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Re: tentative hybrid design.

At 10:52 AM 3/1/96, Kevin C Houston wrote:
>Kevin sees Brian's "pocket change" and rasies one dollar.  ;)
>I don't have much time right now, so this will be short.
>Here's the idea I'm thinking of.
>the ship starts off as a hybrid structure.  a MARS-like front end, with
>an explorer-like backend.
>the ship accelerates out of Sol System with a simple maser sail.  The
>large fuel tanks (used by the MArs as RM, but used by explorer like
>fuel)  on the MARS keep us shielded from interstellar speed-induced
>radiation.  As we approach the halfway point, (speed ~ .9905 C)
>the two ships separate.  the MARS begins converting the masers to
>electricity, cutting it's photon derived thrust to ~5 m/s^2 (1/2 G)
>under computer control, the fuel is thrust out the back end so that it's
>speed is just under the MARS's velocity.  The velocity of the and mass of
>the exhaust can be tailored to the needs of the explorer, since there
>will be no humans aboard the MARS

Given that the Explorer will be slowing down, and the Mars accelerating,
this would have the fuel raceing ahead of the ship at up to near light
speeds.  Even if you could kill the fuel speed you'ld have accuracy
problems.  The ships wouldn't have time to separte much more than a half
light year, but the fuel could spend a long time drifting between.  Plus of
course this would be a tremendous amount of fuel to carry.  I'm not sure
you could carry that much fuel?

Might be better to put a Mini mars microwave sail on the droped ship and
have the main ship transmit power to it.

>Meanwhile, the explorer spreads a large ram scoop out *behind* itself.
>This scoop grabs the (already) ionized fuel, (no containers, just gas)
>and fuses it, redirecting the exhaust at the retreating MARS.  The
>redirected exhaust protects the crew sections from erosion by the fuel.

Neat trick.  How does the explorer catch fuel behind it and fire the exaust
ahead of it?  Be simpler to make the frount end a combined
scoop-motor-shield.  The scop would funnel anything it caught into the
bowel shaped reaction chanber shield.  The high drag (if you slow the fuel
down a lot), compresion/fusion drage, and reverse thrust could get a lot

>The MARS continues along toward TC, getting closer and closer to the
>speed of light.  just before it enters Tau Ceti itself, hundreds of small
>probes luanch away (at perpendicular velocities) get some slight bending
>from the star, and streak away to fly-by various other stars.  The big
>tanks (now empty) and the lineac core crash straight into the star, and
>make nary a splash.

At near light speed?  Wouldn't it at least cause a flare?

The probes wouldn't have any course change near the star.  Their velocity
would be too high (near light speed), but the mars would be a hell of a
good long range observatory.  Oh, I forgot about optical distortion due to

>The crew deploys self-replicating robots (under some human direction) to
>construct the return masers, and a simple manufacturing plant handles the
>return sail (much like chicken wire)  the explorer, after ditching it's
>fusion motor, sails off back toward Sol, where the original masers sit
>waiting for our return.  :)

I'ld really think that having the first stage Mars retransmit a microwave
beam back to the drop ship would solve a lot of your problems, and lighten
the ship mass.



Kelly Starks                       Internet: kgstar@most.fw.hac.com
Sr. Systems Engineer
Magnavox Electronic Systems Company
(Magnavox URL: http://www.fw.hac.com/external.html)