Travel to interstellar planets ...

[gallileo]

Got to agree with Rogue..do the math. But - my hat is off to you for at least thinking this is a problem that should be considered and not wished away by hand - waving. Start thinking that way about everything ! Hey, do your own reasearch on this too!!

OK now here's my take on the radiation with some interesting links.
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I would think that travel at .1 c might involve more shielding than we are used to seeing in chemical rocket spacecraft. Like to see some calculations of what the cosmic ray flux would be at that speed.

Shielding though seems like not a problem if we were to build a massive 8Mton rocket..my estimate is thats the mass of a 400 yard dia solid nickel or iron asteroid. So we could get a much larger one, with 60 ft walls, no problem, and travel in style (or steel !) with lots of shielding.

The radiation and impact hazards don't seem to be addressed to much in what little I have read so far. My guess is that it is manageable. Jorge, do your calculations please ! What is the effect of cosmic rays & or micrometeorites on 60 ft of steel or iron ?

Here are a few titles I found that are in larger libraries..check worldcat and your zip ..


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The starflight handbook : a pioneer's guide to interstellar travel
by Eugene F Mallove; Gregory L Matloff
Book
Language: English
Publisher: New York : Wiley, ©1989.

Prospects for interstellar travel
by John H Mauldin; American Astronautical Society.
Book

--Articles--
Forward, Robert, L., "Feasibility of Interstellar Travel: A Review," Journal of the British Interplanetary Society, 39, 379-384, 1986.

Crawford, I. A. "Interstellar Travel: A Review for Astronomers," Quarterly Journal of the Royal Astronomical Society, 31, 377 (1990).

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Heres the abstract of the R L Forward review-

Abstract: Interstellar travel is difficult, but not impossible. This review paper discusses the relative feasibility of a number of different technologies that will allow travel to the stars. It gives examples of one-way and rendezvous unmanned interstellar probe vehicles that can return data on the number and nature of the planets around the target system within less than 50 years after launch. These initial exploration probe missions will be followed by manned or robotic exploration and colonisation missions. These can range from relatively feasible long slow missions using "world ships" propelled by existing nuclear pulse or nuclear electric technologies and carrying self-producing human crews, to high risk, high speed missions using beamed power, antimatter, or interstellar ramjet technology. For the nearer stellar system, speeds of 0.1 to 0.3 the speed of light will suffice to explore the 17 nearest stellar systems with 25 visible stars and hundreds of planets in trip times comparable to a human lifetime. Some emergent high energy density technologies that are under development for other purposes, such as laser and electron beam imploded fusion and solar powered lasers and masers, show promise of providing us with propulsion technologies that will make rapid interstellar travel feasible within the foreseeable future.

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Finally, a whole host of links from ..NASA Glen Research Center.

See http://www.nasa.gov/centers/glenn/technology/warp/bibliog.html

[oxmixmudd]

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Sam, are you serious? Are you sober?

Given a distance (D) and a speed (v), the travel time is simply (D/v).

The "impossibility" is determined NOT by such trivial arithmetic but
rather by the realization that at such speeds there are effects that
render the trip i-m-p-o-s-s-i-b-l-e. In other words, try
thinking beyond a 4th grade level (unless you're wanting to join
your pal Jim at that level).

I challenge you to refute my simple, straightforward argument.
In other words : I will give you a 400,000 ton spaceship capable
of traveling at 0.1c. Now show me how it will get to a star that
is 4.4 light years away WITHOUT ending its journey in transit
in a tragic way.

I'll even be nice and show you how: consider the average density of
mass in interstellar space. Consider also the cross section area of
the spaceship. From that and the speed, compute the intercepted
volume which translates into intercepted mass. From that calculate
the kinetic energy transfer. From that arrive at conclusion: game over!
And this does not even consider a "large" object (say, 1 gram or larger)
that happens to be in the flight path. The effect of that would be, to
say the least, explosive! Think, kiddo .. THINK!

Go ahead, I wait for your rebuttal and stop being so silly. Geesh!

Jorge

Oh dear. Did Jorge really just act as if the energy transfer of collisions with the interstellar medium (ISM) over 44 years (alpha-centauri at .1c) could be summed and treated as an instantaneous energy transfer (a single impact with a body of that equivalent mass?). And this is the president of C.O.P.E!

In fact Jorge, the primary issue at .1c is the heat transfer associated with molecular level collisions. Can the ship radiate away the heat faster than it is being produced. If it can, no problem. If not, then yes, there is a problem. Everything I've read on the subject indicates that at .1c its not a problem.

