Spacex falcon9 to GTO in 7 min.

[Calvin19 0]

http://www.spacex.com/webcast/

yay!

[fallfast69 2]

Thanks Calvin...that was amazing!

Jon

[zoobrothertom 5]

Thanks Calvin.

____________________________________
I'm back in the USA!!

[JohnMitchell 14]

This mission is the second Falcon 9 launch to a geosynchronous transfer orbit, targeting a 295 x 90,000 km orbit at 22.5 degrees inclination.

Not sure what the 90,000 km dimension means. I can imagine it might be in a highly elliptical orbit pending geostationary insertion, but that's only about 38,000 km up. Can anyone translate for me?

[Calvin19 0]

I remember reading that the target orbit was gong to be a supersynchronous orbit. Can't find it now though.

But I don't understand the benefit of a 90k apogee transfer orbit either.
hehe... 295x90,000 is a hell of a roller coaster. count me in.

[Calvin19 0]

Found it.

Quote

For Hawthorne, Calif.-based SpaceX, the Thaicom 6 launch demonstrated the company’s ability to return to flight in short order following the successful Dec. 3 launch of Luxembourg-based SES’s SES-8 telecommunications satellite. For Thaicom 6, SpaceX placed the satellite into a higher apogee — 90,000 kilometers — than was used for SES-8. Higher apogees of supersynchronous orbits are used to remove the inclination relative to the equator as the orbit is lowered toward final geostationary orbit circularized at about 36,000 kilometers over the equator.

Exact orbital injection parameters were not immediately available, but SpaceX said its target was an apogee of 90,000 kilometers, a perigee of 295 kilometers and an inclination of 22.5 degrees relative to the equator.

http://www.spacenews.com/article/launch-report/38959spacex-delivers-thaicom-6-satellite-to-orbit

-SPACE-

[JohnMitchell 14]

Wow, I knew it took a LOT of energy to get rid of orbital inclination. Wish I knew the orbital mechanics involved to translate that altitude to inclination change. Interesting. Now I have a new subject to look up.

Too bad my calculus sucks. .

[champu 1]

Plane changes require less energy the higher you conduct them which means you can use higher efficiency thrusters (that have lower overall output) and still get the job done in a reasonable amount of time.

Not sure what they mean by "remove the inclination as the orbit is lowered" though. You lower the apoapsis with burns at periapsis and you remove the inclination with burns at apoapsis. You'd want to do the latter prior to the former, not at the same time.

[JohnMitchell 14]

champu

Plane changes require less energy the higher you conduct them which means you can use higher efficiency thrusters (that have lower overall output) and still get the job done in a reasonable amount of time.

Ahh, thanks for the new factoid.. .

Quote

Not sure what they mean by "remove the inclination as the orbit is lowered" though. You lower the apoapsis with burns at periapsis and you remove the inclination with burns at apoapsis. You'd want to do the latter prior to the former, not at the same time.

Exactly.
No really, that makes sense..

[labrys 0]

Quote

Not sure what they mean by "remove the inclination as the orbit is lowered" though.

I read that as lowering the orbital [speed] from super to geosynchronous as it hits the target slot, but I could *totally* be wrong.

Owned by Remi #?

[Calvin19 0]

labrys

Quote

Not sure what they mean by "remove the inclination as the orbit is lowered" though.

I read that as lowering the orbital [speed] from super to geosynchronous as it hits the target slot, but I could *totally* be wrong.

Using higher impulse, lower thrust engines I think it would take time, as in the burn would be a large portion of the orbit track. (?)

Im guessing that to put something into a 90,000 X 250 km orbit takes about the same energy as putting something into a stable. 36,000km orbit.(?) Precision is a big deal, as is zeroing inclination for geostationary, with a high inclination the two can be done at the same time with less impulse. (?)

(?)=I failed maths four times and HATE/LOVE Tsiolkovsky.

[champu 1]

Calvin19

Im guessing that to put something into a 90,000 X 250 km orbit takes about the same energy as putting something into a stable. 36,000km orbit.(?)

E = -1/2 GMm/a
a = (r1+r2)/2

E_elipse_orbit / E_circle_orbit = a_circle_orbit / a_elipse_orbit = (in this case) 0.8228

...so it's about 82% of the way there in terms of total energy. You do have to use some energy to eventually lower the apoapsis (which is more or less "wasted"), but this is less than the energy saved by performing a plane change from 22.5 deg to 0 deg at 90,000 km vs performing it at 36,000 km.

[Calvin19 0]

champu

, but this is less than the energy saved by performing a plane change from 22.5 deg to 0 deg at 90,000 km vs performing it at 36,000 km.

I may have lost track of a negative in there, but I think I understand.