Author Topic: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread  (Read 32611 times)

Offline Chris Bergin

As part of our increasing coverage to cover more on the spacecraft - as opposed to mainly the rockets - here's a dedicated thread for the SES-8 satellite, by Orbital.

I've written an article based on the confirmation of its shipping, with as much details on the bird as I could muster:

SES-8 heads to Florida for next Falcon 9 v1.1 launch
http://www.nasaspaceflight.com/2013/10/ses-8-florida-next-falcon-9-v1-1-launch/

So this thread can cover discussion on this spacecraft. Anything on the launch vehicle can be covered in the relevant SpaceX threads.
« Last Edit: 10/02/2013 10:42 PM by Chris Bergin »

Offline StarryKnight

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Thanks for starting this, Chris. I'm a spacecraft kind of guy, not so much a rocket man. So I appreciate a thread like this.
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Offline dsobin

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Great thread Chris! I'd like to see more like this.

We heard Elon say that the SpaceX contract with SES requires full expendable-style performance. Does this mean
that SES will be able to load more prop into its tanks? If some performance had been reserved for booster stage re-lights, would the SES-8 tanks have been only partly full? What would this do to spacecraft lifetime?

What other considerations go into this requirement as a contract consideration, as opposed to a technical necessity?


Offline Joffan

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Orbital's fact sheet

Quote
SES-8, a hybrid Ku- and Ka-band spacecraft, is the sixth GEOStar-2™ satellite ordered by SES S.A. The satellite is based on Orbital’s Enhanced GEOStar-2 bus, and will carry 24 active Ku-band transponders of 36 or 54 Mhz capacity switchable amongst 33 channels and two beams. Certain channels in each beam are cross-strapped to multiple frequency bands, enabling flexibility for new services. In addition, the spacecraft features a Ka-band payload. The spacecraft will generate approximately five kilowatts of payload power and will feature two 2.5 x 2.7 meter super elliptical deployable reflectors and a 1.45 meter fixed, deck-mounted antenna.
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Offline kevin-rf

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Looking at the satellite simulated image, one thing just bugs the heck out of me (and everyone manufacture seems to do it).

In flight the solar panels looking from the ground are located above and below (north and south) of the satellite body and orbital plane, the two dishes are located to the left and right (east and west) of the satellite body and orbital plane.

They (like everyone else) are depicting the satellite on it's side!

End mini rant... Sorry Chris, I'll go get some coffee now.
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Online pippin

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For Ariane dual launches, will we then have a dedicated spacecraft thread for both sats or one combined for both in the future?
There's one of these Orbital StarBus babies on almost every Ariane 5 launch since they are the typical "secondary" candidate due to their small size and weight (they fit into Sylda).

Offline Lurker Steve

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Interesting that this is the "smaller" of the GEOstar family, although that does seem to be a fairly decent number of transponders on this comm stat.

What is the mix of GEOstar sats launched to date ? How many GEOstar-2 vs GEOstar-3 for instance ?

I wonder if the GEOstar-3 is too heavy for a F9.

Offline parham55

Looking at the satellite simulated image, one thing just bugs the heck out of me (and everyone manufacture seems to do it).

In flight the solar panels looking from the ground are located above and below (north and south) of the satellite body and orbital plane, the two dishes are located to the left and right (east and west) of the satellite body and orbital plane.

They (like everyone else) are depicting the satellite on it's side!

End mini rant... Sorry Chris, I'll go get some coffee now.

Now for a very basic spacecraft question, why are the spacecraft oriented this way in flight and not the other? Thanks.

Offline kevin-rf

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It has to do with the sun and the solar panels. The panels rotate about the satellite body from east to west (Clockwise?) to track the sun. To do this the axis of rotation has to be north to south, leaving the east, west (right,left) sides of the satellite available for large antenna.
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Offline StarryKnight

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Lot's of good questions so far. I'll do my best to answer them as many as I can.

We heard Elon say that the SpaceX contract with SES requires full expendable-style performance. Does this mean
that SES will be able to load more prop into its tanks? If some performance had been reserved for booster stage re-lights, would the SES-8 tanks have been only partly full? What would this do to spacecraft lifetime?

What other considerations go into this requirement as a contract consideration, as opposed to a technical necessity?