But then there is the fact Phank mentions that most of this molecular material is ionized, and sufficiently strong magnetic field can divert it around the ship itself. But it probably is not necessary at .1c given a sufficiently massive front end and heat transfer technology to radiate the heat away.

My guess is heat and radiation from the propulsion system is going to be more of a problem than heat from friction with the ISM. But the answers to these questions are likely already known and the calculations have already been done ... by those investigating the feasibility of travel to the stars.


Jim

[phank]

Oh dear. Did Jorge really just act as if the energy transfer of collisions with the interstellar medium (ISM) over 44 years (alpha-centauri at .1c) could be summed and treated as an instantaneous energy transfer (a single impact with a body of that equivalent mass?). And this is the president of C.O.P.E!

No, I don't read his post as saying this. I read him as looking at the cumulative energy transfer over the course of the entire trip, which you are treating (quite properly) as heat dissipation. And whether or not an object experiencing as much energy input as Jorge says would prove explosivve at some point during the trip, depends on the number and size of micro-collisions. Which in turn depends on BOTH a reasonable estimate of the ISM density, and a reasonable assumption about density variation over the course of the trip. There MIGHT be some fairly dense gas clouds in your path, invisible from here.

I've read a good deal of speculation on this, and as far as I can tell heat dissipation wouldn't be a problem (or in other words, in order to BE a problem, the ISM density would have to be enough to be visible from our telescopes).

Then again, Jorge is quite correct that a chunk of something more massive, even a few grams, would have enormous impact at .1c. I don't believe the probability of such an impact can be calculated with any confidence. It's true that such junk is almost surely far more common near stars, and we are very near a star. And it's also true that such bits of junk impact the space station from time to time, traveling about .0001c (say, 20 miles per second), and do real damage. If I were riding on Jorge's proposed ship, I'd expect some serious impact shielding.

And that's one reason why recent STL travel stories involve very large moving habitats, like hollowed out asteroids or comets, or even good sized moons, driven with various propulsion technologies. With a few hundred feet of rock between you and space, heat transfer or most collisions are less likely. If you should happen to hit another large rock, of course, well, you'll never know it.

[Carrikature]

For my part, it's because Jorge has ambitions outside of your normal YEC. He wants to hob-nob with the "big guys:" Sanford, Baumgardner, et al. and wants to influence public policy through "academic" articles, conferences and, now, actual organizations. Making him defend his statements (or at least demonstrating that he won't defend his statements) at the very least creates a nice paper trail in case he ever makes any headway toward his goals.

—Sam

Fair enough. How much paper trail is enough?

[Ansgar Seraph]

Fair enough. How much paper trail is enough?

Oh, we're probably there, it's true. But Jorge tends to come out with New Things every now and then that merit picking apart. On threads like this, though, it probably is more of a guilty pleasure than anything

[oxmixmudd]

No, I don't read his post as saying this. I read him as looking at the cumulative energy transfer over the course of the entire trip, which you are treating (quite properly) as heat dissipation. And whether or not an object experiencing as much energy input as Jorge says would prove explosivve at some point during the trip, depends on the number and size of micro-collisions. Which in turn depends on BOTH a reasonable estimate of the ISM density, and a reasonable assumption about density variation over the course of the trip. There MIGHT be some fairly dense gas clouds in your path, invisible from here.

I've read a good deal of speculation on this, and as far as I can tell heat dissipation wouldn't be a problem (or in other words, in order to BE a problem, the ISM density would have to be enough to be visible from our telescopes).

Then again, Jorge is quite correct that a chunk of something more massive, even a few grams, would have enormous impact at .1c. I don't believe the probability of such an impact can be calculated with any confidence. It's true that such junk is almost surely far more common near stars, and we are very near a star. And it's also true that such bits of junk impact the space station from time to time, traveling about .0001c (say, 20 miles per second), and do real damage. If I were riding on Jorge's proposed ship, I'd expect some serious impact shielding.

And that's one reason why recent STL travel stories involve very large moving habitats, like hollowed out asteroids or comets, or even good sized moons, driven with various propulsion technologies. With a few hundred feet of rock between you and space, heat transfer or most collisions are less likely. If you should happen to hit another large rock, of course, well, you'll never know it.

