Interstellar travel; possible or not?

[eburacum45]

Originally posted by tracer
A quick back-of-the-envelope calculation in an article I read about space-borne "magnetic sails" deduced that a magnetic ram-scoop would generate more drag than its own thrust could overcome!
In which case a magnetic sail would be most useful in deceleration, cutting down on the amount of fuel needed to perform this operation,
and decreasing the amount of fuel required for initial acceleration by a much larger amount.

[JRDelirious]

[quote]from Tuckerfan
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Originally posted by scr4
Don't we have the technology for long-term storage of sperm and ova? You can carry a fairly large selection of genes that way.
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That we do, but still, how many folks are we gonna need? After all, when the ship arrives, you're not going to want half the population to be infants or sitting around in storage, waiting to be implanted in a womb. So whilst we can carry millions of sperm and egg, we're still gonna need a certain number of fleshy humans as well.

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Originally posted by BioHazard
I don't think the Initial population really needs to be very big. I would say maybe 10 males and 50 females, from as many different ethnic populations and different parts of the world as possible (the females are more important in this case IMHO). A male is assigned ... (etc., directed-breeding program)
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That's a lot of "control" over an initmate part of people's lives. I can't really see folks agreeing to that, or it lasting for very long, ...

[quote]

Hmmm....

Let's assume this SF scenario:

First, of course, that there will be the technological development to build WHATEVER is a generation-ship that can handle multicenturial or multimillennial deep-space manned travel with high reliability and safety.

Assume also that a few hundred more years of development of reproductive technology, lead to the development of (a) foolproof birth-control (b) reliable long-term conservarion of reproductive nuclei (c) reliable and safe artificial conception and (b) reliable and safe artificial wombs.

Hypothetical assumptions established, then,

Then we could build a long-term generation-ship that is really a moving O'Neill colony, with an "initial population" in the low thousands, like the crew of a large naval vessel or the population of a small town -- and at least half again and maybe twice as many as absolutely necessary to run the operation, just to be on the safe side. Let the ship have the carrying capacity for a society at least twice as large again as the original crew, to accommodate for fluctuations in population, and more than that in terms of "idle space" to let people have some private time. That's right, considerations of "tight efficiency" would have to go out the window if you want people to live their whole lives inside the vehicle.

.

Then:
The ship can carry a "stock" of ova/sperm from maybe hundreds of thousands different people of each sex, NOT related to the crew.
During flight, you establish a strict population policy that still allows for natural reproduction and couple-forming but keeps the total birthrate at less than replacement levels....
...and periodically "replenish" the population with children born out of the "gene stock", shuffling the ova/sperm, by implantation in willing mothers or else by using the auto-wombs and being "fostered" or given in adoption to the extant crew who may want children above the aforementioned limits. The 'foster children' would get a confidential consanguinity record in their medical chart to avoid potential incestuous situations when/if they decided to reproduce. That way you keep periodically inserting fresh genes into the mix AND maintain a population appropriate for the carrying out of the mission.

Once you get wherever you want to get, and establish a viable colony, you then keep bringing genetic material out of "stock" to let the population grow to whatever is the carrying capacity of the location.

Yes, it DOES require you to essentially create a society with a distinct set of values; such as use of birth control being the default behavior; acceptance of birth limits; non-stigma to unidentifiable paternity and willingness to accept children "not of your blood"; if there is a difference between the number of "replenishment" births and the number of willing adoptive/surrogate/foster parents, a disposition towards communal raising. That I am also giving us a few hundred years to work on.

[eburacum45]

I really do recommend small, light payloads for interstellar ships- zygotes and artificial wombs, robots to look after the children, and didactic programmes (if feasible) to give the children a suitable education...
something similar to a self replicating robot would be a great help at the destination star-
fully replicating devices would involve automated mining and refining of metals and volatiles, and using replicating technology,
a suitable habitat could be constructed, as the chance of finding an earth-type planet is probably less than one in a thousand.

