engineering and implementation. And, primarily, reusability.

That maybe an argument for inexpensive access to space it's not argument for effective BEO exploration which in my view you do need more exotic technology for. Long round trip times to even relatively close at hand destinations such as Mars is always going to present close to insurmountable obstacles for wide scale human exploration, the only way to resolve this is reduce travel times drastically and you're not going to be able to do this with conventional propulsion technology.
« Last Edit: 11/06/2014 05:55 pm by Star One »

Offline nadreck

Re: Are we reaching the limit of space technology?
« Reply #47 on: 11/08/2014 07:36 am »
Between the late 1880's and early 1900's things that were not brand new came together to take something that had been stated as an engineering limit based on the square/cube law and known technology that manned heavier than air flying craft were impossible. The internal combustion engine eventually provide several orders of magnitude improvement on power to weight ratios, but less than one full decimal order of magnitude improvement was enough.  Coincidentally the theoretical work for something offering several more orders of magnitude than the highest power to weight ratio of an ICU was also happening at that time.

Albert Einstein's Special Theory of Relativity was published in 1905 and while many were inspired to go off on wilder theoretical tangents, one fictional application for interstellar travel was described in a novel written a dozen years later.

No we are no where near the limits of what we know about now. HOWEVER, that doesn't mean we even know how to approach those limits yet. An engineer in 1880 would have called you nuts to propose a 50 breaking horse power engine weighing in at 1000 pounds, in 1905, probably the same engineer would call you nuts saying that this engine could be improved by 10 fold with only incremental improvements on materials and design. If you tried to convince most engineers in 1905 what Special Relativity implied ...

Fission/Fusion promise limits more than 3 orders of magnitude higher ISP than existing chemical rockets.  There is a lot of step wise refinement to get there. In fact, we need a break through before even starting step wise refinement in fusion BUT the ground work was being laid even as Orville and Wilbur started their projects.

What limits I wrote about above involves what we know, and what we know we don't know. Earlier in this thread the words Warp and Superluminal  were tossed out. Those were imagined concepts just like Doc Smith's "inertialess drive", they are constructed in imagination, described without any basis in real world phenomenon. Language gives us the power to postulate and to abstract, that doesn't create anything, but it allows us to be creative. Being creative can lead us to uncover things we didn't know about. Is there something else more powerful than nuclear energy that can be applied to moving mass? Is there a non inertia/mass/momentum way to get from A to B? Language allows me to ask the question, but asking the question, imagining the result of the answer, is not a step towards creating the possibility.

It is quite possible that some theoretical work out there does describe the principles needed to push the limits past what we know today, but no one has made that connection known yet.

It is all well and good to quote those things that made it past your confirmation bias that other people wrote, but this is a discussion board damnit! Let us know what you think! And why!

Offline Robotbeat

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Re: Are we reaching the limit of space technology?
« Reply #48 on: 11/09/2014 02:12 am »
With the exception of really good TPS, I don't think we NEED amazingly good or exotic space technology to make utilization of space inexpensive. What we NEED is demand and just good engineering and implementation. And, primarily, reusability.

That maybe an argument for inexpensive access to space it's not argument for effective BEO exploration which in my view you do need more exotic technology for. Long round trip times to even relatively close at hand destinations such as Mars is always going to present close to insurmountable obstacles for wide scale human exploration, the only way to resolve this is reduce travel times drastically and you're not going to be able to do this with conventional propulsion technology.
You can get trip times down to 120 days easily with conventional propulsion. So what if orbital mechanics says two years per window, you just need to have a permanent base on Mars and you'll be fine.

It's interstellar travel that needs breakthroughs, not Mars.
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Offline llanitedave

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Re: Are we reaching the limit of space technology?
« Reply #49 on: 11/09/2014 03:08 am »
With the exception of really good TPS, I don't think we NEED amazingly good or exotic space technology to make utilization of space inexpensive. What we NEED is demand and just good engineering and implementation. And, primarily, reusability.

That maybe an argument for inexpensive access to space it's not argument for effective BEO exploration which in my view you do need more exotic technology for. Long round trip times to even relatively close at hand destinations such as Mars is always going to present close to insurmountable obstacles for wide scale human exploration, the only way to resolve this is reduce travel times drastically and you're not going to be able to do this with conventional propulsion technology.
You can get trip times down to 120 days easily with conventional propulsion. So what if orbital mechanics says two years per window, you just need to have a permanent base on Mars and you'll be fine.

