First Ark to Alpha Centauri
AA Institute
make a slight 'thought' contribution (albeit fictionally) to this
group:-
http://uk.geocities.com/aa_spaceagent/firstarktoalphacentauri.html
Enjoy...
Abdul Ahad
Alfred A. Aburto Jr.
It's either that Abdul, or we'll have robot craft leaving "Star Gates"
on every world :-)
Al
AA Institute
Hi Al,
Well, you never know. There will be some pet robots inside the ship to
help with the day to day housekeeping, I have jazzed up my screenplay
a bit since to make sure it's looking more "futuristic". But then
again, how much technology advancement can one realistically expect
inside a confinded, (6 mile x 20 mile) enclosure of the Aster-Com?
Abdul
George Dishman
"On a voyage spanning 50,000 years ..."
Materials have been announced with an areal density of ~3gm/m^2
which can withstand 2500C.
http://www.space.com/businesstechnology/technology/carbonsail_000302.html
Caption: "At 3 grams per square meter, the fiber is 25 times
lighter than standard copier paper. (Credit: ELSI)"
Find a way to put a reflective coating on that able to withstand
the temperature and you can get to Alpha in less than 3,500 years:
http://www.inspacepropulsion.com/tech/sails.html
We have the human genome so put it on a DVD and reconstruct people
at the other end. No, we don't have that technology yet, but we
have 3,500 years to develop it if the probe phones home for the
plans when it arrives, and it's likely we will be able to launch
this century.
My colonists will be there 46,500 years before yours ;-)
George
Rob Dekker
Hi Abdul,
I am a bit disappointed :
After your posting (in August?) of this asteroid ark story, you triggered a
few hundred responses. I think it was the largest thread in 2004 on this
newsgroup. So clearly interstellar travel speaks to the imagination of
people here. But did you make any changes as a result of all the problems
with this idea and suggestions for change which were posted ? I forgot the
details of your previous story..
The most significant issue I recall was that an asteroid would be a
specifically bad choice for an interstellar vehicle. Hard to construct, way
too heavy to manouver and not needed for protection if you move as slow as
you do. Couldn't you change it to something else ? Like super large
styrofome hollow spheres (with windows?) pushed by a small craft with the
engines, or something that balances scientific sanity with an original and
inspiring design ?
A second major issue that came up is the duration of the trip with a 900
people eco-system. 900 people is too small a population to survive.
Evolution theory suggests minimum of 40,000. Also, if we managed to
de-stabilize a huge eco-system like earth in a few hundred years (as you
suggest as the reason for launching the ark), that what makes you think that
a tiny ecosystem can survive for 50,000 years ? By continuing to
trash-and-burn everything it finds on its way to Alpha Centauri ? Is that
the message ?
Oh, and I miss the love story...
Keep on writing !
Rob
P.S. You got me curious about the ending now ! Let me guess : the New Earth
is already inhabited (by humans?), and they are building an ark which is
about to set course for Earth since New Earth was treated the same way as we
treat Earth ?!!
"AA Institute" <abdul...@ntlworld.com> wrote in message
news:adbf5bc1.04111...@posting.google.com...
AA Institute
>
> My colonists will be there 46,500 years before yours ;-)
>
things that yours would have missed. How boring it would be to leave
one planet here (Earth) only to arrive at another one exactly the same
(another Earth).
Best of luck.
AA Institute
>
>
> Keep on writing !
>
Thanks Rob. This isn't about speed, physics or hard scientific
rationale anymore... otherwise we get into another 200 thread
argument.
No, this is purely about adventure, living inside a *curved* miniature
world with rivers and forests in the "sky", cosmic sightseeing,
stunning dream views of interstellar night skies, deep sky astronomy
under pure star light on an ice world, creepy nightmares...! I think
it may be better to expand the whole thing into a novel in the long
term...
Abdul
AA Institute
>
> The most significant issue I recall was that an asteroid would be a
> specifically bad choice for an interstellar vehicle. Hard to construct, way
> too heavy to manouver and not needed for protection if you move as slow as
> you do. Couldn't you change it to something else ? Like super large
> styrofome hollow spheres (with windows?) pushed by a small craft with the
> engines, or something that balances scientific sanity with an original and
> inspiring design ?
>
strength of asteroidal material when you rotate the beast fast enough
to give you one - g of Earth gravity. It's not feasible, when the
asteroid is 5km in radius!!!
My god it's sheer high rotation speed is going to shred the thing
apart! Now, why the hell did I not think of something as basic as
that???
The rotation speed "v" would be v = (Rg)^0.5. So for my Aster-Com
design where the radius of the internal biosphere floor is about 3
miles (4.8 km), v = (4800 * 9.8)^0.5 = 217 metres/second ! That is 500
miles per hour!!! As pointed out by Alfred Aburto Jr, at that speed a
low density object of 2.9 grams/cm^3 (like asteroid Ida) would not
hold itself stable under the differential inertial stresses!
So I am seriously looking to build the 5km radius by 15km length
cylindrical starship out of synthetic materials and throw in the soil,
plants and animals for biosphere. So what are my options? If the
answer is there is no material that we can use within the limits of
our current technology... then I will stick with my asteroid idea as a
pure "fantasy" (scientifically inaccurate) concept. But you know how
much I'd hate to do that...
Thanks for any ideas!
Abdul
Laura
How about keeping the asteroid, but hollowing it out less, and installing in
it a rotating cylinder in which everything would take place. The asteroid
would not be stressed as much (it would actually be gyrostabilized if I'm
not mistaken, so wouldn't tumble), and would act as a shield against small
impacts and radiation (which could well be important on such a long voyage).
Of course, the huge added mass would cost more to accellerate and
decellerate with, but you had that problem to begin with anyway :-)
It might even, in a very hypothetical situation, be useful as camouflage.
Perhaps that could be worked into the story, as an unintended but ultimately
beneficial side effect :-)
AA Institute
> It might even, in a very hypothetical situation, be useful as camouflage.
> Perhaps that could be worked into the story, as an unintended but ultimately
> beneficial side effect :-)
You mean it might stop the nightmares? No, that would spoil the story.
I have decided to shelve my asteroid idea and go for a complete
synthetic construction in Earth orbit. So, I have had to rename the
ship too, it's not called the "Aster-Com" any more... the 'Aster'
element originally stood for 'asteroid'...
http://uk.geocities.com/aa_spaceagent/firstarktoalphacentauri.html
Laura
No, I actually meant to inadvertently avoid destruction or worse at the
hands of hostile passers-by on the way. Unlikely, I know, but might make for
an exciting and even humorously ironic episode in the movie :-)
In any event it would be good for stopping particle impacts - something a
synthetic thin-skinned vessel would be very susceptible to given the very
long duration of the voyage.
It's your story, though :-)
AA Institute
It's an idea, sure. The story probably looks kind of gloomy and
quiet... definitely there'll be some humour and bright moments! Just
because the starship is sailing in dark waters... plenty of bright,
sunshine (simulated by lights) and picturesque scenes inside will keep
things lively...
There is a fine balance between realism and dullness!
I wonder if cosmic rays can make objects of certain chemical
composition "glow in the dark"? So the ship might pass through a zone
of glowing gas or icy meteoroids acting as substitute for shooting
stars on Earth!
AA
Rob Dekker
> Actually, I have come up against a major major obstacle: tensile
> strength of asteroidal material when you rotate the beast fast enough
> to give you one - g of Earth gravity. It's not feasible, when the
> asteroid is 5km in radius!!!
>
> My god it's sheer high rotation speed is going to shred the thing
> apart! Now, why the hell did I not think of something as basic as
> that???
>
All hope is not lost Abdul :
Rotation speed is only an intermediate number. Did you do the
calculation which determines the stress forces in the material for
an asteroid of radius R ?
After all, speed is irrelevant. Only stress is important to determine
if your asteroid will stay in one piece, and how thick the wall needs to be.
I have the feeling that the problem is not so bad, especially if you
scale the asteroid to a factor 10 larger (to 100km radius or so).
