There is also the issue that the commercial operator wants the Earth facing side of the satellite for their antennas. It is hard to find room for amateur band antennas. We ran into this problem while trying to get NASA payloads a ride on commercial satellites.

John WA4WDL

-------------------------------------------------- From: "Alan P. Biddle" [email protected] Sent: Monday, October 10, 2011 5:50 PM To: "AMSAT-BB" [email protected] Subject: [amsat-bb] Re: Geostationary Satellites

Don,

Cost, which is enough to drop any other issues to noise level. That is the High Rent District, and given how much the commercial users pay, they would not want to have an "amateur" satellite wandering around. More practically, it would be nice to have a package on a commercial satellite. They provide the power, pointing, and control. We just provide the RF. Again, cost, though we have been looking for the right opportunity.

Another drawback is that a geosynch only provides coverage to _about_ a third of the earth, and it is always the same third. Birds like AO-13 and AO-40 covered just about all of it over the space of a few days. Did I mention cost? It is fun to think about having 3 which could be linked for true global coverage.

Alan WA4SCA

-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of ka9qjg Sent: Monday, October 10, 2011 4:23 PM To: [email protected] Subject: [amsat-bb] Geostationary Satellites

Hello Hope Everyone is doing Well, I know people say no such thing as a dumb question So here goes What is the reason We do not have any Type of geostationary Satellites. Is it because they are for World Wide Use and If stationary one could Hit it 24/7 and Maybe park there butt on it and Run a Beam and Amp and take it over

Thanks

73 De Don KA9QJG

---

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On Mon, 10 Oct 2011 18:41:05 -0400 "Tom Schaefer, NY4I" [email protected] wrote:

Seriously, you think it gets boring talking to us same guys on AO-51 each day? Try that for a giant repeater in space.

Talking to the same guys would be nice, but it would never happen.

OLA! OOOOOHLA! OOOOOOHHHHH-LAAAAAAA! OLA! OLA! OOOOOOHLAAAAAAA! <whistle> <whistle> OLA! <whistle> <whistle> OOOOOOHLAAAAA! OLA! <whistle>

I am 300million short and have no experience raising capital, but if (and I guess there isn't any way for hams to raise 300mil), there was, I'd volunteer to do as much as I could ...

Maybe that means soldering boards all night, or passing out a tin cup for donations ....

but I'd do what I could...as a volunteer

maybe one day something will make going geo possible <shrugs>

Was that estimated 300mil for the entire bird? Would it be less to just be a package (perhaps of a few) on a commercial sat?

N2EHG

On Oct 10, 2011, at 7:42 PM, Jim Jerzycke wrote:

Numbers for just the cost of an Amateur payload, or numbers for the whole satellite?

A 'typical' satellite costs from 150 million to 300 million, depending on what hardware it carries.

The cost of a launch to Geosynchronous Transfer Orbit ranges from 95 million to 150 million depending on the launch provider.

Jim KQ6EA

On 10/10/2011 10:41 PM, Tom Schaefer, NY4I wrote:

...

Has anyone run the numbers? Are we talking 20 million, 100 million?

Let's see, there are at best 5000 satellite ops. So, if it cost $20,000,000 we are each in it for $4000. I'm game. Now to convince 4999 of my friends. :)

Seriously, you think it gets boring talking to us same guys on AO-51 each day? Try that for a giant repeater in space. That would be wide area. I know we hear that something like P3D would just cost too much, but this is a lot of dough to talk to friends across the country at drive time. The wider orbits make for more interesting conversations. Not that I don;t want to talk to you every day :)

Tom

Tom Schaefer, NY4I [email protected] EL88pb Monitoring EchoLink node KJ4FEC-L 489389 DSTAR Capable APRS: NY4I-15

On Oct 10, 2011, at 5:50 PM, Alan P. Biddle wrote:

...

Don,

Cost, which is enough to drop any other issues to noise level. That is the High Rent District, and given how much the commercial users pay, they would not want to have an "amateur" satellite wandering around. More practically, it would be nice to have a package on a commercial satellite. They provide the power, pointing, and control. We just provide the RF. Again, cost, though we have been looking for the right opportunity.

Another drawback is that a geosynch only provides coverage to _about_ a third of the earth, and it is always the same third. Birds like AO-13 and AO-40 covered just about all of it over the space of a few days. Did I mention cost? It is fun to think about having 3 which could be linked for true global coverage.

