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banquo's_bumble_puppy
2003-Aug-29, 01:59 PM
Given the current state of space technology; does anyone believe that an instellar flight might occur before the end of this century?

kucharek
2003-Aug-29, 02:10 PM
Currently there are four interstellar flights under way, but we already lost contact with two of them. ;-)

Please define, what kind of interstellar flight you mean.

banquo's_bumble_puppy
2003-Aug-29, 02:15 PM
launched in this century and travelling at least 10% light speed and capable of reaching the closest star system within a human lifetime...say 50 years travel time

kucharek
2003-Aug-29, 02:20 PM
Try to get Deep Space Probes (http://www.praxis-publishing.co.uk/space/dsprobes.htm) from the library. The cover and title are a little bit misleading, as it is actually about interstellar space probes.

And, regarding your mission profile: I'd say no. But I hope, I'll be proofed wrong. As long as we don't find a very interesting planet as a target for such a mission, I can't imagine that plenty of money would be thrown onto such a mission - except we find a totally new and cheap propulsion system.

Kaptain K
2003-Aug-29, 02:38 PM
I would bet on one-way generation ships before the end of the century, assuming lack of faster propulsion methods. :wink:

Colt
2003-Aug-29, 06:09 PM
A nuclear-driven, generation space arcology is the only thing that I can think of.. We're coming Alpha Centauri! :D -Colt

mike alexander
2003-Aug-29, 06:39 PM
No. :cry:

Avatar28
2003-Aug-29, 06:51 PM
Okay, so if you had the opportunity to, with your family, go on one of these one way generation ships, would you take it?

semi-sentient
2003-Aug-29, 07:21 PM
I would, if they could guarantee the following:

1) Will not run out of food, water, etc.
2) Will not slam into a star, planet, or black hole.
3) Protection from radiation.
4) Cable (Comedy Central, Sci-Fi, Discovery Science, ESPN, etc.)
5) The ability to do space walks.

:P

Avatar28
2003-Aug-29, 08:32 PM
I would, if they could guarantee the following:

1) Will not run out of food, water, etc.
2) Will not slam into a star, planet, or black hole.
3) Protection from radiation.
4) Cable (Comedy Central, Sci-Fi, Discovery Science, ESPN, etc.)
5) The ability to do space walks.

:P

1) Water can be recycled, food can be grown. It would be a large, closed ecosystem. Of course, might have to do without meat, unless the ship was REALLY big (I'm talking RAMA here).

2) Well, most of that stuff should not be a problem to detect well enough in advance. I would be more worried about stray debris. I guess a rogue planet COULD be an issue in interstellar space since you may not see it until you were almost on top of it. But the odds are PRETTY far against it.

3) Since the ship would probably be a rotating cylinder with the "ground" and ship's hull beneath you, shouldn't be too big a deal. Plus in interstellar space radiation shouldn't be too much of a deal anyways.

4) I see no reason why most of that couldn't be beamed from earth via laser, at least for a long time. And I'm sure there would be a HUGE library of materials brought from the earth. Every movie and TV show ever made for instance, most books written in the last couple hundred years, etc. And we could get new stuff until the ship got out of range of the communications laser.

5) Join the crew and I'm sure you might be able to. Elsewise, I'm sure there would be a nice zero gee rec area towards the hub of the ship.

Ripper
2003-Aug-29, 09:26 PM
I am not very good at math. At 1G of acceleration, how long would it take to get to say, 50% the speed of light? I am sure I have it in one of my books, but it would take me forever to find it.

Avatar28
2003-Aug-29, 09:50 PM
I am not very good at math. At 1G of acceleration, how long would it take to get to say, 50% the speed of light? I am sure I have it in one of my books, but it would take me forever to find it.

Speed of light is 299,792,458 m/s. Half of that is 149,896,229. Divide that by 9.8m/s^2 gives an answer of 15295533 s. Rounded off, that's about 4250 hours or 170 days. So about 5 1/2 months of continous acceleration. Of course, the amount of fuel required for that acceleration would be ENORMOUS. You would need some sort of fusion at the least and I'm really not sure that even THAT would provide nearly enough specific impulse. More likely would need some sort of antimatter or antimatter assisted fusion drive.

Ripper
2003-Aug-30, 01:50 PM
I think we have to be able to make the round trip in a lifetime. I do not think there are many people ready for one-way trips. Being able to accelerate and decelerate (accelerate in the other direction) at 1G for the entire trip would solve a lot of problems. It would get us to the nearest stars and back in less than two decades.

