Project Bifrost: (Fission) Rockets of the Future? 148
astroengine writes "Researchers from Icarus Interstellar Inc. and General Propulsion Science have announced their intention to pursue the development of Nuclear Thermal Rockets and other fission-based space technologies. The aim? To revolutionize space travel, ultimately paving the way to the goal of sending a probe to another star."
Good luck (Score:5, Insightful)
Anytime anyone even thinks about mixing "nuclear" and outer-space (even radioisotope generators as used on many space probes) all the anti-nuclear groups kick up a huge fuss.
Unless this mob has something different they can use to convince the anti-nuclear mob that its safe, they will have a hard time actually launching anything without massive protest.
Re:Good luck (Score:4, Insightful)
My opinion is if this thing blows up, it will kill the crew and pollute an area of space millions of kilometres from anything I personally give a shit about. This is pretty much the same end result as if a chemical rocket blows up. Sounds like a fantastic application for nuclear, makes good use of what nuclear is good at (fuel energy density) while minimising what it is bad at.
I figure, presumably after the engine actually works and has been tested etc. we put this thing in orbit without any fuel, make sure it's an orbit that will stay stable for at least 20 years if something screws up. We then send up the fuel in small amounts, so if anything goes wrong, the amount of poisonous uranium or plutonium or whatever released is not going to kill whatever forest or reef or city etc it lands on.
Then if something goes like really bad, we fire up the partially fueled engine and fly it into the sun. If not, we complete the mission.
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Flying something into the sun is rediculously difficult (compared to Earth's orbit, the sun is pretty small). Much easier to just send the thing on its way and forget about it. If it's got enough delta-V to get it out of the solar system, we need not worry about it ever again.
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From Wikipedia:
Earth orbital speed: 29.78 km/s
Sun's escape velocity at Earth (42.1 km/s)
Thus, the delta V to completely de-orbit from Earth's orbit is far lower than to escape the solar system. After de-orbiting, hitting the sun is quite easy, it just will tend to fall in.
Re:Good luck (Score:4, Interesting)
Yes, the escape velocity is 42.1km/s. But anything in Earth's orbit already has a velocity of 29.78km/s (+/- a bit if in orbit around the Earth). This means that the delta-V required to escape the solar system from Earth's orbit is 12.32km/s. Less than half that required to de-orbit and fall into the sun.
This is actually a mistake that I make quite often (forgetting to factor in the current orbital velocity).
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I don't think you understand how "falling" works.
Earth is moving at about 30 km/s relative to the Sun. That happens to be just the right velocity to keep it in an orbit at a distance of about 150 M km.
Apply thrust along that same vector, and you go into a higher orbit. Apply thrust against that same vector, and you go into a lower orbit. Apply enough thrust against your vector long enough -- long enough to change your velocity by about 30 km/s, which is a heck of a lot -- and you eventually intersect the Su
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You don't have to apply the entire 29.78km/s, just enough that the thing passes through the corona at some point in it's orbit.
Re:Good luck (Score:4, Informative)
From Wikipedia:
Earth orbital speed: 29.78 km/s
Sun's escape velocity at Earth (42.1 km/s)
Thus, the delta V to completely de-orbit from Earth's orbit is far lower than to escape the solar system. After de-orbiting, hitting the sun is quite easy, it just will tend to fall in.
Hogwash. You do not know your stuff. Think before quoting Wikipedia.
As you have Earth's velocity of 29+ km/s already for free when departing from Earth in its orbit around the Sun, you are virtually "halfway to anywhere" (Robert A. Heinlein) when making it into Low Earth Orbit (LEO). Thus, the delta v needed for going from Earth surface to escape velocity out of the solar system is *much less* (~12.9 km/s) than for going to the Sun. In order to do the latter, you first need to get into LEO and then you need to decelerate from Earth's orbital velocity of 29.8 km/s to 0. So, your total delta v is around 40 km/s (!!!). More than three times than for going to infinity (and beyond ...). Good luck.
Hitting the Sun is anything but being "quite easy" (your words). That is the reason why it has never been done before.