It's interstellar travel that needs breakthroughs, not Mars.

Strongly agree.  Most of the technology breakthroughs we need to expand out as far as the asteroid belt are already invented.  What's needed is the learning how to combine them, integrate them, organize them, and manage them into a coherent project.  That takes time and a willingness to invest.

I'd argue we only need one more major breakthrough to conquer the outer solar system -- and that's practical, reliable and compact fusion power.  Wake me up when it happens. 
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Offline Robotbeat

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Re: Are we reaching the limit of space technology?
« Reply #50 on: 11/10/2014 02:18 am »
Mars isn't enough for you? ;) can't satisfy anyone these days. :)
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

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Offline Stellar_Speedster

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Re: Are we reaching the limit of space technology?
« Reply #51 on: 11/10/2014 06:39 am »
Mars isn't enough for you? ;) can't satisfy anyone these days. :)

Would it be impossible to visit the Jupiters Europa moon for instance ?

Offline pagheca

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Re: Are we reaching the limit of space technology?
« Reply #52 on: 11/10/2014 08:52 am »
Strongly agree.  Most of the technology breakthroughs we need to expand out as far as the asteroid belt are already invented. 

I guess with you mean expand with HSF, not only automated probe (we already have them).

Can you make a list of those breakthroughs?
« Last Edit: 11/10/2014 07:51 pm by pagheca »

Offline the_other_Doug

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Re: Are we reaching the limit of space technology?
« Reply #53 on: 11/10/2014 05:56 pm »
...Most of the technology breakthroughs we need to expand out as far as the asteroid belt are already invented.  What's needed is the learning how to combine them, integrate them, organize them, and manage them into a coherent project.  That takes time and a willingness to invest.

I bolded the important part of this.  How many trillions of US$ will it cost to establish and maintain a permanent base on Mars?  And why should the average person-on-the-street believe that our country, or indeed the entire world, should pour that much money into translocating a few hundred people at most to another planet?

As much as I want to see it, I don't see the economics working out.  The limit isn't the technology itself -- the limit is the expense of deploying the technology to the extent required to establish a base.

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Offline Nilof

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Re: Are we reaching the limit of space technology?
« Reply #54 on: 11/10/2014 08:19 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.

not sure...

check out this NASA paper about propulsion techs... there are some chemical propulsion techs that are considered TRL<3

http://www.nasa.gov/pdf/501329main_TA02-InSpaceProp-DRAFT-Nov2010-A.pdf

HIGH ENERGY DENSITY MATERIALS
- Metallic Hydrogen
- Atomic Boron/Carbon/Hydrogen
- High Nitrogen Compounds (N4+, N5+)



there are tons of different propulsion techs described in the paper above (it doesnt even consider warp, wormhole, propellantless, etc, until the end (just a single paragraph for all of them).


fact is, we are far from reaching the limits of space tech.

I would not quite consider metallic hydrogen chemical propulsion. The other two would minor improvements in ISP, and would be more or less like fluorine-based oxidizers operationally in terms of being a PITA (A.K.A. being a fluorine chemist's wet dream).

I think the real breakthrough in propulsion will rather be breaking the paradigm that you have to bring your fuel and/or propellant with you. The first step of the revolution, beamed energy including solar power, is slowly happening. The more revolutionary part will be breaking the assumptions of the rocket equation by not bringing the reaction mass with you. That can be done with tethers, mass drivers, magbeams, space-fountain like constructs with smart pellets, solar sails, magsails etc etc. A lot of problems just disappear when you don't have to worry about the tyranny of the rocket equation.

Rather than invoking extremely hard to deal with technologies to slightly improve rockets, I think it is more interesting to consider what may ultimately replace them.
« Last Edit: 11/10/2014 08:26 pm by Nilof »
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 pagheca

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Re: Are we reaching the limit of space technology?
« Reply #55 on: 11/11/2014 09:41 am »
Thanks, I got your points guys, and I will start by saying, again, I don't have a final opinion on this issue yet. I see some clues there is a problem with some leading-edges technologies. Just to make some examples:

- ITAR ITER: controlled fusion is still "a few" decades to come. Like when I was a kid.

