SpaceX Falcon 9 v1.1 - Thaicom 6 - DISCUSSION THREAD

[AJW]

There were also a number of points during the transmission where the signal was lost.  If video buffering is used, this could pause the video while time is passing, and then restart again at the LOS point.  The upper right clock is added in the studio after the signal arrives, so be sure to check the clock in the bottom left corner since that is more likely to be coming from the video source.

[Mapperuo]

No matter how much I seem to rant about it, it seems some people still don't seem to get it that SpaceX webcasts are not in sync with just about anything else and take the events as happening on screen at face value. The fact is the on-screen clock is not in good sync with the audio which is not in sync with video which is not in sync with video from *another source*. This leads to discussions about pad aborts at T+2 seconds, vehicle lifting off not at T-0 but later, etc. They are an artifact of the sync problem. Check these videos out for an example of video with an audio source that is *not* significantly delayed - my guess a conventional radio transmission from the range center or something:
www.youtube.com/watch?v=6-_vdpY9n-M
www.youtube.com/watch?v=DfSsnpjZbys

I, too, was fooled into thinking there was an abort with Thaicom 6 when the view switched from a closeup of the engines to the wide pad shot that seemed to show no liftoff at first (looked like a shutdown actually!) since that wide shot historically seemed to be *ahead* of other pad views, not behind. It does go to show that you should not trust anything you see on screen, especially if you time one event from one video source and another event from another.

I think the last webcast we briefly saw a PC desktop shot where VLC had an IP link. From that I think they send maybe 3-4 feeds from the Cape to their broadcast center in Hawthorne via the internet, you see them pixelate at times, especially in the venting. So it makes sense that they will be slightly out of sync with one another.

[Elvis in Space]

No matter how much I seem to rant about it, it seems some people still don't seem to get it that SpaceX webcasts are not in sync with just about anything else and take the events as happening on screen at face value. The fact is the on-screen clock is not in good sync with the audio which is not in sync with video which is not in sync with video from *another source*. This leads to discussions about pad aborts at T+2 seconds, vehicle lifting off not at T-0 but later, etc. They are an artifact of the sync problem. Check these videos out for an example of video with an audio source that is *not* significantly delayed - my guess a conventional radio transmission from the range center or something:
www.youtube.com/watch?v=6-_vdpY9n-M
www.youtube.com/watch?v=DfSsnpjZbys

I, too, was fooled into thinking there was an abort with Thaicom 6 when the view switched from a closeup of the engines to the wide pad shot that seemed to show no liftoff at first (looked like a shutdown actually!) since that wide shot historically seemed to be *ahead* of other pad views, not behind. It does go to show that you should not trust anything you see on screen, especially if you time one event from one video source and another event from another.

I think the last webcast we briefly saw a PC desktop shot where VLC had an IP link. From that I think they send maybe 3-4 feeds from the Cape to their broadcast center in Hawthorne via the internet, you see them pixelate at times, especially in the venting. So it makes sense that they will be slightly out of sync with one another.

Absolutely. Does it make more sense that a relatively modest web broadcast is out of sync or that Spacex launch team, vehicle, master clock, etc. are off by seconds and nobody at Spacex or the customer takes notice?

[mr. mark]

We are lucky to get a webcast at all. This type of event is not on the average person's radar.

[AJW]

Just a quick checks on clocks by reviewing the video.

at ignition:

17:05:58 displayed on the ground camera (EST) and 00:00 on the screen overlay

at separation:

22:09:13 displayed on the 2nd stage camera (UTC) and 03:00 on the screen overlay

Right there is a 15 second discrepancy between the clocks.

[edkyle99]

Just a quick checks on clocks by reviewing the video.

at ignition:

17:05:58 displayed on the ground camera (EST) and 00:00 on the screen overlay

at separation:

22:09:13 displayed on the 2nd stage camera (UTC) and 03:00 on the screen overlay

Right there is a 15 second discrepancy between the clocks.

But still doesn't account for the second stage duration.

 - Ed Kyle

[beancounter]

Just a quick checks on clocks by reviewing the video.

at ignition:

17:05:58 displayed on the ground camera (EST) and 00:00 on the screen overlay

at separation:

22:09:13 displayed on the 2nd stage camera (UTC) and 03:00 on the screen overlay

Right there is a 15 second discrepancy between the clocks.

But still doesn't account for the second stage duration.

 - Ed Kyle

Is it really that important?  I reckon the important point is that the mission launched on time and as far as I can tell was 100% successful.  SpaceX stated that they weren't try for a first stage recovery.  What more is there to tell?
Me?  I'm now looking forward to the next launch.
Cheers.