I think it is a forgone conclusion that we are not going to manage interstellar travel with chemical rockets. A generation ship could cover interstellar distances at chemical rocket speeds, but it would have to be huge. A ship the size of a city would take a lot of fuel just to get moving at the speed of some of our faster probes.

darkhunter
2003-Aug-30, 04:09 PM
I am not very good at math. At 1G of acceleration, how long would it take to get to say, 50% the speed of light? I am sure I have it in one of my books, but it would take me forever to find it.

Speed of light is 299,792,458 m/s. Half of that is 149,896,229. Divide that by 9.8m/s^2 gives an answer of 15295533 s. Rounded off, that's about 4250 hours or 170 days. So about 5 1/2 months of continous acceleration. Of course, the amount of fuel required for that acceleration would be ENORMOUS. You would need some sort of fusion at the least and I'm really not sure that even THAT would provide nearly enough specific impulse. More likely would need some sort of antimatter or antimatter assisted fusion drive.

Go to Saturn. Grab a BIG (I'm talking kilometers...) chunk of ice and birng back to Earth orbit (covered with mirrored reflectors to keep it cold. Build our starship in the middle. Strap on some souped up NERVAs that use melted ice water as the "propellant"--use as many as you need for the desired acceleration.

You've got your shilding, reaction mass, and space all in one (rather large) package....

Colt
2003-Aug-30, 04:21 PM
The thing about that though is that it would have to be huge to just contain what you were taking with you. I can't remember where exactly but in one of the Man-Kzin Wars books they use a huge iceshield on the front of a slowship to propellant and a as a shield against interstellar debri. -Colt

darkhunter
2003-Aug-30, 04:49 PM
That's what I meant when I said about a kilometers big chunk of ice....building into a small asteroid would allow for landing craft, hydroponics, and anything else you need. Can also use the spin-off tech use to build our starship for building colonies on other planets and in asteroids. So

Take a nickle-iron asteroid and strap a couple of ice asteroids to it for the first interstellar colony--although when they get there, they might just grab a couple more asteroids and press on, leaving whoever wants to stay on an inhabitable planet...

Until we (if at all possible) develope some sort of FTL travel, for intersellar journeys we have to think long-term and BIG

mutant
2003-Aug-30, 07:17 PM
I would guess that with financing problems and the usual beaurocratic hoops to jump through I would guess that no, it would not happen.

Reacher
2003-Aug-30, 08:20 PM
This is a stupid question. I know it is. It reeks of stupidity. But I'm asking anyway. How would a nuclear-powered spacecraft work? I don't need a big long answer, though i wouldn't mind one.
I mean, I understand how a nuclear sub works, and a chemical spacecraft(duh), but I just can't see where the propulsion comes from.

darkhunter
2003-Aug-30, 09:26 PM
This is a stupid question. I know it is. It reeks of stupidity. But I'm asking anyway. How would a nuclear-powered spacecraft work? I don't need a big long answer, though i wouldn't mind one.
I mean, I understand how a nuclear sub works, and a chemical spacecraft(duh), but I just can't see where the propulsion comes from.

Just a few examples of the top of my head (well, not literally--I don't have spaceships parked there--they're out in the garage... :lol: )

Like Hero's Engine (http://history.msfc.nasa.gov/rocketry/02.html)--take a nuclear reactor--it will be over the boiling point of water. HEat the water to steam, and shoot it out a nozzle at the back of the rocket. It worksLike this (http://www.dunnspace.com/dumbo.htm)--Another example (http://internet.cybermesa.com/~mrpbar/rocket.html) They call the concpt a NERVA (http://ans.neep.wisc.edu/~ans/point_source/AEI/sep95/rocket_programs.html) Engine. Here's another NERVA site (http://www.sfwrg.org/n002.html)

Can also be used to power an ion drive (http://www.madmadscientist.com/iondrive.html) for low thrush over a really long period of time--might even be able to get the reaction mass from the ice...
One space probe (http://nmp.jpl.nasa.gov/ds1/) that has used an ion drive -- It worked (http://nmp-techval-reports.jpl.nasa.gov/DS1/IPS_Integrated_Report.pdf) (Link to a PDF Document) (This link also has some technical specifications...)

Fission would work, but fusion would be better--can split the water to produce the fuel for the reactor, and use the oxygen to replisnish your ships supply, and use the exhaust of the reactor to augment the thrust.

Edit: :oops: Forgot about Orion (http://www.sfwrg.org/o001.html)--basically throw nuclear bombs under a heavy plate and detonating them--could be used to put an aircraft carrier into orbit--or a battleship with several space shuttles and gunships strapped to it. The sad thing about forgeting this one is that I'm reading Footfall and am at the part where Hairy Red started working for the guys building the Michael :-?

edit fix embaressing spelling mistake :oops: :oops:

darkhunter
2003-Aug-30, 09:28 PM
I would guess that with financing problems and the usual beaurocratic hoops to jump through I would guess that no, it would not happen.