Alan WA4SCA

-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of ka9qjg Sent: Monday, October 10, 2011 4:23 PM To: [email protected] Subject: [amsat-bb] Geostationary Satellites

Hello Hope Everyone is doing Well, I know people say no such thing as a dumb question So here goes What is the reason We do not have any Type of geostationary Satellites. Is it because they are for World Wide Use and If stationary one could Hit it 24/7 and Maybe park there butt on it and Run a Beam and Amp and take it over

Thanks

73 De Don KA9QJG

---

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---

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At 08:51 AM 10/11/2011, Lynn W. Deffenbaugh (Mr) wrote:

Just a novice guess here, but aren't the geostationary orbits MUCH higher than our satellites run? And therefore cost a lot more to get boosted to that orbit?

Got it in one, that's the main reason we don't have any geostationary ham satellites, along with the need to have 3 for global coverage.

73 de VK3JED / VK3IRL http://vkradio.com

On Oct 10, 2011, at 3:03 PM, Ken Ernandes wrote:

1. There are a finite number of orbital slots at Geostationary. That is essentially like water front property.

I've heard that asserted before, but I question the reasoning.

My understanding is that spacing of satellites around the geostationary orbit is dictated by the beamwidth of the ground station antennas. In other words, it's a matter of spatial frequency sharing. The satellites have to be far enough apart that a ground station antenna can illuminate one of them without causing too much harmful interference to the ones in the adjacent slots, after all the expected errors (orbital and ground station pointing) are taken into account.

If that's correct, since amateur radio satellite operate on different frequencies from the commercial satellites, there is no conflict between amateur radio satellites and commercial satellites for orbital slots.

Where have I gone wrong?

73 -Paul [email protected]

You are viewing it only from the point of view of signal interference. In reality, the greater issue is maintaining our position and the risk of collision. There is a very tight band that defines geostationary and there are some significant disturbing forces: Earth's triaxial gravity distribution, lunar and solar gravity, and solar radiation pressure. This mandates that there be vigilance in monitoring the satellite's orbit and those of its neighbors and to also have a propulsion system capable of station-keeping on a regular basis. Even without the risk of collision, not holding the position tightly nullifies the benefit of fixed antenna pointing.

For those believing in the large space, small satellite theory, the risk of collision is more real than one might think. I could only imagine the legislation and regulations that might be placed on amateur satellites if we failed to control our bird and it collided with a very expensive commercial or government asset. Until AMSAT can build enough experience to operate a propulsion system reliably for the long term, I don't think we can responsibly operate a satellite bus on a congested orbital highway.

73, Ken N2WWD

Sent from my iPad

On Oct 10, 2011, at 10:59 PM, Paul Williamson [email protected] wrote:

On Oct 10, 2011, at 3:03 PM, Ken Ernandes wrote:

...

1. There are a finite number of orbital slots at Geostationary. That is essentially like water front property.

I've heard that asserted before, but I question the reasoning.

My understanding is that spacing of satellites around the geostationary orbit is dictated by the beamwidth of the ground station antennas. In other words, it's a matter of spatial frequency sharing. The satellites have to be far enough apart that a ground station antenna can illuminate one of them without causing too much harmful interference to the ones in the adjacent slots, after all the expected errors (orbital and ground station pointing) are taken into account.

If that's correct, since amateur radio satellite operate on different frequencies from the commercial satellites, there is no conflict between amateur radio satellites and commercial satellites for orbital slots.

Where have I gone wrong?

73 -Paul [email protected]

...

the risk of collision is more real than one might think.

I would think the risk of collision is so tiny as to be effectively negligible.

I think it is, but when "negligible" incurs about a BILLION$$$ worth of loss, it magnifies the risk.

If we position our satellite halfway between two... "slots"

I think that is the problem. One has to stay there. GEO orbits are impacted by the sun, moon and tides and solar wind. All GEO orbits drift*. Hence 90% of the mass of these GEO birds are fuel for station keeping. And that is where the risk comes from. As soon as a spacecraft loses fuel, or command/control, or any other problem that causes it to no longer keep its station, it becomes a drifting hazard, moving literally FOREVER along this extremely narrow orbit, the same orbit that all of these other satellites are in! It becomes a real hazard to them all.

That is why all nations now subscribe to the requirement that all GEO spacecraft must have 10% reserve fuel to propel an aging satellite out to the graveyard orbit. And this must be done before there is loss of command/control.

Is there no clever trick of orbit design that can be used to avoid collision?

