Well, Spike's discussion about Interstellar Dust and the need to
figure out just what our capabilities would be if we could enshround
the Sun and collect all of its power output led me to get off my
lazy butt and crunch some numbers.
The assumptions I started with were the Project Daedalus mission
which was a carefully studied effort to design in interstellar
flyby probe for surveying nearby solar systems. The mission
parameters were a total flight time of 40 years, 500 tons
of dropoff payloads (survey satellites), 1000 ton dry
mass, 2 stage fusion starship with ~150,000 tons of Deuterium
and Helium-3 as fuel. The energy produced to accelerate this
ship to 0.16c was ~1.64*10^12 Tons of TNT (6.8*10^26 J) using
an inertial fusion reactor (similar to the National Ignition
test facility currently being built at LLNL).
For comparison purposes the Space Shuttle weighs ~200 tons
empty and ~2000 tons fueled. The International Space Station
will be about 100 tons when it is completed.
I changed things slightly by assuming you would build solar
system infrastructure (mass drivers or lasers) to provide
power for launching the ships. The results are quite interesting.
The sun gives you enough power that you could launch 300 fueled
ships a second (fueled because you want to use the fuel to decelerate
at the destination). That would allow you to launch the entire
Earth's population into interstellar space in less than a year
(at 1 person per ship!). And you still leave behind the solar
system in much the same condition as you found it. You probably
need to dismantle a small fraction of the moon for the material
to build the ships (1.5*10^18 kg) and has has been previously
discussed in my Planetary Dismantlement paper, you only need a small
fraction of Mercury or the moon to enshroud the sun in solar cells.
Though if the Solar System Green Party has its way you probably
have to dismantle the solar cells and mass drivers on upon
leaving the system so it can remain as a pretty "natural" star.
So, the next question is what if you don't want to send probes
with people on them. What if you want to send automated probes
until you run out of material... Well that picture is *very*
different. Even using 100% of the Sun's output it still takes
you 300 million years to fire off all the material you have
available to construct ships from. So, you can move entire
planetary civilizations relatively quickly but moving all
the mass of a solar systems takes a long time.
Now, of course this brings us to the missing mass question.
It would appear that if the launches are done via solar
sails or mass drivers, then you are not going to leave
hot thrust production signatures outside of the starting
system or the destination system. Minimal energy requirements
for single individuals are around probably around a hundred watts,
perhaps adding some computer support (you can talk to Hal for
the 40 years it takes), maybe pushes you to a few thousand watts.
Radiate that much heat over a fairly large surface area and it is
going to be very difficult to notice. If you have uploaded into a
nanocomputer before the start of the trip, you simply put yourself
in a big box of lead to shield yourself from the cosmic rays and have
the ship reboot you after a specified time period. Very low
power consumption indeed.
Now, lets say a galaxy gets to the ~ Kardashev Type III level and
they decide they all want to throw a party. Maybe Kieth Henson's
infamous "Far Side" party. They tell everyone to meet at such
and such a location at such and such a time (perhaps a million
years in the future due to the long interstellar travel times
required). Now what happens on the day of the party is you have
100 million trillion single person ships (give or take a few orders
of magnitude) decelerating and opening communication channels within
a single solar system. Things may get tight, accidents may happen,
but boy if you survive, what a rush! And that my friends just might
be what astronomers refer to as an Extragalactic BL Lacertae object.
Robert
P.S. For those unfamiliar with BL Lacerte objects, from the
GCVS (General Catalog of Variable Stars):
"...compact quasistellar objects showing almost continuous spectra
with weak emission and absorption lines and relatively rapid irregular
light changes with amplitudes up to 3 mag in V or more. Sources of
strong X-ray radiation and radio waves, their emission displays strong
and variable linear polarization in the visible and infrared spectral
regions."
This archive was generated by hypermail 2b30 : Mon May 28 2001 - 09:50:38 MDT