I agree that in building such a ship, you would want to take care of handling any impacts with any piece of material you had a non-negligible chance of hitting. And that even very small pieces of matter pack a significant wallop at .1c. But what is the probability of hitting something bigger than current science and technology can deal with? Figuring out how big a piece to protect against would be the trick. I do think some kind of multilayer structure that preceded the ship could probably absorb most of the impacts that could be expected to be encountered. But Jorge's op is not about safety, but possibility. The interstellar medium itself is very sparse. Inside a solar system is where you'd have the greatest possibility of hitting something like real dust or micro-meteoroids, but the speeds would be much lower since both the acceleration and deceleration times would be fairly large.

If Jorge wanted to change his op to safe and comfy travel with little to low risk, I'd agree with him. If he wanted to change his op to such a trip being funded or it being practical to build given current science and technology I'd agree with him. But He didn't and won't. He goes to it's impossible with current science - and in that he's just wrong.


Jim

[Carrikature]

If he wanted to change his op to such a trip being funded or it being practical to build given current science and technology I'd agree with him.

I've always maintained that commercial mining is the single most plausible factor for launching humans into regular space travel. Already, we are seeing the creation of corporations such as Planetary Resources and Space Adventures. As the private sector begins to realistically explore intra-system travel, the technologies will be developed that will launch us into interstellar space. Weyland-Yutani, here we come!

[Ansgar Seraph]

It's all smiles . . .

alien_xenomorph_01.jpg

[Jorge]

Sorry, Jorge. I just find this too, too funny. You started this thread as an escape hatch to keep from having to answer questions elsewhere. You maintained throughout that contemporary technology is insufficient to allow interstellar travel. gallieo countered by arguing that the Orion project showed that interstellar travel is possible using conventional nuclear technology. You asked him to name a star and you would show some "basic math" proving such travel to be impossible. He referenced Alpha Centauri and the ball was in your court.

But instead of doing the math you promised to do, you veered off into a side topic about micro-collisions. Now I don't particularly know or care whether we can get to Alpha Centauri in a century or whether a multi-generational ship is a worthwhile expenditure. But here's just another example of you promising big and under-delivering in a, pardon the pun, stellar fashion. I mean, what's the point of making promises that you have no intention or ability to keep?

Either do the math you promised, showing that travel to Alpha Centauri at 0.1c is impossible with conventional technology or quit making grandiose statements and empty promises!

--Sam

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Good - freagin' - grief !!!

There are but TWO options here :

(1) You don't have the IQ to comprehend the argument.

(2) You are able to comprehend the argument but are
intellectually dishonest and refuse to admit its validity.

Pick one, Sam. Either option you select, you are not worth my time.

Jorge

[Jorge]

I agree that in building such a ship, you would want to take care of handling any impacts with any piece of material you had a non-negligible chance of hitting. And that even very small pieces of matter pack a significant wallop at .1c. But what is the probability of hitting something bigger than current science and technology can deal with? Figuring out how big a piece to protect against would be the trick. I do think some kind of multilayer structure that preceded the ship could probably absorb most of the impacts that could be expected to be encountered. But Jorge's op is not about safety, but possibility. The interstellar medium itself is very sparse. Inside a solar system is where you'd have the greatest possibility of hitting something like real dust or micro-meteoroids, but the speeds would be much lower since both the acceleration and deceleration times would be fairly large.

If Jorge wanted to change his op to safe and comfy travel with little to low risk, I'd agree with him. If he wanted to change his op to such a trip being funded or it being practical to build given current science and technology I'd agree with him. But He didn't and won't. He goes to it's impossible with current science - and in that he's just wrong.


Jim

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It doesn't surprise me that you aren't able to grasp the relatively simple
aspects of my argument. I mean, you can't (or won't) grasp the very
simple arguments against Evolution - Theistic or any other.
The "intellectual pattern" is clearly manifested.

I outlined (for Sam) how to go about calculating the impossibility of
this 400,000 ton spaceship at 0.1c. Any intelligent high-schooler
can do the math and follow the logical argument. It has nothing
to do with impacting a "large" object, such as a car-sized boulder
or what-have-you. It is simply the interstellar mass density that
we KNOW exists. The rest is just very simple physics and math.
Of course, impacting a "large" object ends the show immediately.

And, NO, it is NOT easy to 'eliminate' ANY mass from the flight path.
Your suggestion of a "multi-layer structure preceding the ship" is naively
embarrassing, Jim. Think Conservation of Energy and do the math!