Unfortunatly true...however, I hope that one day we will be allowed to build one (I beleive we already have the capability)

SAMU
2003-Aug-30, 11:19 PM
With a nuclear powered spacecraft you use the nuclear power to produce electricity and use the electricity to produce a high tempreture electric arc (think electric iron furnace(or some other electro plasma thrust)) to heat the propelant. Not as efficient as ion propulsion but a lot simpler and a lot higher thrust.

The spacecraft would be unmanned and would not stop every time they came near a planetary system but would flyby and take high res pictures(think Hubble telescope). If they found a nice planet then we might send a manned ship. Of course when we send them we will send several so that, regardless of their speed, we can be assured of one or the other of them arriving at a new star system every few years. The calculation works like this: At 10% light speed each ship will arrive at a new star system every 40 years or so. Launch 40 ships and you will on average have one arrive at a new system approximately every year.

Interstellar by the end of the century? This century? Sure. Last century I suspect that we only used nuclear rocket propulsion for secret interplanetary manned operations. Unless we were given extraterrestrial spacecraft technology through contact with E.T.s or stole some by evesdropping on their transmisions through S.E.T.I. and assuming that extraterrestrial spacecraft technology is more powerfull than that described above.

Colt
2003-Aug-31, 01:49 AM
Not a stupid question, Reacher. :) I doubt alot of people would really understand the more complex bits of nuclear propulsion. Basically though, imagine it like a tea kettle. The fuel (even plain water) is heated extremely fast and to a very high temperature so that it flashes into steam and jets out of the back. Same concept as a chemical rocket, expanding gases go out of a nozzle. In a nuclear rocket you would run the fuel over the nuclear material and that would cause the fuel to flash into a gaseous state. The greater difference in temperature between the nuclear material and the fuel the better the efficiency of the rocket. These type of rockets are commonly referred to as Steam Rockets. :D A common myth is that these would produce radioactive rocket plumes.. Not at all. No radioactive material escapes the propulsion system in a working engine. They would be about as safe as the nuclear submarines which are prowling the oceans today.


Shame on you Dark. :) Footfall is near the top of my SF best list, I read it a couple of weeks ago for the first time. You have to love Michael. Space battleship anyone? :wink: This should help you imagine what Michael looks like: http://www.up-ship.com/apr/michael.htm. It's surprisingly close to what I thought it would look like. I didn't start a thread on Footfall because I was kind of busy at the time. Maybe you should start one about it when you finish the book and I can chip in?

I'm a really big fan of Orion as you can probably tell by this animation I made for it: Orion test animation (http://www.geocities.com/wandererofthewastes/orion_test.gif) (if the link doesn't work go to the Aerospace section on my site). I cobbled that animation together as a test, I've noted several things that need fixing. :D Orion doesn't have to look like that either, we could literally strap a destroyer onto the drive section and launch it into orbit easily. The original drawings of it looked like a giant bullet. :) The reason I didn't mention it for a generation arcology is that I think that it would make for a bumpy ride with something like an ecosystem to think about. It is possible though.

Here is a really good site on nuclear propulsion: http://www.nuclearspace.com/.

Nuclear is the way to go. :D -Colt

Musashi
2003-Aug-31, 02:42 AM
Nice animation Colt =D>

eburacum45
2003-Aug-31, 02:55 AM
I doubt that we will even get an unmanned interstellar probe off this century; if we do, the craft won't get there for another century or two; however if we develop enough solar collection satellites in orbit around the sun we could start mass producing antimatter, and this would allow a fantastic specific impulse -
http://www.orionsarm.com/ships/amat-pulse.html
from
http://www.orionsarm.com/ships/drives.html
and a much faster journey.
but the generation ship is a bit of a dead end; if these are ever built, they will need fantastic amonts of fuel, even with an antimatter drive-
and they will be so slow that faster ships will be built later and arrive first, taking all the good real estate.

Stylesjl
2003-Sep-02, 05:31 AM
Given the current state of space technology; does anyone believe that an instellar flight might occur before the end of this century?

For machines built by humans, yes for humans travelling themselves no or it will be first time shortly next century

publiusr
2005-Mar-03, 07:29 PM
With the new painted sail, we might have a good TAU mission in 20-50 years.

If we push Heavy Lift.

Nicolas
2005-Mar-03, 07:35 PM
With the new painted sail, we might have a good TAU mission in 20-50 years.

If we push Heavy Lift.

What do you mean with "the new painted sail"?

