SteveZilla Posted October 18, 2012 Report Share Posted October 18, 2012 Re: More space news! Hey, after that much time, what's 8 years? Quote Link to comment Share on other sites More sharing options...
Cancer Posted October 18, 2012 Report Share Posted October 18, 2012 Re: More space news! Two more presidential election campaigns. Quote Link to comment Share on other sites More sharing options...
gojira Posted October 21, 2012 Report Share Posted October 21, 2012 Re: More space news! Just for fun, let's see if I did this right. Voyager deep space probes are just now (roughly) passing the orbit of Pluto and heading into actual deep space, leaving our solar system. In 35 years, they've gone 39.5 Astronomical Units = 0.000624607383 light years, according to Google. 39.5 AU is what I found for the orbit of Pluto, and Google says that's about six-ten-thousands of one light year. Yeowzer. No wonder interstellar travel is such a PITA. Quote Link to comment Share on other sites More sharing options...
SteveZilla Posted October 22, 2012 Report Share Posted October 22, 2012 Re: More space news! Space is freakin' huge and C is, in those terms, freakin' slow. Quote Link to comment Share on other sites More sharing options...
megaplayboy Posted October 22, 2012 Report Share Posted October 22, 2012 Re: More space news! Just for fun, let's see if I did this right. Voyager deep space probes are just now (roughly) passing the orbit of Pluto and heading into actual deep space, leaving our solar system. In 35 years, they've gone 39.5 Astronomical Units = 0.000624607383 light years, according to Google. 39.5 AU is what I found for the orbit of Pluto, and Google says that's about six-ten-thousands of one light year. Yeowzer. No wonder interstellar travel is such a PITA. That's really slow. Is there a known upper limit for proven(i.e., stuff that's actually been used before) propulsion tech, and then a probable upper limit for known tech(stuff we kinda sorta know how to build but maybe haven't fully fielded yet)? Do either of these come remotely close to even .001 c?(i.e., 1/1000 of light speed). Quote Link to comment Share on other sites More sharing options...
Christopher Posted October 22, 2012 Report Share Posted October 22, 2012 Re: More space news! Space is freakin' huge and C is' date=' in those terms, freakin' slow.[/quote'] After all it's called Light-Year because even the light takes must travel a Year for it. Quote Link to comment Share on other sites More sharing options...
Cancer Posted October 22, 2012 Report Share Posted October 22, 2012 Re: More space news! Do either of these come remotely close to even .001 c?(i.e.' date=' 1/1000 of light speed).[/quote'] Neither has a propulsion system to speak of; they are coasting on the gravitational slingshot boost they got from their last planetary encounters. Current velocities with respect to the Sun in km/s are 17.045 and 15.440 for Voyager 1 and 2 respectively. The latter is about 0.0000515 c. EDIT: BTW, the two now are 121.9 and 99.6 AU out: well past Pluto. Quote Link to comment Share on other sites More sharing options...
gojira Posted October 22, 2012 Report Share Posted October 22, 2012 Re: More space news! That's really slow. Is there a known upper limit for proven(i.e.' date=' stuff that's actually been used before) propulsion tech, and then a probable upper limit for known tech(stuff we kinda sorta know how to build but maybe haven't fully fielded yet)? Do either of these come remotely close to even .001 c?(i.e., 1/1000 of light speed).[/quote'] So far, the only actual "known tech" we have are rockets. Throw mass out the back to make it go forward, that's it. Everything thing else has only been demonstrated on a small scale (solar sails) or is completely hypothetical. Nothing we have actually gets anywhere near even a small fraction of light speed. Quote Link to comment Share on other sites More sharing options...
Christopher Posted October 22, 2012 Report Share Posted October 22, 2012 Re: More space news! So far' date=' the only actual "known tech" we have are rockets. Throw mass out the back to make it go forward, that's it. Everything thing else has only been demonstrated on a small scale (solar sails) or is completely hypothetical. Nothing we have actually gets anywhere near even a small fraction of light speed.[/quote'] Well actually we do have an Ion-Drive: http://en.wikipedia.org/wiki/Ion_Drive It has a phenomenal weight/thrust ratio (or specific Impulse). All you need is energy (wich can reliably be collected by solar panels). It is well tested on dozens of sattelites. The only caveeat is, the the acceleration is also incredibly slow. Often less than 1/1000 of G (with the weight of the powersoruce figured in). So it is only suiteable for unmanned probes. Maybe for a sleeper ship. There is also the Orion Drive (Nulcear Pulse Propulsion), but how viable that is is something many doubt. Quote Link to comment Share on other sites More sharing options...
L. Marcus Posted October 22, 2012 Report Share Posted October 22, 2012 Re: More space news! Nitpick: An ion drive is still a rocket. Quote Link to comment Share on other sites More sharing options...
Old Man Posted October 23, 2012 Report Share Posted October 23, 2012 Re: More space news! There is also the Orion Drive (Nulcear Pulse Propulsion), but how viable that is is something many doubt. Technologically, or politically? Quote Link to comment Share on other sites More sharing options...
SteveZilla Posted October 23, 2012 Report Share Posted October 23, 2012 Re: More space news! The Spitzer Space Telescope data brings down the uncertainty of the expansion rate to just 3 percent. Quote Link to comment Share on other sites More sharing options...