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You are right. It's very hard to hit the sun. You could do it with less energy than the 40km/s delta implies by doing multiple slingshots, starting with the moon.
Re:Good luck (Score:4, Funny)
I like your style.
I'd be like the half-qualified director of NASA and would make this rousing as hell speech "do you want to be remembered as just some ordinary guy, or as the hero who flew a nuclear powered spaceship into the sun" and all of these cynical know it all guys would be like "you dumbass, you forgot to subtract Earth's orbital velocity from the Sun's escape velocity". And you'd be the promising young mathematician would would run to the front of mission control with a stack of paper and diagrams and be like "no, we need to launch this deadly broken nuclear spaceship at the moon first", then I'd smile and puff my cigar, knowing that everything would be awesome in the end.
I'd pay my $8 to see that movie, I really would.
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Re:Good luck (Score:4, Informative)
Dropping something into the corona of the sun from LEO....
Okay, assume that that requires us to get down to ~3,000,000 km (about four times the radius of the sun).
orbital speed up at this end of the hohmann ellipse is ~5900 m/s.
If we assume our orbital speed in LEO is about 7100 m/s (corresponding to an escape speed of about 10 km/s), then a single burn of about 18800 m/s is required to reach the corona of the sun.
Note, for reference, that from the same LEO, solar escape speed requires ab out 8800 m/s deltaV.
No matter how you slice it, it's easier to just toss something out of the solar system than it is to toss it into the sun...
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I won't answer it again (siblings posts have done a far better job of it than I could), but to sum up- no. That isn't how space works.
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Really we just steer it into a comet, and let her take it into the sun for us
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"My opinion is if this thing blows up, it will kill the crew and pollute an area of space millions of kilometres from anything I personally give a shit about. This is pretty much the same end result as if a chemical rocket blows up. "
You mean like the Challenger and Columbia? Except with nuclear fallout. I know the reactors in spaceships are usually much smaller than a nuclear plant, but this is definitely bigger risk than a chemical rocket.
Re:Good luck (Score:5, Interesting)
You mean like the Challenger and Columbia? Except with nuclear fallout.
What, are you a Flash Gordon fan!?
Nobody designs even a chemical-powered interplanetary spaceship to land it's main mass (including it's main propulsion system) on a planet surface. That's what landers are for. Even Apollo used a Lunar Module to land on the moon and a small Command Module for Earth re-entry.
This thing would be assembled in orbit and would never land on a planet. For something like a nuclear-powered interstellar spaceship, I imagine most of the construction would be done in low Earth orbit and then moved to a parking orbit at a La Grange point for final departure preparations, including loading the nuclear fuel.
I think you understand this, but are allowing your nuclear fears to cause you to post ridiculous and unrealistic scenarios in an effort to fight the idea of nuclear-powered space propulsion systems.
Strat
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If not, why not use a nuclear engine to get off the surface?
Short answer: Shit happens.
Longer answer:
Why tempt Murphy's Law and/or an unlucky turn of the odds? Seems to me to just be smart risk management if you choose NOT to have critical fission piles screaming through the atmosphere of an inhabited planet at thousands of miles per hour if it's not necessary, even if the tech itself is very mature.
Besides, the mass of shielding and armoring/hardening for the reactor core necessary to make it reasonably safe and resilient in a crash on the Earth's surface or in the
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Usually because you won't get enough thrust out of the engine. At an unachievable optimum efficiency, you need a theoretical 48 watts of power per kilogram just for the thrust to counteract gravity at the surface of the earth. This is ignoring aerodynamic effects entirely, of course, but it's just illustrative. So, if you want to actually go up, you need more power than that. So, the absolute maximum that 1 MW could lift would be a bit more than 20 tons. With an imaginary efficiency of 25 % (still unrealist
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I'm talking about accidents, obviously. Space rockets are more fragile and less reliable than our usual nuclear power plants. That's what I'm talking about. Assembling the thing in the orbit doesn't really change the fact that space rockets are prone to fail.
