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#711
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tomcat;
As far as radiation goes, new materials can stop radiation without the weight of lead. If astronauts get irradiated it will be because someone didn't use what is available. There are 'plastics' that can stop radiation as well as new light weight metals. Remember: Beryllium steel reflects neutrons. That is why it is used in atomic bomb casings. Beryllium steel is light compared to iron/steel and thin sheets of it can work wonders. Lead foil might be used around crew quarters. Gold foil is fairly dense as well. Why is you mind still in the gutter as to any need of protecting whatever TBI and DOA astronauts from radiation? I was asking about those spendy CNTs, about their taking a radiation overdosage and surviving. What the hell is wrong with the three brain cells you've got left to work with? BTW; it's snookered damn fools like yourself that suggest other materials that are launchable can turn the tide against the TBI factors of human space travel. It takes roughly 0.7" of lead to cut hard-X-ray dosage in half. For God's sake, do the math. If volume is not a factor, then the less density of whatever substance the better because of such creating fewer secondary/recoil photons, thus indeed the CNTs as piled high to perhaps 100 meters worth of depth might become better off than a given layer of lead. I believe that besides the usual barrier of aluminum, a substantial layer of circulated water is what's doing 90% of the attenuation job as well as essential cooling for ISS. A good spaceplane capable of SSTP (Single Stage To the Planets) should pierce the Van Allen belt at about 100,000 mph. So, length of that radiation should be minimal. Remember, however, that in most of my posts I am referring to a SSTO (Single Stage To Orbit), not a SSTP. Whether the advantage of ultralight nanotube hulls will allow for SSTP is questionable. Along with the new 'atomic hydrogen' with 5X thrust, then an SSTP cargo hauler should be immediately possible. The Van Allen zone or rather expanse of death is worth 70,000 km, a bit more if your spaceplane is being near the moon where there's a SAA sort of significant lunar dip that reaches a bit further, and at times even a bit past the moon. So, you'd best multiply your 44.7 km/s by at least 2 fold, whereas at an average of 89.4 km/s is going to require 782 seconds, better than 13 minutes worth of going through the Van Allen badlands if you're not headed anywhere towards the moon, especially if it's on the backside of mother Earth. Of course going fast is only half the energy equation, whereas slowing yourself down get a wee bit testy unless you're taking advantage of near-miss aerobreaking notions, of which the lunar atmosphere of radon and argon is going to require that your spaceplane drag one hell of a parachute as it passes multiple times at less than 10 km off the lunar deck (actually 1 km off the deck would do some serious aerobreaking as well as kicking up some moon-dust on each exciting pass). Now you know why I am upset with NASA announcing 12 years to the Moon in capsules. 3 years and 3 billion dollars and a sub-orbital can be built. 5 years and 5 billion dollars and an SSTO can be built. 8 years and 8 billion dollars and a SSTP can be built. Why is NASA taking 12 years to send an old fashioned rocket with an ancient capsule on it to the Moon? Good grief and holy Christ on a stick "tomcat", hopefully you'll soon realize as to "why I am upset" with the sorts of snookered damn fools like yourself, as individuals being so easily dumbfounded that they think for a minute we actually had such viable fly-by-rocket landers and having those EVA/moonsuit butts that actually walked upon a nearly dust-free moon that upon average offered a clumping albedo of extremely thin soil of 0.55 or brighter. Please impress me by way of showing us village idiots exactly where the hell there's any zone average of 0.55+ albedo upon the moon. Obviously our perpetrated cold-war NASA rusemasters have to first R&D from scratch an actual fly-by-rocket lander that'll likely have to end up at roughly 30 tonnes worth, if not a whole lot more. Adding payloads of technology, crew and lots of spare fuel that'll safely de-orbit and down-range with energy to spare is going to take a little time, spendy R&D prototypes plus lots of real world pilotted flying with appropriately scaled units as flown right here in River City. Of course, getting the likes of a 30+ tonne craft and of it's 20+ tonne CM/return craft on their way to/from merely orbiting the moon will be rather a nifty accomplishment that should only pollute mother Earth with yet another 