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Re: MARS HYBRID DESIGN II (First Draft)
At 4:57 PM 3/1/96, Brian Mansur wrote:
>>From Brian
>March 1, 1996
>
>Here it is: the detailed design I promised (as detailed as I can make it at
>the moment anyway). But first: does the "interstellar drive group"
>selection that I now see on my address book now account for everyone in the
>discussion team? Okay, on with the show.
>
>Note that this is my first draft. The lab is about to close and I have a
>lot more ideas to cover but they may have to wait a bit. Things like sail
>shielding and mirror array design are among them. Sill I'm going to send
>what I've got to let you all have some fun ripping it apart :)
>
>MARS HYBRID DESIGN II (Kevin already submitted the first this morning)
>
>Total mission time: 50+ years
>Pathfinder(s) mission flight time: 40+ years
>Asimov flight time: 24+ years
>Asimov exploration phase time: Undetermined
If its going to take 50 year to get there. I think people would put it off
until they could think up a faster ship. Or just lose interest in the
project.
>ASSUMPTIONS:
> It is assumed for this mission plan that a high degree of robotic
>automation has already made possible the production of at least 1E18 W
>needed to power 1E7 masers without much human supervision. It is also
>assumed that this maser array is totally dedicated to the mission and that
>the beam will be left throughout the mission.
>
>PHASE 1: LAUNCH OF PATHFINDERS
> At least one heavy pathfider vessel will be sent before the Asimov
>using maser sail to reach a terminal velocity of 1/3c. Pathfinder carries
>several thousand, heavy duty, heavy weight, individually targetable,
>disassembled mirror arrays that will be deployed roughly 30 years later near
>TC (see reflectors in an upcoming posting). These arrays (probably making
>an effective 1000 km+ wide reflector) will reflect maser energy back to the
>Asimov for the deceleration phase. The Pathfinder may or may not have a
>crew depending on the level of automation available at the time of launch.
> Also, it may or may not carry emergency supplies for the Asimov should they
>choose to match speed and dock during the deceleration phase.
Are you assuming the beam would be tight enought to be reflected after 11
light years. Not to mention assuming a mirror could hit the ships sail
with the reflected beam, a few light years away?
>PHASE 2: LAUNCH OF THE ASIMOV
> The Asimov is maser pushed to a high %c terminal velocity. It is
>hoped that the maser propulsion system will be efficient enough to push the
>Asimov to a speed at which the effects of time dialation will be useful to
>the crew. At the very least, a max speed of .75c is assumed here.
> This ship will consist of an ion drive for in system shuttling around
>TC. It will also carry the exploration team and their supplies for the
>mission. Among the supplies already mentioned in other discusions are seed
>robots. They will be used to start a robot workforce that will help
>construct, among other things, a precision mirror array to reflect the maser
>energy from Sol back to the Asimov's maser sail when the exploration phase
>is completed.
>
>PHASE 3: DECELERATION OF THE ASIMOV
> The exact process has many variations. If there are several
>Pathfinders, each, the one closest to the Asimov will deploy its reflector
>array and then move to a safe range from the beam path. The array will
>enter the beam path and redirect the maser energy back to the Asimov. The
>Asimov, of course, will have turned its sail around (a slow and delicate
>process). It will also have moved slightly to the side the maser beam
>coming from Sol to prevent blocking of the array.
I assume 'array' refers to the reflectors on the pathfinders.
If the Pathfinders are reflecting the beam off to one side. They will be
pushed out of the beam in the other direction, and accelerated forward.
Given that the beam presure is strong enough push the ships in the first
place, it would be to strong for the ships thrust against.
> Some method of periodic or even continuous course correction on both
>the Asimov's part and the array's will be required to correct for the angle
>at which the maser beam must be reflected. The Asimov may simply angle its
>sail slightly with the edge furtherest from the Sol to array beam tilted
>back toward Sol. The array will have to use built in rockets, or else tilt
>from time to time in the proper direction to allow vectorial force to push
>it back into the center of the beam.
This might be complicated given the main sail would be curved like a
parachute, not flat.
> Now, assuming that the doplar effect will cause problems with
>reflection of the maser beam, another Pathfinder could deploy it's array and
>continue the decelation process. Note that I don't know if the most
>efficient thing that the Asimov can do with the redirected maser beam will
>be to simply bounce it back to space or to power a ion drive. The exhaust
>from an ion drive would make for nice shielding against large particles.
> One final note. As the Asimov and Pathfinder speeds reach equilibrium
>they have the option of docking (assuming the deceleration of the Asimov
>brought it close to the Pathfinder when speed equilibrium was reached. At
>this point, any crew on the Pathfinder could cross over. Note that the
>Asimov could dock with only one Pathfinder.
It could dock with more than one. But that wold depend on their speeds and
relative positions.
>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.
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.
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 soread 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.
> 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.
The array is the mirrors on the pathfinders. 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.
Kelly
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Kelly Starks Internet: kgstar@most.fw.hac.com
Sr. Systems Engineer
Magnavox Electronic Systems Company
(Magnavox URL: http://www.fw.hac.com/external.html)
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