- Concorde: we tried, and we failed. There are still a lot of projects going on, but noone materialized as expected in the field of a cheap, reliable, convenient supersonic flight. Average flight speed in commercial aviation is more or less identical to 40 years ago.

- particle accelerators: in a few decades we reached a sort of max level. I was a student at the time. Then we almost stopped. No more room for "easy" improvements. We need a technology breakthrough to overcome present limitations.

My point is that if there is a ceiling that cannot overcome, due to basic physical laws, we may reach it soon or later, but we don't know when it will happen. Second of my points is that not all technologies present the same challenges. For example: you can create a working car with a 1.5 HP engine. A single F1 team yearly spend an amount comparable to what is spent in a decade to build a large, state-of-the-art astronomical observatory. However, the increase in performances is of the order of a few percent, not only due to increasing in restrictions. For example, I read that every year the time to change gear of an F1 car is reduced by about 10%, that makes the consequent performance improvement logarithmic.

However, there is not a minimum limit for speed to make wheeled vehicles usable. This give you a lot of room for other improvements. You can partially say the same for an aircraft: you can have very little engines for aircraft with limited speed and performances (like solar or man powered experimental aircrafts).

But you can't with a rocket as the gravity well requires minimal energy density requirements to reach LEO. Most of those "new technologies" for propulsions listed in theat interesting summary (see would be good once in space, not for reaching orbit. We haven't seen that big improvements since the '60. Actually we filled quickly a gap, and then almost stopped. This is a fact. That lasts since many decades. Rockets are expensive, extremely noisy and heavily impacting on the environment and safety, relatively unreliable. All of this put them in a little niche. Unlike cars or computers.

SpaceX is introducing some improvements, but I don't have unlimited faith on them until they have been demonstrated they can do it. In any case, this is not an improvements in performances or breaktrough technologies - like it was a Space Shuttle or a Lunar Module, but in overall cost.

All of this, let me say, is disturbing for me. I feel like I haven't seen a real improvement in the latest 30 years of my life in some leading-edge technologies. Little things, right, but not very much or a single change of paradigm in the field of ST. I can have "faith", as you do, that this is a very limited, tunneled vision from an observer life spanning just a few decades, but to be honest I cannot see an exit strategy yet from what I feel like an impasse.

Maybe that "stepped evolution" is the solution (point 4 of my initial list), as I really hope. But what you said till now is repeating more or less "don't worry, it happened always in the story of the world that you fell there is a limit, but it has never been true". Right. But there are also signs that patents number is decreasing, for example, and if you create a graph with rocket thrust/weight vs. time you don't see very much after the sixties.

What I mean is that, with all due respect, I read a lot of faith in unlimited progress to date, but (almost) no data from you. This is not a demonstration we reached that ceiling (I do NOT think so), but neither of the opposite.

ADDED: Another clue: speed. We evolved in a world where typical speeds were of the order of 10 km/h. Cars added an order of magnitude (100 km/h). Airplanes one more. Orbital rockets and BLEO added 1 or 2 more. As a consequence, if you hit something with a car you may probably survive. This is much more unlikely with an aircraft (a single bird can be fatal). With rockets, even a micrometeorite maybe unsurvivable. We reached in this case some physical limitations requiring the implementation of not obvious countermeasures. This is going to be a basic problem when you need to add other another order of magnitude or two to your speed to reach very distant objects.

Moreover, there is still the Fermi paradox, and its possible solution that interstellar distances could not be crossable, although I think if this was the solution we still should have seen at least a few communications leaks...
« Last Edit: 11/11/2014 12:14 pm by pagheca »

Offline rklaehn

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Re: Are we reaching the limit of space technology?
« Reply #56 on: 11/11/2014 11:02 am »
Thanks, I got your points guys, and I will start by saying, again, I don't have a clear opinion on this issue yet. I see some clues there is a problem with some leading-edges technologies. Just to make some examples:

- ITAR ITER: controlled fusion is still "a few" decades to come. Like when I was a kid.

That is absolutely not true. There has been a huge amount of progress in fusion technology. In the 60s people really did not know much about plasma confinement. But given the large recent successes in controlled fission and uncontrolled fusion, they were optimistic that they would somehow get controlled fusion to work in 30 years.