That might be needed any way, since the population should be in
the tens of thousands.
Also, you could reduce the artificial gravity to 0.5g. That would make
a fun story also (imagine anything that is fun at low gravity..)
Rob
AA Institute
> since the population should be in
> the tens of thousands.
Cheers, Rob. You need such a large number of people to keep the gene
pool wide over 500 generations, right?
>
> Also, you could reduce the artificial gravity to 0.5g. That would make
> a fun story also (imagine anything that is fun at low gravity..)
Oh it's so much fun with a rotating starship like that. You could spin
up/spin down to adjust the level of gravity... that should keep the
generations entertained!
I have settled for a synthetic construction in the end, since there is
hope that in 200 years time when the ship launches, we will have made
great strides in material science to come up with much tougher
synthetics that could withstand the stresses. I also read somewhere
that low density bodies such as comets break up on close approaches to
planets within the Roche Limit. Since my starship is going to use
close gravity assisted fly-by's of giant planets like Jupiter and
Saturn for initial escape from the solar system, I felt it will be
better to use a synthetic construction...
Abdul
Rob Dekker
"AA Institute" <abdul...@ntlworld.com> wrote in message news:adbf5bc1.04112...@posting.google.com...
> "Rob Dekker" <r...@verific.com> wrote in message news:<XMjpd.26786
>
> > since the population should be in
> > the tens of thousands.
>
> Cheers, Rob. You need such a large number of people to keep the gene
> pool wide over 500 generations, right?
>
Right. Otherwize you will end up with a bunch of mutants and sick people,
or most likely they will just die out before they make it even halfway.
Nature is pretty harsh when it comes to small gene pools.
Incidentally, most so are most human social and religious rules :
It is NOT acceptable behavior to marry your cousin.
AA Institute
> "AA Institute" <abdul...@ntlworld.com> wrote in message news:adbf5bc1.04112...@posting.google.com...
> > "Rob Dekker" <r...@verific.com> wrote in message news:<XMjpd.26786
> >
> > > since the population should be in
> > > the tens of thousands.
> >
> > Cheers, Rob. You need such a large number of people to keep the gene
> > pool wide over 500 generations, right?
> >
>
> Right. Otherwize you will end up with a bunch of mutants and sick people,
> or most likely they will just die out before they make it even halfway.
> Nature is pretty harsh when it comes to small gene pools.
I agree. However, accommodating a number of people beyond a couple of
thousand is going to be a real problem in my fictitious starship of
just 6 mile (diameter) x 9 mile (length) cylinder. To give the mission
the fairest possible chance I will go for people from every single
race on Earth...from aborigines through caucasians to negros... and
mongoloids! Only hope is they don't start to hack each other to death
in their cultural divides..
>
> Incidentally, most so are most human social and religious rules :
> It is NOT acceptable behavior to marry your cousin.
Yes in most countries that's true. Pakistan is one nation well known
for making it some kind of a 'rule' to keep marrying within first and
second cousins. I know, because a couple of friends of mine from that
country were forced to do this. It's very very bad practice, it makes
the offsprings have all sorts of weird allergies like exma, and other
illnesses since the diseases do not get a chance to get diluted over a
wider gene pool.
I'm very glad to say that where I come from in Bangladesh, we don't
have such a silly practice of 'in-breeding'! Ugggghhhh!
Abdul
George Dishman
> "Rob Dekker" <r...@verific.com> wrote in message news:<XMjpd.26786
>
>> since the population should be in
>> the tens of thousands.
>
> Cheers, Rob. You need such a large number of people to keep the gene
> pool wide over 500 generations, right?
Your web page said 50,000 years, that's between 2000 and
2500 generations.
> Oh it's so much fun with a rotating starship like that. You could spin
> up/spin down to adjust the level of gravity...
Not easily - conservation of angular momentum. Letting very
large masses move away from the ship and pulling them back
in would do it, like a skater's arms, but the range will be
limited. Also there will be a narrow band to prevent calcium
loss from bones. A change of a few percent wouldn't even be
noticed.
> ... Since my starship is going to use
> close gravity assisted fly-by's of giant planets like Jupiter and
> Saturn for initial escape from the solar system, I felt it will be
> better to use a synthetic construction...
Check how fast you can get this way. A single pass will give
a small increase which you can build up until you reach escape
speed but after that, you cannot turn back for another boost.
The real problem however is how you stop at the other end. You
cannot use the same technique since you cannot control your
entry into the system sufficiently accurately and even tiny
errors in measurements from Earth prior to launch time mean
the planets may not be where you want them when you get there.
George
George Dishman
"AA Institute" <abdul...@ntlworld.com> wrote in message
news:adbf5bc1.04112...@posting.google.com...
> "Laura" <la...@nospam.me> wrote in message
> news:<co3kl8$1vq0$4...@news.cybercity.dk>...
>> "AA Institute" <abdul...@ntlworld.com> wrote in message
>> news:adbf5bc1.04112...@posting.google.com...
>> > "Laura" <la...@nospam.me> wrote in message:
>> >
>> > > It might even, in a very hypothetical situation, be useful as
>> > > camouflage.
>> > > Perhaps that could be worked into the story, as an unintended but
>> > > ultimately
>> > > beneficial side effect :-)
>> No, I actually meant to inadvertently avoid destruction or worse at the
>
> It's an idea, sure. The story probably looks kind of gloomy and
> quiet... definitely there'll be some humour and bright moments! Just
> because the starship is sailing in dark waters... plenty of bright,
> sunshine (simulated by lights) and picturesque scenes inside will keep
> things lively...
Lights would be inside. Calculate how much total power
your nuclear reactor (or whatever) will produce then you
can work out the outer skin temperature to radiate that
amount. Enrgy is conserved so no matter how you use the
power, eventually it ends up as heat. If the temperature
is too low for comfort, good thermal insulation on the
skin will raise the internal temperature. You could also
gold plate the outside.
Camouflage tries to blend in with the background. The ship
would glow with long wavelength infra-red against a cold
background but it's hard for us to even spot brown dwarf
stars, never mind an object only a few miles across. In
fact we have great trouble finding rocks within the solar
system.
...
> I wonder if cosmic rays can make objects of certain chemical
> composition "glow in the dark"? So the ship might pass through a zone
> of glowing gas or icy meteoroids acting as substitute for shooting
> stars on Earth!
http://www-ssg.sr.unh.edu/tof/Outreach/Interstellar/?Interdepth.html
75% hydrogen, 25% helium, both transparent, at about 1 atom
per cc, and a tiny amount of fine, black dust. Although the
density is very low, you may still need to consider drag
over such a long voyage.
George
AA Institute
> Your web page said 50,000 years, that's between 2000 and
> 2500 generations.
Out of interest, what formula do you use for this? I just did a
simplistic 50,000/100 to get 500 generations! (Assuming a lifespan per
person of 100 years)
It's not that simple , right?!
>
> > Oh it's so much fun with a rotating starship like that. You could spin
> > up/spin down to adjust the level of gravity...
>
> Not easily - conservation of angular momentum. Letting very
> large masses move away from the ship and pulling them back
> in would do it, like a skater's arms, but the range will be
> limited. Also there will be a narrow band to prevent calcium
> loss from bones. A change of a few percent wouldn't even be
> noticed.
In this mission, no such spin ups/spin downs are planned... so I wont
have to worry too much here. Once the ship reaches its nominal 1-g of
artificial gravity (at a biosphere rotation speed of c. 800 km/hour)
using its spin thrusters, it should stay at that speed indefinitely.
If *small* adjustments are needed along the journey, the spin
thrusters will be used.
>
> > ... Since my starship is going to use
> > close gravity assisted fly-by's of giant planets like Jupiter and
> > Saturn for initial escape from the solar system, I felt it will be
> > better to use a synthetic construction...
>
> Check how fast you can get this way. A single pass will give
> a small increase which you can build up until you reach escape
> speed but after that, you cannot turn back for another boost.