The thinking level of you people is pathetically shallow. No wonder
you have fallen prey to gigayears and Evolution. I now understand well
why I have had all the difficulties with you people during these years.
I'm glad I went through this exercise - I learned something useful.

But, alas, all this appears to be beyond you people.

Go learn something ... anything ... I'm done here.

Jorge

[RBerman]

I outlined (for Sam) how to go about calculating the impossibility of
this 400,000 ton spaceship at 0.1c. Any intelligent high-schooler
can do the math and follow the logical argument. It has nothing
to do with impacting a "large" object, such as a car-sized boulder
or what-have-you. It is simply the interstellar mass density that
we KNOW exists. The rest is just very simple physics and math.
Of course, impacting a "large" object ends the show immediately.

And, NO, it is NOT easy to 'eliminate' ANY mass from the flight path.
Your suggestion of a "multi-layer structure preceding the ship" is naively
embarrassing, Jim. Think Conservation of Energy and do the math!

I thought you were going to do the math showing that there's a problem. Did I miss the post where you did that?

Really, these theoretical concerns will be verified experimentally long before we launch a manned interstellar ship. I remember from reading Space Age literature that two worries were: (1) Our ships will be unable to shed excess heat in a vacuum since conduction will be negligible, and (2) Will the lunar module sink in ten feet of moon dust?

We now know from experience that both of those concerns were unfounded. If we want to ever visit Alpha Centauri or any interstellar destination with men, we'll have to show "proof of concept" with an unmanned ship which will gather data on questions like, "What's the radiation exposure given shielding X?" and, "How much debris danger is there at 0.1c?" Only then will we able to address your concerns with anything approaching confidence. That's the scientific method: Try, measure, try again.

[Jorge]

I thought you were going to do the math showing that there's a problem. Did I miss the post where you did that?

Really, these theoretical concerns will be verified experimentally long before we launch a manned interstellar ship. I remember from reading Space Age literature that two worries were: (1) Our ships will be unable to shed excess heat in a vacuum since conduction will be negligible, and (2) Will the lunar module sink in ten feet of moon dust?

We now know from experience that both of those concerns were unfounded. If we want to ever visit Alpha Centauri or any interstellar destination with men, we'll have to show "proof of concept" with an unmanned ship which will gather data on questions like, "What's the radiation exposure given shielding X?" and, "How much debris danger is there at 0.1c?" Only then will we able to address your concerns with anything approaching confidence. That's the scientific method: Try, measure, try again.

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RBerman : what I read above displays superficial, sophomoric, naive 'thinking'.
Furthermore, you aren't even reading what I've written - if you are reading
it, then you aren't comprehending any of it since I clearly answer
most of what you bring up. Good grief ... you people are very frustrating!

Jorge

[phank]

************************************************

RBerman : what I read above displays superficial, sophomoric, naive 'thinking'.
Furthermore, you aren't even reading what I've written - if you are reading
it, then you aren't comprehending any of it since I clearly answer
most of what you bring up. Good grief ... you people are very frustrating!

Jorge

But your "answers" consist of wild-eyed unsupported assertions sandwiched in insults. No data, no evidence, no past experience, no math, no making your assumptions explicit. You just keep repeating that the density of interstellar matter is much too high for a ship of your suggested dimensions going at your suggested speed. Where did you get that density? You don't say. Could the ship successfully go more slowly? You don't say. Could a hollowed asteroid taking many generations reach another star? You don't say, or even address it.

So I confidently expect you to say NONE of these things, and if anything, to repeat your assertions - made even more "true" by boldface, italics and underlining.

[RBerman]

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RBerman : what I read above displays superficial, sophomoric, naive 'thinking'.
Furthermore, you aren't even reading what I've written - if you are reading
it, then you aren't comprehending any of it since I clearly answer
most of what you bring up. Good grief ... you people are very frustrating!

Jorge

Putting aside your insults, it appears that your answer is, "I am not going to show any math to support my assertions." That's all I wanted to know.

[rogue06]

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Good - freagin' - grief !!!

There are but TWO options here :

(1) You don't have the IQ to comprehend the argument.

(2) You are able to comprehend the argument but are
intellectually dishonest and refuse to admit its validity.

Pick one, Sam. Either option you select, you are not worth my time.

Jorge

Third option: You claimed you would provide the math that would demonstrate that interstellar travel was impossible -- even going so far as to demand that a star be named so you could do that math. But as seems to be all too typical you failed to deliver the goods and start accusing everyone who realizes this of being drunk, stupid, dishonest or insane.