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#521
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Questions about "The High Frontier"
or the technology that's going to be somehow developed that makes that
happen, despite the fact that rocket efficiency has been fairly constant since the mid 1960's... It might all well happen within the limits of chemical rockets. Give me an explanation of how that's done from a technical point of view. Show me a concept of making a chemical rocket that has a isp of around 1,000. I'm not asking for a working drawing, I just want the basic concept. Ask and ye shall receive: Boron / lithium / boron spiked H2/LOX: Isp 530s (theoretical max 700s - toxic as hell) H2 + Fl: Isp 446s H2 + O3: Isp 580s Air-augmented kerosene: effective Isp 550s (researched for Soviet mobile ICBM stages) Monatomic H: Isp 650s (produced in lab but tends to blow up easily) Metastable He-IVa: Isp 2200s (produced in lab - storable as a solid, no dodgy magnetic storage) Metastable He-IV*: Isp 3100s (cute, but HIGHLY unstable and has half- life of 2.3 hours anyway) H2 + tetroxygen: Unknown performance, thought to be superior to H2/O3 Metallic hydrogen / tetrahydrogen: Isp 1200-3000 (produced by rapid shock compression, can be metastable and storable if surrounding pressure rapidly quenched to ambient: storage density 10x that of liq. H2 so very nice if achievable) And I didn't even have to go to Nyrath's website. Of course, a 1000 sec chemical rocket won't bring space travel under the $200/kg mark. It could be done with air-launched rockets burning hydrogen peroxide and kerosene with a linear aerospike. Something like the USAF Dark Horse spaceplane study. Possibly even getting to orbit in a single stage because the fuel density is so high. No cryogenic handling issues, no pad issues, just load up and go. http://physci.llnl.gov/Organization/.../ComQuest.html http://www.dcr.net/~stickmak/JOHT/joht13rocketprop.htm http://www.strangehorizons.com/2004/...talodd-a.shtml isdc2.xisp.net/~kmiller/isdc_archive/fileDownload.php/? link=fileSelect&file_id=361 - Bet you didn't picture a CPU that had a multi-gigahertz processing capability twenty-five years ago, or a hard drive that could store 500 megs... and have those both sitting inside of something of around two cubic feet in size in your living room either. So much for the foreseeable future. :-D 5 years ago I was expecting 5GHz processors to be coming out "sometime soon." Now, we have computers that cause hearing damage with their cooling systems. I think it worth pointing out that a decent gaming rig puts out more waste heat than a sweaty human in an EVA suit. At least it's giving me a chance to realize that I was right all along, and that Robert Zubrin really does sound like Bruce Dern out of "Silent Running". ;-) Hmmm... better keep him away from shovels, then. And nuclear detonators. Pat Note to future spacecrew recruiters: do not hire wild-eyed biologists with long curly hair. |
#522
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Questions about "The High Frontier"
bealoid wrote: How much human supervision is a robot-machine allowed until it reaches the point where it becomes a non-robot-machine? Does it make any difference if that supervision is provided at a console next to the machine down the mine, or at a console at the surface, or at a console some miles away? That could be a really tough question to answer, because the two could fade into each other. Many years ago, someone pointed out that a Sidewinder missile is a robot that certainly doesn't obey Asimov's three laws of robotics, in that its aim is to cause harm to come to people...the pilot of the enemy aircraft it's homing on. Once launched, it homes on the enemy all on its own, so it is a pure, if very simple, robot. A Sparrow III missile on the other hand requires that the target be illuminated by the attacking aircraft's radar as it homes on the reflected signals of that, so it probably isn't a pure robot. A Phoenix missile is even more confusing...during the early phase of the flight, the F-14 gives it commands to change its course to close on its target, but once it gets close enough it begins to home on it all on its own. So sometimes it's a robot and other times not. Let's see what Wikipedia says: http://en.wikipedia.org/wiki/Robot Their definitions are all over the place also. :-) When a robot becomes a android is kind of iffy also. If it looks human, but you can easily tell it's a robot, is that a android or not? The full-sized Asimo prototype could be confused with a person wearing a spacesuit. Even the production small one looks more like person in a spacesuit than what I'd expect a robot to look like. Its proportions are very human...I always pictured something like Robby from Forbidden Planet, or the Pol-Robs out of Magnus, Robot Fighter. Asimo could be C3PO's great-grandfather. On the other hand, that could be a very logical approach to things; Robby would have a hard time going up stairs (his feet are too large) or fitting in a conventional automobile. At least he made up for the scary robot/android in Metropolis, and helped give robots their good name back after the scary robots from the movie serials. Pat |
#523
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Questions about "The High Frontier"
