dystopic dystopic

bussard ramjets, cryonic stasis, and exoplanetary colonization

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bussard ramjets, cryonic stasis, and exoplanetary colonization

what will it take?

from GalCiv2 Forums
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!
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Reply #251 from GalCiv2 Forums Top
i get that, but those thrusters are only making minor alterations. the position of things in orbit is maintained primarily by the forces of gravity at work. but gravitational force decreases exponentially with increased distance. stars and black holes hold their relative positions to each other in a galaxy because they're so much more incredibly massive than a space station, or even a planet.

my intution, at least, is that in deep space it'd take considerably more thrust to make up for the lack of a strong gravitational force nearby than the shuttle needs to maintain orbit (at the perfect distance where their gravitational influences balance out, it actually wouldn't take any thrust at all to keep the shuttle at the same distance from the earth). in other words, the shuttle's thrusters are correcting its orbit - a deep space station would need some kind of thrust to create its orbit.

i may of course be wrong; the space station isn't that big, and wouldn't need that much force (compared to a force of gravity a star creates) - but the exponential part of how gravity works leads me to believe it'd take considerably more thrust than shuttle needs - per unit of mass, of course.
Reply #252 from GalCiv2 Forums Top
you forget gravity pulls on everything at the same force. a massive black hole is being held in place by the same amount of force that is holding our star in place. ie if you drop a feather and a rock on the moon they will both hit at the same time.
Star Control: Origins
Reply #253 from GalCiv2 Forums Top
you forget gravity pulls on everything at the same force.


True.

gravitational force decreases exponentially with increased distance.


Also true.

if you drop a feather and a rock on the moon they will both hit at the same time.


Ah, but this is only true if the rock and the feather start at the same altitude (and the absence of resistance, or course). However, if you started them significantly far away from the moon, they would fall very slowly, and as they got closer their acceleration would increase. They still, however, reach the ground at the same time.


Provided that the station encountered no resistance, it would be easy enough for it to establish an orbit of a distant star; it would just orbit very, very slowly. However, the interstellar medium would probably produce significant resistance, so you would need some amount of thrusters to counter this resistance.
Reply #254 from GalCiv2 Forums Top
so you would need some amount of thrusters to counter this resistance.


i agree but we will not know until we get into it. that will be voyager when ever they get there.


Ah, but this is only true if the rock and the feather start at the same altitude (and the absence of resistance, or course).


this is why i choose the moon but since there is a very small atmosphere on the moon the feather may get slowed down not sure.
Reply #255 from GalCiv2 Forums Top
As of August 10, 2007, Voyager 1 is over 15.49 terameters (15.49×1012 meters, or 15.49×109 km, 103.6 AU, or 9.6 billion miles) from the Sun, and has thus entered the heliosheath, the termination shock region between the solar system and interstellar space,
Reply #256 from GalCiv2 Forums Top
Provided that the station encountered no resistance, it would be easy enough for it to establish an orbit of a distant star; it would just orbit very, very slowly.


okay, fair enough. and the same would be true of its orbit around the black hole at the center of the galaxy - assuming it actually is a black hole (something in the center of our galaxy is causing gravitational lensing, that's for sure).

i'm sure computers could computer exactly where the station is supposed to be based on its orbit. you were right, danielost.

though this does bring to mind the fact that 'star maps' would indeed change over time, albeit very slowly: the relative positions of stars to one another, the same way the planets have changing positions relatively to one another.

heliosheath


i've always heard that referred to as the heliopause. tomato/tomahto, i'd say.

Reply #257 from GalCiv2 Forums Top
heliopause


i think this is where it ends

remember it has ten years to cross it.

so that is 93. million x 3 per year x 10 number of years= total distance


2.79 billion miles that is almost a third of what it is from us now
Reply #258 from GalCiv2 Forums Top
heliopause




i was wrong this is the beginning of it
Reply #259 from GalCiv2 Forums Top
here we go (thanks to wikipedia).



though it's not labelled, the heliosheath occurs between the termination shock and the heliopause, according to wikipedia. also note the exponential, rather than linear, scale - what i didn't know at all is that the ort cloud is actually outside the heliosphere.
Reply #260 from GalCiv2 Forums Top
ok so you are not outside of the solar system until you are past the oort cloud. why because it is in orbit around the sun. however you leave the suns atmosphere before you enter the oort cloud.


so the question is will voyager survive that part of its trip. and will it still be working when it gets there. nasa says it should keep working until 2020. not a long time away anymore.


i have one more question do we share the oort cloud with alpha. because according to the map it looks like it might be half way. and since alpha is a little bigger.
Reply #261 from GalCiv2 Forums Top
i have one more question do we share the oort cloud with alpha. because according to the map it looks like it might be half way. and since alpha is a little bigger.


no. the scale is exponential, not linear. in other words, each increment on this chart is 10x bigger than the previous increment, moving from left to right.

so the earth is 1 AU, saturn is 10, the heliopause is 100, the oort cloud is 1,000, and alpha centauri is somewhere between 10,000 and 100,000 AU way from our sun. no time to do the math to figure it exactly, but the oort cloud is at least 10 times closer to our sun than aC.
Reply #262 from GalCiv2 Forums Top
well the edge of the cloud it what 100,000 AU (10 to the 5th right?), and A centauri is 1,000,000 AU, so not really halfway, more like 1/10th away.

