Discussion The next 100 years..

[T.Neo]

You can say colonizing Mars is easy compared to colonizing Alpha Centauri.

Doesn't make colonizing Mars easy.

Mars is so easy by comparison, that as hard as it may be, I would never try to equate the two in even the vaguest sense.

 

[Linguofreak]

Thank you.



I don't know when you started reading this thread.

At about the point you came in, actually.

In case you haven't seen it I'll repost the three vehicles I imagine:

Yes, I have already seen that. Not only from you, but from other's as well. You're not the first to come up with the concept. Robert Heinlein mentioned it as early as 1949.

Prior to lunar propellant coming online, any propellant delivered to orbit must be done with vehicles needing a lot of delta V. If they're reusable they also must endure re-entry abuse (I represent this as a yellow vehicle).

After lunar propellant comes online, orbital propellant could be delivered with smaller, simpler, reusable vehicles.

Yes, and it's a great scheme once you've got a brisk enough flight rate to justify the startup costs.

One thing you're missing is that the vehicles involved will indeed be smaller and reusable, but they won't be simpler. Reusability is an engineering challenge. An expendable vehicle can be built cheap: It only has to guarantee that it will survive one flight and impart the needed delta-V. It does not have to guarantee that it can then be refurbished to perform another flight with the same degree of safety. A reusable vehicle doesn't save money by being simpler or cheaper, it saves money by amortizing its cost over multiple fights. This is one reason that you have to have a high flight rate for a reusable to pay off.

The other thing you're missing is that there's no way that anything short of colonizing another planet could provide the flight rate necessary to justify setting up ice mining infrastructure on the moon.

Scientific exploration isn't the only possible use of propellant.

It's not the only possible use of propellant, but it's the only feasible use barring the magical appearance of a colonizable planet somewhere in the solar system. What are you thinking of?

It does make it a non-issue by comparison.

If you ever venture into the realm of propulsive braking, you will run screaming, chased by monsters. It really is that scarily bad. :lol:

Also, you don't display a very good knowledge of the true difficulty of the technological requirement for aerobraking, as evidenced by you calling aerobraking "abuse". As Urwumpe pointed out, that isn't abuse of the system... abuse is more like taking a Mini Cooper and trying to drive like a 4x4 with it, or trying to chop stone with an axe.

Why do you keep coming back to propulsive braking?

*Anything* is a non-issue compared to propulsive braking.

I completely agree with you that HopDavid is overlooking the issues of making reusable vehicles that do not see regular maintenance, and of setting up an infrastructure on the moon to supply something that is readily available on Earth, and is probably overestimating the difficulties of aerobraking, but the whole "Aerobraking is a non-issue compared to propulsive braking" thing on your part is a complete strawman and isn't helping him understand the real issues. Aerobraking 8 km/s off *is* an issue compared to doing little or no braking at all.

 

[T.Neo]

I completely agree with you that HopDavid is overlooking the issues of making reusable vehicles that do not see regular maintenance, and of setting up an infrastructure on the moon to supply something that is readily available on Earth, and is probably overestimating the difficulties of aerobraking, but the whole "Aerobraking is a non-issue compared to propulsive braking" thing on your part is a complete strawman and isn't helping him understand the real issues. Aerobraking 8 km/s off *is* an issue compared to doing little or no braking at all.

Well, yes. But the "8km/s" bit isn't the major issue, which is my point. HopDavid keeps on insisting that shedding 8 km/s of velocity via aerobraking is a huge, massive issue, but I don't see any effort from him to try to understand what makes dealing with aerobraking a challenge and how that challenge can be dealt with.

Maybe I just deal with the rocket equation too often, that when I hear "8 km/s velocity change" I am instantly wired to think about all the propellant that will require, and all the engines, and pumps, and pipes, and nozzles, and tankage, and propellant, and... :uhh:

Compared to all of that, a passive thermal protection system is not really problematic. As far as I know, the major issues with the TPS on the Shuttle had very little to do with the actual reentry procedure itself, and mostly to do with debris falling off the external tank. Add to that the fact that a TPS need not necessarily be as fragile as that on STS.