> The real problem however is how you stop at the other end. You
> cannot use the same technique since you cannot control your
> entry into the system sufficiently accurately and even tiny
> errors in measurements from Earth prior to launch time mean
> the planets may not be where you want them when you get there.
>
It's complicated, hence this is only a fantasy voyage...
Tim Auton
>"George Dishman" <geo...@briar.demon.co.uk> wrote:
>
>> Your web page said 50,000 years, that's between 2000 and
>> 2500 generations.
>
>Out of interest, what formula do you use for this? I just did a
>simplistic 50,000/100 to get 500 generations! (Assuming a lifespan per
>person of 100 years)
>
>It's not that simple , right?!
You don't plan to have children when you're 100? I'll be happy if I
hold out that long; I expect my balls will have shriveled long before
then. 25 years is, very roughly, a generation. People tend to have
kids around that time (+/- 10 years, very roughly). That may not be
all that's important evolutionarily, but the genetics are fixed at
conception, and that's what we're talking about.
Tim
--
Foo.
Greg Neill
news:qsshq0l4b4961jlbb...@4ax.com...
Until quite recently in our history the average age for
starting a new generation was about 16. You started there
and kept at it until you or the missus dropped dead of old
age at about 35 (Well, disease actually; bodies wore out
pretty quickly from malnutrition and constant battles with
disease).
AA Institute
<snip>
> then. 25 years is, very roughly, a generation.
I thought as much. So 50,000/25 = 2000. I stand duly corrected, the
2,000th generation will eventually get greeted by the warm sunshine
from Alpha Centauri!
With an initial crew make-up of just 900 people, they will have
"inbred" hundreds of times over that expected for natural conditions
on Earth, right? And there'll be all diseased and weak, etc when they
arrive at New Earth...
There is a way around this: you can take frozen eggs and sperm from a
much wider gene pool on reserve from Earth; the Centauri Princess'
(name of the starship) computer monitors births and deaths along the
voyage for each person/family. It calculates roughly after how many
natural births one needs to expand one's gene pool. The ship's medical
team then advise their passengers *when* they should start drawing on
the frozen fertility ingredients...
So there is a solution (assuming frozen genetic material can keep for
50,000 years of course!)
One question: when the 50,000th year party celebrations are to be
thrown on the ship right at the end... what would you call that? It's
not the 50,000th "centenary"? A new word is needed in the future
spaceflight dictionary...
Abdul
George Dishman
"AA Institute" <abdul...@ntlworld.com> wrote in message
news:adbf5bc1.04112...@posting.google.com...
> <snip>
>
>> then. 25 years is, very roughly, a generation.
A few hundred years ago, it was common for the woman
to get pregnant and then get married, just to check
there were no problems. This might have been in the
late teens and typical family size was roughly 5 to
10 children with two year gaps. Mean age of the
parents at birth was around 22.
Then social attitudes changed and being born "out of
wedlock" was the worst thing possible. Better health
care meant fewer infant deaths and high living standards
meant less dependence on your children in old age so
family size tended to fall. A later start but fewer
children meant a slight rise in average age of the
parents.
Currently, there is a problem. In many countries the
average family is less than 2.4 children, which is not
even sustainable, and couples are waiting until their
thirties so that they have their careers established
before taking a break for a family.
You need to consider how attitudes and lifestyle will
be affected to work out the average age, and of course
over so many generations, there will be many changes.
> I thought as much. So 50,000/25 = 2000. I stand duly corrected, the
> 2,000th generation will eventually get greeted by the warm sunshine
> from Alpha Centauri!
>
> With an initial crew make-up of just 900 people, they will have
> "inbred" hundreds of times over that expected for natural conditions
> on Earth, right? And there'll be all diseased and weak, etc when they
> arrive at New Earth...
They would probably be producing children so deformed
that they would be sterile, or even be dieing before
puberty, within a few dozen generations.
> There is a way around this: you can take frozen eggs and sperm from a
> much wider gene pool on reserve from Earth; the Centauri Princess'
> (name of the starship) computer monitors births and deaths along the
> voyage for each person/family. It calculates roughly after how many
> natural births one needs to expand one's gene pool. The ship's medical
> team then advise their passengers *when* they should start drawing on
> the frozen fertility ingredients...
>
> So there is a solution (assuming frozen genetic material can keep for
> 50,000 years of course!)
The couples involved would ignore that advice completely
because they want to have _their_ children, not someone
else's. The first generation or two might stick to it
because they started the voyage knowing what was needed.
After that, why should kids stick to rules made by their
great-great-grandparents? They have the right to choose,
etc.
If a couple does ignore the advice, what could be done?
Enforced abortion followed by enforced artificial
insemination? I don't think so. Then again, who would
enforce it? If that was done to one couple, would they
then apply those rules to their children and grand-
children? It seems highly unlikely and remember the
problems don't show up until several generations later.
The solution is to have a population the size of
"Babylon 5". You should also consider that a population
the size you propose wouldn't have enough people to have
a league in most sports and couldn't support much of an
entertainment industry. It's going to be a very boring
place. The majority are going to be simple farmers, what
else is there to do?
> One question: when the 50,000th year party celebrations are to be
> thrown on the ship right at the end... what would you call that? It's
> not the 50,000th "centenary"? A new word is needed in the future
> spaceflight dictionary...
50000th anniversary
500th centenary or centennial
50th millennium
There may be new words in their vocabulary though. Consider
what we call the time 50000 years ago:
Lower Paleolithic -- (the oldest part of the Paleolithic
Age with the emergence of the hand ax; ended about 120,000
years ago)
Middle Paleolithic -- (the time period of Neanderthal man;
ended about 35,000 years BC)
Upper Paleolithic -- (the time period during which only
modern Homo sapiens was known to have existed; ended about
10,000 years BC)
What arrives in your story will have evolved to be quite
different to the humans that get there by faster (unmanned)
means and spent 45000 years exploring and adapting to an
alien planet.
George
Laura
<snip>
> One question: when the 50,000th year party celebrations are to be
> thrown on the ship right at the end... what would you call that? It's
> not the 50,000th "centenary"? A new word is needed in the future
> spaceflight dictionary...
>
> Abdul
It would be the 5,000th centenary, since centenary means something that
occurs every 100 years.
Laura
Oops... too quick for my own good :-)
500th, of course.
AA Institute
<snip>
> ...
> > I wonder if cosmic rays can make objects of certain chemical
> > composition "glow in the dark"? So the ship might pass through a zone
> > of glowing gas or icy meteoroids acting as substitute for shooting
> > stars on Earth!
>
> http://www-ssg.sr.unh.edu/tof/Outreach/Interstellar/?Interdepth.html
>
> 75% hydrogen, 25% helium, both transparent, at about 1 atom
> per cc, and a tiny amount of fine, black dust. Although the
> density is very low, you may still need to consider drag
> over such a long voyage.
>
Very interesting.
"Our sun (and solar system) are currently moving through a cloud of
interstellar gas." - quote from the above article.
As far as I know, the so-called "Pioneer effect" was never
satisfactorily resolved and I think both probes were retarded by
microscopic amounts in their solar system escape trajectories out
towards interstellar space. Do you suspect the interstellar
winds/medium could have had a part to play in this?
Thanks
AA
AA Institute
> You should also consider that a population
> the size you propose wouldn't have enough people to have
> a league in most sports and couldn't support much of an
> entertainment industry. It's going to be a very boring
> place. The majority are going to be simple farmers, what
> else is there to do?
My story shows never a dull moment. Mining comets, shopping, boating
trips along the river in the sky, taking shuttles out on starship fly
arounds, 360-degree night sky views (24 hour astronomy!), having the
freedom of job rotations, as well as catching up on all the local
gossip and mischief that's part of being who we are... There was even
going to be a "Miss Centauri Princess" competition... which I've had
to cut short due to time pressure...
There'll be sports facilities onboard too. No, it's a "miniature
Earth" alright albeit in a fantasy land...
>
> What arrives in your story will have evolved to be quite
> different to the humans that get there by faster (unmanned)
> means and spent 45000 years exploring and adapting to an
> alien planet.
