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Re: Some P4 moon landing ideas :-)



"yes you need tracking" ...

Agreed!

Earlier this year there was an occultation of Saturn by the moon, ... now I
don't have a telescope but I do have a 700X zoom on my Sony camcorder, ...
and set it up on the tripod I had to continually move the camera to keep the
moon in the centre of the picture, ... it was remarkable how quick the moon
moves :^)

All I will say is that given the Moon's gravity model, ... trying to land it
at a pole *might* be easier in the long run than trying to orbit it. MasCons
rule!

73 Paul, VP9MU

----- Original Message -----
From: "Bruce Bostwick" <lihan161051@earthlink.net>
To: <amsat-bb@AMSAT.Org>
Sent: Monday, July 01, 2002 7:50 PM
Subject: Re: [amsat-bb] Some P4 moon landing ideas :-)


> Remember, though, that the moon librates several degrees either side of
> earth-facing, thanks to an elliptical orbit and its polar moment of
> inertia.  If you have an antenna with a beam tight enough to illuminate
> the earth without much overillumination, you're going to have periods
> about every other week when the beam completely misses the earth.  If
> you make the beam wide enough to cover the earth throughout the
> libration, you're going to lose several dB you can't afford.  The
> tracking mechanism won't have to track far, but it will definitely need
> to track over a few degrees as the earth moves back and forth in the sky.
>
> Only reason this isn't discussed more than it is is that a) the only
> time people were on the moon they weren't there more than a few days at
> a stretch, and b) the last time lunar libration was a major issue for
> most folks was when we were doing intensive photo-mapping of the lunar
> surface from earth to plan landing sites, and libration helped NASA map
> about 55% of the lunar surface by terrestrial photography.
>
> Yes, you need tracking.
>
> On Monday, July 1, 2002, at 05:26 PM, Reicher, James wrote:
>
> > The high gain antenna wouldn't need any steering to look back at Earth,
> > once
> > it was set.  The Moon is in a tidal lock with Earth and is ALWAYS
> > showing
> > the same side to us.  Aiming a gain antenna to lock in would be
> > relatively
> > easy since once the aim is set, you'd never have to move it again!
> >
> > You could do aim your Earth-based antenna with a sighting scope and
> > merely
> > adjust manually over time as the Moon travelled overhead.
> >
> > -----Original Message-----
> > From: Edward R. Cole [mailto:al7eb@ptialaska.net]
> > Sent: Monday, July 01, 2002 4:00 PM
> > To: amsat-bb@AMSAT.Org
> > Subject: RE: [amsat-bb] Some P4 moon landing ideas :-)
> >
> >
> >
> >> I'd like to see a concept in which a lunar-based relay would be more
> >> advantageous than a satellite.  The Moon is about 8 times further away
> >> than
> >> AO-40 at apogee (~18 dB more path loss).
> >>
> >> Ken Ernandes, N2WWD
> >
> > Yep!  And the high gain antenna will need precise stearing to stay
> > looking
> > at the Earth.  I more probable project might be just a lunar-based
> > repeater...for use by the Astronauts to talk back to Lunar Base One from
> > their rover!  No particular advantage for Earth-based hams, though!
> >
> > Ed, AL7EB
> >
> > ----
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> >
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