Remember the map is not linear, when I first looked at it, I though it couldn't be right A centauri being so close, then I looked at the scale and it made more sense. Nice pic too, btw!
Reply #263 from GalCiv2 Forums Top
maybe the intersteller meduim is the oort cloud.
Reply #264 from GalCiv2 Forums Top
"If I want to accelerate from rest to, say, 150,000 km/sec, or about half the speed of light, I have to do it gradually, so that my body will not be torn apart in the process. In order not to be pushed back into my seat with a force greater than 3 Gs [...] it would take some 5 million seconds, or about 2 1/2 months, to reach half light speed!"

WWW Link


i found the above to by a good look at speed although the info is 10 years old.
Reply #265 from GalCiv2 Forums Top
Nice pic too, btw!


thanks! though greater thanks belong to wikipedia.

i found the above to by a good look at speed although the info is 10 years old.


nice link... sheesh, it's kinda depressing for me to think that any website is 10 years old... mine is probably the last generation that 'remembers a time before the internet', at least before it was commonplace in popular consciousness.

okay, aC is about 276,000 AU away. the oort cloud is about 50,000 AU at its outtermost. so it's about 20% of the way to aC when space becomes 'clear'.

i read that at its nearest the cloud is believed to be 50 AU, but maybe that's because they're not sure how to distinguish it from the kupier belt. i'd thought that'd be a lot of time worrying about potential objects for collision, a serious consideration if you wanted to accelerate freely, but then i read: "The outer Oort cloud is commonly thought to contain several trillion individual comet nuclei larger than ~1.3 km, each tens of millions of kilometers apart." yeah, at those densities it wouldn't be like the scenes from Star Wars when the Millenium Falcon is going through an asteroid belt.
Reply #266 from GalCiv2 Forums Top
i am wondering and there is no way to know but could intersteller space. the so called dark matter just be what the oort cloud is supposed to be made of.
Reply #267 from GalCiv2 Forums Top
Hey, I was just thinking it might be interesting to do a Star Trek: Voyager-esque story about the hardships of colonist life aboard the ship in transit to the new colony. Maybe if your first goes well you can write a prequel .
Reply #268 from GalCiv2 Forums Top
heliopause

sounds like a disease...

They said if man were meant to fly he'd be born with wings.

Then we invented the plane...

I'm sure in the next world war technology with boost itself and we will be headed for the stars.
Reply #269 from GalCiv2 Forums Top
"I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones."
-Albert Einstein





sorry, i just had to...
Reply #270 from GalCiv2 Forums Top
i am wondering and there is no way to know but could intersteller space. the so called dark matter just be what the oort cloud is supposed to be made of.


no. they're fairly sure they know of what the oort cloud is made of, and even if every star had one way bigger than ours, it wouldn't account for the "missing mass." we can see oort cloud objects with telescopes, though usually they're pretty small and we have to use additional methods to tell they're there.

as for dark matter, here's a definition from wikipedia:
"In astrophysics and cosmology, dark matter is hypothetical matter of unknown composition that does not emit or reflect enough electromagnetic radiation to be observed directly, but whose presence can be inferred from gravitational effects on visible matter. According to present observations of structures larger than galaxy-sized as well as Big Bang cosmology, dark matter accounts for the vast majority of mass in the observable universe."

i think they say something like only 10% of the mass in the universe is visible.

a linguistically related phenomenon is the so-called 'dark energy.' there's some force acting on the matter of the universe that's causing things to accelerate away from each other, but we don't know what force that is. if it weren't there, we'd expect things to be decelerating after the big bang, and it threw a wrench in a number of cosmologies when we started confirming that things are actually accelerating.

but these two phenomenon might be related physically, but since we know almost nothing about either, you guess's as good as mine. they're called 'dark' for no reason except that we can't directly measure either of them.