 

[n0mad23]

Aerobraking, I would think, can lead to about the most economically efficient dV shedding system possible. Friction certainly can be this Orbinauts friend, and while I really avoided aerobraking when I first started off with OSFS206. Now I'll look for any excuse possible to use the technique. The thrill of the simulator....

NukeET posted this in the "NASA, the war continues" thread, and I think the conclusion of Jerry Pournelle's blog is worth reposting here.

I will say it one more time: if we want to explore space, determine what we think that’s worth and put up prizes. A $5 Billion prize for a reusable craft that goes to orbit and returns 11 times in 12 months, nothing to be paid until someone does it. A $12 Billion prize for putting up a Lunar Colony of 31 Americans to be kept alive and well on the Lunar surface for three years and a day, again nothing to be paid until the task is accomplished. If no one does it, there is no cost to the taxpayers. If someone claims the prize the world will cheer. But of course neither of those courses will employ the NASA standing army. The Iron Law Prevails. http://www.jerrypournelle.com/reports/jerryp/iron.html

Link to Pournelle's page - http://jerrypournelle.com/chaosmanor/?p=1992

 

[HopDavid]

One thing you're missing is that the vehicles involved will indeed be smaller and reusable, but they won't be simpler. Reusability is an engineering challenge. An expendable vehicle can be built cheap: It only has to guarantee that it will survive one flight and impart the needed delta-V. It does not have to guarantee that it can then be refurbished to perform another flight with the same degree of safety.

Yes, doing maintenance on an orbital vehicle or a reusable ascent/lander will be a challenge. But there are several maintenance issues that are much less severe.

The shuttle had to jettison it's external tank each trip. The subsequent trip it had to have new ET attached. With a 5 km/s delta V budget, there is no need to jettison a tank and attach a new tank each trip. Single stages don't have to be repeatedly separated and reattached as a multi-stage reusable would.

Another maintenance challenge for shuttle was TPS. Since re-entry abuse is extreme, a considerable amount of time and effort was spent checking and repairing the shuttle's TPS each trip. The TPS and ablation shield of the red vehicle will need some maintenance, but it doesn't endure nearly the abuse the shuttle does. This is the point I was trying to make by comparing the Shuttle's shedding 8 km/s over an hour vs the red vehicle having to shed 3.1 km/s over several perigee drag passes.

So while maintenance is an issue, they don't face some of the extreme maintenance issues the yellow vehicle suffers.

One of the prerequisites for lunar infrastructure (in my opinion) are able telerobots. A dextrous robot that moves it's head, arms and torso in the same fashion as it's operator would be useful. Will we have something better than Robonaut? That remains to be seen. But such a robot would make repairs in a vacuum more doable.

It's not the only possible use of propellant, but it's the only feasible use barring the magical appearance of a colonizable planet somewhere in the solar system. What are you thinking of?

1) LEO to GEO transfer This Boeing pdf estimates communication satellite transfers from LEO to GEO could generate a steady demand of 700 tonnes of propellant each year (bottom page 11).

2) Cleaning orbital debris. There is a growing space debris problem. For a reusable tug to rendezvous with various debris in different orbits would take lot of propellant. Propellant from earth would come via Centaur or some other upper stage. In which case why not just send up a single use tug instead of a propellant delivery upper stage? Reusable tugs do not make much sense if their propellant must be delivered with multi-stage expendables.

3) Maintaining and upgrading sats. Since communication sats are so difficult to reach, our present paradigm is design, build, launch and discard. If travel about our earth moon neighborhood in reusable vehicles becomes routine, it might become economic to design upgradeable modular satellites amenable to repair.

4) Manned space exploration Having propellant, water for radiation shielding, and life support consumables available at EML1 and 2 would make manned trips to Mars and NEOs much more doable. This would also simplify manned trips to the moon.

---------- Post added at 12:42 AM ---------- Previous post was at 12:27 AM ----------

HopDavid keeps on insisting that shedding 8 km/s of velocity via aerobraking is a huge, massive issue,

In the same place where I was insisting the moon is covered with water: the posts from your feverish imagination.

Reading comprehension. Get some.

 

[T.Neo]

Yes, doing maintenance on an orbital vehicle or a reusable ascent/lander will be a challenge. But there are several maintenance issues that are much less severe.