These *faster* means of interstellar travel are still equally in the
realm of theoretical spaceflight, otherwise we would have launched a
few unmanned flights by now...
It's all in the future.
AA Institute
Thank you Laura. Very well, "500th Centenary Celebrations" it shall be!
Abdul
Dale Hurliman
Why not eliminate the men entirely and take along, oh, a gallon or so
of frozen sperm?
AA Institute
>
> P.S. You got me curious about the ending now ! Let me guess : the New Earth
> is already inhabited (by humans?), and they are building an ark which is
> about to set course for Earth since New Earth was treated the same way as we
> treat Earth ?!!
Not quite... keep on guessing.
AA
George Dishman
"AA Institute" <abdul...@ntlworld.com> wrote in message
news:adbf5bc1.04112...@posting.google.com...
>
>> http://www-ssg.sr.unh.edu/tof/Outreach/Interstellar/?Interdepth.html
>>
>> 75% hydrogen, 25% helium, both transparent, at about 1 atom
>> per cc, and a tiny amount of fine, black dust. Although the
>> density is very low, you may still need to consider drag
>> over such a long voyage.
>
> Very interesting.
>
> "Our sun (and solar system) are currently moving through a cloud of
> interstellar gas." - quote from the above article.
That's right but it is very thin. Outside the
cloud it would be even thinner.
> As far as I know, the so-called "Pioneer effect" was never
> satisfactorily resolved and I think both probes were retarded by
> microscopic amounts in their solar system escape trajectories out
> towards interstellar space. Do you suspect the interstellar
> winds/medium could have had a part to play in this?
http://spaceprojects.arc.nasa.gov/Space_Projects/pioneer/f23.gif
Pioneer is still inside the termination shock so
subject to the force of the solar wind and radiation
pressure (light) going radially out from the Sun.
The anomalous acceleration is towards the Sun so
in the wrong direction. To put them in context,
the radiation pressure is about a thousand times
(IIRC) larger than the solar wind force (both are
inverse square with distance). The anomalous
acceleration exceeded the radiation pressure when
the craft was at about 14AU.
Many people think the effect is just the pressure
of stray thermal radiation but it's hard to find
enough to account for the size of the effect (about
63W).
George
Joseph Lazio
GD> "AA Institute" <abdul...@ntlworld.com> wrote in message
GD> news:adbf5bc1.04112...@posting.google.com...
>> I wonder if cosmic rays can make objects of certain chemical
>> composition "glow in the dark"? So the ship might pass through a
>> zone of glowing gas or icy meteoroids acting as substitute for
>> shooting stars on Earth!
GD> http://www-ssg.sr.unh.edu/tof/Outreach/Interstellar/?Interdepth.html
GD> 75% hydrogen, 25% helium, both transparent, at about 1 atom per
GD> cc, and a tiny amount of fine, black dust. Although the density is
GD> very low, you may still need to consider drag over such a long
GD> voyage.
It's also worth pointing out that the Sun is in a region of relatively
low density called the Local Bubble, within which is a "small" cloud
of material known as the Local Fluff. I don't remember if Alpha
Centauri is within the Local Fluff as well, but, even the Local Fluff
is fairly rarified. Also, the size scales for these objects are
large. Based on the speed of your ark, it could easily take a
generation for it to pass through any such region, though I suspect
that it is unlikely that any exist.
--
Lt. Lazio, HTML police | e-mail: jla...@patriot.net
No means no, stop rape. | http://patriot.net/%7Ejlazio/
sci.astro FAQ at http://sciastro.astronomy.net/sci.astro.html
George Dishman
"AA Institute" <abdul...@ntlworld.com> wrote in message
news:adbf5bc1.04112...@posting.google.com...
> <snip>
> <snip>
>> You should also consider that a population
>> the size you propose wouldn't have enough people to have
>> a league in most sports and couldn't support much of an
>> entertainment industry. It's going to be a very boring
>> place. The majority are going to be simple farmers, what
>> else is there to do?
>
> My story shows never a dull moment. Mining comets,
your craft is travelling so fast you can't mine comets.
First they are so far apart you could never locate them
and then you couldn't slow down, get to the comet and
then catch up to your craft hauling materials without
using more then you can carry in fuel. Anyway your
craft has to be self-sufficient or it can't cross the
space between the stars.
> shopping, boating
> trips along the river in the sky,
Those sound good.
> taking shuttles out on starship fly
> arounds,
Why, it's probably a completely reflective surface
in a black sky, what's worth seeing to risk getting
vapourised by a passing grain of sand?
> 360-degree night sky views (24 hour astronomy!),
No Sun, no planets, no comets, no asteroids, nothing
but stars that don't change in a generation.
> having the
> freedom of job rotations, as well as catching up on all the local
> gossip and mischief that's part of being who we are... There was even
> going to be a "Miss Centauri Princess" competition... which I've had
> to cut short due to time pressure...
Those are the real stories, there's nothing outside
of interest.
> There'll be sports facilities onboard too. No, it's a "miniature
> Earth" alright albeit in a fantasy land...
Mostly sounds good but I still think you need to scale
up a bit.
>> What arrives in your story will have evolved to be quite
>> different to the humans that get there by faster (unmanned)
>> means and spent 45000 years exploring and adapting to an
>> alien planet.
>
> These *faster* means of interstellar travel are still equally in the
> realm of theoretical spaceflight, otherwise we would have launched a
> few unmanned flights by now...
Pioneers? Voyagers? There is still a lot to do but
probably the biggest challenges are getting sufficient
autonomy into the software and developing MEMS devices
to do self-maintenance. However, look at the Deep Space
project and its aims. We will be sending highly capable
robots to the outer planets in a few decades.
> It's all in the future.
Yes, but it's all being funded and worked on now.
George
AA Institute
> your craft is travelling so fast you can't mine comets.
> First they are so far apart you could never locate them
> and then you couldn't slow down, get to the comet and
> then catch up to your craft hauling materials without
> using more then you can carry in fuel.
My ship is travelling at conventional speeds not much faster than the
Voyagers and Pioneers. There is a method of forward navigation which I
illustrate here:-
http://uk.geocities.com/aa_spaceagent/fiction/FAQ.html
The starship's onboard computer maintains continuous radio contact
with a series of remote sensing, robotic "observation platforms" which
operate at, say t+10 days, t+50 days, t+200 days,... ahead of the
starship's current position (where 't' is the current ship time).
These observation platforms (dubbed Alpha, Beta, Gamma, Delta,...) are
critical "trailblazers" and serve as effective early warning alert
systems for upcoming cometary bodies (or lack of them). At each
mining/refuelling rendezvous point, the ship's navigation team weighs
up information relayed back by these robotic platforms to determine
potential risks to projected resource requirements. This decision
process is handled by the onboard computer system, with manual input
and overseeing by the navigation team.
The ship is thus continually moving forward on *known* resource
islands charted way ahead in its forward path. The crux of it is
though *mining* is more of a "just in case" strategy. Knowing what's
ahead of the ship is important also to avoid hitting anything large...
> Anyway your
> craft has to be self-sufficient or it can't cross the
> space between the stars.
Oh, absolutely. It's got enough nuclear reserves for power to last the
whole journey and if the biosphere cycle works right, the system is
sufficiently *air tight* to keep everything recycled over and over.
The 'mining' part is more of a "just in case" requirement...
> >
> > These *faster* means of interstellar travel are still equally in the
> > realm of theoretical spaceflight, otherwise we would have launched a
> > few unmanned flights by now...
>
> Pioneers? Voyagers?
True they are our first interstellar probes, but the Pioneers and
Voyagers are still travelling at conventional speeds and if they were
headed to Alpha Centauri, they'd take 30 to 50,000 years. I was more
implying about the 10% light speed missions which are still in the
realm of theoretical spaceflight...
cheers
Abdul Ahad
George Dishman
> "George Dishman" <geo...@briar.demon.co.uk> wrote:
>
>> your craft is travelling so fast you can't mine comets.