It is a shame to insist on high tech solutions,
but using self replicating tech, and as small a payload as possible, might make it possible to deliver a payload at a nearby star.
To move a generation ship would require a small asteroid made entirely of antimatter- unless the journey lasted hundreds of thousands of years.

[eburacum45]

And by the time interstellar missions are possible, the genome will be no doubt digitised, so that children may be born with randomly shuffled genes with no specific father or mother-

Moores law would suggest that a vast gene pool- perhaps a 'gene ocean' could be encoded on a physically small hard drive of some sort.

some people living today might find this odd, but so is travelling to a different star.

[Tuckerfan]

Just had a thought! What about animals? Would we, could we take them? Art? Would we allow people to take original works of art by the great masters with them, or would all of those have to remain on Earth? (Knowing that eventually the Earth's gonna get wiped out by the sun, would we even plan on sending things like the pyramids with future colonists?)

[BioHazard]

Originally posted by eburacum45
In which case a magnetic sail would be most useful in deceleration, cutting down on the amount of fuel needed to perform this operation,
and decreasing the amount of fuel required for initial acceleration by a much larger amount.

Did you read my post a couple pages back?

[eburacum45]

Originally posted by BioHazard
Did you read my post a couple pages back?
The very long one?
Yes.
Very Good.
Probably no point in using the field till you need to decelerate, as it is quite good at creating a drag.
I am of the opinion that antimatter really will be necessary to make interstellar flight feasible, and the vast amounts of energy available near the sun will be able to power even the most inefficient methods of manufacturing the same.
The postulated Antimatter Farm (http://www.orionsarm.com/eg/a/Am.html#amat_farm) is not very efficient, but if built in near solar orbit, it will not need to be.

[BioHazard]

My idea may cause drag, but it will also protect the Ship from erosion from the hydrogen. Plus if the particle accelerator is efficient enough, the drag should be negligable.

[eburacum45]

Antimatter Fusion hybrid (http://www.orionsarm.com/ships/amat-pulse.html)ships are also quite possible, and can't really be classed as star trek science-
warps and wormholes are fine for fictional purposes, but need a lot of handwavium...

[eburacum45]

Ok, no doubt the first few ships that we build will no doubt be similar in many respects to the ones you describe-
an ice shield is also advisable as pointed out in this thread, to intercept any dust particles that get through
one way or another we will get there...

[Mangetout]

Originally posted by eburacum45
I really do recommend small, light payloads for interstellar ships- zygotes and artificial wombs, robots to look after the children, and didactic programmes (if feasible) to give the children a suitable education...
Again, I ask why? What does it matter if the human genome never leaves the solar system?

[eburacum45]

There is every chance that it will not-
exploration may very well commence without humanity, is artificial intelligence proves to be possible-
the computer minds may replicate themselves rapidly, and set off to the stars with or without us- we are after all heavy baggage to take on such a long voyage...
the scenario I would hope for is one where humanity does manage to sneak out of thw solar system and find an indeterminate number of other world s to live on-
and it is not just for us,
we would no doubt take as much of the Earth's biosphere with us as we can carry...

[BioHazard]

I've always thought that we will never find any evidence of alien lifeforms, untill the second we leave the solar system. Then the aliens will land and say "Welcome to the Galactic Federation!"

[tracer]

Originally posted by BioHazard
I've always thought that we will never find any evidence of alien lifeforms, untill the second we leave the solar system. Then the aliens will land and say "Welcome to the Galactic Federation!"
And they'll be Vulcans greeting Zephram Cochrane, right? ;)

[Guy Montag]

I'd say NEO deflection/destruction. We develop most of the technology in probes that would roam the solar system, (most likely) pushing comets and meteors around -- how many would one need for complete coverage? It would only be a matter of time before you wanted to make a few smaller, faster ships to catch short-notice NEOs, and faster and faster probes are made. It's not much of a step from there to add people, and send it to the stars.

