A diamond hull will not be enough!

nacnud · Sep 14, 2004

I don't think that interstellar travel is going to happen any time soon, probably not even within 100 years at the rate things are happening at the moment. I picked the Daedalus idea because I'm most familiar with that concept, if you don't like the Daedalus method then pick one of these other possibilities. The Daedalus can be reconfigured to stop if needed but it will increase the journey time somewhat. The ship is built in two stages the first stage accelerates to 0.07c and then separates. The second stage boosts the final speed to 0.12c the idea being to get to the nearest stars in a single human life time. You could use the second stage to slow down at the target system instead. Other methods of breaking include magnetic 'parachutes' and light sails. So double the journey time but you can stop at the other end and I’m sure you could scale up the system to get to the 0.1c I was talking about not that the extra journey time is all that important as I was suggesting sending machines not humans

yurkin · Sep 14, 2004

I think an interstellar probe launched within the next hundred years is reasonable. As far as manned interstellar travel I think within a thousand years is very optimistic.

mcbethcg · Sep 14, 2004

I think an Orion can reach .1C, or so I have read. It would have to be a big one, though.

Maddad · Sep 15, 2004

Oh, boy, but have we gone around in circles on this Orion idea. My biggest objection is that no material, including the pusher plate, can withstand the temperatures involved.

mcbethcg · Sep 15, 2004

With the Orion, experiments and computer studies indicated that less than 1 inch of pusher plate would ablate away. It has been thouroughly studied, Maddad- you ought to actually look at the research- you could not have worried about the plate getting too hot if you really knew about it. Orion is the only ride in town, and it has no drawbacks, other that psychological, if launched from deep space. It is possible with 1958 technology. Fusion and anti matter drives are fantasy. We can't do controlled fusion or anti matter and possibly never will. By psychological, I mean 1) that people have an aversion to nuclear bombs, and 2) it does not look like a star ship that any scifi fan could love. Pogo sticking through space.... Similar psychological problems led to the space shuttle. If it looks like an old fashioned space ship, a man flies it in a cockpit, and it is reusable, IT MUST BE A GOOD DESIGN! Who cares that it has doomed the American space effort. Every other interstellar design other than Orion has to be launched from deep space too, BTW.

paradoxical · Sep 15, 2004

I notice that most people are referring to the problem of 'propulsion', which I am assuming means expelling some form of propellant, matter, or energy. We should let go of this ancient concept of expelling energy in order to produce force. Rather, we need to consider such highly probable concepts as the 'diametric drive' or the 'pitch drive'. These concepts consider the possibility of distorting the ST Continuum (known as creating a disjoint field) in order to pull the ship along, as opposed to propelling it. If such drive systems were possible, I have no doubt that ships far into the future could exceed 30% C. I’m sure we are all aware that such concepts are being given consideration by NASA (http://www.grc.nasa.gov/WWW/bpp/) even if they’re not being all that serious about it. This leads back to the original problem. How the hell do we overcome hull deterioration? It doesn’t matter how we do it: regenerative shields, miles of ice, worm holes, ablative energy – either way, the ship’s hull will rapidly deteriorate at anything above 500,000 KMH. It is in the nature of the universe that all things are subject to arising and cessation. The race who overcomes this will become greater than God.

nacnud · Sep 15, 2004

The only solution to hull deterioration is to limit the speed of ships so the rate of deterioration is manageable. Even then it would probably be necessary to stop at every star system to replenish the shield, whatever it is made of. Another way to speed up interstellar travel would be to slow down our perception of reality. I don't mean slow down time or to use relativistic effects to distort time although these effects are useful in speeding up journey times, I mean reducing our 'sampling rate' of reality and living longer. For example we are aware of events roughly 1/4 of a second after they happen, it takes that long for the brain to process the information, although some clever tricks make this time seem instantaneous. If we slowed this time down we would still perceive things happening as rapidly as they do now even if they actually took longer. Possibly this would require creating a new species of humans with long life spans and slow metabolisms who would travel between the stars while us original humans lead our fast lives on worlds around stars and carried between them only as DNA or information in a database.

