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Re: Geostationary Satellites?



 >Hi Gang...

 >A friend on a local repeater asked me an interesting question the other day. Why are there no "geostationary" amateur satellites?  Are any in the works?

 >Frank
 >wb2bxo

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Mostly because of cost. There was a discussion around about 1990 or so when
Phase 3D was in the formative stage. At that time it was decided that a
geosynchronous ham satellite would be too expensive but a three-axis
stabilized Molynia type satellite (Phase 3D) could be built at an affordable
cost. Neither Amsat-NA nor Amsat-DL nor any of the other Amsat organizations
could afford to build it alone, but by pooling resources Phase 3D was
possible. The problem with a geostationary satellite is that if you park it
over the western hemisphere, the hams in Europe and Asia are not going to be
inclined to support its construction, any more than US and Canadian hams would
want to support a satellite parked over Europe and Asia. Phase 3D is not
available 24 hours a day but it is (or will be) available to a more diverse
group of hams in both hemispheres.

There have been discussions about piggy-backing a ham payload onto a
commercial or military geosynchronous satellite. Commercial geosync satellites
are almost always mass limited, the satellite owner fills the fuel tanks until
the satellite is at the maximum weight limit for its launch vehicle in order
to insure a long and profitable lifetime on orbit. Carrying a ham payload
would subtract mass from the fuel margin and reduce the useful life of the
satellite, it would cost real money with little or no benefit to the satellite
owner. Launches to synchronous orbit are almost always mass limited for the
same reason, so a ham satellite would have a hard time getting a ride as a
secondary payload. That is not to say that it will never happen, only an
explanation of why it hasn't happened to date.

There are a lot of back-of-the-envelope geosynchronous satellite designs
floating around, if you come to the annual meeting in the fall you can join
one of the all night bull sessions and design one yourself. After Phase 3D is
in orbit, when Amsat is in the "what shall we do now" mode, the idea may be
revived again and there may someday be a geosynchronous ham satellite. It's
just not going to happen this year or next. 

Dan Schultz N8FGV

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