dystopic dystopic

bussard ramjets, cryonic stasis, and exoplanetary colonization

bussard ramjets, cryonic stasis, and exoplanetary colonization

what will it take?

hello everyone,

i'm a bit of a writer, and i can't help but feel drawn to science fiction. that shouldn't be surprising.

lately i've been reading up a great deal on theoretical physics, exobiological speculation, and all that. i was dismayed at first to learn that the chances of faster-than-light travel being physically possible are slim. it was also pretty discouraging when i sat down and looked at the actual speeds that'd be required to traverse sizable parts of the galaxy in a single conscious lifetime. it was a kick when i was down to learn about how difficult terraforming probably would be. but the more i've been learning, the more i've been excited about telling a different kind of science fiction story.

to draw an analogue to our world, the thing that made both the european colonial age and the modern process of globalization have been technology. it's not that we couldn't go to various places around the world before, it just cost too damn much to make anything worth it. i got my BA in sociology, and these sorts of things interest me.

if FTL travel isn't possible, then more than likely it'll be too damn costly to ever colonize beyond our own solar system as the way it's been envisioned in most of the celebrated scifi universes. But there are examples such as Arthur C. Clarke's Songs of a Distant Earth or Sid Meier's Alpha Centauri where humans colonize to escape destruction on earth.

recently i had the chance to meet both Kim Stanley Robinson and Geoff Ryman. Robinson is a hard scifi writer after my own heart; the Mars Trilogy is a really interesting look at our first attempts to colonize within our own star system. Ryman was actually more interesting to talk to, though. maybe because few people have ever heard of him (i was only there because i work at UCSD where he was being hosted). but i actually got to talk to him. he said he thinks we probably won't ever leave our galactic neighborhood.

i'm interested in writing a hard scifi story (or series) myself. i'm interested from a sociological point of view: what would drive us to colonize space? from a writer's point of view, i want to keep the earth around, so i'm not interested in a flight from disaster. what would societies be like after colonies were established? trade would be difficult, but not impossible. same goes for war.

while i'm certainly interested in contributions along those lines, i'm also interested in learning more about the hard science and engineering behind interstellar travel. i've got a lot of questions i haven't been able to answer through wikipedia and google alone. but i'm not about to list them all here.

it seems like a discussion about real ("real") colonization and space travel could use a place on these boards.

i'll kick it off. i've been reading up on propultion especially, and bussard ramjets seem like the most economically feasible option since they gather their fuel as they go - perhaps especially if it could be hybridized with another form such as antimatter-catalyzed fusion. the wikipedia article on bussard ramjets describe that they'd probably need what is essentially a magnetic funnel or ramscoop to gather interstellar hydrogen as propellant.

The mass of the ion ram scoop must be minimized on an interstellar ramjet. The size of the scoop is large enough that the scoop cannot be solid. This is best accomplished by using an electromagnetic field, or alternatively using an electrostatic field to build the ion ram scoop. Such an ion scoop will use electromagnetic funnels, or electrostatic fields to collect ionized hydrogen gas from space for use as propellant by ramjet propulsion systems (since much of the hydrogen is not ionized, some versions of a scoop propose ionizing the hydrogen, perhaps with a laser, ahead of the ship.) An electric field can electrostatically attract the positive ions, and thus draw them inside a ramjet engine. The electromagnetic funnel would bend the ions into helical spirals around the magnetic field lines to scoop up the ions via the starship's motion through space. Ionized particles moving in spirals produce an energy loss, and hence drag; the scoop must be designed to both minimize the circular motion of the particles and simultaneously maximize the collection. Likewise, if the hydrogen is heated during collection, thermal radiation will represent an energy loss, and hence also drag; so an effective scoop must collect and compress the hydrogen without significant heating.


talk about kick-butt imagery! spirals of heated gas careening towards a ship only to be fused and expelled in a jet plume? sweet.

anyway, i've written enough, and i hope it hasn't put anyone off. some of the the community here has proven to be very well read with regard to these kinds of science, so i thought it'd make a great topic for discussion: all things related to space exploration and colonization with reasonable extrapolations of current technology.

my biggest point of curiostiy was with respect to ramjets, so i'll take the kickoff: could the spiral motion of the inbound gas somehow be harnessed to artficially generate gravity by rotating the ship, instead of producing drag?

any volunteers?

final words: i hope no one minds my double-motive. i won't try to steer any dicussion, though if things quiet down i might pose more general questions to keep it going; i encourage anyone interested to pose your own!
436,398 views 930 replies
Reply #376 Top
we already have this design. it is no faster than the chemical. it is stronger.


