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Re: Engineering Newsletter
Tim replies to Kelly:
>I can't see how staying would be safer. Unless you expect the drive system
>to fail? Your still relying on the the same life support systems.
I think I was expecting the drive to fail or blow up, but then again, if the
risk was so high, it would have been likely to blow up on the outward
journey. Since even a small risk (more than 1:1000) would not really be
acceptable, you are probably right.
>>I've doubts about that, a lot of things are unnessary renewed also a lot of
>>effort is used to develop new things, if we would maintain the current
>>level of technology and not innovate, we probably had a lot more spare time.
>Actually most companies only spend about %5 on research and development. The
>rest goes to manufacturing. So I don't expect a big saving there.
OK, but we don't need much manufacturing after the initial build up. It
takes much less effort to keep what you have than to build something from
Also a big amount of the 95% spend on manufacturing are the cost for raw
materials, I expect the cost of mining raw materials will be less at TC
because we can pick the easiest sites. No deep-sea oil drilling, most ores
we need will be somewhere near the surface.
I still don't see why it is not possible to scale things down. If you need 1
million people to feed 3 million people why can't you do with 100 workers
for 300 people?
I think a lot of organizational and social professions almost unneeded on TC
because it is such a small community that doesn't have direct economic purposes.
>Later in this letter you mentioned this idea again and suggested if systems
>were designed to be maintained they would require less replacement. To a
>degree true. But after a couple decades everthing wears out; and the reason
>we got used to throwing away things rather than repairing them, is its
>cheaper and takes less effort.
Yes, but in those decades you would need much less new materials meaning a
lot less work. The cheaper-throwing-away habit will not work on TC because
it will take more effort to build a completely new object than to replace a
single part. The reason that I mentioned this was not to say that things
wouldn't wear out, but that the amount of work needed would be less since
not all parts of the object have to be replaced each time.
If you would throw away an object because one part breaks down, it would
mean that the average life time of most objects would not be probably less
than 3 years.
>> What I meant is that a new planet would give us more than Antarctica could,
>> I don't mean that it could be a place to live, but a place to get much new
>> scientific information.
>Agreed. For scientific purpose a alien biosphere would be a goldmine! But
>it wouldn't help the crew to survive.
No indeed, at least not for the first 20 years. But the mission would mainly
be a scientific one. So you may want to stay longer at TC then the southpole
just because there is much more to investigate.
>>>That asumes the engines can provide the thrust equivelent to 1,000,000 times
>>>their own weight. No engines now made can do that. The best fusion
>>>engines I've heard specilated about can do 6 times there weight. We could
>>>probably expect that to go up to 20, but not a million.
>>OK, take 1 engine that could acclerate itself and 19 other engines, than the
>>other 19 engines didn't need to accelerate themselves anymore so they could
>>use all their power to accelerate the ship.
>That works for 20 to one. But you still have the weight of the fuel for the
Yes, but now you have 20 engines instead of 1 to push the fuel (the amount
of fuel is not multiplied by 20 but by less than 20, depending on the weight
of the engine).
Here an anti-note (saying you may be right)
I've tried setting up some formulas, from them it follows that you are
right, I still don't see why though. (Formulas have a habit of not giving a
>> Storing fuel doesn't need much that much facilities.
>But it does take a lot of facilities to carry and move it.
But do they need to be serviced all along the trip?
>> I don't see why good
>> planets without live could not be used.
>Probably any planet about earth size would have life (assuming its not
>radically hot or cold.
Wow, you are really optimistic. Or are you assuming that most earth-sized
planets are too hot or too cold?
Most Earth sized planets will have a dense atmosphere (not necessary oxigen
rich). The ones that are cold are too far from their Sun or have too few
greenhouse gasses. The ones that are too hot are too close to their Sun or
have too many greenhouse gasses.
Should too hot or too cold be a problem? Too hot maybe, it is easier to make
something warm than to make something cold. But why are cold planets not good?
