DirecTV 4s (1 Viewer)

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HoTat2

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Jun 12, 2012
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Humph ...

Don't get it ...

Would have thought T4S would be moved to a higher disposal or "graveyard" orbit, and therefore moving west away from 101W.

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nelson61

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Humph ...

Don't get it ...

Would have thought T4S would be moved to a higher disposal or "graveyard" orbit, and therefore moving west away from 101W.

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either a fuel problem, relocating, or maybe the epoch caught it in transition? Next update should clarify.

Something like 130 km below geo orbit.

The license including permission to deorbit was approved back in 2012 and there are not other more recent licenses to relocate. So, if the epoch is correct, this is some type of deorbiting movement. Bad epoch????
 
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sty6

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Definitely trash it if there is any anomaly or the gas tank is getting low. Too much crap up there that were never deorbited or could not be still in LEO. Heck even Canada's first satellite launched in the late 60's is still circling earth.
 

JohnL

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I want to know how in the world do you de-orbit a satellite in the "Clarke" belt. DirecTV's satellites are 23,000 miles above the surface of the Earth. Satellites in Low Earth orbit are easy to de-orbit, I can't remember any Clarke Belt satellites being deorbited to the earth.

John
 

nelson61

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I want to know how in the world do you de-orbit a satellite in the "Clarke" belt. DirecTV's satellites are 23,000 miles above the surface of the Earth. Satellites in Low Earth orbit are easy to de-orbit, I can't remember any Clarke Belt satellites being deorbited to the earth.

John
It is satellite speak. When they say "deorbit" for the geostationary satellites, they are saying they are going to increase the elevation by 200-300 km . Then the satellite circles the earth in an area not used for commercial service (essentially forever)for practical purposes..

So when the data says this one was lowered, it does not fit standard practice.
And, sometimes things go wrong in this movement.

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nelson61

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"The De-orbit Plan" as submitted in the approved license extension.

Although not subject to the requirements of Section 25.283(a) of the Commission’s rules, at the end of the operational life of the satellite, DIRECTV will maneuver DIRECTV-4S into a disposal orbit with an altitude no less than that calculated using the IADC formula: 36,021 km + (1000·CR·A/m). The calculated value of CRA/m in this instance is based on the following parameters: CR = Solar Pressure Radiation Coefficient = 1.2 A = Total Solar Pressure Area = 90 m 2 m = Dry Mass of Satellite = 2132.5 kg Using these values in the IADC formula results in a minimum de-orbit altitude of 36,072 km, or approximately 286 km above geosynchronous altitude. To provide adequate margin, the nominal disposal orbit will be increased above this calculated value of 36,072 km to a value of 36,086 km, resulting in a disposal orbit approximately 300 km above geosynchronous altitude. Approximately 16.4 kg of propellant will be allocated and reserved for final orbit raising maneuvers to this altitude. This value was determined through a detailed propellant budget analysis. In addition, DIRECTV has assessed fuel gauging uncertainty and this budgeted propellant provides an adequate margin of fuel reserve to ensure that the disposal orbit will be achieved despite such uncertainty.
 

slice1900

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Unless they have a reason why they want to put it in a graveyard orbit at a different location, it seems like they are moving it elsewhere to be used by someone else. If so we should see the filing pop up on the FCC site soon (not sure how long it takes from submission to actually going up on the site)
 

navychop

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THAT is the oddity. Deorbit, in most if not all contexts, IMHO, means burn it up in the atmosphere. Graveyard orbits may be cheaper, but inevitably mean at some future date the crap in the way must be cleaned up. Perhaps by a redirect to the sun over a multi year trajectory.


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slice1900

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THAT is the oddity. Deorbit, in most if not all contexts, IMHO, means burn it up in the atmosphere. Graveyard orbits may be cheaper, but inevitably mean at some future date the crap in the way must be cleaned up. Perhaps by a redirect to the sun over a multi year trajectory.


Redirecting to the Sun is not possible. It takes a LOT of energy to get there, it isn't something a satellite could ever do. Not only would it require more fuel to go all the way down rather than a little bit up, it would be a lot more risky to deorbit and burn up a satellite in geosynchronous orbit than it is to park it a few hundred miles above GSO. There is a greater potential for damage from something encountered on the way down (even a fleck of paint off something launched decades ago would tear through the satellite like tissue paper due to the differential velocity, leaving more debris behind) and more fuel is required to steer it out of the way of larger things in orbit we know about. If it stops working on the way down it would remain in orbit for years and be a long term navigational hazard.
 

navychop

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Space tug. Assuming technological advances and the need to remove the junk.


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slice1900

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Space tug. Assuming technological advances and the need to remove the junk.


Someday sure, but the retired GSO satellites in the graveyard orbit a couple hundred miles above GSO are the last thing they need to worry about cleaning up. The much bigger problem is on LEO where the space station lives and soon a LOT more satellites will be in place. There's a lot of debris there from accidents, ASAT weapon tests, dropped tools during spacewalks and so forth. NASA tracks it all down to a fairly small size, but even the stuff too small for them to track could kill an astronaut on a space walk. That small stuff in LEO is a much bigger concern, but it is also much more difficult to clean up.

Sure, we could send a space tug up there with a big net to capture all the satellites in graveyard orbit but that isn't really solving any problems we have. They are big and in very stable orbits, so they are easy to avoid when we launch stuff out of Earth's orbit. There are so few it would be almost impossible to hit them even if we weren't looking. Imagine if they were sitting on the Earth's surface, and you picked a random 100m^2 spot on Earth. The odds one of them would be in that spot are probably a billion to one. And the "surface area" of the graveyard orbit is something like 30x larger! The satellites in graveyard orbit just aren't worth our trouble, and probably never will be.
 

navychop

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Probably. But how much will it build up over the next hundred, two hundred years?


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doctor J

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D4s still at lower orbit, presently about 88 degrees west and headed EAST at ~ 1.7 degrees per day???
No postings I've found yet

Doctor j
 

slice1900

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D4s still at lower orbit, presently about 88 degrees west and headed EAST at ~ 1.7 degrees per day???
No postings I've found yet

Doctor j

Yes I saw a filing made on Sept. 30th on the FCC site when I looked today, so I guess they can get them out pretty quick when they want to. If they have sold D4S to a foreign interest I think that company would be responsible for filing and I don't think they would need to file with the FCC for such a move. They'd file with their own authority who I presume simply notifies the FCC but doesn't need their approval. Other than "they've filed but it hasn't been posted yet" that's all I can come up with.
 
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