Not necessarily. You have to factor in the different things involved.

The shuttle had to jettison it's external tank each trip. The subsequent trip it had to have new ET attached. With a 5 km/s delta V budget, there is no need to jettison a tank and attach a new tank each trip. Single stages don't have to be repeatedly separated and reattached as a multi-stage reusable would.

Does anyone actually have numbers of how much stacking a vehicle costs? Other than "I think it's really expensive"? :dry:

Another maintenance challenge for shuttle was TPS. Since re-entry abuse is extreme, a considerable amount of time and effort was spent checking and repairing the shuttle's TPS each trip. The TPS and ablation shield of the red vehicle will need some maintenance, but it doesn't endure nearly the abuse the shuttle does. This is the point I was trying to make by comparing the Shuttle's shedding 8 km/s over an hour vs the red vehicle having to shed 3.1 km/s over several perigee drag passes.

:beathead:

How many times do people have to explain, that it is not reentry "abuse".

It was not the reentry that caused problems with the shuttle's TPS, but debris strikes.

Do we have to go over that again and again and again?

One of the prerequisites for lunar infrastructure (in my opinion) are able telerobots. A dextrous robot that moves it's head, arms and torso in the same fashion as it's operator would be useful. Will we have something better than Robonaut? That remains to be seen. But such a robot would make repairs in a vacuum more doable.

Big difference between working on a vehicle yourself in an extensive Earth-based facility and working on a vehicle from 300 000 km away through a telerobot working in a limited facility.

This sort of servicing and work is expensive enough on Earth.

1) LEO to GEO transfer This Boeing pdf estimates communication satellite transfers from LEO to GEO could generate a steady demand of 700 tonnes of propellant each year (bottom page 11).

Actually, I count an upmass to "geosynchronous orbits" of roughly 150 tons in 2010. Assuming a dry payload fraction of 0.85 and the performance of the RL-10B-2, you would have a propellant demand of maybe 430, not 700 tons.

Of course, you will need more propellant if you want to return those 'space tugs' to LEO, and that propellant will also have to be lifted to GEO... but since you are not shipping anything from GEO, and the stages are much lighter than the payloads, this will not be (that) much propellant.

3) Maintaining and upgrading sats. Since communication sats are so difficult to reach, our present paradigm is design, build, launch and discard. If travel about our earth moon neighborhood in reusable vehicles becomes routine, it might become economic to design upgradeable modular satellites amenable to repair.

Actually, maintaining and repairing satellites was a planned function of the Shuttle, and one that failed entirely... :shifty:

In the same place where I was insisting the moon is covered with water: the posts from your feverish imagination.

Reading comprehension. Get some.

Considering that you repeatedly talk about "8 km/s reentry abuse", I have difficulty imagining that you are making such a point in my imagination only. :dry:

 

[ElTaco]

To be honest, for the next 100 years I don't see the traditional heavyweights in the space industry as having a major influence on future events. (i.e NASA, RSA). In particular, NASA's drive of the 20th century seems to have been left behind in the transition to the 21st.

Rather, I hold optimism for private enterprise in space for the foreseeable future.

 

[Wishbone]

T.Neo, one cannot right all wrong beliefs on-line. Yes, I'm being selfish here, since would like to see more add-ons from you.

 

[Urwumpe]

Since re-entry abuse is extreme, a considerable amount of time and effort was spent checking and repairing the shuttle's TPS each trip.

If you use a hammer for putting a nail into a wall, you use it, you don't abuse it. If you use a hammer for keeping your books from falling from the shelf, you abuse it. Notice something?

The problem for the TPS is only the debris problem during launch and orbit. The tiles themselves are pretty much designed for everything that mother nature can throw against them during reentry, but a single damage on the wrong place can make the whole TPS useless - but that points have no tiles, but RCC panels.

The places with tiles can survive even massive damage:

Was pretty lucky anyway, the damage in a spot was so massive during that flight, that only an L-Band antenna (TACAN) prevented structural damage.

But the chances for LOCV had been pretty low despite this, in the worst case, it would have been a write-off of the Orbiter after landing.

STS-107 was much different there: A single large panel was damaged - the same kind of damage that can even doom massive ablative heat shields. If the launch would have been aborted by RTLS, the damage would have been easily visible and fixed.