The injection orbit for SES-8 is called a super-synchronous GTO (GTO = Geosynchronous Transfer Orbit) which means that the apogee is above the GEO synchronous altitude of 35,786 km. (A satellite in a circular orbit at GEO altitude has an orbit period of 1 day, matching the Earth's rotation rate). A typical GTO (like you get off of Ariane, Land Launch, Sea Launch, and some other launchers) is an ellipse that has apogee at or near GEO altitude and perigee altitude of somewhers between a couple of hundred kilometers to a few thousand kilometers. It is then up to the satellite to use onboard thrusting to raise perigee up to GEO.

The super-synch GTO also has a fairly low perigee, but it's apogee is usually 10's of kilometers above GEO. This means the satellite's orbit has higher energy. So even though you have to now both raise perigee to GEO and lower apogee to GEO, there is still a fuel savings. For the SES-8 mission, most of the Falcon 9's performance will go into putting the spacecraft in an orbit over 80,000 km altitude at apogee. Some of the rocket's performance will also lower the orbit inclination from about 28 degrees (the lattitude of Cape Canaveral) to a little under 21 degrees, also reducing the amount of fuel that the satellite will require to get to its final orbital slot.

The SES-8 satellite's propellant tanks will be loaded as full as possible for the Falcon 9 to acheive the desired injection orbit. Again, since this is a high energy orbit, less proplellant will be required in the satellite than for a typical GTO to get the satellite to the desired orbit.


Kevin-rf - Yeah those drawings always bug me, too. The Earth is also always too big for a satellite being at GEO altitude. All I can say is artistic license does not reflect physical reality. (maybe I should add that saying to my signature  :) ).  However there are some satellites (e.g. Loral's FS-1300) which do deploy solar arrays very soon after launch and remain like that throughout the orbit raising period. But I don't know if the reflectors are deployed at that time or if they wait until the satellite gets to GEO.


LurkerSteve - 27 STAR-2's and no STAR-3's, yet. The STAR-3 will be fine on an F9. But the injection orbit won't be as high as the SES-8 or Thaicom-6 missions. It still may be able to reach super-synch, just not as high as 80,000+ km.
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Offline Star One

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #10 on: 10/03/2013 03:05 PM »

Lot's of good questions so far. I'll do my best to answer them as many as I can.

We heard Elon say that the SpaceX contract with SES requires full expendable-style performance. Does this mean
that SES will be able to load more prop into its tanks? If some performance had been reserved for booster stage re-lights, would the SES-8 tanks have been only partly full? What would this do to spacecraft lifetime?

What other considerations go into this requirement as a contract consideration, as opposed to a technical necessity?

The injection orbit for SES-8 is called a super-synchronous GTO (GTO = Geosynchronous Transfer Orbit) which means that the apogee is above the GEO synchronous altitude of 35,786 km. (A satellite in a circular orbit at GEO altitude has an orbit period of 1 day, matching the Earth's rotation rate). A typical GTO (like you get off of Ariane, Land Launch, Sea Launch, and some other launchers) is an ellipse that has apogee at or near GEO altitude and perigee altitude of somewhers between a couple of hundred kilometers to a few thousand kilometers. It is then up to the satellite to use onboard thrusting to raise perigee up to GEO.

The super-synch GTO also has a fairly low perigee, but it's apogee is usually 10's of kilometers above GEO. This means the satellite's orbit has higher energy. So even though you have to now both raise perigee to GEO and lower apogee to GEO, there is still a fuel savings. For the SES-8 mission, most of the Falcon 9's performance will go into putting the spacecraft in an orbit over 80,000 km altitude at apogee. Some of the rocket's performance will also lower the orbit inclination from about 28 degrees (the lattitude of Cape Canaveral) to a little under 21 degrees, also reducing the amount of fuel that the satellite will require to get to its final orbital slot.

The SES-8 satellite's propellant tanks will be loaded as full as possible for the Falcon 9 to acheive the desired injection orbit. Again, since this is a high energy orbit, less proplellant will be required in the satellite than for a typical GTO to get the satellite to the desired orbit.


Kevin-rf - Yeah those drawings always bug me, too. The Earth is also always too big for a satellite being at GEO altitude. All I can say is artistic license does not reflect physical reality. (maybe I should add that saying to my signature  :) ).  However there are some satellites (e.g. Loral's FS-1300) which do deploy solar arrays very soon after launch and remain like that throughout the orbit raising period. But I don't know if the reflectors are deployed at that time or if they wait until the satellite gets to GEO.