IsaacKuo wrote: Maybe the lunar material is collected using a hexagonal formation of inverted funnels. A puff of oxygen gas throws up a bunch of lunar dust/regolith. Around the "impact" is a formation of six upward pointed funnels, so dust/regolith collects at the center. Since there's no atmosphere to worry about, even fine dust particles will quickly fall down back into the collection funnels. At the base of each funnel are heating elements to begin processing the ore; as the ore near the bottom is melted it flows into heated pipes for the rest of the processing. This mechanism may be less efficient than scoops, but the reduced maintenance issues may be worth it. The only moving parts are valves for the gas puffers and wheels for moving from one place to another. A powerful magnet could pick up ferrous materials in a even simpler technique as it's pulled across the surface. One problem nobody's mentioned yet is the lunar night. Unless you limit your mining activities to the lunar poles, and haul the materials up to the top of a "eternal light" mountain for processing, you are going to have two weeks gathering and processing and two weeks sitting around and waiting for the sun to come back up. If you are going to start running ore refineries and mass drivers with nuclear power during the night period, you are going to need some walloping big reactors, as the total BTU released by the reactor is going to be the limiting factor for how much heat you have to refine things with. Pat |
#524
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Questions about "The High Frontier"
Mike Combs wrote: Give me an explanation of how that's done from a technical point of view. Show me a concept of making a chemical rocket that has a isp of around 1,000. You seem to assume that the cost/lb is primarily a function of ISP. That may not be the case. We aren't sure about that. although the big dumb cheap booster is a very fond dream of everyones, the infrastructure to move it around and launch it may be more trouble that the lower cost of the vehicle justifies. There's a rough middle ground...you don't need engines with the isp and complexity of the SSME, but you don't want things as simple and low cost as V-2 engines either, because you end up with a fairly small payload riding on something the size of WvB's Cargo Rocket. If you are going to try and make the vehicle completely reusable, either in one piece or in stages. you are going to have to use very high isp engines just to have any usable payload left due to the TPS and recovery systems. The Russians may have hit fairly near the mark with their R-7 series of rocket derivatives which are pretty bulky for what they do, but are also fairly cheap and very reliable. One thing that the space tourism crowd hasn't ever seemed to recognize is that if they are going for orbital flight, then after 50 years of work, we still haven't been able to get past around a 95-97% reliability rate with our orbital rockets. That's okay for satellites put start extrapolation it into some sort of passenger carrying service that has a fairly high launch volume, and you had better have one mighty effective and reliable LES and abort capabilities, or the fatalities are going to start piling up. Bet you didn't picture a CPU that had a multi-gigahertz processing capability twenty-five years ago, or a hard drive that could store 500 megs... and have those both sitting inside of something of around two cubic feet in size in your living room either. Yes, but has any of that lead to a robot that you can tell to go upstairs and get your glasses? That's the kind of thing we were anticipating we'd have by the 21st Century. Thought we'd have fusion...and personal autogyros and flying cars for that matter also. We are probably around 50 years off from Asimov's world, but on the other hand we do have some robots being integrated into things, and we still haven't put a person on Mars, built even a small prototype SPS, or put up even a small manned Moon base. Even our ISS is a long shot from WvB's 1950's space station, regarding crew size in particular. We were supposed to have Gemini spacecraft on Mars by now: http://www.ninfinger.org/~sven/model...inggemini.html Despite possible landing problems: http://membres.lycos.fr/marsetsf/rc2/snap01034.jpg ;-) Pat |
#525
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Questions about "The High Frontier"
Hop David skreiv:
# can sense its environment, and manipulate or interact with things in it # has some degree of intelligence or ability to make choices based on the environment, or automatic control / preprogrammed sequence That doesn't help much. Every object "interacts with things", even an inert rock "interacts" with every other thing in the universe by way of gravity. "sense" is one of those words that are hard to define again. In any case, by the WikiPedia-definition my car is certainly a robot. It interacts with the environment, plenty even, and it has automatic control and preprogrammed sequences. For example, if it senses that it starts to rain, it independently starts the windshield-wipers. If it senses that it will crash it goes trough a checklist and inside of 50ms does on the order of 20 things to increase survival-chance (ranging from increasing the pressure in the brake-assist to tensioning safety-belts to inflating airbags, shutting off fuel-supply, cutting main power etc etc etc) and the car is neither brand-new nor fancy, infact it's the smallest Skoda you can buy. Most people don't think of their cars as robots. I think my point stands: there is no clear separation. Certainly no universally agreed upon separation. But whatever name you give to a machine, John's point still stands: Where are the working mines with no people in it because they've all been replaced by machines? There are neither. No mines operated -solely- by machines. And no asteroid-mines operated by humans. We're talking science fiction, so this should hardly surprise anyone. Eivind Kjørstad |
#526
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Questions about "The High Frontier"