Not and be geostationary. I think long term drift is the final state of any GEO orbit. Though there are , I think, *two spots on the entire GEO orcit which are stable.. but guess what. NO ONE WANTS them, because that is where all the junk collects and that is where the chances of a collision with all that junk is highest.

We can even tolerate some long-term motion... Perhaps these extra freedoms would make it possible to design an orbit that's close enough to geosynchronous for our purposes, but far enough from the commercial orbits to be safe?

I'd guess that being in an orbit closer to earth would be best so that with time we get further from the GEO arc. But closer in, moves faster and so all we have to do is chose the DRIFT rate. Let it drift a full cycle once a year, and the result is that any given country only sees it for 4 months a year. No matter where we put it, it will be out of view to any one station 2/3rds of the time. But now that it is in its own special orbit, there wont be any cheap rides to get there...

Our best bet is to piggy back on someone else's bird.

Oh, and it takes almost 10,000 times more power to hit a GEO bird at 22,500 miles away compared to hitting a LEO bird directly overhead (225 miles).

Just my 2 cents

Bob, Wb4APR

Question, what is the closest spacing for geo satellites to share the same slot? Is this theoretically practical and or possible?

I think someone already said that there are no such thing as physical slots. Slots are FREQUENCY based. Meaning their separation only has to be as great as the beamwidth of the grouind based antennas that will use them IF they are on he SAME frequency.

So "C" band satellites were originally at 4 degree separation (10 foot dishes) then went to 2 degree separation by making evrey other TV channel be oppositely polarized.

Such spacing only applies to large constellatiosn of birds on the SAME identical frequency plans. (such as consumer TV downlinks).

If we had ground receive antennas that had beamwidths the width of the moon, then we couild have nearly 720 slots (each 0.5 deg wide). If a GEO constellation used laser communications links, with user ground stations using OPTICAL telescopes, there could be a million slots because the telescopes could resolve them down to .0003 degrees?

Oh, for HAMS with an OSCAR array and beamwidths of say 30 degrees, then there could be 12 slots.

Bob, WB4APR

How about a high altitude drifter above the geo belt? In fact wasn't that talked about by a few amsat people in the early 80's. I seem to remember hearing it discussed by the late Rip WA2LQQ on the 75 meter Amsat net back in the day.

Dave Marthouse N2AAM [email protected]

How hard (Energy) budget is it to have that giant elliptical orbit, I can't remember what bird had it, but it was an orbit named like moylina or something like that where the perigee was very low but the apogee was like WAY out there giving passes that were extremely long.

Joe WB9SBD

The Original Rolling Ball Clock Idle Tyme Idle-Tyme.com http://www.idle-tyme.com

On 10/11/2011 3:27 PM, Gordon JC Pearce wrote:

On Tue, 11 Oct 2011 15:08:01 -0400 Ken Ernandes[email protected] wrote:

<snipped>

...

I hope this is somehow helpful in understanding what AMSAT would really be up against if it wanted to have an independent GEO satellite or consider a sub-GEO drifting orbit.

Thank you Ken, for the rocket scientist's take on it ;-)

It's refreshing to hear someone who actually has sat down and done the maths comment on how easy or hard it would be to put a satellite into a high orbit.

What you're describing is the AMSAT Phase 3 paradigm which IMHO is still the most viable way to go.

I would never say never, but we (AMSAT) haven't had great success with propulsion systems in our amateur satellites. That is why I'd like to have more experience with successful propulsion events in Molniya-like orbits before I'd recommend attempting maintaining a GEO orbit.

73, Ken N2WWD

Sent from my iPad

On Oct 11, 2011, at 4:41 PM, Joe [email protected] wrote:

How hard (Energy) budget is it to have that giant elliptical orbit, I can't remember what bird had it, but it was an orbit named like moylina or something like that where the perigee was very low but the apogee was like WAY out there giving passes that were extremely long.

Joe WB9SBD

The Original Rolling Ball Clock Idle Tyme Idle-Tyme.com http://www.idle-tyme.com

On 10/11/2011 3:27 PM, Gordon JC Pearce wrote:

...

On Tue, 11 Oct 2011 15:08:01 -0400 Ken Ernandes[email protected] wrote:

<snipped>

...

I hope this is somehow helpful in understanding what AMSAT would really be up against if it wanted to have an independent GEO satellite or consider a sub-GEO drifting orbit.

Thank you Ken, for the rocket scientist's take on it ;-)

It's refreshing to hear someone who actually has sat down and done the maths comment on how easy or hard it would be to put a satellite into a high orbit.

---

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