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I'm talking about accidents, obviously. Space rockets are more fragile and less reliable than our usual nuclear power plants. That's what I'm talking about. Assembling the thing in the orbit doesn't really change the fact that space rockets are prone to fail.
What kind of "accidents" do you mean here? We're talking about an interstellar spaceship that stays in space and doesn't ever land. If you're worried about a meltdown or explosion in space, then I hate to break it to you, but there are a whole lot of extremely dangerous, deadly-radiation-emitting, and lethal things in space. One of the most dangerous is a titanic ongoing thermonuclear reaction millions of times the size of Earth only about 93 million miles away, which is practically in our laps.
Assuming the
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...closest Earth-Moon La Grange point (L2)...
Oops. Should read L1, not L2.
http://en.wikipedia.org/wiki/Lagrangian_point [wikipedia.org]
Strat
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Well, what about using Biofuels? And also, if the crew was vegan, it would save a lot of energy on food! Meat take a lot of energy to produce, each time you eat at KFC it's the same thing as drinking half a barrel of petrol!
GAIA!
Biofuels!?
But...but...
We'd have to wait until we find aliens to give carbon credits to!
I'm surprised at your irresponsible environmental attitude. It's reckless plans like yours that will result in an AUW catastrophe (Anthropomorphic Universe Warming) and completely destroy the natural course of entropy! [shudder]
You make baby stars cry.
Strat
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[sarc]
Well, obviously, the fuel will be sent up in one huge and extremely dangerous near-critical-mass lump to maximize the possible danger rather than some other boring way, like over time in small quantities on multiple.Earth-to-LEO launches.
[/sarc]
C'mon, dude! Seriously!?!?
I know this is rocket science and nuclear science, but this is Slashdot!
Please turn in your geek card at the door on your way out for not being able to figure out
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but this is definitely bigger risk than a chemical rocket.
You'd rather get showered in hydrazine than plutonium?
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pollute an area of space millions of kilometres from anything I personally give a shit about.
Though in space things don't stay where you put them - they have an annoying habit of forming closed orbits (unless they're going fast enough). So the area of space that you personally don't give a shit about could soon find itself on an intersecting path with a person, place or planet that you do have some small gravitational attachment to.
Added to which, if the engine does go <bang> then it's hard to say which pieces will go in which directions, and at what speed - so making any predictions about w
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To the uninitiated, I agree it sounds bad. "OMGWTFBBQ we're putting NUKES in SPACE!!1!"
But it's not actually that bad. The fact is, uranium is not that radioactive before it has been in a nuclear reactor. I have held kilogram-quantities of uranium in my hands -- and still have all 10 fingers to show for it. Plutonium is more radioactive -- half a kilogram is warm to the touch -- but it's not deadly as long as it stays external to your system.
The nastiness starts coming in after the re
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I have held kilogram-quantities of uranium in my hands -- and still have all 10 fingers to show for it. Plutonium is more radioactive -- half a kilogram is warm to the touch
Just out of curiosity, have you ever tried to figure out what went down in between all those times when you got angry and those times you woke up somewhere in torn pants?
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Re:Good luck (Score:5, Informative)
Anytime anyone even thinks about mixing "nuclear" and outer-space (even radioisotope generators as used on many space probes) all the anti-nuclear groups kick up a huge fuss.
Sucks to be them, then. Any time you push beyond the inner solar system, you need some sort of nuclear power to get electricity, as you can't burn things or use hydroelectric or wind-power. You can use solar panels in the inner solar system, but the further out you go the less practical that becomes. IIRC, solar is a no-go much beyond about the orbit of Mars, even for relatively low-power applications. High thrust engines are not low-power!
What's more, as long as you're outside the Earth's magnetosphere, any nuclear explosion is exceptionally unlikely to contaminate Earth (or the Moon) as the solar wind will push all of the small particles out to interstellar space. Yes, you could be hit by a large piece even so, but that would be amazing bad luck; space is damn big.
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Yes, look at the fuss kicked up over New Horizons and Curiosity... Oh, wait there wasn't any.