LurkerSteve - 27 STAR-2's and no STAR-3's, yet. The STAR-3 will be fine on an F9. But the injection orbit won't be as high as the SES-8 or Thaicom-6 missions. It still may be able to reach super-synch, just not as high as 80,000+ km.

How big would the Earth look if you were an astronaut perched on top of a GEO satellite & looked down?

Offline smoliarm

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #11 on: 10/03/2013 03:16 PM »
Looking at the satellite simulated image, one thing just bugs the heck out of me (and everyone manufacture seems to do it).

In flight the solar panels looking from the ground are located above and below (north and south) of the satellite body and orbital plane, the two dishes are located to the left and right (east and west) of the satellite body and orbital plane.

They (like everyone else) are depicting the satellite on it's side!

End mini rant... Sorry Chris, I'll go get some coffee now.

Kevin,
note that -- if you look at GEO satellite from some point at equator and 90° off (to West or East) from satellite's longitude -- you see it in this very orientation: solar panels are horizontal (left and right) and dishes are vertical (top and bottom). So, they just showed the view from some equatorial paradise ;)

Offline StarryKnight

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #12 on: 10/03/2013 03:22 PM »
Star One,

The Earth as seen from GEO is approximately 17 degrees in diameter.
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Offline kevin-rf

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #13 on: 10/03/2013 03:36 PM »
Kevin,
note that -- if you look at GEO satellite from some point at equator and 90° off (to West or East) from satellite's longitude -- you see it in this very orientation: solar panels are horizontal (left and right) and dishes are vertical (top and bottom). So, they just showed the view from some equatorial paradise ;)

Aaah, so the satellite art work is for business execs. pontificating from tropical paradises while the rest of us slave away in the cubical mines of the northern rust belts. Now it all makes sense ;)
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Offline smoliarm

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #14 on: 10/03/2013 03:36 PM »

...
How big would the Earth look if you were an astronaut perched on top of a GEO satellite & looked down?

Yes :) I got the same number :) 17°
And it's pretty damn big, e.g. angular size of the Moon from Earth is about 0.5 deg
or some 30+ times smaller.

Offline smoliarm

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #15 on: 10/03/2013 03:49 PM »
Kevin,
note that -- if you look at GEO satellite from some point at equator and 90° off (to West or East) from satellite's longitude -- you see it in this very orientation: solar panels are horizontal (left and right) and dishes are vertical (top and bottom). So, they just showed the view from some equatorial paradise ;)

Aaah, so the satellite art work is for business execs. pontificating from tropical paradises while the rest of us slave away in the cubical mines of the northern rust belts. Now it all makes sense ;)

Of course it makes sense - "must be funny in a rich man's world!!"
It's always sunny there too, unlike in the cubical mines ...

Offline kwan3217

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #16 on: 10/03/2013 05:59 PM »
It says in the news article that the spacecraft will be parked in an undisclosed location in Florida until the shutdown lifts, because Astrotech is unavailable. Why is that? I thought Astrotech was a private company with it's facilities off-base.

Offline Antares

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #17 on: 10/03/2013 09:07 PM »
Astrotech already has its processing bays booked?
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Offline Eer

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #18 on: 10/03/2013 09:32 PM »
Article says
Quote
... the immediate post-flight discussions revolved around the potential to tweak the second stage, following an anomaly relating to a secondary task to attempt a re-entry, per SpaceX’s reusability ambitions.

I didn't think the 2nd stage anomaly had anything to do with any secondary task for it to attempt re-entry - I thought stage ONE was the only one trying to do re-entry, and stage TWO had a secondary task to burn-to-depletion - thus all the discussion about whether it could make it to Mars or not...

Did I miss something?

Offline Jim

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #19 on: 10/04/2013 12:04 AM »
It says in the news article that the spacecraft will be parked in an undisclosed location in Florida until the shutdown lifts, because Astrotech is unavailable. Why is that? I thought Astrotech was a private company with it's facilities off-base.

I thought it was going to Spacex facilities and with KSC shutdown access is only via the south gate which might not be able to take the transporter.

Offline Zed_Noir

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #20 on: 10/04/2013 07:27 AM »
It says in the news article that the spacecraft will be parked in an undisclosed location in Florida until the shutdown lifts, because Astrotech is unavailable. Why is that? I thought Astrotech was a private company with it's facilities off-base.