Troy wrote: On Nov 8, 9:38 pm, Pat Flannery wrote: Hop David wrote: Hop David wrote: Pat Flannery wrote: (snip) Do you honestly believe miners are a bunch of clumsy morons? You arrogant, ignorant, little prick. I DID NOT WRITE THAT. No, you didn't and I believe Hop was expressing regret at what he wrote: Quote from Hop: "I've always regarded you as a gentle soul and a wonderful story teller. It distresses me to read some of my replies to you in this thread. " So first he lies about what I wrote, then he says that he's sorry he wrote what he did, then he killfiles me...all in one posting? Is there any logic in that? Pat |
#527
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Questions about "The High Frontier"
John Schilling skreiv:
Classically, it's a robot if it has the ability to sense and respond to the external environment. Pragmatically, it only counts if the "sense and respond to the external environment" bit applies to the normal exercise of the primary function of the device; safety overrides and/or feedback control of secondary functions need not apply. A car does not become a robot when you add anti-lock brakes; it becomes a robot when it steers itself down the road. But my electric heater is a robot. It senses the external environment (namely the temperature) and responds to it (by turning on or off the heating). This is it's primary function, indeed it does its thing unsupervised for weeks at a time, it is clever enough to know when I'm at work and when I'm sleeping, so allows temperature to drop further at those occcasions. I've got a robot heating my bathroom-floor too. I give it orders twice a year. The rest of the time it senses and responds to the environment independently. Eivind Kjørstad |
#528
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Questions about "The High Frontier"
OM wrote: ...As long as this thread has progressed, I'm starting to see more of this happening. Apparently some of you guys aren't watching your attribs while trying to trim your quotes. Keep a cooler head about yourselves, and watch those attribs before you flame each other for the wrong reasons! Note how it was posted; with only a single quotation bar in front of it. That had to be intentional. I made a unintentional slip like that with the comment about the draft, but it wasn't anything insulting, and I did leave both quotation bars intact. I also immediately apologized for it once it was brought to my attention, and removed the message from all the newsgroups it was posted to. Pat |
#529
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Questions about "The High Frontier"
Troy wrote: These are interesting combos, but I never liked the concept of the super-powerful monopropellants, because if something goes a little funny in the storage tank, there is a very big explosion. And I didn't even have to go to Nyrath's website. Of course, a 1000 sec chemical rocket won't bring space travel under the $200/kg mark. It could be done with air-launched rockets burning hydrogen peroxide and kerosene with a linear aerospike. Something like the USAF Dark Horse spaceplane study. Possibly even getting to orbit in a single stage because the fuel density is so high. No cryogenic handling issues, no pad issues, just load up and go. Henry Spencer took a couple of years to do it, but he talked me into trusting H2O2 as a oxidizer (bad memories of the Me-163 and hydrogen peroxide powered submarines kept crossing my mind). It's fairly easy to work with if you treat it right (certainly a lot safer than hydrazine or RFNA) as is cheap and easy to produce in volume. http://physci.llnl.gov/Organization/.../ComQuest.html I like these two statements from that webpage: "Metastable metallic hydrogen would have a very high density of stored energy because it would have a density about ten times that of liquid H2 at 1 bar. Thus, the stored energy released by reversion to the diatomic insulating fluid would also be very large and metastable metallic hydrogen would have widespread applications as fuels. If this energy were released relatively slowly or quickly, metallic hydrogen would be either a clean propellant, as gasoline, or an explosive, respectively." and "If solid metallic hydrogen has sufficient strength, it might be useful as a light-weight structural material. For example, automobiles made of metallic hydrogen would be ~10 times lighter than current ones made of steel, enhancing fuel efficiency and reducing conventional fuel emissions. The ideal would be to synthesize metallic hydrogen to be either extremely metastable, as diamond, for use as a structural material or readily reactive, as gasoline." Me, I'm not keen on driving around in something made of explosives. ;-) "Introducing...the new 2025 Honda Hindenburg!" Anyway, it's pretty early to be speculating on its properties without even a fraction of a gram of it to study. Pat |
#530
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Questions about "The High Frontier"
On Fri, 09 Nov 2007 01:00:26 -0600, Pat Flannery
wrote: When a robot becomes a android is kind of iffy also. ....The difference has pretty much been acknowledged as follows: If it looks like a human, behaves like a human, and can perform basic tasks exactly like a human, it's an android. On the other hand, if it can perform bodily functions just like a human, but using mechanical processes using parts that are designed to function *AND* look like human parts, then it's a synthezoid. Of course, if it's just a box on wheels with two armatures and claws, it's a goddamn robot...:-P OM -- ]=====================================[ ] OMBlog - http://www.io.com/~o_m/omworld [ ] Let's face it: Sometimes you *need* [ ] an obnoxious opinion in your day! [ ]=====================================[ |
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