50,000 tonnes worth of nasty pollution that no one seems to want to talk about that issue or of the 500+ billions it's take without any respect for the global environment of Earth. Would you like to help build a spread-sheet as to the true cost and pollution tally? Meanwhile, at perhaps 0.1% the cost and not 10% the timeline, all sorts of robotics could have been accomplishing and thus extracting absolutely terrific sorts of hard-science about our moon and of Earth-science related factors, thus not hardly contributing even 1% as to pollution to boot. So, what part of this is still over your easily snookered and even easier dumbfounded head? Manned space flights anywhere external to the Van Allen expanse are not only going to remain as horrifically spendy but also somewhat DNA and quite possibly even CNT testy. BTW wizard "tomcat"; how the heck is your CNT spaceplane going to manage to detect the sorts of cm3 or smaller sorts of incoming or passing through debris, some of which will be having a greater than closing velocity of 100 km/s? If such small items were somehow detected at a reasonably good radar range of 1e6 km, and if you're making that 44.7 km/s or better velocity, thus easily having to deal with a closing velocity of 100 km/s = 10 seconds before impact (- whatever radar signal delay time), how is it even remotely possible to safely avoid coming in contact with such lethal debris? Even at a 1 degree off dead-center encounter, as a glancing blow, what's the KE worth of even a 4 g/cm3 items going to represent to the structural integrity of your spendy CNT spacecraft? Are we talking about a shield depth penetration of a crater or gouge being 0.1 m or perhaps even worth a full meter? I believe some of space debris is rather metallic, and thereby worth 8+g/cm3, and not always of less than a cm3 in size. And, what's to say from which direction is most important? Don't you ever think for a moment that since viable detections of such debris is going to remain somewhat unlikely, and that having sufficient warnings of any sort are not going to give your passengers and crew any real-world options, other than to sit tight, whereas such it might become a damn good idea if your CNT spaceplane had perhaps a 10+meter depth of a basalt composite surround as your physical and radiation shield? ~ Life upon Venus, a township w/Bridge & ET/UFO Park-n-Ride Tarmac: http://guthvenus.tripod.com/gv-town.htm The Russian/China LSE-CM/ISS (Lunar Space Elevator) http://guthvenus.tripod.com/lunar-space-elevator.htm Venus ETs, plus the updated sub-topics; Brad Guth / GASA-IEIS http://guthvenus.tripod.com/gv-topics.htm Kurt Vonnegut would have to agree; War is war, thus "in war there are no rules" - In fact, war has been the very reason of having to deal with the likes of others that haven't been playing by whatever rules, such as GW Bush. |
#712
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"Len" wrote:
The initial launches might be for experimental quantities to address questions such as what type of payload is most appropriate: water for electrolysis, LOX/LH2, LOX/kerosene? That question cannot be answered by the launching company, nor by users today. It's best to stick to what we know, today, to be useful forever - water and LOX. Orbital angle and altitude should be selected on the same basis - not what's most reachable, but what's most likely to be desireable in the future. The goal here is to provide supplies, at a reasonable cost, for the future. Any other effect is secondary of necessity. Otherwise, we might as well hold a lottery. D. -- Touch-twice life. Eat. Drink. Laugh. -Resolved: To be more temperate in my postings. Oct 5th, 2004 JDL |
#713
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OK, I admit I'm rather late to this topic, but as an admitted "NASA
fanboy," - and who, having personally witnessed the launches of both Apollo 16 and 17 couldn't help but be one? - here's my take: This plan and NASA, given it's manned spaceflight track record over the past two decades, deserve all the scrutiny and skepticism they are getting. That said, it seems to me to be a reasonable, and reasonably cost effective, architecture to use in returning to the moon and as a basis for missions to Mars. Mr. Simberg, I've read many, many of your articles, dating back to your New Republic (?) pieces circa 1980 questioning the safety of the Shuttle. I can see why you might be skeptical of both the NASA and its plans. But here's my question: What am I missing? Why is *this* plan so misguided? I don't get it. Further, if you were in charge, what sort of arhcitechture *would* you endorse for missions like these? Or if it's the mission themselves that are the trouble, and you were in control of - let's say - policy, funding, and technology, what would you have NASA do? I'm a free market guy, so if we are to relegate NASA to more fundamental science and unmanned research, leaving the rest to the market, how and when *do* we get back to the Moon and on to Mars? Only when entrepreneurs get the capital together? I'm not saying that's wrong, I'm just curious. You seem so down on the program, that in all seriousness, I'm interested in hearing what you think *would* be the correct way to go? Thanks in advance for taking time to answer. frank |