I thought it was going to Spacex facilities and with KSC shutdown access is only via the south gate which might not be able to take the transporter.

Does that mean the SpaceX core transporter also could not access SLC-40 as well? Since it's bigger than the SES-8 transporter.

Offline sdsds

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #21 on: 10/04/2013 08:35 AM »
For the SES-8 mission, most of the Falcon 9's performance will go into putting the spacecraft in an orbit over 80,000 km altitude at apogee. Some of the rocket's performance will also lower the orbit inclination from about 28 degrees (the lattitude of Cape Canaveral) to a little under 21 degrees, also reducing the amount of fuel that the satellite will require to get to its final orbital slot.

Wow that's high! For comparison on the Intelsat 22 launch ILS targeted a 65,000 km apogee (with a 3,791 km perigee and an inclination of 28.5 degrees). Optimally these apogees should be directly above the equator, even with the orbit inclined to the equatorial plane, right? So what did Elon mean when he said, "We can technically do [GTO missions] without a restart, we can do them as a single burn, but it means the satellite has to do more work to change the plane of its orbit to equatorial." If the decision were made to use only a single burn of the Falcon upper stage (without a restart) then could the spacecraft still be delivered to an orbit with that apogee, but not with the apses at the equator? How much of a penalty would that impose?
-- sdsds --

Offline StarryKnight

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #22 on: 10/04/2013 02:26 PM »
Eer,
I can't speak as to whether SpaceX was attempting to do a re-entry of the second stage. But SES wanted SpaceX to demonstrate the relight because a second burn of the upper stage is needed for the SES-8 mission.


sdsds,
Yes it's very high. There's a possibility that the Thaicom-6 mission may be even higher. But I understand they may still be looking at other apogee altitudes.
Yes, apogees have to be nearly above the equater. The penalty can be pretty large if it is too far off. I don't know what Elon may have been refering to. You quote him as saying a plane change (i.e. inclination). So that doesn't mean the apogee is not above (or nearly above) the equator. It means that the upper stage won't be able to knock down the inclination much. For a launch out of the cape, without the rocket reducing inclination, you'll end up with about a 28 degree inclination orbit (the latitude of the launch site). As I noted earlier, the inclination on the SES-8 mission is targeted to be just under 21 degrees. So that's 7 degrees of inclination that the satellite does not have take out by the time it's done with its own delta-v maneuvers.
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Offline Chris Bergin

Speaking of which, Thaicom-6 is another Orbital bird, so we'll do the same coverage for that mission too (LV in SpaceX section. Spacecraft in this section).

Offline kevin-rf

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #24 on: 10/04/2013 03:21 PM »
Just make sure they orient the bird the right way ;)
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Offline baldusi

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #25 on: 10/04/2013 04:32 PM »
Is it pure chance or a cheap Falcon 9 means a lot of good business chances for OSC satellites?

Offline StarryKnight

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #26 on: 10/04/2013 04:45 PM »
It's probably just a coincidence that the first two commercial GEOs on a Falcon 9 are Orbital built spacecraft. In both instances, the end customer (SES and Thaicom) purchased the launch vehicle, not Orbital. The reasons for them to do this were some combination of the cost of the launch (including insurance) and the performance obtained by launching into a very high supersynch mission (which directly relates to a higher spacecraft on-orbit maneuvering life, OML).
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Offline jimvela

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #27 on: 10/04/2013 04:51 PM »
Is it pure chance or a cheap Falcon 9 means a lot of good business chances for OSC satellites?

A SpaceX that is successful in providing reliable, lower-cost launches is good for *EVERY* spacecraft builder and spacecraft operator.

I can't wait to see the first of the S/C that I've worked on launch on a Falcon...

Offline Arthree

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #28 on: 10/04/2013 05:00 PM »
If the decision were made to use only a single burn of the Falcon upper stage (without a restart) then could the spacecraft still be delivered to an orbit with that apogee, but not with the apses at the equator? How much of a penalty would that impose?

A single-burn GTO injection can (and would) result in an orbit with perigee/apogee over the equator.  The advantage to a 2-burn method is that by waiting for the launch vehicle to pass over the equator, inclination can be lowered at the same time that apogee is increased, which leaves the payload in an orbit that requires less delta-v to transfer out of into GEO.