>> First they are so far apart you could never locate them
>> and then you couldn't slow down, get to the comet and
>> then catch up to your craft hauling materials without
>> using more then you can carry in fuel.
>
> My ship is travelling at conventional speeds not much faster than the
> Voyagers and Pioneers.
That's still >10km/s. You need reaction mass to slow
down, more to reach it and more for the mining vessel
to catch up to your ship.
> There is a method of forward navigation which I
> illustrate here:-
> http://uk.geocities.com/aa_spaceagent/fiction/FAQ.html
>
> The starship's onboard computer maintains continuous radio contact
> with a series of remote sensing, robotic "observation platforms" which
> operate at, say t+10 days, t+50 days, t+200 days,... ahead of the
> starship's current position (where 't' is the current ship time).
> These observation platforms (dubbed Alpha, Beta, Gamma, Delta,...) are
> critical "trailblazers" and serve as effective early warning alert
> systems for upcoming cometary bodies (or lack of them). At each
> mining/refuelling rendezvous point, the ship's navigation team weighs
> up information relayed back by these robotic platforms to determine
> potential risks to projected resource requirements. This decision
> process is handled by the onboard computer system, with manual input
> and overseeing by the navigation team.
>
> The ship is thus continually moving forward on *known* resource
> islands charted way ahead in its forward path. The crux of it is
> though *mining* is more of a "just in case" strategy. Knowing what's
> ahead of the ship is important also to avoid hitting anything large...
Do some research on how far apart they are, how big they
are and how you might find them. The chances of ever
detecting one by anything other than chance occultation
of a distant star are negligible.
>> Anyway your
>> craft has to be self-sufficient or it can't cross the
>> space between the stars.
>
> Oh, absolutely. It's got enough nuclear reserves for power to last the
> whole journey and if the biosphere cycle works right, the system is
> sufficiently *air tight* to keep everything recycled over and over.
> The 'mining' part is more of a "just in case" requirement...
Then it isn't effective because you are provisioning for
something that is going to be almost impossible. It's a
waste of resources if it isn't absolutely essential.
>> > These *faster* means of interstellar travel are still equally in the
>> > realm of theoretical spaceflight, otherwise we would have launched a
>> > few unmanned flights by now...
>>
>> Pioneers? Voyagers?
>
> True they are our first interstellar probes, but the Pioneers and
> Voyagers are still travelling at conventional speeds and if they were
> headed to Alpha Centauri, they'd take 30 to 50,000 years. I was more
> implying about the 10% light speed missions which are still in the
> realm of theoretical spaceflight...
Current materials can get as low as 3gm /sq metre:
http://www.space.com/businesstechnology/technology/carbonsail_000302.html
If that can be mirrored and deployed as a solar sail
1 micron thick with 90% reflectivity, it can reach
0.12% of the speed of light, or Alpha Centauri in
about 3500 years. My best guess is that we can have
the software and payload ready by the end of this
century and a speed of 0.25%c will be feasible by
then. I doubt we will have the technology to slow
down from 10%c, even though launching at that speed
could be achievable.
The bottom line though is that the real interest in
your story is the human side of living in such a
ship, these considerations don't really matter.
George
abdul...@ntlworld.com
1 micron thick with 90% reflectivity, it can reach
0.12% of the speed of light, or Alpha Centauri in
about 3500 years.<<<
Crikey, still as much as 3,500 years? We will still require a
generation ship to accommodate 140 generations along the voyage!
cheers,
Abdul
Bryan Heit
> <snip>
>
>Nature is pretty harsh when it comes to small gene pools.
>
>
This is not entirely true - in fact it appears that we modern humans owe
our existence to our ancestors population shrinking to a very small size
(I've seen a variety of estimates from 40 to 4000 as a minimum
population). Both genetic and fossil evidence support that this
happened. Basically, a large population is resistant to evolutionary
change - the impact of new alleles (different forms of genes) and new
genes are buffered by the large size of the populations. As a result
evolution of large population tends to be very slow, with only large
changes in selective pressures resulting in significant changes. Small
populations lack this buffering capacity, so a new allele or gene can
rapidly (i.e. in a dozen or so generations) spread throughout the entire
population. As a result small populations can rapidly evolve into new
organisms. This type of start-stop evolution has been written about
extensively - Stephen J Gould is one of the stronger proponents of this
form of evolution and has written many books/published many scientific
papers on the subject.
Who knows, this kind of change could even make for an interesting
side-line in AA's story. . .
Bryan
Anthony Cerrato
<abdul...@ntlworld.com> wrote in message
news:1101987591....@c13g2000cwb.googlegroups.com...
All in all, I think this thread shows IS travel by Gen ships
is not as easy as it looks! If we take into account the
probability of total ship failure due to malfunctions,
particle collisions, fuel [mass] exhaustion, radiation, and
all manner of social problems including disease, mutation,
political friction/wars, etc etc, the cance of survival over
lengthy voyages is small I think. It is no wonder they have
not reached Earth's neighborhood by now--if, even further,
the number of intelligent civs in the galaxy on average is
normally sparse, the answer to Fermi is pretty darn clear.
...tonyC
George Dishman
"Anthony Cerrato" <tcer...@optonline.net> wrote in message
news:7jSrd.4460$V03....@fe12.lga...
>
> <abdul...@ntlworld.com> wrote in message
> news:1101987591....@c13g2000cwb.googlegroups.com...
>> >>>If that can be mirrored and deployed as a solar sail
>> 1 micron thick with 90% reflectivity, it can reach
>> 0.12% of the speed of light, or Alpha Centauri in
>> about 3500 years.<<<
>>
>> Crikey, still as much as 3,500 years? We will still require a
>> generation ship to accommodate 140 generations along the voyage!
>> cheers,
>> Abdul
Your post hasn't shown up on my server or on Google
so I can only reply to the quoted text above.
You seem to be forgetting that was proposed as an
unmanned probe. Using a solar sail means the payload
is limited, perhaps in the region of 100kg.
> All in all, I think this thread shows IS travel by Gen ships
> is not as easy as it looks! If we take into account the
> probability of total ship failure due to malfunctions,
> particle collisions, fuel [mass] exhaustion, radiation, and
> all manner of social problems including disease, mutation,
> political friction/wars, etc etc, the cance of survival over
> lengthy voyages is small I think. It is no wonder they have
> not reached Earth's neighborhood by now--if, even further,
> the number of intelligent civs in the galaxy on average is
> normally sparse, the answer to Fermi is pretty darn clear.
> ...tonyC
Most of the engineering problems could be overcome. The
real problems would be social, you can't re-engineer
the passengers (though perhaps that's another story).
George
AA Institute
> It is no wonder they have
> not reached Earth's neighborhood by now--if, even further,
> the number of intelligent civs in the galaxy on average is
> normally sparse, the answer to Fermi is pretty darn clear.
> ...tonyC
The kinds of virtually insurmountable obstacles highlighted in my
story and the fact that those would be precisely the same obstacles
that any spacefaring civilisations crossing interstellar space would
be facing, have always caused me to steeply discount UFO sightings as
evidence for *real* visits by alien beings...
Abdul Ahad
Matt Giwer
>> <snip>
If I am wrong I will buy the first round but I have this gut feel
this small population is not the right explanation. It is the simplest
and Occam rules but it is really to convenient.
The negative factor is archaic HSS, use google and look at the
skulls. They are not our kind of humans, period. But they are
considered the same species. And if you agree archaic is not us them
we have the same "bottleneck" occurring twice.
There is no necessary problem with that but the other homo non-saps
do not appear to have had a problem with propinquinty nor filling the
land to a natural saturation point for the species.
Just a gut feel but there was something more than this bottleneck
going on.
--
If Arafat dies, how quickly will Israel find a new
excuse to avoid peace with the Palestinians?
-- The Iron Webmaster, 3280
AA Institute
> Small
> populations lack this buffering capacity, so a new allele or gene can
> rapidly (i.e. in a dozen or so generations) spread throughout the entire
> population. As a result small populations can rapidly evolve into new
> organisms. This type of start-stop evolution has been written about
> extensively - Stephen J Gould is one of the stronger proponents of this
> form of evolution and has written many books/published many scientific
> papers on the subject.
