MARS

[Brian Mansur <bmansur@oc.edu>]

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?

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.

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

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?

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.