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Re: MARS



Hi Brian

> High Kevin, Kelly, and Tim.  It's Brian.

> I've finally had the time to research a few of the old newsletters about
the 
> maser design, trying to understand it better.  I have a few questions that
I 
> was hoping you would have the time to answer.

> 1. Kevin said that the RM mass weight will go up from what was originally 
> hoped for on the decel phase to TC.  Kevin told me in  a previous e-mail 
> that exhaust speeds between .75 and .8c were to expected and that was down 
> from the envisioned .9996c.  Have you been able to figure just how much
more 
> RM we will have to carry?

I can't answer this.  Last time I remembered we were having problems in that
the push from the maser would overwelm the power of the reversing engine.  So
It couldn'r slow down.  That was Kevins big problem.  Using your decelorator
might get around that, but you'ld need a huge amount of fuel.  Not nearly as
much fuel as my fusion rocket idea, but a lot.

> 2. I'm concerned about the size and weight of the maser sail.  Actually I'm

> concerned about anything that has a diameter of a sizable moon.  Do you
have 
> any good idea as to how much the sail will weigh?  After all, if it gets 
> much above say 100,000 tons (E5 tons), it will probably be too heavy to 
> carry enough RM to stop.

I'ld like to know this too.

> 3. This maser thing.  What exactly is a maser?  A microwave > beam
generator? 

Its the microwave equivelent of a Laser beam.  Oterwise a normal microwave
sources would fan out to much.

> Is there a way to reflect these microwaves with good efficiency?  Perhaps 
> we could somehow rig a reflector to detact from our ship and reflect back 
> the beam and do away with a linear accelerator.

Any wire mesh will reflect them. But reflecting them in a way that you can
decelerate doesn't work unless the reflector is separte from the ship.  If it
is, it qiukly couldn't reflect onto the ship.


> 4. Has anyone figured out just how long the accelerator needs to be since
it 
> has to be linear?  More to the point, can we keep the linear accelerator 
> short enough and, therefore, light enough to produce relativistic exhaust 
> velocities?

Another very good question.

> 5. Can we even produce the magnetic fields in an accelerator necessary to 
> get an exhaust velocity of .9996c for .62kg/sec. or even a .75c exhaust 
> velocity using say a 1km long accelerator?  My understanding is that field 
> generators that confine magnetics fields have a tendency to blow up.  I
hope 
> I'm wrong but I thought you might know if this concern applies to the 
> designs we've discussed.

Your probably right.  Since we've been stuck trying to get past theoretical
imposibilities.  We nerver worked out all of the practical difficulties.

Kelly