Christopher Posted October 23, 2012 Report Share Posted October 23, 2012 Re: More space news! Nitpick: An ion drive is still a rocket. Both attain Thrust by accelerating matter. However the way the matter is accelerated is fundamentally different. Technologically' date=' or politically?[/quote'] Technologically it seems rather sound. They still have to do engineerign work, but it seamed feasible at the time of the race to the moon. Politic could be the real hassle. And getting this thing into space without too much fallout. Quote Link to comment Share on other sites More sharing options...
tkdguy Posted October 23, 2012 Author Report Share Posted October 23, 2012 Re: More space news! The thing with ion drives is that they work well in space, but they still need traditional rockets to get them there. Quote Link to comment Share on other sites More sharing options...
AmadanNaBriona Posted October 24, 2012 Report Share Posted October 24, 2012 Re: More space news! Technologically' date=' or politically?[/quote'] Orion drives are all politics and Environmental Impact Reports. The physics are comparatively simple (after all, it's the space program equivalent of putting a firecracker under a can), it's all those pesky atmospheric nuclear detonations that have folk worried about Orion Quote Link to comment Share on other sites More sharing options...
Old Man Posted October 24, 2012 Report Share Posted October 24, 2012 Re: More space news! I don't even think it's atmospheric detonations. Even putting some plutonium in a thermal reactor for a probe generates some vocal protest. You could use chemical rockets to put your Orion in orbit but you'd have the same hippie issue plus I imagine it would violate some treaties about putting nuclear weapons in orbit. Quote Link to comment Share on other sites More sharing options...
Cancer Posted October 24, 2012 Report Share Posted October 24, 2012 Re: More space news! There's the issue, too, that it's a rather large and massive thing. You need a massive pusher plate to stand between the nuclear blast and the spacecraft. We can't get that much mass into orbit now. It'd be like trying to break the Great Wall of China into one-foot cubes, hand-carry each cube to another location (say, the Tibetan border) and reassemble it there. In principle that could be done, but in fact that specific task will never get done. Quote Link to comment Share on other sites More sharing options...
Christopher Posted October 25, 2012 Report Share Posted October 25, 2012 Re: More space news! There's the issue' date=' too, that it's a rather large and massive thing. You need a massive pusher plate to stand between the nuclear blast and the spacecraft. We can't get that much mass into orbit now. It'd be like trying to break the Great Wall of China into one-foot cubes, hand-carry each cube to another location (say, the Tibetan border) and reassemble it there. [i']In principle[/i] that could be done, but in fact that specific task will never get done. The original design called to start the drive on the ground. It can be it's own Rocket for reaching space, without any trouble. If you want to bring it up there with rockets you have to built it rather small. And the smaler/lighter you built it, the less efficient it get's (it even has a minimum feasible size). Quote Link to comment Share on other sites More sharing options...
Old Man Posted October 25, 2012 Report Share Posted October 25, 2012 Re: More space news! There's the issue' date=' too, that it's a rather large and massive thing. You need a massive pusher plate to stand between the nuclear blast and the spacecraft. We can't get that much mass into orbit now. It'd be like trying to break the Great Wall of China into one-foot cubes, hand-carry each cube to another location (say, the Tibetan border) and reassemble it there. [i']In principle[/i] that could be done, but in fact that specific task will never get done. I wonder if it would be possible to cut the plate out of an iron asteroid. Quote Link to comment Share on other sites More sharing options...
Christopher Posted October 25, 2012 Report Share Posted October 25, 2012 Re: More space news! I wonder if it would be possible to cut the plate out of an iron asteroid. It must be a concave plate and there needs to be a mechanism to coat it with a special graphite-oil (that prevents ablation of the material). Quote Link to comment Share on other sites More sharing options...
Old Man Posted October 26, 2012 Report Share Posted October 26, 2012 Re: More space news! How does the graphite oil resist ablation that nickel-iron cannot? I am intrigued. Quote Link to comment Share on other sites More sharing options...
SteveZilla Posted October 26, 2012 Report Share Posted October 26, 2012 Re: More space news! Also, once outside of an atmosphere, how does a nuclear detonation result in any appreciable push without ablating some of the pusher plate? Unless the nukes are specially prepared with a large amount of "wrapping material" beforehand... Quote Link to comment Share on other sites More sharing options...
SteveZilla Posted October 26, 2012 Report Share Posted October 26, 2012 Re: More space news! NYU Scientists Are Seriously Working On A Tractor Beam Quote Link to comment Share on other sites More sharing options...
Tom Carman Posted October 26, 2012 Report Share Posted October 26, 2012 Re: More space news! Also' date=' once outside of an atmosphere, how does a nuclear detonation result in any appreciable push without ablating some of the pusher plate? Unless the nukes are specially prepared with a large amount of "wrapping material" beforehand...[/quote'] My vague recollection is that yes, they are wrapped in reaction mass. Also that they achieved a "shaped charge" effect to direct a higher portion of the mass at the pusher plate instead of wasting it equally in all directions. A somewhat more extreme version of this is referred to as a "Casaba Howitzer" (details of which are still classified): essentially a nuclear-powered plasma shotgun. Quote Link to comment Share on other sites More sharing options...
Christopher Posted October 26, 2012 Report Share Posted October 26, 2012 Re: More space news! How does the graphite oil resist ablation that nickel-iron cannot? I am intrigued. Also' date=' once outside of an atmosphere, how does a nuclear detonation result in any appreciable push without ablating some of the pusher plate? Unless the nukes are specially prepared with a large amount of "wrapping material" beforehand...[/quote'] Read yourself: http://en.wikipedia.org/wiki/Project_Orion_%28nuclear_propulsion%29 Quote Link to comment Share on other sites More sharing options...
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