SpaceX Falcon 9 v1.1 - SES-8 - DISCUSSION THREAD

[Lee Jay]

What's the perigee? Should be able to figure out when it'll eventually come down.

Per press kit, target orbit was 295km x 80,000km at 20.75 degrees.

Target, any idea how close they got?

CelesTrack is showing something labeled "Object A" with a launch date of 12/3/2013 from Florida.  It has international designator 2013-071A and NORAD catalog number 39460.

The TLE for this object is:

1 39460U 13071A   13337.40768818 -.00000413  00000-0  00000+0 0    37
2 39460  20.5531 242.7832 8534855 179.4250 185.5374  0.87290738    01

So it looks like 397 km by 79341 km at 20.55 degrees.

On such a long orbit, how accurate are these likely to be so soon after launch?

[dante2308]

On such a long orbit, how accurate are these likely to be so soon after launch?

I really don't understand. If you have position and velocity, what's so difficult about finding the orbit? The only unknown is drag and perhaps solar pressure.

[rdale]

CelesTrack is showing something labeled "Object A" with a launch date of 12/3/2013 from Florida.

What is the source of that TLE?

I think he said it above - Celestrak.

http://www.celestrak.com/NORAD/elements/tle-new.txt

[Lee Jay]

On such a long orbit, how accurate are these likely to be so soon after launch?

I really don't understand. If you have position and velocity, what's so difficult about finding the orbit? The only unknown is drag and perhaps solar pressure.

Well, you're extrapolating a large ellipse from a relatively short segment of data (I don't know how short, as I don't know when the data that was used to generate this set was collected).  Also, if this is from one scan, you don't have a lot of points to average together to get a more accurate estimate of the true position and velocity around the orbit.  Or, perhaps I don't understand how these are generated compared to how, say, the orbit of an newly-found asteroid or comet is generated?

[Lars_J]

On such a long orbit, how accurate are these likely to be so soon after launch?

I really don't understand. If you have position and velocity, what's so difficult about finding the orbit? The only unknown is drag and perhaps solar pressure.

Most (or all?) radar systems require several hits to gauge exact velocity. The more returns you get from an object, the more you reduce the error in the estimation of velocity.

[ChrisWilson68]

CelesTrack is showing something labeled "Object A" with a launch date of 12/3/2013 from Florida.  It has international designator 2013-071A and NORAD catalog number 39460.

The TLE for this object is:

1 39460U 13071A   13337.40768818 -.00000413  00000-0  00000+0 0    37
2 39460  20.5531 242.7832 8534855 179.4250 185.5374  0.87290738    01

So it looks like 397 km by 79341 km at 20.55 degrees.

What is the source of that TLE? IT exactly matches the current TLE on the space-track.org site and I thought rules existed about publishing space-track.org TLE's.

I got it from CelesTrak's "Last 30 Days' Launches" page.  I didn't see anything on that page or the two CelesTrak pages leading up to it saying it couldn't be reposted.

http://www.celestrak.com/NORAD/elements/tle-new.txt

[Step55]

At 1:48 this video appears to show both stage 1 and stage 2 firing with fairing separation on stage 2.

[ChrisWilson68]

You have to differentiate between cost and price. I am pretty sure that the actual launch costs are not the same as the launch price advertised on their web site. I might even go out on a limb and assume that the actually paid sum for a launch is not the same as the value given at the web site  8)

I'm going to go out on a limb and assume all of that is pure speculation on your part.  It's purely based on comparing SpaceX to other launch providers and not being able to believe SpaceX's costs could be lower.

SpaceX has, from the start, behaved differently from any other launch provider.  Why is it so hard to believe that different behavior can lead to different results?

[ChrisWilson68]

At 1:48 this video appears to show both stage 1 and stage 2 firing with fairing separation on stage 2.

Yes, in a sense.  What the first stage is firing at that point is its RCS thrusters, to flip around as if it were going to do a slowing burn.  If you look carefully, you can see the individual short pulses from the thrusters.  SpaceX did that to do another test of their ability to control the stage and to see how it behaved re-entering without a speed-killing burn.

[Robotbeat]

At 1:48 this video appears to show both stage 1 and stage 2 firing with fairing separation on stage 2.

Yes, in a sense.  What the first stage is firing at that point is its RCS thrusters, to flip around as if it were going to do a slowing burn.  If you look carefully, you can see the individual short pulses from the thrusters.  SpaceX did that to do another test of their ability to control the stage and to see how it behaved re-entering without a speed-killing burn.

L2.

[tj]

SpaceX Falcon 9 has a GPS on board (maybe mostly for primary use in range safety- i.e. GPS metric tracking) ULA is qualifying GPS metric tracking on Atlas V and Delta IV.