[marshal]

From orbital

 

Orbital-Built Thaicom 6 Communications Satellite Successfully Launched

-- 149th Satellite Produced by Company to Provide Communications Services Across Southeast Asia and Africa --

-- Spacecraft Activation and In-Orbit Testing Procedures Now Underway --

(Dulles, VA 7 January 2014) -- Orbital Sciences Corporation (NYSE: ORB), one of the world’s leading space technology companies, today announced the THAICOM 6 communications satellite, built by the company for THAICOM Plc., was successfully launched into orbit yesterday aboard a Space Exploration Technologies Falcon 9 rocket from Cape Canaveral, Florida. Lift off occurred at approximately 5:06 p.m. (EST) on January 6 and the satellite was successfully separated from the rocket and deployed into a super-synchronous transfer orbit approximately 31 minutes later.

Over the next several weeks, Orbital’s satellite engineering and operations team will work with their THAICOM counterparts to conduct orbit-raising maneuvers and in-orbit testing to verify all the spacecraft systems are functioning properly before it is officially turned over to THAICOM for full operational control and commencement of commercial service.

“Early in the initial check-out and testing process, the THAICOM 6 satellite is performing very well,” said Mr. Christopher Richmond, Orbital’s Senior Vice President of communications satellites. “This is the first GEOStar communications satellite we have built for THAICOM and we are proud to be a part of their team, helping to address an increase in demand for telecommunications services across Southeast Asia and Africa.”

Orbital designed, built and tested the THAICOM 6 satellite at its satellite manufacturing and test facility in Dulles, VA. The satellite carries a hybrid Ku- and C-band payload that operates with approximately 3.5 kilowatts of payload power. The Ku-band payload is comprised of eight active transponders (9x36-MHz Transponder Equivalent) providing services to Thailand, Laos, Cambodia and Myanmar. The C-band payload features 12 active C-band transponders providing services via a regional beam to Southeast Asia and six active C-band transponders (12x36-MHz Transponder Equivalent) providing services to Africa. THAICOM 6 will be located in orbit at 78.5 degrees East Longitude.

With this launch, 149 Orbital-built satellites have been produced and delivered to commercial, civil government and national security customers during the last 30 years. Of these, 32 have been GEOStar-class geosynchronous communications and broadcasting spacecraft for commercial customers around the world, while another 45 have been LEOStar-class low-orbit commercial communications and imaging satellites. Seventy two additional satellites have been built for various government agencies and scientific organizations. 

http://www.orbital.com/NewsInfo/release.asp?prid=1881

[edkyle99]

Just a quick checks on clocks by reviewing the video.

at ignition:

17:05:58 displayed on the ground camera (EST) and 00:00 on the screen overlay

at separation:

22:09:13 displayed on the 2nd stage camera (UTC) and 03:00 on the screen overlay

Right there is a 15 second discrepancy between the clocks.

But still doesn't account for the second stage duration.

 - Ed Kyle

Is it really that important?  I reckon the important point is that the mission launched on time and as far as I can tell was 100% successful.  SpaceX stated that they weren't try for a first stage recovery.  What more is there to tell?

The success of the mission is apparent.  I'm just wondering if the company is communicating flight parameters to the press that don't align with what actually happens - or if there is some other explanation.

 - Ed Kyle

[sdsds]

The success of the mission is apparent.

Indeed! Reading the tea leaves it seems clear the upper stage had plenty of margin. Getting that close to the target orbit implies guidance-based engine cutoff (rather than low propellant); also the large delta-v difference between payload and second stage implies lots of GOX was vented.

I'm just wondering if the company is communicating flight parameters to the press that don't align with what actually happens - or if there is some other explanation.

Nicely phrased! Asking Emily Shanklin (the contact listed in the press kit) about the discrepancy might work.

[LouScheffer]

Just a quick checks on clocks by reviewing the video.

at ignition:

17:05:58 displayed on the ground camera (EST) and 00:00 on the screen overlay

at separation:

22:09:13 displayed on the 2nd stage camera (UTC) and 03:00 on the screen overlay

Right there is a 15 second discrepancy between the clocks.

But still doesn't account for the second stage duration.

 - Ed Kyle

If I put on my engineering hat, and use Occam's razor, I'd guess that perhaps they decided to run the second stage at 97% thrust (on average, anyway) and so it ran 15 sec longer, and they forgot to tell the PR department.

[sdsds]

I'd think that after releasing the satellite, they would use any remaining delta-V/venting/RCS to reduce the perigee, not increase it. That would help create a quicker re-entry and less space junk with its chance of collision.  Raising the perigee would seem to do exactly the opposite....

My theory is they are trading time-to-decay against likelihood of debris reaching the surface intact.

Background: I think the uncontrolled re-entries with the least likelihood of injuring someone on the ground are those where the re-entry flight-path angle (gamma) is essentially zero, or only slightly negative. That happens naturally when an object re-enters from a circular orbit.

If the launch vehicle operator caused the spent second stage to have a lower perigee, then in the limit case at least (of immediate re-entry) gamma would be large. If on the other hand the perigee is raised then over the course of many months the apogee will be slowly lowered and the re-entry gamma will be closer to zero.