#714
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tomcat,
This CNT report actually isn't half bad, only 500~1000 fold under the mark of what the Liftport/ESE tether might eventually require. Meanwhile, plain old basalt fibers of 4.84 GPa have been right off the lunar shelf, of continuous fibers none the less, plus only of somewhat better GPa if having been produced upon the moon, though considerably more massive/cm3 than CNT, thus offering your spaceplane a way better external anti-meteor density shield as sort of a moon-dirt cheap alternative to the nearly aerogel worth of all that extremely spendy CNT. http://nanotechweb.org/articles/news/4/8/13/1#Zhang1 The nanotube sheet produced was an electronically conducting, anisotropic aerogel with a density of 0.0015 g/cm3. "A densified stack of 18 nanotube sheets that were orthogonally oriented to their neighbours had a strength of 175 MPa/(g/cm3). This compares well to the Mylar and Kapton films used for ultralight air vehicles, which have a strength of about 160 MPa/(g/cm3), and ultra-high-strength steel at about 125 MPa/(g/cm3)." Impressive, but far from the required target of 100+GPa as suggested for terrestrial space elevator tethers, though certainly terrific as is for your spaceplane. - BTW; instead of a nearly 100% CNT do-everything and all-in-one spaceplane that take a licking and keep on ticking, I'm thinking these considerably massive basalt composite items as your external shield would most certainly be left in orbit, thus your multi-hundred billion dollar CNT spaceplane could come and go from a given atmospheric supported planet or moon without involving all the added mass. Once having returned back into orbit and before entirely leaving town for any other planet or moon, these basalt composite items that were specifically made to form-fit entirely about your spaceplane would simply be reutilized for whatever interplanetary trek. ~ Life upon Venus, a township w/Bridge & ET/UFO Park-n-Ride Tarmac: http://guthvenus.tripod.com/gv-town.htm The Russian/China LSE-CM/ISS (Lunar Space Elevator) http://guthvenus.tripod.com/lunar-space-elevator.htm Venus ETs, plus the updated sub-topics; Brad Guth / GASA-IEIS http://guthvenus.tripod.com/gv-topics.htm Kurt Vonnegut would have to agree; War is war, thus "in war there are no rules" - In fact, war has been the very reason of having to deal with the likes of others that haven't been playing by whatever rules, such as GW Bush. |
#715
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Derek Lyons wrote:
"Len" wrote: The initial launches might be for experimental quantities to address questions such as what type of payload is most appropriate: water for electrolysis, LOX/LH2, LOX/kerosene? That question cannot be answered by the launching company, nor by users today. It's best to stick to what we know, today, to be useful forever - water and LOX. Orbital angle and altitude should be selected on the same basis - not what's most reachable, but what's most likely to be desireable in the future. The goal here is to provide supplies, at a reasonable cost, for the future. Any other effect is secondary of necessity. Otherwise, we might as well hold a lottery. D. Yes, agreed, the eventual goal is to do something useful for a reasonable cost. We apparently agree on the eventual goal, but disagree on how to get there. Unfortunately, other factors complicate things. You obviously think central planning works well--even for U.S. space program, which, IMO, has been served very poorly by central planning. We chose the unproven, poorly designed, conceptual SSME over the at-least partially tested XLR-129 for purely political reasons. One also has to wonder whether or not Fletcher's being from Utah had anything to do with insisting upon SRMs for the basic Shuttle concept. If the central planning is bad enough, it may be better to leave things to chance. IMO, it is always better to leave things to real competition. Under these circumstances, I have come up with a specific, if somewhat arbitrary, orbit to improve chances that the water/propellants in orbit will actually be useful. Forced to make an immediate