 

[Keatah]

Why don't we just build a proper vehicle like the Starship Enterprise?
Because once you start taking away the environmental infrastructure provided by Mother Earth, things start to go wrong.

This is a great article! I have more fodder for the pro-unmanned space program. Man does not belong in space, not yet.

 

[T.Neo]

Why don't we just build a proper vehicle like the Starship Enterprise?

Because the Starship Enterprise is a complete load of nonsense and even the Moon Rocket in the Tintin comic Destination Moon is more scientifically sound?

Because once you start taking away the environmental infrastructure provided by Mother Earth, things start to go wrong.

No, things generally go wrong when you don't know what you're doing. That's why you have to learn what you are doing.

This is a great article! I have more fodder for the pro-unmanned space program. Man does not belong in space, not yet.

Oh great. :dry:

Yeah, let's get all... ahem... pessimistic about human spaceflight and axe it in favour of "pro-unmanned" spaceflight. Because when there are problems, you just don't solve them, because they're, y'know, difficult, and therefore you get nowhere. It really is such a great paradigm for getting things done. :dry:

 

[Codz]

Why don't we just build a proper vehicle like the Starship Enterprise?
Because once you start taking away the environmental infrastructure provided by Mother Earth, things start to go wrong.

This is a great article! I have more fodder for the pro-unmanned space program. Man does not belong in space, not yet.

Why can't we do both? Why must it be one or the other? That's incredibly short sighted.

 

[Ghostrider]

Because the Starship Enterprise is a complete load of nonsense and even the Moon Rocket in the Tintin comic Destination Moon is more scientifically sound?

Hey, the starship Enterprise is some cool vintage '60s design. If the Mad Men had to design a starship, that would be it. And Jean Shrimpton could ride it, what with the miniskirt uniforms and all.

 

[Keatah]

Because the Starship Enterprise is a complete load of nonsense and even the Moon Rocket in the Tintin comic Destination Moon is more scientifically sound?

No, things generally go wrong when you don't know what you're doing. That's why you have to learn what you are doing.



Oh great. :dry:

Yeah, let's get all... ahem... pessimistic about human spaceflight and axe it in favour of "pro-unmanned" spaceflight. Because when there are problems, you just don't solve them, because they're, y'know, difficult, and therefore you get nowhere. It really is such a great paradigm for getting things done. :dry:

First off, the Starship Enterprise is not a load of BS. It is the style of ship we're gonna need if we are to do any serious exploring. Granted we don't need EVERYTHING the Enterprise has. But our craft should be of similar size and have similar propulsion capabilities. Perhaps not warp drive, but something much better than chemical rockets. Much better. Not phasers, but perhaps terrawatt lasers which is almost doable now. Forget the transporters, if we can build a ship similar to the Enterprise, surely we can build SSTO and similar landers.

We'll need the room it offers and durability of materials. You don't undertake a journey unless you are prepared. And we are NOT prepared, emotionally, psycho, politically, financially, physically. If you disagree, well then that is just fine by me. 20 years from now we'll *STILL* be farting around in LEO.

Humans have too many issues when you stuff them in a zero-G tin can. Radiation, fluid redistribution, exercise, sanity, clarity of thought for creative and critical thinking. All that goes out the door for the common man. Hell, it even goes out the door for well-trained professionals such as scientists and pilots and other professions where you need to have it together. Today's astronauts, or lack of, now, are a special breed that have had the best training and ground support we can muster. And that's just for screwing around in low Earth orbit. Imagine a trip to the outer planets or Kuiper Belt.. ??

We're done with the initial pioneering folks, it's time to move out in better ships! If we can get past the political hurdles.

And while we are playing with Powerpoint spacecraft, we'll continue to send unmanned probes out there and get useful knowledge. And farting around in LEO will continue to underscore the need for better ships. And that's great!

Meantime I'll keep laughing at all the petty nonsense that is the space program of today..