silylene old · Sep 15, 2004

The ice shield would be adequate for the task, especially if it was laminated with layers of other material to prevent fractures splitting the shield; I cannot understand what is your basis for this claim. Please prove it. Simple physics argues just the opposite, no shield will be adequate, see my prior posts. And what is your "other material"? Please define. <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center">- - - - - - - - - - - - - - - - - - - - - - </div><div class="Discussion_UserSignature" align="center">I really, really, really miss the "first unread post" function. </div> </div>

silylene old · Sep 15, 2004

Everything has to have at least a slight charge. A strong enough magnetic field would be able to repel any particle. Let's test this claim. Assume the cross-sectional radius of the lightcraft is 5m (the ship is 10m in diamter). If a particle is encountered, it would have to be moved a minimum of 5m sideways before the craft arrives at that point in space (which would produce a collision). Assume we have a magnetic field so strong it is capable of moving the particle sideways 5m with an accelration of 360,000 g's (3585643 m/sec^2). It would take 0.00167 s to move the particle 5 m even at this fantastic acceleration. In the course of 0.00167 s, our lightcraft moving at 0.5c will have moved 250500 m (250 km). This means the magnetic field must be enormously strong 250 km ahead of the lightcraft. Don't forget that magnetic field strength of static objects decreases with distance^2. However, the lightcraft generating the magentic field I believe can be represented a moving charge. So the Biot-Savart Law needs to be applied. In this case, the magnetic field strength decreases with r^3. So the magnetic field at the origin (the spacecraft) would need to be exceedingly strong, approximately as strong as the magnetic field extending from a large erupting sunspot to generate the required field strength 250 km away to accelerate a particle at 360,000 g's out of the path of the craft. Conclusion: the magnetic field generator is science fiction. p.s. What would be the biological effect of this magnetic field on the occupants of the spacecraft? (this field is "slightly" stronger than a cellphone!) <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center">- - - - - - - - - - - - - - - - - - - - - - </div><div class="Discussion_UserSignature" align="center">I really, really, really miss the "first unread post" function. </div> </div>

thechemist · Sep 15, 2004

Silylene : p.s. What would be the biological effect of this magnetic field on the occupants of the spacecraft? (this field is "slightly" stronger than a cellphone!) Stable static magnetic fields (by way of superconducting magnets) are at present around 21 Tesla. If you can make such kind of strong magnet, Bruker Spectrospin or Varian will make you rich ! Nothing can survive so close to such strong magnetic fields. <div class="Discussion_UserSignature"> I feel better than James Brown. </div>

mcbethcg · Sep 15, 2004

I think the way to go would be to use a paper-thin sheild a thousands of miles ahead. Any dust that hit it at those velocities would be pulverized to atoms. Put a charge on it, and those atoms would be charged particles. Replace frequently.

a_lost_packet_ · Sep 15, 2004

maddad - My biggest objection is that no material, including the pusher plate, can withstand the temperatures involved. Here is a referrence for experimental results on degradation and temperature concerns with an "Orion" like propulsion system. Project Orion: Life, Death and Possible Rebirth .."Extensive work was done on plate erosion using an explosive-driven helium plasma generator. The experimenters found that the plate would be exposed to extreme temperatures for only about one millisecond during each explosion, and that the ablation would occur only within a thin surface layer of the plate (21). The duration of high temperatures was so short that very little heat flowed into the plate; active cooling was apparently considered unnecessary. The experimenters concluded that either aluminum or steel would be durable enough to act as plate material..." Ref: 27) "27. T.W. Reynolds, "Effective Specific Impulse of External Nuclear Pulse Propulsion Systems", Journal of Spacecraft and Rockets 10 (Oct. 1973), pp. 629-630" <div class="Discussion_UserSignature"> I put on my robe and wizard hat... </div>

summoner · Sep 15, 2004

We all keep discussing shields, but why not a very large laser. It really only needs to be powerful enough to vaporize small particles(anything very large at all would destroy the ship regardless of shields). Assuming we are talking about a future that we can travel at some fraction of c, then we should be able to figure some power supply that would prove adequate. <div class="Discussion_UserSignature"> <table cellpadding="0" cellspacing="0" style="width:271px;background-color:#FFF;border:1pxsolid#999"><tr><td colspan="2"><div style="height:35px"><img src="http://banners.wunderground.com/weathersticker/htmlSticker1/language/www/US/MT/Three_Forks.gif" alt="" height="35" width="271" style="border:0px" /></div>

mcbethcg · Sep 15, 2004

Assuming you mean that it should be on contiuously for a hundred or more years, sweep a path as wide as the ship, with enough energy to vaporize anything, I think it might indeed be an insurmountable amount of energy.