Seriously, this myth (about anti-nuclear activists) needs to die in a fire. Over time, the protests have gotten quieter and quieter and come from ever further out on the lunatic fringe - until, over the last few years, they've become es
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Probably because noone told them there were RTG's on those spacecraft. It's not like they glow from radiation, after all (and I suspect that many of the anti-nuke whackjobs really do believe that "nuclear" power plants/etc GLOW)....
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Sending up small amounts is now accepted. Sending up the amount needed for NERVA would drive the same group that objected to the IFR batty. ANd yes, they would protest.
But there is a simple solution. Send up a small processing/breeder unit to space, and then send up safe uranium. At that point, it gets bred to plutonium and allowed to be used.
I wonder if a NERVA can be used to land on the moon? If so, that would become a truck. I noticed that Japan found Uranium on the surface, though quantity
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I don't believe NERVA can be throttled that deeply... if that's true, it can't be used as a lander engine.
Re:Good luck (Score:5, Insightful)
Nearest Star = 4.2 light years. At the moderate speeds we would be able to generate to accelerate, but then an equal amount of fuel to decelerate to enter orbit around such a star in time measured in something larger than 10s of thousands of years at survivable speeds that don't erode the probe down from "plasma erosion" like you have with a plasma jet cutting machine.
Helium, Hydrogen and Protons and electrons hitting any metal or ceramic surface at huge speeds eventually cut through, even if only in thousands or tens of thousands of years.
A signal back from the probe would then take 4.2 light years to reach back to earth......if it didn't hit the smallest little rock or ice chunk along the way, which is a real undetectable possibility, and at the high speeds it takes, those would be fatal.
I understand the thrill of the thought process and the income if you are on the program and getting paid.
As a taxpayer, it leaves me as cold as intersteller space.
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As a taxpayer, it leaves me as cold as intersteller space.
It leaves me with a warmer feeling than most of the things we spend our money on. Er, excuse me, we spend our kid's and grand kid's money on.
Your cold hearted appraisal of the issues certainly has validity, but stuff like that hasn't stopped us in the past.
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Where are you getting your data from? The hydrogen in interstellar space is very sparse and what little there is might be scooped up and used for fuel with a magnetic scoop. A super-Orion sized craft could reach speeds of up to about 0.1c. At that speed Alpha Centauri is only 44 years away. The chances of hitting a macro sized object in interstellar space are low. The vast majority of matter in the galaxy has already clumped into solar systems.
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Citation needed, on the travel time aspect.
Project Orion (the 1970's attempt at a thermonuclear rocket) would have take 44 years to reach Alpha Centauri (assuming a fly-by with no deceleration time, and excluding 36 days worth of acceleration to it's top speed). A long time by human standards, but a very very long way short of "10s of thousands of years". If you launched one today, you could get your first pictures back in almost the same amount of time as between Apollo 11 and today. That's travelling abou
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Project Orion (the 1970's attempt at a thermonuclear rocket) would have take 44 years to reach Alpha Centauri (assuming a fly-by with no deceleration time, and excluding 36 days worth of acceleration to it's top speed).
That was Freeman Dyson's calculation of what sort of extreme the technology could be pushed to; it's by no means a sure thing. However, the Orion drive was vastly more complicated (and expensive) than the nuclear thermal rockets they're talking about in the article, which would never be able
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Yeah, they can build it, they just won't be able to fuel the reactor. Governments get nervous at the thought of plutonium in private hands that can leave an easily monitored site.
I'm thinking recalculate for http://www.thorium.tv/en/thorium_reactor/thorium_reactor_1.php [thorium.tv]thorium reactors. Thorium reactors don't go 'boom'.
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However, the Orion drive was vastly more complicated (and expensive) than the nuclear thermal rockets they're talking about in the article
Not really, no. Ol' put-put is a dirt simple device: a gun to fire bombs a short distance, and a big honking pusher-plate on heavy suspension. A NTR needs some pretty esoteric construction materials to maintain integrity at the very high operating temperatures used (and some rather creative layout of the fuel elements to allow good hypersonic flow), whereas the Orion drive just needs to be big and heavy. The bigger the better, in fact; it scales up better than it scales down.
