The Sirius birds are in an "Inclined Orbit".
Is this type of orbit can be a solution for the next HEO?
The reference to the Molniya orbit could be to recall the orbit of AO-13... slow high-altitude lingering Northern Hemisphere apogees, rotating ascending nodes about the globe to distribute coverage more evenly around the globe. Over the US, next over Europe, then over Asia. This was very popular at the time, and would likely be welcomed again.
I would suspect that a 'tundra-inclined orbit', fixed over the US as the Sirius Radio Sats are, would not be as internationally well supported. /;^)
My employer used to operate the 3 Sirius Radio Satellites for them. They are highly inclined Geosynchronous, and are set so at least one of the 3 is always over North America. The idea is to have a higher look angle for most of their customers, reducing dropouts from obstructions. The Kep data for the 3 of them as well as XM radio's birds is available from Celestrack at http://www.celestrak.com/NORAD/elements/other-comm.txt .
The 3 Sirius birds currently in orbit are Space Systems Loral FS 1300 Series birds modified so they can be flown inclined.
73 DE Mark KK7CU
On 2/22/08, Alan Sieg WB5RMG [email protected] wrote:
The Sirius birds are in an "Inclined Orbit".
Is this type of orbit can be a solution for the next HEO?
The reference to the Molniya orbit could be to recall the orbit of AO-13... slow high-altitude lingering Northern Hemisphere apogees, rotating ascending nodes about the globe to distribute coverage more evenly around the globe. Over the US, next over Europe, then over Asia. This was very popular at the time, and would likely be welcomed again.
I would suspect that a 'tundra-inclined orbit', fixed over the US as the Sirius Radio Sats are, would not be as internationally well supported. /;^)
-- <- WB5RMG is Alan Sieg * http://wb5rmg.somenet.net ->
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----- Original Message ----- From: "Alan Sieg WB5RMG" [email protected] To: [email protected] Sent: Friday, February 22, 2008 6:23 AM Subject: [amsat-bb] Re: sirius orbit name?
The reference to the Molniya orbit could be to recall the orbit of AO-13... slow high-altitude lingering Northern Hemisphere apogees, rotating ascending nodes about the globe to distribute coverage more evenly around the globe. Over the US, next over Europe, then over Asia. This was very popular at the time, and would likely be welcomed again.
I would suspect that a 'tundra-inclined orbit', fixed over the US as the Sirius Radio Sats are, would not be as internationally well supported. /;^) -- <- WB5RMG is Alan Sieg * http://wb5rmg.somenet.net ->
Hi Alan, WB5RMG
I agree with you because a "tundra-inclined orbit fixed over the US as the Sirius Radio Sats are would not cover the whole globe in different times of the day as did the "about" Molniya orbits of OSCAR-10, OSCAR-13 and AO40 having an orbit inclination lower than 63.4 degrees.
By the way there is another very interest orbit suitable for the Amateur Satellites called "Apogee at Constant Time-of-Day Equatorial " or ACE orbit.
http://www.freepatentsonline.com/5326054.html
http://www.patentstorm.us/patents/5326054.html
The ACE orbit developed by Andrew E. Turner and Kent M.Price of Ford Aerospace was described in QEX magazine march 1989 and this article was translated into italian and adapted with great details by my self for Radio Rivista 7/89
In my article I simulated the advantages to use the ACE orbit using the following uptodated keplerian elements in AMSAT format that can be filled by hand into any computer program following the specific software instructions.
For example using InstantTrack the epoch time listed belowe must be introduced this way: 8 172.58333333
Satellite : ACE Epoch time : 08172.58333333 Inclination : 0.2 deg RA of node : 270.000 deg Eccentricity : 0.4873233583 Arg of perigee : 90 deg Mean anomaly : 180 deg Mean motion : 5 rev/day Decay rate : 1.6e-07 rev/day^2 Epoch Rev : 1 Beacon frequency : 145.810 MHz
Additional celestial elements if needed :
S.M.A. semimajor axis : 14454.26194 km Anomalistic Period : 288 min Apogee : 15108 km Perigee : 1028 km
If you run this keplerian elements you will realise that the ACE orbit is sun-synchronous and the acquisition of the satellite during day hours comes at the same local time in any terrestrial area.
With a selected window of the launch epoch-time like in the above keplerian elements the satellite is available for everybody at their favourable social hours.
In addition only one satellite covers the whole terrestrial globe in 24 hours and the time of acquisition is the same in every place and for everybody.
For example the numbar of day hours that the satellite is in range is the same for the East coast of USA and for Japan.
There are many advantages and of coarse disadvanges using an ACE orbit and all of them are discussed into the above mentioned articles.
Enjoy !
73" de
i8CVS Domenico
participants (3)
-
Alan Sieg WB5RMG -
i8cvs -
Mark Lockwood