For the record IANAPhysicist/Astronomer/High School Graduate

[eburacum45]

Yes, grab the NEOs, they are valuable resources in the sky.
They can become potential solar energy collectors, metal mines, habitats and some may even become interstellar probes.
Don't forget
The rule is, with interstellar probes, the smaller the payload the better.

[Tuckerfan]

Just had a thought tonight, there's a former NASA engineer who's trying to develop what would essentially be an artificial gravity drive. If she can get it to work (any day now, just like fusion! ;) ), it would mean an extremely cheap method of getting into space. (It'd take a few kilowatts to get something like the shuttle in orbit.) So, let's say Bill Gates were to suddenly come to his senses, hand her a few billion dollars and within a year, she produces the first working drive. She'd effectively be giving us the stars at this point. What would we do? Would we set sail on the cosmic ocean immediately? Or would we screw around in Earth orbit for fifty or more years before we set off?

[matt]

"...an artificial gravity drive. If she can get it to work (any day now, just like fusion! , it would mean an extremely cheap method of getting into space."

That it would. Trouble is, we know fusion works, it lies within our understanding of the laws of physics, and the problems of controlled fusion are technical, not theoretical.

Artificial gravity drives or other reactionless drives contradict the laws of physics as we understand them, or are based on alternate theories that aren't proven. So you're going to need some kind of evidence that the thing isn't a crackpot's dream before you get any investment (and your Nobel prize!)

As to the last bit, such a drive would make space travel so cheap as to take it out of the hands of governments and into the hands of private enterprise. Someone would strap a big chunk of something for shielding in front of a tug and point it in the direction of Proxima Centauri rather quickly, IMHO.

[Tuckerfan]

Well, according to this (http://popularmechanics.mondosearch.com/cgi-bin/MsmGo.exe?grab_id=9293733&EXTRA_ARG=&CFGNAME=MssFind%2Ecfg&host_id=1&page_id=8901&query=greenglow&hiword=GREENGLOW+) and this (http://www.discover.com/science_news/astronomy/lighter.html) the proposed device doesn't violate or alter any standing laws of physics. This (http://ffden-2.phys.uaf.edu/211.fall2000.web.projects/A%20Mourant/currentresearch.htm) page might have some more info, but unfortunately, the designer decided to make the text and the background nearly the same color. Not sure if this (http://www.americanantigravity.com/podkletnov.html) is a nutjob site or not, but it deals with some of same material. A google search, doesn't turn up anything else really helpful on the matter. I'd like to find out what the progress of her research is, and if I could kick in a few bucks towards making it happen.

[eburacum45]

Given the unlikely scenario that there is a relatively painless form of interstellartransport, we would arrive at the stars to find that they are inhospitable places...
plenty of planets like Jupiterand bigger, plenty of icy moons like Europa and Ganymede, plenty of dry little worlds like the Moon and Mars, a few failed earths like Venus, but very very veryfew Earths.
We had better be prepared to do a lot of terraforming, or construction of large scale habitats, when we get there. This will no doubt need nanoreplicators of some sort.

[tracer]

Originally posted by Tuckerfan
there's a former NASA engineer who's trying to develop what would essentially be an artificial gravity drive. If she can get it to work (any day now, just like fusion! ;) ), it would mean an extremely cheap method of getting into space.
In the decade or so since Podkletnov claimed to see a measurable decrease in the weight of anything placed over his superconducting device, NASA has not been able to duplicate his results....

[eburacum45]

Still, he is a popular topic...
Presumably such a method of propulsion would be expected to use the same amount of energy to get into orbit as the most efficient method not using antigravity- to wit -
the amount of energy that it would take to get a particular mass into space if a space elevator were available.
There ain't no such thing as a free lunch etc

Nevertheless I have no expectations that it will come to anything.
Space elevators, on the other hand- would be very useful, if not on the Earth, then perhaps on Mars.