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Nearest Star = 4.2 light years. At the moderate speeds we would be able to generate to accelerate, but then an equal amount of fuel to decelerate to enter orbit around such a star in time measured in something larger than 10s of thousands of years at survivable speeds that don't erode the probe down from "plasma erosion" like you have with a plasma jet cutting machine.
[...]
As a taxpayer, it leaves me as cold as intersteller space.
Well, it's a good thing then that you aren't paying for it. I imagine people who live much longer than we do, would have a different take on the value and cost of such things. But they'll get to use their own money for that. Nuclear-powered propulsion has more practical uses within the Solar System than without.
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What attempts were made exactly? Citation desperately needed. IIRC, Orion was canceled for political, not scientific, reasons. Nuclear propulsion is the only means we have of traveling interstellar distances in any kind of reasonable time frame. In what way are the concepts flawed?
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What attempts were made exactly? Citation desperately needed.
They did some testing with scale models and conventional explosives. I'm very sorry but I can't seem to find the Youtube link, but if you want a citation and you have a large library try this:
Freeman Dyson, Disturbing the Universe (New York: Harper and Row, 1979)
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You're talking about Orion, not NERVA.
Yes I was, as was the post I was replying to.
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And by "failing" or "not working" I presume you mean "running for nearly two hours straight, including nearly half an hour at full design power".
NERVA worked. It could've put humans on Mars in the time that it took us to send the Shuttle program limping into LEO. The main "flawed concept" was the notion that the US had the political will to see it through.
My college roomate's father worked on the NERVA project back in the 60's. I don't know how he ever got over its ignominious cancellation. I'm not sure I e
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it wasn't because we lost the will. it's because our leaders chose immediate gratification due to our biology and political structure rather then a long term plan that for them at the time, 52~ years ago, which may or may not of payed off at LEAST 20 or 30 years later and in a minimal fashion without a more of a pay-of until now or at most 2020.
they chose to scramble for the remaining earth bound resources and a nonsensical fight against a ideal(communism then, then replaced with terrorism now so the same p
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Car analogies (Score:2, Insightful)
Painted red and whote in hommage to Hergé ? (Score:2)
http://en.wikipedia.org/wiki/Destination_Moon_(Tintin)#Representation_of_space_travel [wikipedia.org]
Re:Painted red and whote in hommage to Hergé (Score:5, Funny)
I think your title was damaged by a radioactive particle.
legal? (Score:4, Interesting)
Re:legal? (Score:5, Informative)
Nothing at all like Orion. This is using hydrogen as the reaction mass, heating it with a fission reactor. Orion uses nuclear bombs set off repeatedly behind a fscking huge steel plate.
You're right about there being international nuclear regulation that may stop it, though - if I recall correctly, there are legal hurdles to even test-flying nuclear reactors up to orbit and all kinds of international agreements following near-misses with both soviet and american test reactors in the 60s.
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Re:legal? (Score:5, Informative)
Nuclear thermal rocket != nuclear pulse rocket. The latter is the classic "Project Orion" engine, utilizing super-critical explosions for propulsive force. The former is actually more akin to a traditional chemical rocket, in that it works by expelling reaction mass from thruster nozzles. However, the energy of the reaction mass is imparted by heat generated in critical or sub-critical (but not super-critical) nuclear reactions. You can use any number of materials for this reaction mass, though the popular ones are hydrogen and water. Neither is inherently harmful, nor is there any reason they would need to pick up radioactivity from the reactor (any more than the cooling water which cycles through the heat exchangers of nuclear electrical plants or naval vessels becomes radioactive).
The test ban treaty has nothing to do with this. Nuclear pulse rockets are certianly forbidden by the test ban treaty - after all, they are literally exploding nuclear bombs as part of the engine's normal operation - but there's no reason nuclear thermal rockets would be that I can see. The argument about a "dirty warhead" is potentially valid (in that some would claim it, not in that it would be a plausible danger when you consider we already have nuclear-tipped ICBMs). However, there's no law or treaty against launching radioactive material into space. In fact, quite a few of our space probes and planetary rovers use radioactive thermal generators.
