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Re: For Consideration
Tim says in response to Brian:
> As long as the fuel is prelaunced there is no problem, but you were
> suggesting to use the fuel as shielding. If you planned using that fuel for
> deceleration, it could not work because there isn't an engine that can stop
only true for internally powered engines, an externally powered MARS
design, would be able to carry enough reaction Mass (I hope) to overcome
both the photonic thrust, and slow the ship at 1 G (10 m/s^2)
Now Brian says
> >Of course, using Kevin Houston's maser idea would be divine and with it we
> >could accelerate/declerate the whole way. But I just don't see how he is
> >going to keep a maser beam on a starship that is 11.8 ly away. Or is it
> >11.9 or even 12.2 ly. I can't find a single pair of sources that agree on
> >how far away Tau Ceti is!
there is in existence today, a laser interferometer gyroscope, that by
all accounts is accurate to within one wavelength of light. assuming you
are using something at 580 nanometers, this translates into only 680
Kilometers divergence after 12.0 lightyears. If the maser antenna is
wider by that radius, (ie, if the maser beam is 1000 Km in radius, the
antenna should be 1680 km in radius) or, if the maser beam is wider than
the antenna (just switch the above numbers,) then either the beam will
allway rest upon the antenna (in the first case), or the antenna wil
allways be within the beam (in the second case)
However, Since you missed much of the discussion between the newsletter
dying (how that listserver coming Dave?) and the time you joined, I will
re-iterate the main monkey-wrench in the system. Before I do so, let me
re-state the main Idea.
By accelerating the Reaction Mass (RM) to near light speed, we could
increase it's momentum endlessly (by approaching the speed of light ever
closer) thus allowing less RM to escape out the back of the ship. by
using the maser antenna as a "sail", and retro-reflecting most of the
energy, we could accelerate away from earth at a nice 1 G (and since the
exhaust speed would be C (photons) the RM would be zero. at the
turn-around point, instead of reflecting the maser beam, we would convert
it to electricity, and accelerate RM in the direction of TC. But there
wont be enough energy to overcome the momentum imparted by the photons
absorbed, to raise the exhaust speed up to .9996 C. Thus our mass costs
will go up. instead of accelerating a small amount of RM to Near-light
speed, we will have to accelerate a larger amount to some lower speed
(perhaps .75 or .8 C) I would love to tell everyone that I had solved
this little mystery, but alas, I have been very busy with school-work.
While you are correct, in that proteins and sugars come in left and right
handed forms, the choice is not completely arbitrary. We use Left-handed
Proteins, and right-handed Sugars, (from now on, it's RH and LH) but
anything that uses carbon and oxygen will use some kind of sugar. and
unfortunately, RH sugar is the most thermodynamically stable. Thus if
the Alien bugs use Sugar at all, they will have figured out how to handle
RH glucose. as for proteins, This does appear to be an arbitrary choice
made by life early in it's developement. It may be that protiens _must_
be LH if Sugars are RH, or it may be something different, However, even
if the bugs couldn't digest our proteins, we would not like them eating
our glucose and reproduceing ad infinitum. because if they can't eat us,
it's a sure bet that our immune system would be completely stymied.
on anti-biotics, Kelly is right. all my Bio-Chem Books show that
Anti-biotics attacks certain specific Key reactions that all life must
use. For example, Sulfa drugs attack the Flavin pathway. Thus unless
the bugs are supplied with the component, they cannot survive (unless
they have a mutant enzyme which can distinguish between the proper flavin
precursor and the sulfa drug. This is what I meant by the evolutionary
age of the life being important. We carry many genes within us that are
deactivated. Some of them are very old, from the days when we were
fish. (fetuses have gills at one point) the same is true of bacteria,
they have genes that code for long surpassed chemical weapons.
Bacteria A developes weapon.
Bacteria B developes defense to that weapon
Bacteria C-Z die for not having the defense,
Bacteria B thrives and al future bacteria have the defense gene
Bacteria A stops making the weapon, because it is no longer effective.
The weapons get better and better, and the more of them your ancestors
were exposed to, the better your chance of fending off an attack by an
alien bug. A good SF book on this is "The War against the Chtorr" by
David Gerald it's a book, not about an invasion, but about an
infestation. and the aliens are trying to Chtorraform our planet to suit
themselves. but their evolution is much older than ours, so all thier
bugs learned how to master penicillin millenia ago (and any other
anti-biotic we could come up with) plus all the Chtoran life-forms have
chemical weapons and defenses that earth life had never seen before.
the long and the short of it is. we are losing. and the human race has to
figure out how to survive in a world that is changing around us.
anyway, gotta go now.