Offline StarryKnight

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #29 on: 10/04/2013 05:48 PM »
Quote
A single-burn GTO injection can (and would) result in an orbit with perigee/apogee over the equator.

Only if that single injection burn also stradles the equitorial plane. Performing a prograde burn will increase the height of the orbit 180 degrees from where the vehicle is when the burn is performed. So if you start with a 28 degree inclinatioin and wait until the the vehicle is at the southern most point of the orbit to do a burn, the apogee will occur over the northern most point of the orbit. Usign this type of burn is how you can get into a Molniya orbit (though that's a 63.4 inclination, 40,000 km apogee).

You are correct about burns for inclination changes have to occur as the vehicle passes the equitorial plane. That is to say to at least do the burn efficiently. An out of plane burn in other places in the orbit can also impact the inclination, but the effect is reduced relative to a burn above the equator.

[Edited to correct Molniya orbit info.]
« Last Edit: 10/04/2013 05:54 PM by StarryKnight »
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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #30 on: 10/04/2013 06:42 PM »
Von Karman is regularly quoted as having once said "given enough power, ANYTHING can fly" (aerodynamically speaking...)

I guess the orbital mechanics equivalent is "given enough DV ANY orbit is good"... :)
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Offline StarryKnight

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #31 on: 10/04/2013 06:50 PM »
I once had a boss who said "I can get you to any orbit you want using 3 burns."  Of course this ignores the current state of technology since in the extreme cases you'd need more powerful/fuel efficient engines than have been imagined by anyone except the best science fiction writers.
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Offline Arthree

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #32 on: 10/05/2013 01:32 AM »
Quote
A single-burn GTO injection can (and would) result in an orbit with perigee/apogee over the equator.
Only if that single injection burn also stradles the equitorial plane

There is no requirement for the injection burn to ever pass through the equator in order to get an apo/perigee over the equator.  Burning towards or away from the center of the orbit will affect both the eccentricity of the orbit and the location of the apo/perigee, and it is this method that would be used in a direct-ascent GTO launch profile.
« Last Edit: 10/05/2013 01:35 AM by Arthree »

Offline StarryKnight

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #33 on: 10/05/2013 01:54 AM »
Quote
A single-burn GTO injection can (and would) result in an orbit with perigee/apogee over the equator.
Only if that single injection burn also stradles the equitorial plane

There is no requirement for the injection burn to ever pass through the equator in order to get an apo/perigee over the equator.  Burning towards or away from the center of the orbit will affect both the eccentricity of the orbit and the location of the apo/perigee, and it is this method that would be used in a direct-ascent GTO launch profile.

Correct. That was my point later on about the efficiency. A burn centered a few degrees from the eclipse doesn't cost too much in terms of propellant. But burning 30 degrees away costs a lot.
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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #34 on: 10/09/2013 09:09 AM »
SES-8 ARRIVES AT CAPE CANAVERAL FOR SPACEX FALCON 9 LAUNCH

08.10.2013 


55th SES satellite to serve Asia-Pacific from 95 degrees East

Luxembourg, October 8th, 2013 – SES S.A. (NYSE Euronext Paris and Luxembourg Stock Exchange: SESG) is pleased to announce that the SES-8 satellite has arrived at the Kennedy Space Center in Cape Canaveral (Florida). The satellite will now be processed for a November launch on board a SpaceX Falcon 9 booster.

SES-8 has been manufactured by Orbital Sciences Corporation. The satellite features up to 33 Ku-band transponders (36 MHz equivalent). SES-8 will be co-located with NSS-6 at the orbital location of 95 degrees East to provide growth capacity over Asia-Pacific. The spacecraft’s high performance beams will support the rapidly growing markets in South Asia and Indo-China, as well as provide expansion capacity for DTH, VSAT and government applications.

Martin Halliwell, Chief Technology Officer of SES, stated: “SES looks forward to the maiden launch of an SES satellite on board the Falcon 9 rocket operated by SpaceX. When co-located with NSS-6 at 95 degrees East, SES-8 will not only provide incremental high performance capacity for multiple applications, it will also create greater reliability and additional security for customers. As such, the SES-8 satellite is an integral part of SES’ growing presence in Asia-Pacific.”