Compared to chamical rockets, nuclear thermal rockets have a vastly higher specific impulse, which is to say that a given quantity of reaction mass (rocket fuel or hydrogen flowing past a reactor) can produce a greater thrust (simply put, higher efficiency). This is due to their (much) higher exhaust velocity. Remember, E (in Joules) = mass (in kg) * velocity (in meters/second) squared. If you divide both sides by kilos (fuel or reaction mass), your energy per unit of reaction mass becomes a function of v^2. In other words, doubling the speed of the reaction mass will get you four times as much energy for a given unit of reaction mass.
Since the amount of thrust you can get out of the quantity of reaction mass that can be placed on a spaceship is the current limit on spacecraft range, speed, and payload, increasing that efficiency has the potential to revolutionize space travel.
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The factor of 1/2 is irrelevant here - I'm not talking in absolute quantities (and arguably shouldn't have given actual units at all) but in ratios. E/m (energy per unit mass) is a function of v^2. Since energy is relatively cheap (especially with a fission reactor), but mass is hideously expensive, you want an engine with the highest possible exhaust velocity, as that will maximize the E/m ratio very quickly.
Impulse is another story entirely. Impulse mesures the strength of the engine, not its efficiency.
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NERVA basically pumps liquid hydrogen through a fission reactor core. The core heats up the hydrogen, it expands, escapes through the bottom of the reactor and the nozzle providing thrust. Think 'tea kettle'. It'll help you visualise it.
The best reaction mass for this concept is stabilized m
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Clearly you are either unfamiliar with Project Orion, or you didn't read the article.
Credibility (Score:4, Insightful)
It would be easier to believe in these guys if they provide more technical details in how they pretend to achieve fission propulsion. As it is mentioned in the article, this is not a new idea. Is there any new development that could cast new light on the problem of fission propulsion?
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Is there any new development that could cast new light on the problem of fission propulsion?
What problem? We've built and tested fission rockets; the only problem is getting them into space when politicos would prefer to listen to the anti-nuclear luddites.
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Nothing new (Score:4, Interesting)
There's nothing new here. It's another "study" rehashing technology that's been rehashed over and over for at least sixty years. And anyway nuclear thermal rockets don't address the biggest problem we have with space exploration, which is getting to orbit in the first place. Heinlein famously observed "Get to low-Earth orbit and you're halfway to anywhere in the solar system." But the converse is also true - no matter how good your deep space rocket is you're only half way to where you want to be.
Nuclear thermal rockets have a wonderful ISP, but they don't have as much thrust as chemical rockets, and they're heavy. Even assuming you wanted to use one for the first stage it probably wouldn't have enough thrust to do the job. And you wouldn't want to start one up on earth, either. They never did figure out how to keep bits of the radioactive core from breaking off and entering the exhaust stream,
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You could build the ship in orbit thus circumventing those problems.
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Well, yes, you could. But now you'll have to send up a bunch of extra kg into orbit, and the whole point of having an engine with high ISP is to get really good performance from your fuel because you didn't want to send a bunch of extra kg to orbit.
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No, that's not the whole point of a high ISP engine
Sure it is. A high ISP engine is simply more efficient per kg of fuel. If you supply enough fuel to a high mass ratio chemical rocket you can overcome that efficiency advantage. We don't do that today because it's a whole lot cheaper to send a little rocket on a high efficiency trajectory. But since we're talking about sending many extra tons into orbit, including whatever infrastructure needed for construction activities, what we have to compare the N
This is now antique technology (Score:2)
Imagine an ion drive with 8 or ten modules, all powered by a fission reactor, it would start slow, but by the time it got halfway through the solar system would be cooking along at good clip. How fast is the potential ? No one seems to know, but a constant acceleration sustained for years would get you to a nice portion of C.
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If we wanted to go to another star system far in the future would it be possible to build an electromagnetic ramscoop [wikipedia.org] ship or is that still in the realms of fantasy? Such a ship could get to the centre of the Milky Way galaxy in 25 years ship time, although 50,000 years would have passed by on Earth. The only question is what would the Earth look like politics wise in 100,000 years?