if you want my bet, 'dark matter' is one of two things. it's either normal matter in other spacial dimensions (and those dimensions would account for the weakness of gravity), or it's exotic matter that's capable of warping space, sort of like what'd be needed for the Alcubierre drive we talked about previously. relative to us it'd move FTL, and if 90% of the universe's mass is made up of that stuff and it were moving away from the point of the big bang, it'd "pull" the visible universe along with it (accounting for dark energy) and yet also be repelled by the visible universe (remember gravity pushes exotic matter "up" rather than pulling it down - yet normal matter would still be pulled by it if it had positive mass), causing a ceasely accelerational force.

edit: scratch that second option - the whole thing about the theoretical exotic matter for space warping is that it has negative or imaginary mass - though an imaginary number isn't necessarily negative.
Reply #271 from GalCiv2 Forums Top
it might be interesting to do a Star Trek: Voyager-esque story about the hardships of colonist life aboard the ship in transit to the new colony


you know it interests me that we haven't talked too much about plot so far. personally what i think this forum has done for me is help to work out the setting. and it's not a single setting, of course, so much as the ground rules for settings, or a meta-setting.

to be honest, like i've said i could see writing a series in this universe. i don't even think the series should have a single plot, so much as lots of separate plots that make reference to one another when appropriate (such as in issues of future history). given the appropriate technology to extend human life (or even "cure" natural death) it might also have recurrent characters.

i could definately see an interesting plot having to do with travel through empty space. imagine how lonely you'd get. what if you were a technician and needed to stay awake, but your spouse was a specialist who was in suspended animation. the years of solitude would build, but only on one partner: what sorts of challenges would that present to a marriage? i mean, that's just starters (don't forget, the technology is mainly interesting to me for the sake of having a convincing setting; my real interest is the impact on human lives and cultures).
Reply #272 from GalCiv2 Forums Top
Do you read Popular Mechanics? I just looked at the September issue, and the main article was about plans/projections/theories for lunar and martian bases in the future. It was really interesting, and obviously relevant to our discussion here, in regards to the types of technology that would be deployed.

We had been talking about how you wouldn't really need to ship materials from other worlds, but one thing that the article mentioned (briefly), which is something that I hadn't considered, is the purity of compounds we might find. Apparently the moon has deposits of hydrogen-free silicon, which could be used to make glass and other materials "far superior to anything achievable on Earth", due to its lack of hydrogen impurities. So maybe there would be trade in materials between worlds, materials that are of higher purity than what is found in Sol.
Reply #273 from GalCiv2 Forums Top
Do you read Popular Mechanics?


can't say i do, but that article sounds great. maybe it'll be available on campus.

the purity of compounds we might find


i hadn't considered that either, and it's very worth considering indeed. but i still think, bottom line, if the universe can do it, so can we. it's just a question of efficiency.

if the moon's silicon were more efficiently mined than pure atomic silicon produced by fusion, we'd mine the heck out of it. until it was gone or too hard to get.

i could imagine, though, that sufficiently advanced fusion technology would allow us to create virtually 100% pure elements. i can't remember who pointed it out, but solar fusion has a lot of irregularities. i think if we made it a goal, we could create very stable fusion.

but here's another point to consider along these same lines. while fusion technology might result in the ability to create any element we wanted, quantity might also be a factor to consider. such an apparatus that'd allow us to create 100% pure silicon probably wouldn't be cheap, and it'd only be able to produce so much at a time. if something were needed in great enough quantity relatively quickly, mining would be a better option -- at least mining it from the same solar system in which it'll be used... having to ship it across stars would invalidate the timing issue at least potentially, and it might also invalidate the efficiency issue.

on an unrelated note, i've only ever read the original Ender's Game. a friend of mine told me i should read the series after hearing about this writing projects, that there were some interesting parallels between my interests and what the series did.
Reply #274 from GalCiv2 Forums Top
here is an idea for your book.


you should be able to get two books out of it.


no one has done a story from both points of view.


an example the federation, and the Klingons. yes they have some point of view on next gen. and deep space 5. but i mean an entire story from both points of view.
Reply #275 from GalCiv2 Forums Top
but i mean an entire story from both points of view.


ever read The Rules of Attraction? it's written (quite well) from at least half a dozen points of view.

i'd thought about something similar: what'd happen on one world after it learned about events or lifestyles on another world (in a different star system) that its inhabitants considered deplorable.

i've also been pretty ambivalent about finding aliens. maybe alien life, but not intelligent alien life, at the very least not for a long while. and from my point of view as a writer, there's more than enough oddity in humans alone.

it also sounds like you're describing telling a story from different points of ideology rather than points of view. in my mind, a PoV belongs to an individual. though on the other hand, an individual is still a part of a culture, which means s/he laden with internalized ideologies.

this is actually one of my areas of interest as a writer: creative ethnography (it was a natural transition for me after doing social scientific enthography). it's basically writing in a way that draws the reader's attention to a person's culture more than his or her personal characteristics. it's not that you refuse to look at a person's individuality, it just takes second stage.