Today, we have basically solved controlled fusion. If you build a sufficiently large ITER-style tokamak, it will work to sustain a fusion reaction and will produce a large amount of net energy. If mankind was really desperate for an energy source (e.g. if the pessimistic prognosis of the club of Rome had become true regarding fossil fuels, and solar was uneconomical), we could start building fusion reactors right now.

The "problem" is that there is such an overabundance of cheap energy sources (unconventional fossil fuels, nuclear fission, solar, wind, ...) that it is hard for a fusion power plant to be competitive. And paranoia about radiation is so large that an aneutronic fusion plant becomes desirable. So people are investigating other plasma confinement methods.

Regarding solar: solar panels are now close to grid parity in cost. The energy return on investment is pretty large. So we could run a technical civilization without fossil fuels. We don't do it because fossil fuels are so damn cheap, but fundamentally there is no reason why we need them. That is a major improvement of the last decade right there. Whenever fossil fuels run out, we will not be plunged back into a new dark age, but just maybe have to live with some minor inconveniences like lower range in our cars.

If that isn't a major technical breakthrough of the last decade, I don't know what is.

Quote
SpaceX is introducing some improvements, but I don't have unlimited faith on them until they have been demonstrated they can do it. In any case, this is not an improvements in performances or breaktrough technologies - like it was a Space Shuttle or a Lunar Module, but in overall cost.

You say that as if cost was not an important factor. It is the most important factor there is. Specific impulse, Thrust to weight ratio, reusability are all just useful if they reduce cost.

Offline pagheca

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Re: Are we reaching the limit of space technology?
« Reply #57 on: 11/11/2014 12:50 pm »
Quote
- ITAR ITER: controlled fusion is still "a few" decades to come. Like when I was a kid.

That is absolutely not true. There has been a huge amount of progress in fusion technology. In the 60s people really did not know much about plasma confinement.
[...]
Today, we have basically solved controlled fusion. If you build a sufficiently large ITER-style tokamak, it will work to sustain a fusion reaction and will produce a large amount of net energy.


I appreciate your optimism, but the reality (as reported by thousands of different observers) is that fusion technology doesn't work yet, many issues still need to be addressed, many unexpected problems can rise and there is an extreme need for sustainable energy today that would benefit from advancement in the field. I agree with you that lack of sufficient funding may be one of the reason of the delay, but fusion is by far the most complicated way to produce energy ever, touching the limits of physics laws. That is exactly my point.

Even the ITER consortium say there is the possibility to reach sustained fusion, not certainty:

Quote from: ITER Project website FAQ
Fusion is one of the few potential alternatives for large-scale energy production. ITER is a major step in this direction that will demonstrate the physics and technology on the way to fusion power plants. Achieving success in ITER will not lead immediately to the building of fusion power plants; another step, usually called DEMO (DEMOnstration fusion power plant) will be necessary. Building on the knowledge and know-how acquired within ITER and parallel research, DEMO will mark the transition to the deployment of fusion energy systems.

However, I respect your opinion and would propose to quit this topic down as it was just an example and we have to focus on ST to avoid the thread locked.

Quote
You say that as if cost was not an important factor. It is the most important factor there is. Specific impulse, Thrust to weight ratio, reusability are all just useful if they reduce cost.

Today you can have faster, less consuming and much more powerful cars, or cheaper cars or both than 40 years ago. In rocket propulsion you may have cheaper rockets but not significantly more performant rockets than 50 years ago. Payload fraction and thrust to weight ration have only marginally improved. The difference is striking IMO.
« Last Edit: 11/11/2014 01:10 pm by pagheca »

Offline Robotbeat

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Re: Are we reaching the limit of space technology?
« Reply #58 on: 11/11/2014 12:59 pm »
Speaking of particle accelerators, plasma wake acceleration is being employed now. That's a breakthrough technology that can improve performance by an order of magnitude for the same size.
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Offline pagheca

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Re: Are we reaching the limit of space technology?
« Reply #59 on: 11/11/2014 01:21 pm »
Speaking of particle accelerators, plasma wake acceleration is being employed now. That's a breakthrough technology that can improve performance by an order of magnitude for the same size.

You are right actually: particle accelerators may not be a good example.

However, let's go back to ST. I wouldn't like an interesting discussion to be trimmed because of too many OT.

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