(Note well I am not a ballistic re-entry specialist, and also note those who are might conceivably be constrained in what they can say in a public forum.)

[Dudely]

I'd think that after releasing the satellite, they would use any remaining delta-V/venting/RCS to reduce the perigee, not increase it. That would help create a quicker re-entry and less space junk with its chance of collision.  Raising the perigee would seem to do exactly the opposite....

Wouldn't a different orbit mean a far different chance of it impacting something important? I can imagine the likelihoods of debris impacting something changing substantially based on the perigree of the orbit over its lifetime.

[Garrett]

This still seems weird to me.  I'd think that after releasing the satellite, they would use any remaining delta-V/venting/RCS to reduce the perigee, not increase it. That would help create a quicker re-entry and less space junk with its chance of collision.  Raising the perigee would seem to do exactly the opposite....

The standard is increase to a more stable orbit, as I stated before

No, the standard is that orbit must be unstable, and decay within 25 years.   See the article ... <snip>

By "stable" I think Jim was referring to an orbit that would take a very long period to decay. It's all relative, but one could argue that 25 years is a long period. I even think Jim mentioned before (on another thread) that such orbits were to decay within 25 years.

And as you pointed out, they did not "perform a direct reentry as part of the launcher sequence", which would have required decreasing to a very "unstable" orbit.

[fatjohn1408]

I've been burned recently while trying to interpret catalog data, but like a stubborn child I'll reach towards the stove again here:

2 Objects have now been catalogued by USSTRATCOM.
Object A: 2014-002A/39500 at 0051UTC was in 376 x 90039 km x 22.46° (tentatively Thaicom-6)
Object B: 2014-002B/39501 at 2336UTC was in 457 x 91590 km x 22.39°

My spreadsheet shows the Object A orbit is better for the spacecraft (closer to GEO) than the target orbit, though only by 4 m/s.

Also it shows the minimum delta-v between the Object A orbit and the Object B orbit as 288 m/s. Can that be achieved purely with venting?

(On the topic of standard deviation: I think something like https://en.wikipedia.org/wiki/Monte_Carlo_method is implicit.)

288 m/s? My spider senses tell me this should be an error. Could you check your calculations and perhaps post them for review purposes? Surely if you do a burn somewhere halfway between perigee and apogee you could do this change with just a few tens of m/s. How do you calculate the best position and best direction for a change of so many parameters? Is there an analytical way? How does Kerbal space program do it?

[fatjohn1408]

SpaceX press kit says the mass of Thaicom-6 was 3016 kg while Orbital says it was 3330 kg

I am quite confident to my memory that in SpaceX's Webcast Molly or someone else said that Thaicom-satellite weights 3300 kg. Also Wikipedia says that it weights 3325 kg. Therefore it is good to be critical on sources and that 3016 kg is probably just simple mistake. People often makes this kind of mistakes, because they are not accurate with numbers.

Throw the Wikipedia number out.  The press kit is supposed to be the right number, but isn't always.  It has long seemed to me that SpaceX fudges the numbers on purpose, to create uncertainty.  But it could be that the final propellant loading changed as mission planning proceeded.  In that case, the SpaceX press kit should be the most recent value.   

 - Ed Kyle

Yes perhaps the satellite was made to be able to do a delta-V change of 1800 m/s to Geo and when they fly with SpaceX to SSTO they only need to do a 1500 m/s change. Seems like the accurate mass of propellant you need for the first 300 m/s.

[prime8]

Yes perhaps the satellite was made to be able to do a delta-V change of 1800 m/s to Geo and when they fly with SpaceX to SSTO they only need to do a 1500 m/s change. Seems like the accurate mass of propellant you need for the first 300 m/s.

I believe onboard propellant roughly corresponds to the satellite's operational lifetime. If the launch vehicle provides some extra delta-V, they will most likely fly with their tanks full anyway and gain extra margin on lifetime.

[MP99]

Yes perhaps the satellite was made to be able to do a delta-V change of 1800 m/s to Geo and when they fly with SpaceX to SSTO they only need to do a 1500 m/s change. Seems like the accurate mass of propellant you need for the first 300 m/s.

I believe onboard propellant roughly corresponds to the satellite's operational lifetime. If the launch vehicle provides some extra delta-V, they will most likely fly with their tanks full anyway and gain extra margin on lifetime.

Which would also provide some contingency in case of shortfall from the launcher.

Cheers, Martin

[Prober]

Just a quick checks on clocks by reviewing the video.

at ignition:

17:05:58 displayed on the ground camera (EST) and 00:00 on the screen overlay

at separation:

22:09:13 displayed on the 2nd stage camera (UTC) and 03:00 on the screen overlay

Right there is a 15 second discrepancy between the clocks.

But still doesn't account for the second stage duration.

 - Ed Kyle

under powering engines during test phase?
 

[Robotbeat]

Or maybe they thought engine margin was more important than performance margin.