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Jeff Bezos has billions to spend on rockets and can go at whatever pace he likes! Wow! What pace is he going at? Well... have you heard of Zeno's paradox?

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http://www.orbital.com/SatellitesSpace/Communications/SES-8/

Apparently, that's orbiting some exo-planet that has the same land/water masses as Earth, but has its Arctic Circle around 45o North (IE with a 45o axial tilt, and pictured at Northern Winter Solstice).  ;)

And it's picking up signals from some alien spacecraft nowhere near the exo-planet's surface, and broadcasting them back somewhere that's nowhere near the exoplanet's surface.  ;)

Also, you'd think the solar panels would work better if pointing at the exo-planet's star on at least one axis.  ;) [Although reflections on the solar panels do suggest a second star that is eclipsed from the exo-planet, but is illuminating the satellite.  ;) ]


aint she pretty?

Depends if you think form follows function and what alien conspiracists speculate it's function is supposed to be.  ;)

LOL.

cheers, Martin

PS anyone spot anything else that I've missed?
« Last Edit: 11/03/2013 08:33 PM by MP99 »

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #37 on: 11/23/2013 08:42 AM »
Can someone explain to me how you can raise the perigee AND lower the apogee (or vice versa) with the same burn? Or even multiple burns in the same direction (i.e. all of them being prograde or retrograde)?

Offline deltaV

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #38 on: 11/23/2013 02:44 PM »
Can someone explain to me how you can raise the perigee AND lower the apogee (or vice versa) with the same burn? Or even multiple burns in the same direction (i.e. all of them being prograde or retrograde)?

Let's suppose you're in a circular orbit. Do a single burn thrusting away from the center of the Earth, as if trying to raise the orbit the intuitive but wrong naive way. Immediately after the burn the altitude will clearly increase so apogee must have increased. To first order this burn only changes the direction of velocity, not its magnitude. The vis-viva equation therefore says that the semi-major axis (i.e. average of perigee and apogee) has not changed. We deduce that perigee must have decreased.

Offline Roy_H

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #39 on: 11/24/2013 02:18 PM »
I am not a rocket scientist, and am finding this an interesting education on orbital mechanics. So if I understand correctly, the most cost effective maneuvers for SES-8 from the delivered orbit would be burns directly away from earth at perigee to circularize the orbit, and at apogee in a northern or southern direction to change the plane of orbit. The north/south burns would not be directly north or south, but at some optimal off angle, and they would have to be done when the perigee coincides with crossing the equator. Did I get this right? To take this a little farther, I assume it best to do the plane change first so it is an equatorial orbit, is this done in a single burn?
"If we don't achieve re-usability, I will consider SpaceX to be a failure." - Elon Musk

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #40 on: 11/24/2013 03:45 PM »
I am not a rocket scientist, and am finding this an interesting education on orbital mechanics. So if I understand correctly, the most cost effective maneuvers for SES-8 from the delivered orbit would be burns directly away from earth at perigee to circularize the orbit, and at apogee in a northern or southern direction to change the plane of orbit. The north/south burns would not be directly north or south, but at some optimal off angle, and they would have to be done when the perigee coincides with crossing the equator. Did I get this right? To take this a little farther, I assume it best to do the plane change first so it is an equatorial orbit, is this done in a single burn?

My comment about thrusting away from the center of the Earth was in answer to AJA's question only. AFAIK geosynchronous missions do not make use of burns directed towards or away from the center of the Earth. Even if such a burn were used for circularization it would have to be done when at geosynchronous altitude, not at perigee.

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #41 on: 11/24/2013 06:37 PM »
I am not a rocket scientist, and am finding this an interesting education on orbital mechanics. So if I understand correctly, the most cost effective maneuvers for SES-8 from the delivered orbit would be burns directly away from earth at perigee to circularize the orbit, and at apogee in a northern or southern direction to change the plane of orbit. The north/south burns would not be directly north or south, but at some optimal off angle, and they would have to be done when the perigee coincides with crossing the equator. Did I get this right? To take this a little farther, I assume it best to do the plane change first so it is an equatorial orbit, is this done in a single burn?

No, the most effective way to circulariize any orbit is always to thrust in your orbital direction (if at apogee) or the reverse of that (if at perigee).

