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Re: Moon-based amateur radio transponder



Dear Michael and Piero,

The subject of a moon-based amateur radio transponder surfaces here every
couple of months. I will not revisit the technical arguments in great detail,
you can look in the Amsat-BB archives for more of that. 

I just want to ask what the mission and purpose of a moon based amateur radio
transponder is supposed to be, in order that we can define who we are working
for and to whom we should appeal for funds. 

Specifically is Amsat supposed to be:

1. A ham radio organization, supported by money contributed by radio amateurs
who want satellites for communication between hams on the earth, and aiming to
deliver satellites that are directly accessible to the largest number of ham
radio ground stations?
 
or are we:

2. A space exploration organization, perhaps along the lines of the Planetary
Society, supporting space projects to advance the cause of space exploration,
even if those projects are not directly accessible to a large percentage of
the world's ham population?

As I have posted here before, a transponder on the moon is approximately six
times farther out than AO-40 at apogee, giving by my calculation 16 dB less
performance in each direction than an AO-40 downlink. No matter how you do the
calculations, the number of hams who can work such a lunar transponder will be
some order of magnitude less than those who can work the same hardware in a
high earth orbit. If Amsat starts building such a project instead of something
like Eagle, will there be cries of "elitism" on Amsat-BB from hams who learn
that they cannot work such a transponder with an HT and a rubber duck? Will
people decline to renew their membership because Amsat is not working for the
"little guy"?

I'm not saying that a lunar mission might not be an exciting and inspiring
thing to do. I'm only saying that before you start the technical planning of
such a mission, you must define what the mission is to be and who your
customers are. 

Several Amsat members including myself have made presentations about Amsat in
front of the space interest groups at their annual conventions. The response
has been lukewarm, certainly not the level of support that Amsat enjoys at the
Dayton Hamvention and other large hamfests around the country. This leads me
to think that radio amateurs are and will continue to be our core constituency
for the foreseeable future, and missions should be designed to meet their
communications interests in order to secure their continued support. 

If you can get funding from the Planetary Society or a similar group to build
your moon lander, then by all means please go ahead. But those of us old farts
who have been down that road before recall that we are usually met with blank
stares when we talk to the space interest groups.
  
Your ideas about ion propulsion are right on the mark, I think Amsat needs to
look at this technology as a way to enable high altitude satellite missions,
and I have been collecting information about this in my copious spare time. 

Air bags work on Mars (sometimes- we still haven't heard from Beagle 2)
because they are the terminal part of a total system that uses a heat shield,
parachutes and retro rockets to arrest most of the downward velocity, with the
airbag there at the end to absorb any leftover residual velocity. Heat shields
and parachutes will not work on an airless body such as the moon.

Lastly don't apologize for your inexperience, we are all ignorant of different
things. Those who have been able to get a formal education have simply refined
their ignorance to a higher level. When all is said and done, perhaps the only
reason for the continuing existence of amateur radio in the 21st century is
the opportunity it affords people like us to learn new things. Without that we
might as well just subscribe to our local cable company's internet service and
become good little consumers with no knowledge of how the magic works.

Dan Schultz N8FGV



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