It is not a very good design then! The potential thrust from a nuclear reaction would be astronomically far greater than chemical for it's weight, provided you could build an engine strong enough to harness its power!
Reply #377 Top
It is not a very good design then!


don't know. it was designed in the 60's along side the saturn.
Reply #378 Top
the man told me that we had not had a heavy enough load to use it on. if it wasn't used in 40 years they had to redesign it. federal law.
Reply #379 Top
the man told me that we had not had a heavy enough load to use it on. if it wasn't used in 40 years they had to redesign it. federal law.


hmmm well i don't see them ever using nuclear propelled ships due to environmental effects, Unless there is some kind of emergency.
Reply #380 Top
i just found out that a snail is faster than the speed of light.


the speed of light at the heart of the sun is 1/3 an inch a year.

it can take 200,000 years to reach the surface
Reply #381 Top
That would mean the object's speed would increase as it moved into the black hole.


The object is still increasing speed. The effect is a result of the spacetime warping due to the intense gravity; relativity kicks in and only makes it appear to slow down.

And we do have the theory behind a fusion rocket, we just don't use it. Actually, the ramjet that dystopic started this thread with is one of these fusion rockets attached to a magnetic "scoop" that would take the available stellar hydrogen for use in the fusion rocket.
Reply #382 Top
And we do have the theory behind a fusion rocket, we just don't use it.


Did i miss somthing? have we developed fusion technology already?


Anyway would fusion cause deadly radiation like fission does?
Reply #383 Top
Anyway would fusion cause deadly radiation like fission does?



tell me again what powers the sun
Reply #384 Top
hmmm well i don't see them ever using nuclear propelled ships due to environmental effects, Unless there is some kind of emergency.


you mean like the nuke powered carriers and subs.
Reply #385 Top
have we developed fusion technology already?


What do you think an H-bomb is? H stands for Hydrogen, with which we induce fusion to cause destruction on a large scale. I think you are thinking of fusion reactors, where we would contain a controlled fusion reaction and convert its energy into electricity. That we are still working on. However, we have had H-bombs for a while, and using controlled fusion as rocket fuel is within our grasp, we would "funnel" it like you said. However there are some environmental considerations, like would we really want to irradiate our atmosphere for a fast rocket? I don't think so.
Reply #386 Top
tell me again what powers the sun



I believe the sun produces deadly radiation?

you mean like the nuke powered carriers and subs.



Technically speaking they are infact steam powered. The nuclear power is not used for directly creating thrust, it is just used to create heat for the steam which creates thrust.
Reply #387 Top
Technically speaking they are infact steam powered. The nuclear power is not used for directly creating thrust, it is just used to create heat for the steam which creates thrust.


Nuclear power and propulsion for spacecraft are nothing new. Since the 1960s, the United States has had the capabilities to launch vehicles powered by radioactive materials. Experiment packages on many of the Apollo missions used nuclear power systems as well. In 2006, NASA shut down most of its research into nuclear propulsion technologies, a project the agency had dubbed Prometheus. The agency had contracted with Northrup Grumman, Boeing and Lockheed Martin to propose future propulsion systems based on nuclear power


WWW Link



sorry this hard to do with a cat taking up most of my desk lol


it isnt environmental that is the problem with a nuke rocket. it is what happens if it crashes.
Reply #388 Top
it isnt environmental that is the problem with a nuke rocket. it is what happens if it crashes.


Right, it explodes, spreading fallout and potentially killing people. Thats an environmental issue, a very lethal one.
Reply #389 Top
it isnt environmental that is the problem with a nuke rocket. it is what happens if it crashes.


Right, it explodes, spreading fallout and potentially killing people. Thats an environmental issue, a very lethal one.


But a nuke rocket not crashing, would still lack containment of nuclear radioactive exauhst would it not?
Reply #390 Top
What do you think an H-bomb is? H stands for Hydrogen, with which we induce fusion to cause destruction on a large scale.


I had wondered about that actually, yes it made logical sense it would be fusion but i had not heard anything specifying it was fusion in society, so i just assumed fusion hasn't yet been discovered and somehow they were creating a fission reaction with hydrogen!

