[Laser] Re: Lunar Eclipse #3

[Tim Toast]

I looked up the info about lunar echo's on one of the EME
pages and found out the pulse lengthening is actually about
11.6 milliseconds instead of 5.79 ms. I didn't realize the
pulse hitting the limb of the moon has to travel back the
same distance. So by the time the light reaches the moons
limb, the reflection from the center has already moved one
radius back toward earth, leaving the leading and trailing
edges of the pulse - two radius apart - 3476 km TOF = 11.6
milliseconds.
So this lowers the high frequency limit to 43 Hz instead of
86 Hz as i said before. And if your FOV is about half of
the moon then your frequency limit doubles to 86 Hz. And
any pulse returned from the moon would be lengthend to 11.6
milliseconds plus the intial pulse length.
This is all assuming the moons limb reflects just as well
as the center does, which it seems to do. I did read the
limb has a higher albedo at optical wavelengths than at
radio and that there is a pronounced limb darkening at
radio wavelengths.





      ____________________________________________________________________________________
Never miss a thing.  Make Yahoo your home page. 
http://www.yahoo.com/r/hs