Van Rijn
2005-Mar-03, 08:25 PM
Are we talking manned or unmanned? I think something along the lines of the Starwisp:

http://www.answers.com/topic/starwisp

is possible in that time frame - that is, some kind of beam accelerated low mass probe. I would consider a bulky manned or even unmanned spacecraft far less likely.

Within the century, space based telescope arrays should be able to provide detailed images of earth sized planets in other solar systems, so we would have a pretty good idea of what we would find, even without star travel.

geokstr
2005-Mar-03, 11:39 PM
There is a really strange irony with interstellar travel. Given the length of time it takes to make such a journey, and the rapid pace of technological progress, each probe or ship sent out will be overtaken and passed by later ones. The first one to arrive at a given destination will have to wait, perhaps a hundred years or more, for the earlier missions to arrive in the reverse order in which they left.

Bizarre, ain't it? :-?

publiusr
2005-Mar-04, 05:36 PM
Here are some links of interest:

The painted sail:
http://www.technovelgy.com/ct/Science-Fiction-News.asp?NewsNum=330

A comparison of engines--note the 90% NSWR outclasses most everything--and just needs skillful plumbing--fuel injection tech only:

http://www.projectrho.com/rocket/RocketChart01Work.pdf
http://www.npl.washington.edu/AV/altvw56.html

This concept by Dr. Zubrin is considered far-fetched by many scientists. The fuel is a 20% solution of Uranium tetrabromide in water. The fuel tanks are thin capillary tubes embedded in a neutron damper (like cadmium) to prevent a chain reaction. The fuel is injected into the reaction chamber to create a critical mass. It is basically a continuously detonating Orion type drive with water as propellant. The controversy is over how to contain such a reaction. Zubrin maintains that skillful injection of the fuel can force the reaction to occur outside the reaction chamber. Other scientists are skeptical. Naturally in such a spacecraft, damage to the fuel tanks can have unfortunate results (say, damage caused by hostile weapons fire). The advantage of NSWR is that this is the only known propulsion system that combines high exhaust velocity with high thrust. The disadvantage is that it combines many of the worst problems of the Orion and Gas Core systems. For starters, using it for take-offs will leave a large crater that will glow blue for several hundred million years, as will everything downwind in the fallout area.

In space-use would be fine--and this could produce 1 g thrust for artificial gravity.

With the need for a rugged heavy design--and the need for water, NSWR would make a good payload for this.
http://www.astronautix.com/lvs/searagon.htm

Simply have RP-1 in the first stage two stages and the 'bromide mix for the payload. Get hydrogen and oxygen from sea water by towing behind a vessel like the nuclear icebreaker Arktika. Then add water to the payload. But keep the mix away from the water.

Launch Sea Dragon normally, and when away from Earth, mix the 'bromide solution with the sea water--but only after Earth escape. Fire the payload in such a way as to have the exhaust trail never contacting any planet, and the solar wind will take care of the rest.


Other drives
http://www.projectrho.com/rocket/rocket3c2.html

New concept?
http://www.spacedaily.com/news/fuel-01a.html
http://spaceflightnow.com/news/n0101/19marsnuclear/

New concrete use...
http://infiniti.msn.com/?id=28

Nicolas
2005-Mar-04, 06:50 PM
Oh that is what you meant with the painted sail. There's been a thread about this sail in GA or ATM.

SAMU
2005-Mar-05, 10:53 AM
Yes, but it won't be done using 1940s rocket technology. It will be done using 21st century computer technology.

fossilnut2
2005-Mar-05, 04:34 PM
A big NO.

We don't even have the beginnings of a technology to produce materials to withstand such a flight.

And exactly where is this spacecraft going? Why? A lot of inter stellar spaceflight proponents conveniently 'assume' there is somewhere worth going within a few tens of light years. Where is this planet people are going to jump off onto with just the right air, gravity, radiation, etc.? It's vastly more likely it would be a several hundred year trip where the arriving generation gets to live in a sealed chamber...wow... luxury.

As for human flight. I'll leave that to others. I get antsy after being cooped up on an airplane for 6 hours...let alone the rest of my life.

Sever
2005-Mar-05, 06:51 PM
With the need for a rugged heavy design--and the need for water, NSWR would make a good payload for this.
http://www.astronautix.com/lvs/searagon.htm

Perhaps this would be cheaper. (http://www.astronautix.com/lvs/rombus.htm)
Does anyone have an idea of the travel times and fuel requirments to say... Alpha Centauri?

publiusr
2005-Mar-08, 10:26 PM
Can't say. But Sea Dragon is the cheapest of all mega HLLV's being apressure-fed with shipyard steel.