>
> Who knows, this kind of change could even make for an interesting
> side-line in AA's story. . .
>
On an epic 50,000 year voyage like that the number of alternate
realities and possible outcomes just defies the imagination. In
theory, one could write 50 separate novel sequels, each one covering a
1,000-year epoch in the long history of our distant descendants
drifting through the cosmos on this epic voyage into the complete
unknown...
The future sequels after the ending point of "First Ark to Alpha
Centauri" will be a lot more fantasy filled and exciting, as those
adventures would be truly 100% in the realm of the imagination. I
wanted to keep the initial start of this saga as much connected with
*our* reality as possible.
Now all I need is a $100 million Hollywood scale budget to get the
film rolling! (Any one know what George Lucas' private e-mail address
is by any chance???)
Abdul Ahad - LOL!
Anthony Cerrato
"George Dishman" <geo...@briar.demon.co.uk> wrote in message
news:cops9a$vuh$1...@news.freedom2surf.net...
>
> "Anthony Cerrato" <tcer...@optonline.net> wrote in
message
> news:7jSrd.4460$V03....@fe12.lga...
> >
> > <abdul...@ntlworld.com> wrote in message
> >
news:1101987591....@c13g2000cwb.googlegroups.com...
[snip]
> > All in all, I think this thread shows IS travel by Gen
ships
> > is not as easy as it looks! If we take into account the
> > probability of total ship failure due to malfunctions,
> > particle collisions, fuel [mass] exhaustion, radiation,
and
> > all manner of social problems including disease,
mutation,
> > political friction/wars, etc etc, the cance of survival
over
> > lengthy voyages is small I think. It is no wonder they
have
> > not reached Earth's neighborhood by now--if, even
further,
> > the number of intelligent civs in the galaxy on average
is
> > normally sparse, the answer to Fermi is pretty darn
clear.
> > ...tonyC
>
> Most of the engineering problems could be overcome. The
> real problems would be social, you can't re-engineer
> the passengers (though perhaps that's another story).
>
> George
I do agree that the most serious problems would probably
turn out to be sociologically related, but I don't think we
should underestimate the physical problems either. How can
you solve problems like "particle collisions, fuel [mass]
exhaustion, radiation," (to name only a few)--that is to
say, without massive trade-offs in losing resources and or
energy and sacrificing many other options (e.g.,
particularly, limitations on navigability may be serious.)
Seems to me to be many complex problems with Gen
ships...barring really magical tech advances, that is. Maybe
this will come in the next 10,000 to 100,000 years
though--if we last. :) ...tonyC
AA Institute
>
> I do agree that the most serious problems would probably
> turn out to be sociologically related, but I don't think we
> should underestimate the physical problems either. How can
> you solve problems like "particle collisions, fuel [mass]
> exhaustion, radiation," (to name only a few)--that is to
> say, without massive trade-offs in losing resources and or
> energy and sacrificing many other options (e.g.,
> particularly, limitations on navigability may be serious.)
> Seems to me to be many complex problems with Gen
> ships...barring really magical tech advances, that is. Maybe
> this will come in the next 10,000 to 100,000 years
> though--if we last. :) ...tonyC
Science and religion have a complex interconnection which most "pure"
scientific people sadly in the current era are totally blind to:-
"... If you have the power to pass beyond the zones of the heavens and
the earth, then pass beyond them! But you will never be able to pass
them, except with authority (from God)!" - Qur'an (55:33)
Abdul Ahad
Aidan Karley
> The kinds of virtually insurmountable obstacles highlighted in my
> story and the fact that those would be precisely the same obstacles
> that any spacefaring civilisations crossing interstellar space would
> be facing, have always caused me to steeply discount UFO sightings as
> evidence for *real* visits by alien beings...
>
question from a sceptical viewpoint a few years ago. It's published as
"If in Doubt, Blame the Aliens", ISBN: 0595156932. It gives an
interesting methodology for assessing the evidence in such
poorly-defined issues. To my mind it also illustrates the weakness of
such approaches, but I'll leave that for any readers to assess.
--
Aidan Karley,
Aberdeen, Scotland,
Location: 57°10'11" N, 02°08'43" W (sub-tropical Aberdeen), 0.021233
Bryan Heit
>
>>> Nature is pretty harsh when it comes to small gene pools.
>>
>
> <snip>
> If I am wrong I will buy the first round but I have this gut feel
> this small population is not the right explanation. It is the simplest
> and Occam rules but it is really to convenient.
The strongest evidence for a bottle neck in human numbers comes from
sequencing mitochondrial DNA (mtDNA). Certain genes within the
mitochondria mutate (evolve) at well defined rates - this occurs because
these genes are central to the operation of the mitochondria, and thus
mutate very slowly (most mutations = dead mitochondria). But compared
to the DNA contained in the nuclei of our cells these genes mutate
fairly rapidly, making them good for dating genetic changes which have
occurred in the last 5-million or so years. These types of studies have
been shown to be accurate in a variety of systems, and according to a
few studies have shown that all tested mtDNA's to date (in humans)
descended from a single woman who lived 140,000-290,000 years ago. This
data was first published in Nature in 1987; since then several other
studies have been published which both support, and expand, on this
original paper. Here's a link to the original publication:
http://www.artsci.wustl.edu/~landc/html/cann/
Here's a list of some more recent papers on the subject, with links:
http://www.genomenewsnetwork.org/articles/04_02/human_origins_lit.shtml
The concept of humans having gone through a severe bottleneck has been
well reported in both the science literature and in the media. Here's a
BBC article on the subject:
http://news.bbc.co.uk/1/hi/sci/tech/166869.stm
The relatively small variability between mtDNA's of different races
tells us that modern humans are a relatively new species - the fact that
all lines of mtDNA appear to be derived from the same ancestor tells us
that our founding population must have been quite small.
> The negative factor is archaic HSS, use google and look at the skulls.
> They are not our kind of humans, period.
Not entirely true. If you look at modern humans, across different
races, you will see variability within the structure of the skulls -
indeed, forensic scientists can determine race (to some extent) solely
on skull structure. The earlier skulls of HSS most closely resemble the
skulls of modern sub-Saharan Africans. Not too surprising that the
shape of the skulls has changed over the last 70,000 years or so - in
fact that is exactly what we would expect if humans went through a
population bottleneck (i.e. rapid evolution). And make sure you aren't
mixing up previous species of homo (i.e. Java, etc, which were all
sub-lines of H.sapiens) with our modern species of HSS - HSS has been
around for ~70,000 years, HS for ~ 2 million. Anatomically modern
humans belong to the HSS group, not the HS.
> But they are considered the same species. And if you agree archaic is
> not us them we have the same "bottleneck" occurring twice.
Evidence suggests that multiple bottlenecks have occurred during human
evolution, both at a whole-species level, as well as at the "race"
level. The articles I linked to above go into this in sole detail.
Keep in mind that population bottlenecking doesn't require a population
to shrink to a tiny size - all you need is to isolate a portion of a
population, and that isolated portion will be in a bottle neck. We know
of lots of cases where human populations have become isolated; from the
loss of land bridges due to melting glaciers (native Australians and
native N. Americans), to long-distance settlement (polynesian
populations). More modern examples all exist (i.e. early European
settlements in N. American). In all cases we can identify evidence of
population bottlenecking, and those bottlenecks all correlate quite
closely with the predicted time these peoples were cut off from their
founding populations.
> There is no necessary problem with that but the other homo non-saps do
> not appear to have had a problem with propinquinty
Your proof of this is?
> nor filling the land to a natural saturation point for the species.
Once again, your proof is?
Bryan
Rob Dekker
> real problems would be social, you can't re-engineer
> the passengers (though perhaps that's another story).
>
> George
>
Hi George, You wrote one post earlier, which I found quite brilliant and novel
(never heard this one before) :
"We have the human genome so put it on a DVD and reconstruct people
at the other end. No, we don't have that technology yet, but we
have 3,500 years to develop it if the probe phones home for the
plans when it arrives, and it's likely we will be able to launch
this century."