---------- Post added at 06:50 AM ---------- Previous post was at 03:46 AM ----------

Yeah, let's get all... ahem... pessimistic about human spaceflight and axe it in favour of "pro-unmanned" spaceflight. Because when there are problems, you just don't solve them, because they're, y'know, difficult, and therefore you get nowhere. It really is such a great paradigm for getting things done. :dry:

The one thing we DO have down pretty good is Navigation and Celestial Mechanics. We will not need to spend herculean efforts in that department. Just little refinements here and there. What we have now is more than adequate. Any advances will be bonus rounds and nice additions. See? Our unmanned probes can put a microscope to task and examine rocks up-close from millions of miles away. And the HST has really slick stationkeeping and pointing abilities. All this will carry over to any manned craft we build.

Same thing with Communications. The DSN is still listening to the two Voyagers. The amount of energy they pluck out of the ether is not more than flea fart in a hurricane. And this is using antiquated technology to boot! A little refinement and we'll hear the outgassings of He3 based bacteria gestating in the Oort Cloud. I'm sure!

But..but-but-but - before we should even think about manned ships we need to fix a million problems right here in the design labs! Look, you don't attempt to build a 600HP V8 that also gets 25mpg unless you have the necessary materials and the ability to work with them. Also you need the necessary background and infrastructure and tools. In the case of the engine, you need good sensors, precision CNC tools, good CAD/CAM, and a whole semiconductor industry to build the computer that will monitor the combustion and 20 other engine parameters to ensure correct and efficient operation.

Or put another way, you don't build a world-class sports sedan unless you can build the engine to power it. Surely you're not gonna put a steam engine into it? Right? You don't waste money on trying to do so either. You make sure you've got your shop in order, and then build it.

Right now, our space program is little more than the bronze age, if that. We need to focus solely on unmanned probes and telescopes and orbiters/satellites if we want to rapidly gain knowledge and explore the cosmos. Spaceborne sensors are far more capable and suitable for the environment than man is. While we are doing that can work on bettering our manufacturing and materials/energy design technology.

We should not waste money on the SLS or any other manned program. Not now. Money and political efforts and all that intangible crap that humans generate should be "focused" on unmanned probes and materials/energy development!

Once those two items are better developed THEN and only THEN should man leave Earth. You can argue with me all you like on this. Or not. I don't really give a rat's .. But I can PROMISE you if we continue to blow money & political coherence on Powerpoint spacecraft that SOMETIMES materializes into a sub-standard vehicle we'll NEVER develop the real technologies that will open up space the way you, or the common man, or the educated scientist (and anyone else) envisions.

Whether it be a Type-6 StarFleet shuttlecraft in every garage, or something more down to Earth like a Moller SkyCar with superturbo-orbital-rockets. Or cost effective Space Elevators or daily sub-orbital commercial airliners that go hypersonic.. Nothing! None of it will happen until we get the shop in order.

Go ahead and hoot me all ya'll want. But since Apollo, a political stunt to be sure, we've farted around in LEO. And any knowledge we gained about the universe has come from telescopes and unmanned spacecraft.

You know I am right. You also know, but are afraid to admit it, that the space program is not advancing like the semiconductor/computer/IT industry, the aviation industry, or the automotive industry.

You also cannot expect space travel to develop like the above industries either. Crap! I've even see the manned part of NASA being compared to the Wild West pioneers. What a frakking joke! This is a different beast altogether and we have gotten far ahead of ourselves. We are way out of line. Time is long past due to reel it in and get the shop in order. Then we can go in style. And you too!

 

[orbitingpluto]

Nobody went from [ame="http://en.wikipedia.org/wiki/Caravel"]Caravel[/ame]s to modern ships by not building ships. Or cured scurvy by staying at home. Somebody had to buy that knowledge with time, blood and tears. People will have to work at making spaceflight less dangerous and easier by doing it. Even if jerks on the internet cackle at them, and belittle their work in LEO.

 

[Keatah]

Nobody went from Caravels to modern ships by not building ships. Or cured scurvy by staying at home. Somebody had to buy that knowledge with time, blood and tears. People will have to work at making spaceflight less dangerous and easier by doing it. Even if jerks on the internet cackle at them, and belittle their work in LEO.

Jerks on the internet.. Bwaaahahahaaa what you smokin?
:nono:Sorry bud, that ain't flying with me, no pun intended. And it ain't flying period - as you can plainly see. The US doesn't even have manned capacity anymore, nor do they care. Same deal with much of Europe, not to mention how many other countries in the world? ..that don't have spacefaring capability.