So the radioactive fallout from a H bomb is produced from the fusion reaction or is it just from the fission detonator?
Reply #391 Top
But a nuke rocket not crashing, would still lack containment of nuclear radioactive exauhst would it not?


Well, we have used nuclear powered rockets before, though this isn't referring to the actual rocket, just that there is a nuclear reactor producing the ship's electricity. So there is no fallout from those type of rockets. A rocket that actually used fusion to propel it would leave behind some fallout.

So the radioactive fallout from a H bomb is produced from the fusion reaction or is it just from the fission detonator?


Both. There are two types of hydrogen fuel we can use, however. Deuterium, which doesn't produce as much energy, has much less radiation than the other isotope, tritium, so it would be more attractive as a fuel in a rocket.
Reply #392 Top
millertime335


Thanks for getting me up to speed on a few details!
Reply #393 Top
OK a fusion rocket throws lots of radiation.

a fission rocket throws no radiation into the environment. and some into the rocket if not shielded.

the fission rocket has been built and tested. so this is the one my guy in my cab must have been talking about.




WWW Link


so you can use a fission rocket for take off.

a fusion rocket to get someplace, it is faster but requires a lot more shielding, and the exhaust is radioactive.
Reply #394 Top
OK a fusion rocket throws lots of radiation.

a fission rocket throws no radiation into the environment. and some into the rocket if not shielded.


Looks like there are no fusion or fission rockets.

They are just using nuclear reactions to create heat energy to power the rocket indirectly.

Saying they are nuclear powered rockets is the same as saying you have a petrol powered vehicle but then rip the petrol engine out and put a steam engine in which you then heated by burning petrol! Your still technically correct in saying it is a petrol powered vehicle but it is not quite the same as a directly petrol powered internal combustion engine, vehicle.
Reply #395 Top
Saying they are nuclear powered rockets is the same as saying you have a petrol powered vehicle but then rip the petrol engine out and put a steam engine in which you then heated by burning petrol! Your still technically correct in saying it is a petrol powered vehicle but it is not quite the same as a directly petrol powered internal combustion engine, vehicle.




and yet this non nuclear nuclear rocket is stronger than a chemical rocket.


reminds me of the lady with the antic violin. she had it appraised. the gentleman told her it was a knock off of a Stradivaris and it was only worth 15000 instead of 30000.

at that point i am asking myself does it really matter. it was a family heirloom and she wasn't going to sell it. it had gotten wet and she wanted to make sure it was going to be OK.
Reply #396 Top
and yet this non nuclear nuclear rocket is stronger than a chemical rocket.


Does it have a better thrust to weight ratio than a chemical rocket? Also a chemical rocket gets much lighter as it burns fuel?
Reply #397 Top
according to the rocket scientists it has more power but not more speed that is what i am going on.
Reply #398 Top
Looks like there are no fusion or fission rockets.


I think that is our key problem with the propulsion here. Currently, Nuclear devices are our most destructive weapons. A rocket, is essentially, a controlled bomb. If you were to use a nuclear reaction (fission or fussion), you're essentially trying to controll a small nuclear explosion inside the ship. We'd have to build a ship that is not only capable of handling an internal nuclear explosion, but channeling that force correctly in order to generate appreciable acceleration without ripping itself apart.


With normal nuke reactors, there is tremendous controll and the reactants aren't allowed to "melt down" or reach the state of a full blown nuclear explosion. All current nuclear devices are secondary power sources, usually a heat source to produce say, steam for powering ships and plants.

I like the idea of propelling the ship secondarily, like above. You'd still have to carry a lot of fuel to get the ship moving, but atleast the radioavtice waste could be jettisoned and the heat from the rockect could be used as a power source. Controling mechanisms could be used to switch the rocket ("engine") from engine to generator and back again for maximum space efficiency.
Reply #399 Top
Does it have a better thrust to weight ratio than a chemical rocket? Also a chemical rocket gets much lighter as it burns fuel?


i would think it would also lose thrust. less pressure less thrust.

Reply #400 Top
We'd have to build a ship that is not only capable of handling an internal nuclear explosion, but channeling that force correctly in order to generate appreciable acceleration without ripping itself apart.


Yes! They could make it work like a sparkler tho... the nuke fuel being mixed with other compounds to slow down the reaction.

i would think it would also lose thrust. less pressure less thrust.


does your car go slower because you have less petrol in the tank? Not untill it actually starts running out will there be a loss of power.