Could you elaborate a bit more on this idea, or was it just a wild thought ?
I think the challenge is in the machine that we send on our way now :
Since a machine can only operate reliably within the parameters of what it was
designed to do, this feels like sending a screwdriver attached to a cell-phone into space
and calling it later with the plans on how it should assemble a space shuttle...
George Dishman
> Hi George, You wrote one post earlier, which I found quite brilliant and
> novel
> (never heard this one before) :
Thanks. While I doubt it's original, recent advances
have made it much less fanciful than it would have
seemed a decade ago.
> "We have the human genome so put it on a DVD and reconstruct people
> at the other end. No, we don't have that technology yet, but we
> have 3,500 years to develop it if the probe phones home for the
> plans when it arrives, and it's likely we will be able to launch
> this century."
>
> Could you elaborate a bit more on this idea, or was it just a wild thought
> ?
Well the genome part is somewhat far-fetched, though gene
sequencers are available. There's a long way between what
we have and what would be needed but I think sufficient
first steps have been taken to show that it is feasible
in principle if not yet in practice. However, see the end
of this post for a more interesting variant.
> I think the challenge is in the machine that we send on our way now :
> Since a machine can only operate reliably within the parameters of what it
> was
> designed to do, this feels like sending a screwdriver attached to a
> cell-phone into space
> and calling it later with the plans on how it should assemble a space
> shuttle...
That's about right, land a Swiss Army knife on an asteroid
and tell it to turn it into the ISS ;-)
What we would need to do is send a probe with instructions
to survey the system when it arrived, look for rocky
asteroids, extract the metal and build an Arecibo-sized
antenna and solar panels to power the transmitter, then do
whatever scientific surveys we can imagine of everything it
finds and send back the results. If it was in the Alpha
Centauri system, ten years later (or maybe a bit more) it
would receive instructions to make whatever we decided was
needed for the system. If there were an habitable planet,
that could include starting artificial gestation of humans,
though I think we'd do a lot more investigating first.
My personal thoughts are a solar sail for propulsion because
it is equally effective for slowing down at the far end
without having any technology there, and is a passive system
that can be easily repaired if damaged. Speeds around 400km/s
should be achievable this century. This is a long page but
the best is near the bottom
http://www.inspacepropulsion.com/tech/sails_physics.html
Here's the sort of material we need though we would also
have to make it reflective at high temperature:
http://www.space.com/businesstechnology/technology/carbonsail_000302.html
For navigation, use relative timing of pulsars in the same
way that GPS satellites are used for location on Earth.
For a power, use a radioisotope thermophotovoltaic source
because the active component, basically a solar cell, can
be repaired without exposing a robot to the radioactive
source unlike an RTG.
http://powerweb.grc.nasa.gov/pvsee/programs/tpv.html
and half way down this:
http://www.nasa.gov/home/hqnews/2003/may/HQ_news_c03n.html
The isotope is trickier, my knowledge is limited, but Ni59
has a suitable half life and could be coated to minimise
radiation since only an isolated thermal source is needed.
Control would need to be triplicated at least with a group
of small computers running remote control robots to maintain
and replace each other and the robots. Everything would wear
out over these time scales.
For the robots, we would at least need to develop MEMS
technology to the point that it can manufacture copies of
itself. There's loads of stuff on the web:
http://mems.sandia.gov/scripts/index.asp
http://www.memsnet.org/mems/what-is.html
The best though would be if we can develop to atomic-scale
manipulation. This is old:
http://www.almaden.ibm.com/vis/stm/atomo.html
but could be developed to
http://www.imm.org/Parts/Parts2.html
Of course, not everyone agrees
http://www.imm.org/SciAmDebate2/smalley.html
Most of the technology needed is still well in the future,
but it is all available in development already, and for a
simple scientific research probe, I am fairly sure we could
launch by the end of this century.
Of course if you want to go a little more sci-fi, consider
if we could crack the biological problems of cryonics on
a healthy, fit subject:
http://en.wikipedia.org/wiki/Cryonics
Once frozen, take the subject apart, atom by atom, noting
the relative position of each to its neghbours. Send these
'plans' to the distant star system by radio, reassemble
using local raw material and thaw. It sounds great, but
don't calculate the bandwidth needed ;-)
George
Matt Giwer
I appreciate the papers. And yes there is more genetic variability in
a "tribe" of chimps than in all the human race and so forth.
>> The negative factor is archaic HSS, use google and look at the skulls.
>> They are not our kind of humans, period.
> Not entirely true. If you look at modern humans, across different
> races, you will see variability within the structure of the skulls -
> indeed, forensic scientists can determine race (to some extent) solely
> on skull structure.
I agree I am not a skull expert. I have no related training or
experience. I have looked at a lot of pictures of skulls. When I first
looked at a couple examples I expected to see something familiar. My
first reaction was, not human. I found a passing reference to a
suggestion that some of the pros think it is another species but not
enough to follow it up.
> The earlier skulls of HSS most closely resemble the
> skulls of modern sub-Saharan Africans. Not too surprising that the
> shape of the skulls has changed over the last 70,000 years or so
Those two statements are contradictory. We expect rapid evolution and
yet find none in some sub-saharan. Sub-saharan has much more variation
than everything outside it so there might be one variant that is
similar. So? We can either assume the Ainu are Caucasians or over the
millenia their isolation left them behind (our of) the mongoloid
changes as happened to the Europeans.
> - in
> fact that is exactly what we would expect if humans went through a
> population bottleneck (i.e. rapid evolution). And make sure you aren't
> mixing up previous species of homo (i.e. Java, etc, which were all
> sub-lines of H.sapiens) with our modern species of HSS - HSS has been
> around for ~70,000 years, HS for ~ 2 million. Anatomically modern
> humans belong to the HSS group, not the HS.
What I looked at was clearly labeled archaic and there were different
sources. The fact that they have a separate label of archaic means I
am not the one who sees the differences.
As to the bottleneck that is the problem. It says there was a time
when the number of humans decreased to a very low number. Fine with me
but they had to be in much the same location in order to keep
breeding. Guessing by modern behavior they would be in family, clan
and tribe groupings. The size of a tribe sort of fits the size of the
bottleneck population. And it had to happen in one geographic area
else we have to postulate different bottlenecks in different places
while the population in other locations flourished. And that sort of
negates the whole bottleneck idea.
>> But they are considered the same species. And if you agree archaic is
>> not us them we have the same "bottleneck" occurring twice.
> Evidence suggests that multiple bottlenecks have occurred during human
> evolution, both at a whole-species level, as well as at the "race"
> level. The articles I linked to above go into this in sole detail.
> Keep in mind that population bottlenecking doesn't require a population
> to shrink to a tiny size - all you need is to isolate a portion of a
> population, and that isolated portion will be in a bottle neck. We know
> of lots of cases where human populations have become isolated; from the
> loss of land bridges due to melting glaciers (native Australians and
> native N. Americans), to long-distance settlement (polynesian
> populations).
But in the time frame of HSS we know of exactly one such event of
interest and it does not involve Europe. That is when it was possible
to walk almost all the way from Asia to Australia. Glaciation tends
toward zero near coasts so walking around the Med coast would never
have resulting in isolation. And that is the location of interest.
> More modern examples all exist (i.e. early European
> settlements in N. American). In all cases we can identify evidence of
> population bottlenecking, and those bottlenecks all correlate quite
> closely with the predicted time these peoples were cut off from their
> founding populations.
>> There is no necessary problem with that but the other homo non-saps do
>> not appear to have had a problem with propinquinty
> Your proof of this is?
Proof? Evidence is all anyone can produce outside of logic, math and
the imprecise definition used in law.
>> nor filling the land to a natural saturation point for the species.
> Once again, your proof is?
Ever heard of a species that doesn't? Every indication of human
population increases is that they coincide with more effective means
of producing food or shelter or working conditions or most recently
medicine. The reason farming is a one way street for hunter/gatherers
is farmers produce more children making the farm more productive.
