Re: MARS HYBRID DESIGN II (First Draft)

[Brian Mansur <bmansur@oc.edu>]

>From Brian,

Brian Says:
>PHASE 4: SYSTEM EXPLORATION/CONSTRUCTION OF MASER REFLECTOR
>     The Asimov enters the Tau Ceti star system's Kupier Belt.  At this
>point it disassembles its sail and starts scouting for a low gravity, metal
>rich Kupier body that is not too far from the maser beam path.  Once such a
>body is located, the seed robots are deployed to begin a robot community.
> Since the Kupier body will be too far away from Tau Ceti for solar energy
>collection, it is assumed that the robots will be powered by fusion reactor
>that must be brought along (in addition to the fuel).  Depending on the
>automation technology at the time of launch, these robots will at least be
>responsible for construction of a mirror platform needed for reacceleration
>to Sol.

Kelly Says:
>Why so far out?  That doesn't sound like and area we'ld want to do most of
>our exploring at.  So why make the base there?
>You could fuel the fusion reactors with fuel avalible were you set up the
>operations.

The reason for putting the base so far out is because whatever Kupier body 
we find near the maser beam is going to be orbiting TC very slowly.  It will 
give us time to set up our reflector and get it into position with the least 
amount of effort.  It just occured to me that if you find an object further 
inside the system whose orbit would be just right at certain times to let 
you do the same thing.  Of course that also depends upon the orbital plane 
of TC.

Let me see if I can make this more clear.  Once the mirror is built, it will 
have to be put into the maser beam and it will have to be able to stay 
there.  So any orbital momentum it has must be overcome by either rockets or 
the acceleration force of the maser.  Let's face it.  We won't have enough 
time to weight the mirror down enough to keep it from accelerating.  But by 
putting the reflector in deep space, it should also be relatively free of 
gravitation distraction from TC and other objects, at least until it gets 
fast enough that it won't matter.  So in some ways the acceleration is good.

About getting fusion fuel from the rock we're already mining.  We might be 
able to if we can build a surplus of robot workers.  As I pointed out in the 
summary intro, this whole mission depends on a revolutionary degree of 
automation.

Kelly Says:
>Again, having a mirror reflect back the beam from sol sems unlikely.  Not
>only would the sol beam be spread out over huge distences and diffuse.  If
>it wasn't soraed out a random orbit in the Kuniper belt would quickly drift
>out of the beam path, and if it stayed in the beam it would be about
>impossibly to reflect the beam that precisely.

See above for how we plan to tackle this problem.  Also, the mirror 
components might be equiped with rockets.  Not only do they adjust position, 
but they add weight as well.  On the downside, they are also yet another 
item that must be built in system.

I'm beginning to see that if we can do all the things I'm saying we're going 
to have to, we might just go ahead and make another maser array complete 
with solar energy collectors.  The whole reason for bothering with a 
reflective mirror is to give the Asimov something that is supposed to be 
simpler to assemble at TC than a maser array.  So unless our automation is 
almost 100% automated, we're not going to get much exploring done. 
 Unfortunately, I'd don't see a better alternative on the table than to 
develope this automation.

That reminds me of a quote: "So you say you want a revolution.  Well you 
know.  We don't want to change the world but . . . well, all right."

>     The Asimov leaves the Kupier outpost to continue its exploration of 
the
>star system.  Whatever number of crew is needed to oversee construction
>stays behind.  As the maser reflector nears completion.  The array must be
>somehow weighted down to keep it from flying off.  Keeping it tethered to
>something like the weight of Phoboes would be nice but then Sol would have
>to track it to keep the beam on target.  It will probably be better to
>simply give it enough weight to prevent it from blowing away too fast while
>reaccelerating the Asimov.  I only hope that the required weight won't be
>beyond out ability to put to space.  Also, this entire array will have to 
be
>able to maintain its position inside the maser beam which means some
>powerful rockets or some angling of the array as mentioned in Phase 3.
>
>PHASE 5: REACCELERATION OF THE ASIMOV/RETURN TO SOL
>     This final phase is pretty self-explanitory.  The Asimov's sail 
(having
>been patched up from the flight to TC we hope) is redeployed is manuvered
>into the path of the redirected maser beam.  Again, it is hoped that a high
>terminal velocity will be possible.  As the Asimov nears Sol, the array is
>turned around and the masers focus straight on to the tatered sail. 
 Mission
>ends as the Asimov pulls into the local Starbase.

Kelly says:
>The array is the mirrors on the pathfinders.

No, the pathfinders are history (somewhere in deep, deep space by now) and 
the deceleration arrays are with them.

Kelly says:
>The whole time the beam is
>pointing straight at T.C. at the reflectors.  The ship is riding that beam
>straight back from Tau.  I.E. the Tau reflection is shining on its back and
>the stronger direct source from sol on its frount.  This makes accelerating
>out of Tau, much less getting to high speed, very difficult.

I left out the detail of saying that the Asimov will again be riding the 
redirected be just to the side of the incoming beam from Sol, thus avoiding 
the drag your worried about.  And, of course, we'll have to make course 
corrections on the Asimov and the reflector.


I'll go ahead and put a few ideas I had for mirror and ship course 
corrections here.  We could have the Asimov detach its ion drive and cable 
connect it to an edge of the wire mesh sail and the hab section.  The drive 
could then gently pull the whole set up back onto the beam path.   We could 
also, perhaps have the maser array at Sol periodically decrease power to 
allow this tug to do its job without being microwave fried.  We would have 
to do something about shielding the tug, of course.

Perhaps the tug could be a pair light rockets hanging onto opposite sides of 
 1000km+ wide sail.  They could have their own shielding and would be in 
excellent positions to do their jobs.