choice, I would choose a 40-degree, 450-km orbit so that water/propellant could be transported to a single, potentially useful spot-- without the decision spins that might be inflicted by a bureaucracy and various political and self-serving motives. This particular orbital choice is, IMO, a combination of what is both useful and practical (reachable). I also think that it would provide enough launch flexibility so as not to prejudice specific companies and specific launch sites to any unreasonable degree. With respect to what should be transported, I tend to agree with you that water and LOX are practical and known --and, as you say--useful forever. However, NASA's love affair with liquid hydrogen may have considerable merit. Moreover, it seems like a good idea to accommodate NASA's basic plan as much as possible, while promoting a basically independent market gaurantee program. Accordingly, some experimentation with handling liquid hydrogen on orbit might be justified. And, of course, water seems to imply being able to conduct practical electrolysis operations on orbit--as well as handling, storing, transferring, liquifying (?) etc. the resulting hydrogen and oxygen. This type of experimentation might be done in various orbits without seriously detracting from the eventual goal of a "reservoir" in a specific, usable orbit. Note also, that the main purpose of the experiments would be to provide information for the basis for decision-making. Deciding what should be the basis of an experiment would not be precedent-setting decision. Best regards, Len (Cormier) PanAero, Inc. (change x to len) http://www.tour2space.com |
#716
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Len wrote:
Derek Lyons wrote: My apologies for consistently misspelling "guarantees." Perhaps there should be a prize for spelling guarantees correctly. Best regards, Len (Cormier) PanAero, Inc. (change x to len) http://www.tour2space.com |
#717
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Previous problem with LH2 was density: It was too voluminous.
Then try thinking even inside the box: H2O2 (frozen solid if need be). H2O2 is an all around do-everything product. Add a little C12H26 and you get serious bang for your buck. ~ Life upon Venus, a township w/Bridge & ET/UFO Park-n-Ride Tarmac: http://guthvenus.tripod.com/gv-town.htm The Russian/China LSE-CM/ISS (Lunar Space Elevator) http://guthvenus.tripod.com/lunar-space-elevator.htm Venus ETs, plus the updated sub-topics; Brad Guth / GASA-IEIS http://guthvenus.tripod.com/gv-topics.htm Kurt Vonnegut would have to agree; War is war, thus "in war there are no rules" - In fact, war has been the very reason of having to deal with the likes of others that haven't been playing by whatever rules, such as GW Bush. |
#718
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Here is a URL on 'Atomic Hydrogen'. This is a definitive PDF complete
with pictures of 'atomic hydrogen' immersed in liquid helium. It is very interesting reading. http://gltrs.grc.nasa.gov/reports/20...002-211915.pdf tomcat |
#719
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tomcat,
OK, alright already; http://gltrs.grc.nasa.gov/reports/20...002-211915.pdf 27 pages worth of interesting old stuff that we should have accomplished as of decades ago. I agree that something nuclear/atomic is going to make a given rocket-ship or whatever spaceplane go like a bat out of hell. I've already offered my Radium(RA226) to Radon(Rn222) ion thrusting solution that's good for a half life of 1600 years, that's relatively safe and worth nearly 150,000 km/s. However, as I've said before about going fast in space, eventually out of nowhere that's detectable it's going to bite real fast and extremely hard. The good news is, it'll happen so quickly and with such extensive vaporising of your physically unshielded spaceplane, that no person onboard should have any forewarning nor feel a damn thing. Sorry that you can't grasp the need for extended space-travel requiring a craft of not only being CNT tough but otherwise affording a sufficiently dense shield and thus having a relatively thick outer shell. It takes mass in order to appreciably attenuate the primary TBI influx and still avoid most of the secondary/recoil worth of hard-X-ray generated radiation and, it takes even more structured mass in order to physically save your sorry butt from fast encounters of the lethal kind that are simply too freaking small as to being detected until it's too late. That plus the matter of having to slow down once you've arrived at wherever without your having to drag enormous anchors across the surface terrain of whatever planet or moon, either that or you're going to need an H-bomb or two as your