MMM Classics Year 10: MMM #s 91-100 - Moon Society

gap may be that most of the research community are
scientists and are thinking in terms of a (to them
long, but to us) short time horizon. They may be
thinking in terms of reducing support costs for a
scientific research base, not in terms of a full
fledged, self supporting lunar community. This
paragraph is sheer speculation, unsupported by
careful scientific research.
Even if we wind up with pure mare regolith to
work with, we can still produce aluminum, though.
The process might be different, starting with different
feedstock, and the yield will be lower, but 7 %
is still nothing to sneeze at.
Larry Jay Friesen
On MMM’s Graphic Titles
My wife has commented to me, and I tend to
agree, that the graphics used in MMM article titles
are often too much. A little of that is fine, but we
both find it can be an annoying distraction, because
beyond a certain point, they make the titles
difficult to read. For example, on my second article,
we both found that emphasizing the chemical symbols
in Aluminum and Oxygen was appropriately cute. The
little rocket taking off in "Flight" was a neat
touch. But having an italic font for "Propellants"
(and only for the first part of the word!) and
putting the little tic marks above "Bases" seemed
completely pointless so far as either of us could
see, and made both words quite a bit more difficult
to read. Larry Friesen
[EDITOR’s comment: MMM is not a professional journal in
which unadorned text might be proper, but is a monthly
reading potpourri aimed at a very wide space-interested readership.
MMM tries to cover some of the very all-encompassing
vectors of the space frontier. The idea, and our hope, is to lure
readers to read, rather than skip over, articles about topics in
which they may have had no previous interest. One way of
doing that is with graphics or illustration. My own talent as an
illustrator is very very limited. I have humbly tried to improve
through practice. Solicitations for illustrations have met with
little success. One artist, Dan Moynahan, illustrated three
articles for us six or seven years ago, then disappeared. Others
have offered but not (yet) delivered. Often that leaves me with
graphic illustration of the article title or key word(s) as my only
way to visually set the tone and catch the reader’s eye. I am
sure my achievement score is not good, but I try.
In the case above, the italics of “propell[ant]” were
meant to suggest energy and motion; the “little tic marks”
above the word “Bases” were meant to suggest a space frame
holding up a layer of shielding. The lesson for me is that I must
not assume that what I find obvious, guarantees that others will
find it so. Again, I can only try. As to the valence of aluminum,
of course you are right, as the formula Al2O3 demonstrates (the
abundance being correlative to the valence).
In last analysis, MMM means 60 or more hours of
intense labor of love a month. It’s my football, and if I am no
longer having fun with it, I’m likely to tuck it under my arm,
and just go home. None of us want that. PK]
“Lunar Broadcasting”
by Gregory R. Bennett
Section 3.3 in the Artemis Data Book
As seen from a given point on the Moon, Earth will
wobble in a box that measures plus or minus 7.7 degrees east to
west (longitudinal libration), and 6.7 degrees north to south.
The longitudinal libration is due to the elliptical orbit of the
Moon about the earth, and the latitudinal libration is due to the
inclination of the Moon's axis to the plane of its orbit.
Lunar equator is tilted 1 deg 32 min from the ecliptic
Lunar equator is tilted 6 deg 41 min from its orbital plane
Orbital plane is titled 5 deg 9 min from ecliptic
(these figures add up to make the first numbers)
To put this into perspective, Earth subtends an angle
of about 2 degrees in the lunar sky, so it's moving roughly 3
times its diameter way from a mean point.
Earth subtends an angle of about 1.9 degrees, as seen
from the Moon. Earth will slowly move within this box over a
28-day cycle. The box will be tilted depending on your latitude
on the Moon. At the equator, it's rolled over 90 degrees. At the
poles, it's as I've shown it here. At other lunar latitudes, the
angle of tilt will be ( 90 - latitude ) degrees.
To keep an antenna bore-sighted on Earth, it would
have to slew the rate of about 1/2 degree per day. We'd want
the antenna to cover the whole 2 degrees of Earth to allow for
continuous coverage from horizon to horizon. Of course,
people at a given location on Earth would be able to receive the
signal for half of each Earth day.
Reception Times
Sometimes we'd get prime time in a given city; sometimes
not. Programming could be adjusted for the cities along
the strip of longitudes that will receive the signal in prime time.
Advertisers in Chicago would pay more for a commercial spot
at 7 PM than at 3 AM. That's OK; when it's 3 AM in Chicago
it's 7 PM in Sydney, so our programming will be about what's
up at the Opera House instead of how well the Cubs could play
baseball on the Moon even though people in both of those
cities would be receiving the signal.
Note that this situation, with the Moon halfway
between Sydney and Chicago when it's 7 PM in Sydney, occurs
at a specific phase of the Moon. Moon aficionados on Earth
will learn to tell the phase of the Moon based on what kind of
programming is coming to them, and vice versa.
Earth-tracking techniques
The easiest solution to tracking earth would probably
be to calculate its position, but if we want a stand-alone
antenna guidance system to point an antenna, we could use a
radio direction finder. Earth is radio-noisy across all the bands,
so it should be very easy to close the guidance loop on radio
signals. Infrared should work, too. Earth is a very hot body
against a very cold sky except during a terrestrial eclipse.
During an eclipse, it would be easy to find the limb of
Earth occulting the disk of the sun up to totality. During
totality, use the camera to find the body occulting the solar
corona. I'll bet Earth looks really pretty during a total eclipse,
with the sunlight refracting around the atmosphere to form a
ring of fire. The Luna City Hotel will likely be booked up
decades in advance for those events. GB
Moon Miners’ Manifesto Classics - Year 10 - Republished January 2006 - Page 62