silylene old · Sep 15, 2004

I believe we are talking about different velocities; at 10% light speed a 60m thick ice shield should take you about 10 light years, assuming the dust grains are no more than a milligram or two in size; Prove it. Unsubstantiated statements are just that: unsubstantiated. KE = 0.5 m v^2 120 mm SABOT round: mass of penetrator = 4200 g muzzle velocity = 1676 m/s on a M1A1 KE = 5.9 MJoules 1 mg dust particle at 0.1C mass = 1E-6 kg velocity = 3E7 m/s KE = 450 MJoules So a dust particle at 0.1C has 76x the kinetic energy of a 120 mm M1A1 SABOT round. I really doubt 60 cm of ice is going to offer much protection, since a M1A1 SABOT round (with just 1/76th the kinetic energy of a dust particle at 0.1C) can penetrate about 90 cm of hardened steel. I estimate that 60m of ice, if it were as strong as hardened steel, should survive about 20 dust particle impacts over an area of 1m^2, maximum. This is a very liberal estimate, since ice isn't as strong as tank armor. <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center">- - - - - - - - - - - - - - - - - - - - - - </div><div class="Discussion_UserSignature" align="center">I really, really, really miss the "first unread post" function. </div> </div>

Maddad · Sep 15, 2004

eburacum45 "Freeman Dyson's experiments with the Orion Drive 'put-put' pulse drive rockets showed that a pulse drive gives the pusher plate time to cool down between explosions There were no such experiments. There was speculation. Like I said, we've been over this road before. mcbethcg "Maddad- you ought to actually look at the research Speculation. Not research. No experiments.

nacnud · Sep 15, 2004

Not done the maths but wasn't that 60 meters of ice eburacum45 was referring to, also how hard is water ice at 3 Kelvin, I suspect that it could be extremely tough. Sorry just more questions, couldn't find any answers <img src="/images/icons/smile.gif" />

Saiph · Sep 16, 2004

Just to point out, while dust can get to 1 milligram mass, it's the extreme. It's not to common out there. It's usually 100 to 1000x less than that. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

a_lost_packet_ · Sep 16, 2004

I don't mean to start an argument concerning the validity or practicality of an Orion drive. However, while full scale experimental models were not built, experiments relevent to the ablation of the pusher-plate and possible damage from intense heat were performed. There were details in the link that I posted above. For instance: The durability of the plate was a major issue. The expanding plasma bubble of each explosion could have a temperature of several tens of thousands of Kelvins even when the explosion occurred hundreds of feet from the plate. Following the lead of the Eniwetok tests, a scheme was devised to spray grease (probably graphite-based) onto the plate between blasts (20). It is not known if this scheme was retained in later versions of the Orion design. Extensive work was done on plate erosion using an explosive-driven helium plasma generator. The experimenters found that the plate would be exposed to extreme temperatures for only about one millisecond during each explosion, and that the ablation would occur only within a thin surface layer of the plate (21). The duration of high temperatures was so short that very little heat flowed into the plate; active cooling was apparently considered unnecessary. The experimenters concluded that either aluminum or steel would be durable enough to act as plate material. (21. J.C. Nance, "Nuclear Pulse Propulsion", IEEE Transactions on Nuclear Science (Feb. 1965), p. 177.) There are other related tests performed including chemical powered demonstration models and results of experiments using graphite spheres being propelled by actual nuclear blasts with only minor ablative damage to the surface layers. I'm not a proponet of Orion propulsion. However, it is a propulsion technology that is "workable." In other words, it could be done and doesn't rely on any miracles of invention. There are serious issues with it though: 1) Any Orion system would have to <div class="Discussion_UserSignature"> I put on my robe and wizard hat... </div>

mcbethcg · Sep 16, 2004

Every single idea that could possibly deliver a mission of any form to another star in a reasonable time requires a ship or space-based infrastructure that is several blocks big, and would have to be built and launched from space. Orion is no different in this regard. For instance, all proposed solar sail designs require immense arrays of space-based lasers and generators that would mass millions of tons. Ion drive designs are immense. The unmanned Deadalus Ship design is immense, requiring 50,000 tons of Helium 3 for fuel, which has to brought out Jupiters atmosphere, requiring a zillion tons of other space based equipment. Immensity of payload is desirable, anyway, to carry the things required to stand a chance of survival. No interstellar mission can be built until we have at least a lunar base for the materials to build it in space. And Orion is the only drive that works with current technology. I dout there is much dust out there anyway. We can see a billion light years with telescopes- the space between the stars has to be incredibly empty. A 1 mg piece of dust would be fatal to any mission, but the possibility of a chance meeting is rare, I think.

shuttle_rtf · Sep 16, 2004

I think the key will be the Physics of altering or utilising Space/Time - such as transwarp wormholes etc. That key may only come in many many years time. But I know an Astro Physicist who swears that FTL is possible but not with spacecraft ala ST.........but promptly confused the hell out of me on how <img src="/images/icons/smile.gif" /> Facinating thread.