I'm sure there will have to be some actual hands-on work. But we're working with the same crap we had for the past 30 years! Spin'n round and round! Wheeeee!!! There's only so much that can be done with metals that are X amount strong and Y amount heat resistant.

Even the un-educated (like my idiot brother-in-law) can see that there's a new composite airliner coming to town. A far cry from the fabric covered planes of the early 1900's. It is this new material that has allowed for such a fantastic aircraft to take flight. The same evolution (or revolution if you prefer) will need to happen with spaceflight. And it's nowhere in sight.

It's too costly and risky with the toilet-paper-like materials we have today. Only the best of the best well-educated and learned engineers can see we need to get the shop in order. Can anyone here even understand that? Good grief!?!! I'm not talking about the wars or poverty or hunger issues. That's humanity's baggage. It isn't going away anytime soon. It is in man's nature to kill and hurt others to gain the advantage. This is nothing new. In fact, war, death, and destruction often lead to new technologies faster than any other motivating factor. One can conclude that peacetime technological advances only pale in comparison. Even the lowly RTG owes its existence to Einstein and Oppie. Not to mention Teller & Ulam. And that was borne out of the desire of how to kill more efficiently. Afterall, the fear of dying and need to kill was the very foundation of the Apollo program! One-up the Russians. Apollo was a great front put up to showcase technological prowess and instill fear to the world. Nothing else..

Work in LEO is good for teaching and ingraining logistics and discipline and all the tedious toilings that humans must do, by nature of the beast within. We've done enough of that already. Where's the materials sciences and propulsion mega-grants? A few million here and there ain't gonna cut it bucko. No sir. The space program needs a huge re-organizing. In fact, rip the whole damned-thing apart and start over. And I'm sorry to break it to you bub, but that means dropping manned stuff for a while.

If you think man is gonna make it to space in any worthwhile capacity at the rate we're going - you've got another thing coming. Please, please, please, explain to me how else it would be different. I expect you to be specific!

Ohh well, 25 years from now we'll still be pissing in LEO. Wheeeeeee.....

 

[RisingFury]

Jerks on the internet.. Bwaaahahahaaa what you smokin?
:nono:Sorry bud, that ain't flying with me, no pun intended. And it ain't flying period - as you can plainly see. The US doesn't even have manned capacity anymore, nor do they care. Same deal with much of Europe, not to mention how many other countries in the world? ..that don't have spacefaring capability.

Yea!!! Those stupid third world countries!!! They don't even have food!!! Ha!!!

 

[Keatah]

Yea!!! Those stupid third world countries!!! They don't even have food!!! Ha!!!

A lot of governments, both well-to-do and not-so-well-off, question the need for any kind of space program. Why? I don't really care to take the discussion in that direction. But we could..

 

[orbitingpluto]

So you're pessimistic and jaded. Woo hoo. If you take off your blinders and stop comparing real life to Star Trek, you could see that it is really not bad enough to crawl back into a cave like you propose.

Besides, the point of what you call farting about in LEO is to get ready to go out and do more scientific study in a day than a probe can do in a week.

Even with the US temporarily out of the manned spaceship provider category is doing one good thing; reminding ordinary Americans that we're dependent on the Russians. So we should have something better than theirs, right?:lol:

 

[Keatah]

So your pessimistic and jaded. Woo hoo. If you take off your blinders and stop comparing real life to Star Trek, you could see that it is really not bad enough to crawl back into a cave like you propose.

Not exactly, I'm just explaining why we need to completely re-do and re-think how we go about building a proper space program. What we have now isn't much better than soggy box of Kleenex. It's a sad state of affairs, and you all know it. You just can't see it!

Star Trek or no Star Trek. While it certainly is a model to live up to - It is by no means the only one.

I can tell you, with 100% certainty, that unless we do something radically different from what we are doing now.. Well hell.. in 40 years will still be gassing around in Earth orbit.

Do things *MY* way and we'll undoubtedly have Rama-sized cruise ships sailing the Solar System! But that idea scares you or makes you dismiss it out of impractical idiocy! I'm sure.