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Re: starship-design: Laser or maser?

At 12:38 AM 10/31/96, Timothy van der Linden wrote:
>Kelly wrote:
>>>>>300 and 385 kilometer diameters don't seem like a headache...
>>>>A 300-400 kilometer laser array?  Again it would be a bit hard to fit on
>>>>our moon.  Harder to sycronize since the frequencies are shorter.  Also the
>>>>sail has now gone from a wire mesh to a reflective sheet.
>>>Hard to fit on the moon? I don't understand, its diameter is 3476 kilometers.
>>>The frequency is indeed increased by a factor 3, however having a solid
>>>floor helps a lot.
>>If you have to find a position for the array that has constant direct line
>>of sight at all times.  Your limited to a small polar region.  The farther
>>the target star is from true north or south the narrower the polar region.
>>Also the platforms must be in direct line of sight so they can adjust for
>>one anothers movement (yes platforms mounted on the Moon will more around a
>No, that polar region is not small, it is rather big.
>If a star deviates 45 degrees from the rotation axis of the moon/planet, it
>can be seen downto the 45th longitude. (There is a small band in wich the
>Sun and other planets will move along (on Earth that is between +23 and -23

If it needs to have same-time visibility to the ship and the sun it cuts
things down a bit.

>>>I wonder are semiconductor lasers more efficient and cheaper than ordinary
>>>lasers. What will be the costs compared to masers which cannot be made in
>>Can't remember.  I thought free electron lasers had the highest efficency?
>>>Also on the receiving side, what are the pros and cons?
>>>On the receiver-end we not only need a mirror, but also an absorber. Are
>>>photocells better than skottky diodes?
>>Why an absorber?
>During the deceleration phase, energy is used to accelerate repulsion mass.
>(I know, you proposed some ingenious reflecting system, so that the
>EM-radiation directly accelerates the repulsion mass, but somehow that seems
>to ingenious.)

Ah, I wasn't considering a MARS System

>>>Has anyone an idea where to get this kind of information?
>>>What are the disadvantages of a reflective sheet compared to a wire mesh? Is
>>>it only the weight?
>>Increased drag and more limits in materials I think?
>Yes maybe, however the drag may be far less than the increased efficiency or
>better focusing with a smaller array.
>We (also others than me and Kelly) should try to find some more pros and
>cons about laser and maser.


Kelly Starks                    Phone: (219) 429-7066    Fax: (219) 429-6859
Sr. Systems Engineer                                     Mail Stop: 10-39
Hughes defense Communications
1010 Production Road, Fort Wayne, IN 46808-4106
Email:  kgstar@most.fw.hac.com