It may seem like a silly suggestion, but the simulation game "Kerbal space program" is a *great* about learning basic orbital mechanics. You get to play with orbits, set new orbits, and the game will indicate the most efficient way to thrust to realize that new orbit. It can be surprising and sometimes counter-intuitive.
(EDIT: here is a quick video that shows how KSP can teach you how thrusting in different directions affects your orbit: youtu.be/_aNlR4-1IrM )
« Last Edit: 11/24/2013 06:55 PM by Lars_J »

Offline Eer

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #42 on: 11/24/2013 09:59 PM »
(EDIT: here is a quick video that shows how KSP can teach you how thrusting in different directions affects your orbit: youtu.be/_aNlR4-1IrM )

Thanks, Lars - I found that very helpful ;-)

Offline Nomadd

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #43 on: 11/24/2013 10:58 PM »
 You can always change direction in the middle of the burn.

Offline Avron

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #44 on: 11/24/2013 11:19 PM »
You can always change direction in the middle of the burn.

The burn itself is made to change direction in terms of orbit.. can you change the space craft orientation in mid burn .. yes.. see Apollo 13.. but why?

ooops my bad.. wrong thread...
« Last Edit: 11/24/2013 11:21 PM by Avron »

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #45 on: 11/25/2013 03:17 PM »
SES-8 SATELLITE LAUNCH ON BOARD SPACEX/FALCON 9 SET FOR NOVEMBER 25
 
25.11.2013 

Cape Canaveral, Florida, November 25th, 2013 – SES S.A. (NYSE Euronext Paris and Luxembourg Stock Exchange: SESG) announces that the launch of the SES-8 satellite is slated for November 25th, 2013. The launch window for the maiden launch of an SES satellite on board Falcon 9 stretches from 17:37 - 18:42 EDT (23:37 - 00:42 CET).

SES-8 has been manufactured by Orbital Sciences Corporation. The satellite features up to 33 Ku-band transponders (36 MHz equivalent). SES-8 will be co-located with NSS-6 at the orbital location of 95 degrees East to provide growth capacity over Asia-Pacific. The spacecraft's high performance beams will support the rapidly growing markets in South Asia and Indo-China, as well as provide expansion capacity for DTH, VSAT and government applications.

In North America, the live broadcast of the launch will be available on the SES-1 satellite at 101 degrees West, 21K, downlink frequency 12120 MHz, vertical polarization, Symbol rate 30.00 MSym/s, FEC 3/4, service ID 1.

In Europe, the broadcast of the launch via ASTRA satellite is available at the orbital position 19.2 degrees East, channel 1.028, downlink frequency 11626,5 MHz, vertical polarization, Symbol rate 22.00 MSym/s, 8PSK,  FEC 2/3, service ID 4400, service name SES 8 Launch.

A webcast is available via www.spacex.com/webcast. The video transmission of the launch of SES-8 will begin approximately 30 minutes before liftoff.

To listen to a playback of the press call held on Sunday with Elon Musk, CEO and Chief Designer of SpaceX, and Martin Halliwell, CTO of SES, please dial the following number and access code:

US\Canada:  (855) 859-2056
International: (404) 537-3406
Conference ID:   16853657

Please find a press kit on SES-8 here: http://www.ses.com/16395608/spacex-ses-8-launch-kit.

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #46 on: 11/25/2013 05:14 PM »
SES has posted a video on Facebook - SES-8: from concept to reality:

https://www.facebook.com/photo.php?v=10152001440048189

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #47 on: 11/27/2013 12:07 AM »
For orbital mechanics students etc, the SES plan to get to GSO from LEO is a bi-elliptic transfer, which will never thrust either towards or away from Earth in principle - all burns are along the path of travel for orbit raising, and across the path for inclination change. Probably the major inclination change by SES-8 will be at apogee of the initial high orbit for efficiency, in conjunction with the perigee-raise (a combined burn to do both tasks).


