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Re: Argosy Mission Overhaul

From: L. Parker
To: Brian Mansur
Subject: Re: Argosy Mission Overhaul
Date: Friday, March 08, 1996 11:30PM

>From Brian,

>Well, it sounds like a good idea to me, except I think I would reduce the
>size of these ships to around 50 to 100 tons max and send more than one to
>each destination, at least six.

>I'm not much of a gambler, can you tell?

>Using a combination of solar sails and lasers and RAIR we can get such a
>ship up to around 0.4c fairly easily. Deceleration would have to be a
>combination of drag screen and RAIR as well.

Yesterday, AFTER I sent the mission overhaul letter, I went to the mall and 
found a book called _The Physics of Immortality_.  It described Neumman 
probes (I think I spelled that right) that were launched to the nearer stars 
(including TC!).  These probes explored the system, replicated themselves, 
and launched to other stars.  It was a slow process of exploring the galaxy, 
but is worked simply because it assumed complete robotic automation that 
almost never failed.

In theory we can and will develop such robots but that could be centuries 
into the future.  Assuming that lightsails are the fasted and safest forms 
of propulsion when and if the automation advances occur, humanity will 
expand by first sending his robots to the stars.  They will set up power 
arrays, laser cannons to decelerate incoming colonists, and some 
neighborhoods for those colonists to start new lives in.  They might also 
just terraform a few planets and moons while they are at it.

Something that I have noticed about every design proposal on the board is 
that they almost all have to have high degrees of robotic automation.  That 
or they need A LOT of man power that we probably won't be able to support 
for a simple exploration mission.  Its a real bumber but that seems to be 
the deal.

Think about it.  The maser/laser driven sails need 1E18 (probably  1E20 to 
account for efficiency) to fly.  That means planet size power arrays if the 
source is solar.  The RAIRs need lots of fuel that has to be packaged and 
put into position by some kind of infrastructure.  That _just_ might be 
within the capabilities of human manpower.  Anti-matter energy has to be 
made from an equal (or greater depending on efficiency) amount of energy. 
 That equates to huge power stations to do the matter/anti-matter 
conversion.  Simply launching rockets with fusion pellets as their fuel 
(like the Daedalus) may be doable for small loads but we would quickly run 
out of rare isotope  fusion fuel.  Unless, of course, A LOT more could be 
made by some trick of physics involving fusion techniques perhaps.  Of 
course, a rare isotope factory would most likely require a huge power array 
to run it.

There does seem to be some hope for an easier future, powerwise.  If this 
cold fusion thing that Tim alerted us do is not a hoax or is less fantastic 
discovery than it sounds like, we could be going places we thought were 
going to be out of our reach for decades and centuries.

There is hope.  Let's keep trying.