By the way some people are suggesting on making a real atmosphere on Mars,
wouldn't that dissolve constantly? On Earth gravity is high enough to keep
its atmosphere, but on Mars the atmosphere is probably lost due to lack of
>Right, thats why I keep talking about space colonies. Raw materials are far
>easier to get at in space then on a planet. By mid 21st century we'll
>probably be moving a lot of our heavy industry of earth and into space for
>that reason (expect the third world to screem!), so I expect our starship
>crew would not think of trying to get ore up off a planet.
I'm not sure, would recycling not have a bigger influence on reducing the
need for raw materials? Taking all the rubbish down means that the rubbish
on Earth would increase, and we already have to much of that.
>I was expecting to store standard groceries. Meat, eggs, milk, vegies,
>breads, pasta all that stuff. With the exception of the emergency rations,
>which would be optimized for high nutritian and low weight. Everything would
>be as standard as possible. Thats why I used food weight numbers for home
>consumers, not exploration or military missions.
Huh, you just wrote:
>To keep down the weight I was figuring NO FOOD RAISING on the ship. Instead
>20 years of standard frozen foods in cryo, and 20 years of concentrated
Or did you mean no cows and pigs?
>Well you have to call and end to it sometime. I figured a couple years in
>systems would be all we could manage. Maybe a bit more than 3 years, but
>certainly not anywhere near 10. We need to keep the crews round trip time
>down below 30 years subjective (and not much more than that real time). I
>was also expecting a maximum ship service life of about 40 years.
If the ship doesn't need to travel back anymore a lot of parts are unneeded,
many of these parts are that of the engine, and these are the parts that
wear out most fast and are most hard to replace.
>> Huh, I can't follow you, am I right that you are against refueling or
>> building beaming arrays? If so, than the trip may indeed become very
>Beaming arrays yes. I was hoping we could get by on minning fuel for the
>fusion systems and maybe launching it.
You would need to mining and refine 1E10 kg of fusion materials, is that
possible? I don't know, I have no oversight about these numbers, do you know
what is acceptable?
>I was also assuming a larger number of people then you are. Maybe only a 100
>people on the ground, but I expect total research team would be a thousand or
>more. (Note the size of my ship.)
Yes, I had never noticed that before. That means that all work can be done
about 10 times faster.
>> Yes, we have also very powerful medcines, take penicillin, it has a very
>> broad range, and can kill many diseases at once, probably a lot of
>> extraterrestial ones too.
>The only reason we can use anti-biotics at all is they trip up something
>suttle in the bacteria they attack. Even a slight variation of that bacteria
>species is uneffected. If the stuff effected something biologically
>fundamental. It would kil the patent as well as the desease.
As far as I knew, you have two kinds of anti-biotics, broad-spectre and
small spectre. The small spectre have less side-effects but can kill fewer
bacteria. The broad spectre can kill many different kinds of bacteria. But
OK, I don't know that much about medcine, and I think neither do you. So I
think we can't really discuss it well. I admit alien creatures will be
different, but I just can't believe that it would be so different that we
won't have a single clue how to fight them. I think we just have to disagree
on this untill on of us has more hard data.
>Yeah, I'm begining to think we're doing this more out of habit then anything.
> Maybe thats why Dave can never seem to get around to fixing things on LIT.
> (I just got an E-mail from a new guy who wanted to join the newsletter and
>saw my name in the on-line archive and asked what the status is.)
What did you tell him? Does he join?
By the way I like this habit, I've learned a lot and given the project a lot
of thoughts, before this I had never thought of all the problems that have
>Maybe we should work up a conclusion reprt or something.
Yes, as soon as I have some time, I will make a start, my current timetable
is real busy, I hardly have time to write these letters.
>Well we never could come up with a solid reason why people wanted to go
>there. It was just an assumption for the discussion that people would.
>So yes, maybe even if people could g, they wouldn't bother. We don't bother
>to send people to the moon or Mars? ;)
Sending people to Moon or Mars is cheaper, takes much less time of
preparation and travel. The ship can be much smaller, no 20 year food supply
is needed, even Earth controlled robots are a possibility. So all these
things make it much more worth to go than TC.
If we could go to TC and back in 5 years then the drive to go there may be
much higher. Or if we could expand our lifespan by say 300 years.