EDIT to fix link... which was working at preview, some BB sofware is just too smart for its own good, grumble...
(thanks kevin)
« Last Edit: 11/27/2013 07:01 PM by Joffan »
Max Q for humanity becoming spacefaring

Offline Robotbeat

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #48 on: 12/03/2013 10:24 PM »
Spacecraft status?
EDIT: Looks good!
Peter B. de Selding ‏@pbdes 12s

SES has acquired spacecraft and it is in good health.
« Last Edit: 12/03/2013 10:27 PM by Robotbeat »
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline Joffan

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #49 on: 12/03/2013 11:36 PM »
Do we know when the next burn of SES-8 will occur? Tomorrow morning?
« Last Edit: 12/03/2013 11:36 PM by Joffan »
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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #50 on: 12/04/2013 08:35 AM »
LAUNCH SUCCESS FOR SES-8 SATELLITE ON BOARD SPACEX/FALCON 9

  03.12.2013 

55th SES satellite to serve Asia

Cape Canaveral, Florida, December 03rd, 2013 – SES S.A. (NYSE Euronext Paris and Luxembourg Stock Exchange: SESG) announces that the SES-8 satellite was successfully launched into space at 17:41 EST (23:41 CET) from the Kennedy Space Center at Cape Canaveral. A Falcon 9 booster operated by SpaceX successfully injected the SES-8 satellite into geostationary transfer orbit, 31 minutes after lift-off, in what was SES’s maiden use of a SpaceX/Falcon 9 rocket. SES has three more SpaceX/Falcon 9 boosters under contract.

SES-8 was manufactured by Orbital Sciences Corporation. The satellite features up to 33 Ku-band transponders (36 MHz equivalent). SES-8 is authorized by The Netherlands and will be co-located with NSS-6 at the orbital location of 95 degrees East to provide growth capacity over Asia-Pacific. The spacecraft’s high performance beams will support the rapidly growing markets in South Asia and Indo-China, as well as provide expansion capacity for DTH, VSAT and government applications.

Romain Bausch, President and CEO of SES, stated: “SES’s maiden launch on board a Falcon 9 rocket is yet another example of our company’s spirit of innovation and advancement of the commercial space industry. We congratulate the SpaceX team for the success of a challenging launch campaign and our longstanding supplier Orbital for innovating with us in exploring new paths to orbit while delivering a brand-new, state-of-the-art satellite for Asia. Our customers are looking forward to the new capacity, and we are delighted that SES, in collaboration with SpaceX and Orbital, is all set to deliver following today’s successful launch. Through the co-location with NSS-6 at 95 degrees East, SES-8 will not only provide incremental high performance capacity, notably for DTH services, it will also create greater reliability and additional security for customers. The SES-8 satellite will significantly contribute to SES’s growing presence in Asia-Pacific.”

“Today’s successful insertion of the SES-8 satellite marks SpaceX’s first geo-synchronous transfer mission and confirms the Falcon 9 launch vehicle lives up to the industry’s highest performance standards,” said Elon Musk, CEO and Chief Designer of SpaceX.   “As always, SpaceX remains committed to delivering the safest, most reliable launch vehicles on the market today.  We appreciate SES’s early confidence in SpaceX and look forward to launching additional SES satellites in the years to come.”

Note to Editors:

The next SES launch is slated for early next year, when an European Ariane 5 vehicle will orbit the ASTRA 5B satellite from Kourou, French Guyana.

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #51 on: 12/04/2013 03:49 PM »
Do we know when the next burn of SES-8 will occur? Tomorrow morning?

Bump. So five burns over the next two weeks, does anyone have anything more specific?

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #52 on: 12/05/2013 01:52 PM »
Has this been posted yet? The photos are the same as those previously released, but the narration provides some details:

« Last Edit: 12/05/2013 01:53 PM by corrodedNut »


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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #54 on: 12/11/2013 06:01 AM »
as per heavens-above.com information, SES-8 orbit has been changed to 35819 x 79805 km, inclination decreased to 1.2°

source
http://www.heavens-above.com/SatInfo.aspx?satid=39460&lat=0&lng=0&loc=Unspecified&alt=0&tz=CET&cul=en-GB
« Last Edit: 12/11/2013 06:11 AM by Zannanza »

Offline Jarnis

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #55 on: 12/13/2013 09:30 AM »
..and

Orbit    35,681 x 45,298 km, 0.5°

Almost there.

http://www.heavens-above.com/orbit.aspx?satid=39460&lat=0&lng=0&loc=Unspecified&alt=0&tz=CET&cul=en-GB

Shows the sat fairly close to the planned area over Asia.

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Re: SES-8 - for launch on F9 v1.1 - Dedicated Spacecraft Thread
« Reply #56 on: 12/21/2013 05:32 AM »
35753X35795 km, 0.0960°, probably already settled in its final orbit

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