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| BradGuth... |
 Posted: Thu Jul 02, 2009 9:24 am |
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Guest
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On Jun 29, 4:55 pm, Robert Clark <rgregorycl... at (no spam) yahoo.com> wrote:
[quote:17dc7555c7]On Jun 28, 8:31 pm, Robert Clark <rgregorycl... at (no spam) yahoo.com> wrote:
On Jun 28, 1:41 pm, Richard Clark <kb7... at (no spam) comcast.net> wrote:
On Sun, 28 Jun 2009 17:14:14 +1000, "Peter Webb"
webbfam... at (no spam) DIESPAMDIEoptusnet.com.au> wrote:
Furthermore, the radiation from a reflected area is isotropic - goes in all
directions - and hence very little is directed towards the earth.
Actually, it is lambertian in its distribution, and it would have a
major lobe that was directed in rather typical fashion (at the same,
but negative angle to the norm to the surface). However, as is the
intent of your response, very much less will find its way to the
intended target.
Richard Clark, KB7QHC
This describes the reflection from the Iridium antennas as specular
where most of the reflected light is concentrated in a single
direction:
SeeSat-L Apr-98: Method for predicting flare.http://satobs.org/seesat/Apr-1998/0175.html
About specular reflection:
Specular reflection.http://en.wikipedia.org/wiki/Specular_reflection
We could get even higher concentration of the image by using
parabolic mirror reflectors.
We might want to test this out in Earth orbit first before sending
to the Moon. There are low cost CubeSats only 10 cm on a side that can
be launched to orbit at low cost:
CubeSat.http://en.wikipedia.org/wiki/CubeSat
Say we made the reflective surface on the CubeSat be a square 10 cm
wide. This is .01 m^2 in area, so a factor of 6.25x10^(-3) smaller
than the area of the Iridium antennas. This would result in the
apparent magnitude being dimmed to -2.5.
This is still quite bright and would be brighter than the star
Sirius, the brightest star in the sky. Hmmm. I'm wondering about that.
The sunlight at the Earth's distance amounts to about 1,000 watts/m^2.
So even if this 10 cm wide reflector in space reflected all the light
that fell on it to the Earth's surface it would still be only 10
watts. So this is saying a 10 watt light source at a distance of 780
km would be as bright as a -2.5 magnitude star.
Is this right even if you put behind it say a parabolic reflector as
with a flashlight so all the light was directed forward?
Bob Clark
[/quote:17dc7555c7]
Cheap satellites for the greater good of science and humanity are not
allowed.
For less than 10% of just one Apollo mission, we could had a large
scale platform of science and astronomy instruments parked within the
Earth-moon L1 (Selene L1), as of before the first Apollo test flight
to/from our moon.
~ BG |
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| BradGuth... |
| Posted: Thu Jul 16, 2009 4:36 pm |
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On Jul 16, 6:39 pm, "Peter Webb"
<webbfam... at (no spam) DIESPAMDIEoptusnet.com.au> wrote:
[quote:459171ccd4]Cool !
Nice calculations, Bob !
One thing that comes to mind : when the mirror is actually on the Mars
surface (or the Lunar surface), wouldn't it have to outshine the normal
reflection that the planet (or the moon) radiates back to us, before we
can
see it with a telescope ?
How does that change the mirror sizes ?
Rob
The mirror(s) or whatever array of corner cubes could easily be narrow
bandpass coated. The Apollo missions entirely forgot about such,
along with several dozen other essentials and/or better alternatives.
***************************************
It would be completely stupid to bandpass limit the reflectors. No practical
advantage, and some significant disadvantages. There is no need, and it
would stop the reflectors being used across a range of frequencies as laser
technology develops. Note, as well, that there is very, very little
background light to filter out if the observations are taken when that part
of the moon is not illuminated by the sun. You should really learn a little
science before saying that the Apollo mission designers got it wrong; you
don't even have the basic science knowledge neccesary to work out the
existing experiments work, let alone design new ones.
[/quote:459171ccd4]
Your damage-control flatulence is noted, and just as smelly (enough to
kill flies).
btw; LROC ??????? I've seen all of 16 image at ~1.5 meter resolution
(is it and most all other science instruments broken?)
Are they losing the LOR data as fast and furious as they lost most all
of our Apollo data?
~ BG |
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| Peter Webb... |
| Posted: Thu Jul 16, 2009 7:39 pm |
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Guest
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[quote:fb54ea7cec]Cool !
Nice calculations, Bob !
One thing that comes to mind : when the mirror is actually on the Mars
surface (or the Lunar surface), wouldn't it have to outshine the normal
reflection that the planet (or the moon) radiates back to us, before we
can
see it with a telescope ?
How does that change the mirror sizes ?
Rob
[/quote:fb54ea7cec]
The mirror(s) or whatever array of corner cubes could easily be narrow
bandpass coated. The Apollo missions entirely forgot about such,
along with several dozen other essentials and/or better alternatives.
***************************************
It would be completely stupid to bandpass limit the reflectors. No practical
advantage, and some significant disadvantages. There is no need, and it
would stop the reflectors being used across a range of frequencies as laser
technology develops. Note, as well, that there is very, very little
background light to filter out if the observations are taken when that part
of the moon is not illuminated by the sun. You should really learn a little
science before saying that the Apollo mission designers got it wrong; you
don't even have the basic science knowledge neccesary to work out the
existing experiments work, let alone design new ones. |
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