Would they have forgotten about you? What sort of technology do you really need to construct a ship to constantly accelerate at
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I have read rebuttals to the ramscoop concept. Not sure if they are valid or not. One thing however that seems right: the amount of radiation produced by such a system is thought to be deadly to life. So such ships would have to be unmanned.
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At the point where we can actually do it, perhaps we can create an inverse field to protect crew. But they're theoretically plenty useful for unmanned probes, anyway.
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Ramscoops, as described in the literature have basically two problems:
1. Getting protons (as opposed to deuterium or something heavier) to fuse at a decent rate requires conditions substantially hotter and denser than found in the cores of even quite large stars. Something more like the conditions met in shockwaves in exploding supernovae. Without this your ramscoop isn't much use.
2. The interstellar medium is very unevenly distributed. The sun is deep inside the bubble created by an ancient supernova, so t
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Ok, a VASIMR (a type of an ion engine) can drive an ion out at high speeds. HOWEVER, where does it get the energy to accelerate the ion from? Obviously from a generator or a solar collector. The problem with the solar collector is that not only does it add drag, it does not work as you get further and further from the sun. So, that leaves a nuke reactor. How much does it weigh? A lot. The real problem is one of efficiency and the fact that it will break down. To get electricity, you had to convert
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This type of problem is why fusion is also considered an ideal propulsion system - because the fusion reaction itself is an electrically responsive plasma, so you can go more or less directly from energy generation -> propulsion.
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Regarding the weight of nuclear reactors - I don't know exactly what 'a lot' means, in terms of weight, to WindBourne. I can mention that newer designs of nuclear (fission) power plants are smaller. The steam turbine will be replaced by a helium turbine. One of the advantages of space (when away from stars) is that heat loss due to radiation is high, so cooling is easier, so the difference in gas pressure between helium heated by a fission reaction and that at the other end of the turbine, cool be radiation
It all comes down to exhaust velocity + mass ratio (Score:2)
Basic physics tells you that total delta-V for any kind of rocket comes down to just two things: how much of the ship you can throw away to get thrust (mass ratio) and how fast you can throw it (exhaust velocity). For mass ratios of less than say 1000 (ie ship at launch no more than 99.9% reaction mass at launch), and non-relativistic exhaust velocities, total delta-V is no more than 8-10 times the exhaust velocity. Exhaust velocity of chemical rockets tops out at about 3-5 km/s, nuclear thermal rockets g
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It isn't what we need. (Score:2)
What we need is a reusable and reliable system to get objects out of earth's orbit. I would think the nuclear energy would be better utilized in a magnetic launch system. After that is established, then building an ORION/NERVA powered vehicle in space would be practicle. Using an ORION/NERVA powered launch rocket isn't my idea of a good start, so to speech.
Oh Please! (Score:2)
"Mass ejection" propulsion is so last century. Where are the darn warp drives? I say: "Go FTL or go home."
Warp drive off a planetary surface? (Score:2)
Oh, sure. "Nukes are too scary, so let's just goatse a big hole in space itself right next to an effectively unlimited reservoir of condensed matter."
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Goatse: now a verb!
Trivial to restart NERVA (Score:2)
Legal? (Score:2)
I thought this was banned by international treaty.
Atomic rockets (Score:3)
Reminds me of one of my favourite geek-out websites:
www.projectrho.com/rocket/
If only more writers of science fiction television trash would spend just one afternoon of their life skimming that website...
Queller Drive (Score:2)
Stories for grown-ups, please (Score:2)
Anyone who has any knowledge of space travel knows the issues raised in the referenced article. If you didn't care about space, you wouldn't read the article. Please, can we have reference to more scientific articles which advance the knowledge of geeks (that's what slashdot is for, remember)? I feel dumber just for having read that article.
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To the extent that something that's never been tested can be said to be 'effective' sure.
Seriously, Orion has gained a reputation all out of proportion to reality. Few people seem to realize that not one single significant component has ever been built, let alone tested at even the most modest scale. None. Zero. Zip.
Yes, I k
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