plan-B for your retrothrust emergency break. Thanks anyway for the interesting information. However, just for the sport of it all, why not focus upon what's actually extremely nearby and doable within our generation if not at least within a couple of generations, and of what will not further pollute mother Earth to a fairlywell nor bankrupt whatever's left of our piggy-bank that's already somewhat LLPOF warlord depleted, having managed to get more than half the world really ****ed off at us at the same time. ~ Life upon Venus, a township w/Bridge & ET/UFO Park-n-Ride Tarmac: http://guthvenus.tripod.com/gv-town.htm The Russian/China LSE-CM/ISS (Lunar Space Elevator) http://guthvenus.tripod.com/lunar-space-elevator.htm Venus ETs, plus the updated sub-topics; Brad Guth / GASA-IEIS http://guthvenus.tripod.com/gv-topics.htm Kurt Vonnegut would have to agree; War is war, thus "in war there are no rules" - In fact, war has been the very reason of having to deal with the likes of others that haven't been playing by whatever rules, such as GW Bush. |
#720
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tomcat,
CNT or not, at any decent velocity is where debris avoidance seems essential, thus radar tracking of the 0.1 m3 and larger items needs to be good for at least 1e7 km, whereas items of less than 0.1 m3 may have to be armor deflected or perhaps laser cannon vaporised before impacting your spaceplane. Having a GJ class of 0.05 milliradian laser beam at your disposal should come in real handy, thus an onboard 300 MJ worth of a continuous energy resource for charging up and at least providing a 10% duty cycle as based upon a 33% efficiency factor seems perfectly rational. I mean to say, what decent spaceplane is going anywhere without a spare 300 MJ reactor onboard? For the ultimate in personal spaceplane protection, think of it as a massive composite condom for your CNT spaceplane, meters thick sections of interlocking armor as made of mostly basalt and perhaps silica composite fibers plus a serious bunch of JB-WELD epoxy or whatever ceramic binders. Therefore... instead of a nearly naked though otherwise 100% CNT do-everything and all-in-one spaceplane that'll somehow have to take a licking and keep on ticking, I'm still thinking about utilizing these considerably massive basalt composite items of external armor as having been fabricated on behalf of their form-fitting as your external shield, as armor that would have been easily created from the lunar basalt and thus effectively provided by way of the massive LSE-CM/ISS facility and near zero gravity depot that roughly 64,000 km off the lunar deck, as once having created these items would subsequently remain in orbit, thereby your multi-hundred billion dollar CNT spaceplane that hardly weighs anything could come and go from being in orbit about a given atmospheric supported planet or moon without ever involving all of the extra mass getting to/from the surface. Once having returned back into orbit and before leaving town for any other planet or moon, these basalt composite items that were specifically made to form-fit entirely about your spaceplane would simply be reutilized for whatever interplanetary trek that going to take weeks if not months as best. Even when Venus is within merely 100 fold the distance of our moon, that's still going to represent more than 50e6 km worth of spaceplane frequent flyer miles each way as based upon a 18 month stay-over. If the average in going velocity of this spaceplane were to be 50 km/s = 1e6 seconds or 278 hours = 11.6 days worth of being wide open to what ever's coming along or gets run into. However, instead of the round trip taking 23.2 days it's more than likely going to take 58 days due to the fact of leaving Venus for the trek back to Earth isn't going to have any nifty moon available as a terrific velocity booster, nor is the gravity pull of the sun going to take any days off while the same spaceplane thrust energy that made the average incoming velocity into 50 km/s is going to be somewhat butt dragging along at perhaps averaging all of 12.5 km/s getting away from Venus. ~ Life upon Venus, a township w/Bridge & ET/UFO Park-n-Ride Tarmac: http://guthvenus.tripod.com/gv-town.htm The Russian/China LSE-CM/ISS (Lunar Space Elevator) http://guthvenus.tripod.com/lunar-space-elevator.htm Venus ETs, plus the updated sub-topics; Brad Guth / GASA-IEIS http://guthvenus.tripod.com/gv-topics.htm Kurt Vonnegut would have to agree; War is war, thus "in war there are no rules" - In fact, war has been the very reason of having to deal with the likes of others that haven't been playing by whatever rules, such as GW Bush. |
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