OHM SDO

[OrbitHangar]

Author: BrianJ

Solar Dynamics Observatory

NASA's solar science satellite launched Feb.11 15:23 UTC, on AtlasV AV021 from LC-41.

Put SDO into an 28.5deg inclined Geosynchronous orbit centered over 102deg West.

Ascent and 185km x 3590km parking orbit autopilots available. SDO HUD features mean surface longitude, drift rate, and other useful data.

Add-on requirements:

MRO add-on
http://www.orbithangar.com/searchid.php?ID=3711

Vinka's "multistage2.dll" (full package)  available at Vinka's website http://users.swing.be/vinka/

29 March 2011: Updated for Orbiter 2010-P1


DOWNLOAD

 

[TonyZ2525]

Your link to the MRO add-on appears to be a dead link.perhaps you have a different link for this required addon?

 

[PeterRoss]

Fixed:
[ame="http://www.orbithangar.com/searchid.php?ID=3711"]MRO[/ame]

 

[tblaxland]

Excellent work as always Brian :thumbup:

Preparing for the flight I was struggling to find a flight plan. The best I could find was this from spaceflightnow which gives the event times and GTO parameters: http://spaceflightnow.com/atlas/av021/100125ascent.html. The "SDO Guide" from NASA mentions that the target mission orbit will be GEO at the "longitude of New Mexico" (about 106°W) and inclined at 28°.

 

[Voyager_VI]

As always Brian, too cool!!

Thanks for another great Atlas V addon!

 

[BrianJ]

Your link to the MRO add-on appears to be a dead link.perhaps you have a different link for this required addon?

Ooops. Will fix the link on OH.

Thanks for the kind words - bit of a rush job! (only started Sunday night)

I noticed a couple of posts about geosynchronous orbits, so I thought a topical real-life example might be of interest. I might add some functionality later.

I think I read somewhere the operational orbit will be over 102deg W. at 28.5 inc. (equatorial), but I can't find the link now. Although the dedicated tracking stations are at White Sands(106deg W.)

Looking at the predicted ground track, initial apogee will be at about 72deg W., so there must be some phasing orbits used to position SDO over 102deg W.

Transfer orbit at Centaur MECO2 is 2500km x 35355km, hence the odd parking orbit of 185km x 2500km.

OK, I'm off to watch the launch on NASATV.
Cheers,
Brian

 

[Urwumpe]

Small note: Please include in the calculations that you can have the perigee altitude increased during the second burn, especially during long burns this is a normal event.

 

[BrianJ]

Small note: Please include in the calculations that you can have the perigee altitude increased during the second burn, especially during long burns this is a normal event.

Yes, that's true.

However, my initial guess of 185km x 2500km parking orbit is way off - you end up making the GEO transfer burn much earlier than indicated by the ground-track prediction,etc.

Using a 185km x 3590km parking orbit gets the timing closer, and if you make the final burn at longitude 164deg East you end up pretty much at the right longitude at the first apogee.

A slightly tweaked version inc.new parking orbit autopilot and launch scenario for 11 Feb now on OH.

Cheers,
Brian

 

[Urwumpe]

However, my initial guess of 185km x 2500km parking orbit is way off - you end up making the GEO transfer burn much earlier than indicated by the ground-track prediction,etc.

Using a 185km x 3590km parking orbit gets the timing closer, and if you make the final burn at longitude 164deg East you end up pretty much at the right longitude at the first apogee.

Did you try looking at the atlas V payload planners files? I think it has a plot with the approximate trajectory there.

 

[Star Voyager]

Page 14 will give you apogee and perigee at SDO seperation from the Centaur.

http://www.ulalaunch.com/launch/sdo/SDO_MOB.pdf

 

[Urwumpe]

Page 14 will give you apogee and perigee at SDO seperation from the Centaur.

http://www.ulalaunch.com/launch/sdo/SDO_MOB.pdf

Yes, this is known. The orbit parameters after MECO-1 is missing.

EDIT: From my old printed version of the guide, the parking orbit is chosen "performance-optimal". From the pure mathematical side of it, this means the apoapsis must be between MECO-1 and MES-2, about in the middle for getting a higher Oberth effect. Maybe this helps combined with the flight time and difference in great circle angle, to estimate the orbit.

 

[ex-orbinaut]

Nice one. :tiphat: Thank you!

 

[Interceptor]

Thanks for the update.:tiphat:

 

[Jer95]

:thumbup: Thank you for putting one of my favorite satellites in Orbiter

 

[Wishbone]

:tiphat:

 

[I00I]

Nicely done..
“Mystery creates wonder and wonder is the basis of man's desire to understand.”