[Tuckerfan]

Originally posted by tracer
In the decade or so since Podkletnov claimed to see a measurable decrease in the weight of anything placed over his superconducting device, NASA has not been able to duplicate his results.... IIRC, Dr. Li's research is only tangetally related to Podkletnov's work and she's the first to develop a type of superconducting disk that's believed necessary to actually succeed in getting "synthetic gravity" (as she terms it) to work. I'd like to know what happened with the research that lead to the "levitating" frog pictures. That certainly appeared promising.

[BioHazard]

The levitating frogs are only magnetics and thats it. They found that anything that is not attracted to a magnet is repelled by it, even water. Plus the magnetic fields neccesary are VERY strong.

[chargin]

Some of the posters on this topic mentioned space telescopes that will be able to image structures on extra solar planets. This absolutely astounds me, I have a 10" dobsonian scope and love using it, Ive read about the TPF system, but actually imaging a planets continents, if any, and then structures and even inhabitants floors me in the utmost. The photons from an object say 2 square kilometers (about the smallest thing we can see on the moon from an earth based scope loooking through our fuzzy atmosphere) would be so spread out that to collect even a few thousand would take a "collector" of a size Im afraid to imagine. Its seems to be common knowledge that its going to happen and soon from this list (which I have just discovered, cool stuff here) where is the sci. to back it up, Id love to read more about this and the tech that will be used or is it all just based on scaling from what we could see 30 years ago so in 50 years we will see 100x as much as we can now if things keep developing?

[eburacum45]

As I'm sure you know, being a telescopist yourself, the Kepler (http://www.space.com/news/kepler_go.html)mission is the most sensitive one planned- to be able to see continents an inerferometer design of multiple linked instruments several tens of AU would probably be required.
It is my wild prediction that such vasrt instuments will be commonplace in the deep future, as the societies in isolated solar systems will want to keep as sharp an eye as possible on each other.

[scr4]

Originally posted by chargin
Some of the posters on this topic mentioned space telescopes that will be able to image structures on extra solar planets.
Actually, that won't be possible for a long time. The goal of the TPF (Terrestrial Planet Finder) is to resolve the planet and the star as separate dots. Right now the glare of the star prevents us from observing the planet directly. But if we can resolve the two as sedparate points, then we can do spectroscopic analysis on just the planet. That will tell us a lot about the planet - atmospheric composition, rotation rate, maybe even surface properties. But to resolve features on those planets require 3 orders of magnitude better resolution than the next generation space telescopes.

In fact, the TPF may not have a particularly high resolution. The main difficulty in resolving a planet is not resolution, but the glare from the star sitting right next to it. The usual analogy is that we're trying to see a firefly sitting next to a car headlight. One way to solve the problem is by using an interferometer which has much higher resolution than a single telescope. Another way is to do everything you can to reduce scattering and diffraction, so that the glare from the sun doesn't wash out the light from the planet. A telescope optimized this way is called a stellar coronagraph, and you'd be amazed at the bag of tricks available for optimizing such a telescope. Both approaches have been proposed for the TPF mission.

[chargin]

Thanks guys. As I said Ive read about the TPF and its pretty amazing in itself, but what Im interested in is what are the nuts and bolts of these "super scopes" they are a HUGE step from a TPF which is just a big hubble really with some more instruments on board. I actually dont think any 10 LY distant planet will ever be imaged that intricately by us, just how many photons are available to image with, at that distance.

[Sam Stone]

The Terrestrial Planet Finder is the largest 'scheduled' mission, even if that schedule is tentative.

But down the road, there's the Planet Imager (http://origins.jpl.nasa.gov/missions/pi.html). This is the telescope I was talking about, that would be able to actually image details on the surface of the planet.

From a theoretical standpoint, there's no reason why you couldn't make interferometers of almost any size. The engineering problems would become very complex, however. Even the planet imager is beyond our engineering capability today, even if theoretically we know how to build it.

But we'll figure it out. One day we'll be looking at planets around other star systems with the kind of resolution we have looking at our moon.

[chargin]

Thats a great link Sam, I like the timeline of the future scopes