Saiph · Sep 16, 2004

actually, if you get up into space, it's relatively clean. Having atmosphere and dust to kick up and contaminate is what makes the bombs really nasty. If you do it at a good distance from earth, any radiation that does get here will be spread to an insignificant density. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

Maddad · Sep 17, 2004

packet "while full scale experimental models were not built, experiments relevent to the ablation of the pusher-plate . . . Dude! There never have been any relevant experiments! If I told you the the heat at the surface of the Sun could not melt steel, you would disbelieve me. I could tell you that I had experimental evidence because I had applied liquid helium, just a few degrees above absolute zero, to the steel, and it did not melt. You would object, saying that the liquid helium was a thousand times too cold to match the temperature of the surface of the Sun. Your objection would be valid. In the very same way the chemical explosive tests are about a thousand times colder than the nuclear bomb blasts that would drive Orion. Chemical explosives give you tens of thousands Kelvin; nuclear bomb blasts give you <big>tens of millions Kelvin</big>. You cannot experimentally test for the melting of steel on the Sun with liquid helium, and you cannot test for the ablating of the Orion pusher plate with chemical blasts. Additionally, you would need 10,000,000 nuclear bomb blasts to power Orion for four months to Mars. Ten million! Want to go on to the nearest star, Proxima Centauri, 750,000 times further? You would need more than a billion nuclear bomb blasts. I know you admit that we have no full scale Orion test to examine, but how about just a teensy weensy little scale test? Maybe only 30 nuclear bomb blasts spaced one second apart? What? You say that we have never subjected anything to multiple nuclear bomb blasts? Not even two? <big>Then what makes you think that there is a shred of experimental evidence?</big>

mcbethcg · Sep 17, 2004

Where in the world did you get the 10 million number? Obviously you have read nothing on the subject, and are talking out your a**. Most plans call for about 1000 blasts for a mars trip, with lengthy coasting. You are off by a factor of 10,000. Additionally, while the core of a nuclear explosion may reach the temperatures you describe, the average temperature of the entire device is lower by several magnatudes. You have 10 KG of plutonium in a bomb that might weigh 2000 KG. The average temperature of the mass would therefore be 1/200th the peak temperature that fleetingly exists in the core. Then that expanding cloud hits the pusher plate after dispersing. As you might be aware, if you knew a damn thing about gases and temperatures- well, if you knew a damn thing about physics, gases temperatures decline as presure decreases. That zillion degree 10 KG mass of plutonium at a zillion atmospheres cools by more magnatudes as the number of atmospheres decline... and youi have a pusher plate that survives with no problems whatsoever. No credible physisists has ever come to the conclusions you have come to- because your conclusions are half baked.

paradoxical · Sep 17, 2004

Saiph, very true…deep space is, well, very 'empty'. But space is not a vacuum. At low sub-space velocities, such as the Voyager 1 & II type probes, the time between encounters with dust particles would probably be decades. And even then, there would be minimal damage on our probe, whose current velocity is a flimsy 3.3 AU per year. However, what I am concerned by is what happens when our probe reaches 10%, 30%, 50% or even 90% C. The encounters between dust particles would turn into hours, maybe even minutes. Something as small as a stray molecule (say ammonia, for instance) would inflict terrible deterioration. A dust particle weighing 1 gram would probably destroy or badly damage a ship travelling at 30%C. We would certainly expect to see an observable astronomical event if the ship hit a sizeable dust particle at C!! Now let's send our ship on a 10 year journey at 30%C with a 1 meter diamond plated hull, in any direction from Earth. Do you think it will survive? According to my very bare understanding of what actually constitutes space, it won’t even make the half way mark! So I don’t believe that engineers of the future will have issues creating ever more powerful propulsion or drive systems. The fundamental problem will always be developing counter-measures for hull deterioration. The higher the velocity of our ship the greater the problem of hull deterioration (sequentially so) and the more impossible it all becomes.

A diamond hull will not be enough!

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