Quickly the population becomes to large to go back to the HG lifestyle.
When HSS left Africa it left behind its natural predators and had
weapons to discourage the new predators from getting a taste for them.
Keep in mind out of Africa isn't hard. Orangutans did it. HErectus
did it. During the ice ages they had the semi-jungles of the Arabian
coast as a passage.
--
Hodie septimo Idus Decembres MMIV est
-- The Ferric Webceasar
Matt Giwer
For this link, Bullshit!!! Maybe only one ! but I got excited.
> The concept of humans having gone through a severe bottleneck has been
> well reported in both the science literature and in the media. Here's a
> BBC article on the subject:
> http://news.bbc.co.uk/1/hi/sci/tech/166869.stm
So let me rephrase it. HSS was uniquely susceptable among all the
apes and monkeys and all the species to be affected by a volcanic
eruption. Why?
Pardon but why would anyone assume intelligence causes a unique
susceptibility to the consequences of a volcanic eruption?
This is an example of science writer syndrome.
If there are not equivalent effects is equal species at the same time
give it a rest.
--
Zionism is warmed over Deuteronomy for atheists.
-- The Iron Webmaster, 3305
Rob Dekker
I like it.
Any trip of thousands of years, with or without humans at the wheel would
be an exceptionally risky business (much chance of failure, little chance of success),
but it an interesting alternative to let the initial work be done by robots.. Including
feeding and educating the first new generation...:o)
Many problems shipping this out any time soon though :
For starters : Imagine designing any complex electro-mechanical system which still
works after 3500 years. We have no experience with that at all.
On the up-side, the communication would probably be the easiest problem to solve.
There is no need to let robots build an Arecibo-size antenna from asteroid material.
We can simply go optical :
Ship a 5 or 10meter telescope (also handy to have a sharp eye with you on the trip
and to look around once you arrive), with a nanosec TW laser for transmission,
and a ns pulse detector for reception.
That makes an excellent interstellar com-link, and is do-able today.
Bandwidth might also not be too problematic : ns pulses allows for about 1Gbit/sec
up-link (towards the ship). And there is time to do this...
Rob
"George Dishman" <geo...@briar.demon.co.uk> wrote in message news:cp5gl2$7g3$1...@news.freedom2surf.net...
George Dishman
> George,
>
> I like it.
> Any trip of thousands of years, with or without humans at
> chance of failure, little chance of success),but it an
> interesting alternative to let the initial work be done by
> robots.. Including feeding and educating the first new
> generation...:o)
My feelings exactly. If I was heading out to a
new star system, I would at least want to know
what was there before leaving. Letting the robots
build a space station and then getting humans
there with minimal risk, without the social
problems of generation ships and without the
enormous power drain needed for "life support"
seems to be an approach with a lot going for it.
BTW, I found the link that tells me this isn't
just sci-fi:
http://www.usatoday.com/news/science/2003-11-13-new-life-usat_x.htm
"Venter notes the synthetic bacteriophage has
5,000 base pairs in its genome. The human
genome has 3 billion, so similar work in human
form probably won't happen in this decade, he
says."
I suspect that thinking in terms of decades is
too optimistic but given a thousand years or
more, it seems inevitable we will achieve it.
> Many problems shipping this out any time soon though :
> For starters : Imagine designing any complex electro-
> mechanical system which still works after 3500 years.
> We have no experience with that at all.
We have quite a lot of information on the way
semiconductor devices degrade and probably a few
decades is the limit. The design starts from the
assumption that every aspect will wear out so the
first requirement is that every part can be
re-manufactured in situ. You want multiple systems
for redundancy against random failures anyway so
each unit would monitor those around it and if
some part fails, the first response would be to
make a replacement and then recover the materials
from the failed unit. Extend that to make
replacements on a regular basis so then most parts
are replaced by new before they fail. The energy
taken and mean life then define the power budget.
Another big advantage is that the probe could be
at a few tens of degrees K which greatly reduces
the mechanisms that cause wear-out so devices
could easily last for centuries rather than
decades. A few watts of power would be adequate
during the trip and of course unlimited solar
(stellar) power would be available once it
arrived.
> On the up-side, the communication would probably be
> the easiest problem to solve. There is no need to let
> robots build an Arecibo-size antenna from asteroid
> material. We can simply go optical :
>
> Ship a 5 or 10meter telescope (also handy to have a
> sharp eye with you on the trip and to look around once
> you arrive), with a nanosec TW laser for transmission,
> and a ns pulse detector for reception.
Exactly, and a large solar sail (say a few km in
diameter) would also make a great reflector if
the shape could be stabilised.
> That makes an excellent interstellar com-link, and is
> do-able today.
> Bandwidth might also not be too problematic ..
It depends on compression. I worked out the raw
data and using terabit rates, it would take
longer than the age of the universe. However,
when you seen one red blood cell, you seen them
all (at least for a given person) and there are
a limited number of configurations of molecules
and redundancy at every level so there is scope
for massive compression.
>: ns pulses allows for about 1Gbit/sec
> up-link (towards the ship). And there is time to do this...
That's the key of course, say it takes 1800 years
to get there, we only need to launch 21st century
technology and even if the initial bit rate is in
the kbit/sec range, it wouldn't take long to upload
the 39th century comms protocols once contact is
established. We already know the background noise
levels so it is just an engineering problem.
Once the comms are in place, upload instructions
to make 39th century tools and then you can build
whatever transmitters and receiver have been
developed by then. Most NASA probes have the
ability to update their on-board software, this
just goes on to include the hardware. After that,
it could be used to create 39th century genome
synthesis equipment if the sytem was attractive.
If not, we could instruct it do manufacture and
launch new probes (using 39th century technology
of course) to another set of more distant star
systems. The aim would be to create a network
of short (<10 light year) links spreading out
into the galaxy.
The biggest problem would probably be getting
sufficient autonomy in the software to survey the
system and find the raw materials when it first
arrives, but autonomy is a problem that is already
being worked on and one we must solve even for
exploration of our own outer planets.
George
javidh...@hotmail.com
>
> BTW, I found the link that tells me this isn't
> just sci-fi:
>
> http://www.usatoday.com/news/science/2003-11-13-new-life-usat_x.htm
>
> "Venter notes the synthetic bacteriophage has
> 5,000 base pairs in its genome. The human
> genome has 3 billion, so similar work in human
> form probably won't happen in this decade, he
> says."
So George, how can one be sure this new virus don't go out of control
and start attacking people with a force deadlier than AIDS? Do you
think the risks are worth playin'?
ATROPINE
Thanks,
--
Atropine
EL PASO, TX
"Life is easy with eyes closed"
N = R * f(p) * n(e) * f(l) * f(i) * f(c) * L
They gotta be out there........somewhere)
"AA Institute" <abdul...@ntlworld.com> wrote in message
news:adbf5bc1.04111...@posting.google.com...
> Since this has a decent level of "Astro" content... I thought it may
> make a slight 'thought' contribution (albeit fictionally) to this
> group:-
>
> http://uk.geocities.com/aa_spaceagent/firstarktoalphacentauri.html
>
> Enjoy...
>
> Abdul Ahad
>
Gary Cavie
abdul...@ntlworld.com says...
> Since this has a decent level of "Astro" content... I thought it may
> make a slight 'thought' contribution (albeit fictionally) to this
> group:-
>
> http://uk.geocities.com/aa_spaceagent/firstarktoalphacentauri.html
>
> Enjoy...
>
> Abdul Ahad
>
Sorry, only just seen this as a result of another reply.
It sounds as though it will make a brilliant movie or novel, and one I
would love to go and see. The other story in a smiliarish vein that I
hope gets made one day is 'Encounter with Tiber', by Buzz Aldrin & John
Barnes.
Johnny Bravo
Here's my new address: Todd Ullum 5963 Whitefield Street
Dearborn Heights, Michigan 48127
The pay here as a diesel mechanic is over $32.00 an hour!!