LV has GPS receiver; sends the raw acquired GPS data via S-band tlm to the ground (launch site area) and converts this raw data into GPS based navigation track real time. Eventually the C-band radar system could be eliminated, It is very old.

Falcon 9 does no use is GPS, I do not believe) for LV guidance/nav on board. I would expect they only use a precision redundant IMU system.

Now once range safety is through with GPS metric tracking (if is used/monitored), the Falcon 9 GPS may actually be used to generate on board precise LV navigation out to beyond SV sep. The GPS data could be sent to Norad to back up their radar,

Still since the velocity and Doppler is quite pronounced in the early climb out, I would expect radar track to be reasonably accurate (within a few KM and very accurate on inclination. If Falcon 9 GPS data is used the accuracy is going to be better than 100 meters I expect

[Lars_J]

At 1:48 this video appears to show both stage 1 and stage 2 firing with fairing separation on stage 2.

Wow, that is amazing footage! At 1:58 and onwards, you can see four separate objects:
 - 1st stage, with RCS bursts
 - 2nd stage burning
 - Both halves of the fairing
(screencap taken at 2:04)

[Helodriver]

At 1:48 this video appears to show both stage 1 and stage 2 firing with fairing separation on stage 2.

Wow, that is amazing footage! At 1:58 and onwards, you can see four separate objects:
 - 1st stage, with RCS bursts
 - 2nd stage burning
 - Both halves of the fairing
(screencap taken at 2:04)

That's a better image than what came out of the launch webcast!  Good capture!

[baldusi]

Just to put the accuracy on perspective:

GTO Insertion Accuracy (respective User's Guide)

Launcher	Reference	Perigee (+/- km)	Apogee (+/- km)	Inclination (+/- deg)	Excentricity	Argument of perigee  (+/- deg)	RAAN  (+/- deg)	Sigma Level	Probability
Soyuz-STB	250km x 35,950km @ 6deg	100.0	100.0	0.100	0.001	0.60	0.60	3.00	99.70%
Ariane 5	250km x 35,943km @ 6deg	1.3	80.0	0.020	0.00045	0.20	0.20	1.00	68.00%
Zenit-3SLB	4,000km x 35,786km @ 23deg	40.0	100.0	0.100		0.20	0.20	3.00	99.70%
Zenit-3SLBF	4,000km x 35,786km @ 23deg	40.0	120.0	0.100		0.30	0.30	3.00	99.70%
Zenit-3SL	200km x 35,786km @ 6deg	10.0	80.0	0.250				2.33	97.00%
Delta IV	185km x 35,786km @ 27 deg	5.6	93.0	0.030				3.00	99.70%
Atlas V	195km x 35,786km @ 25.6 deg	4.6	168.0	0.025		0.20	0.22	3.00	99.70%
Falcon v1.0	185km x 35,768km @ 28.5deg	7.4	130.0	0.100		0.30	0.75		??
H-IIA	250km x 36,226km @ 28.5deg	4.0	180.0	0.020		0.40	0.40	3.00	99.70%
Proton-M/Briz-M	4120km x 35,786km @ 23.2deg	360.0	150.0	0.300		0.80		3.00	99.70%
LM-3A/BE/C	200km x 35,958km @ 28.5deg	10.0	40.0	0.700		0.20	0.20	3.00	99.70%

On the other hand, the actual orbit was required less delta-v to transfer to GSO. So they "failed" to the good side, hardly a bad situation.

[bartonn]

You have to differentiate between cost and price. I am pretty sure that the actual launch costs are not the same as the launch price advertised on their web site. I might even go out on a limb and assume that the actually paid sum for a launch is not the same as the value given at the web site 

I'm going to go out on a limb and assume all of that is pure speculation on your part.  It's purely based on comparing SpaceX to other launch providers and not being able to believe SpaceX's costs could be lower.

SpaceX has, from the start, behaved differently from any other launch provider.  Why is it so hard to believe that different behavior can lead to different results?

According to this article, SES paid 'well under $60 million' for this launch:
http://www.spacenews.com/article/launch-report/37547ses-approves-satellite-shipment-for-falcon-9-launch-despite-questions
Granted, SES-8 is the first GEO mission of the Falcon 9, so the cost would naturally be somewhat lower.  Regardless of the advertised price on the spacex website, spacex's launch prices are significantly lower than other launchers.  Arianespace is reconsidering their launch prices as a result of spacex:
http://www.spacenews.com/article/launch-report/38331spacex-challenge-has-arianespace-rethinking-pricing-policies
Furthermore, I think that the 'sticker price' listed on the spacex website is more of a PR thing than an actual  cost listing, because other launch providers don't list costs on their website.  Additionally, the price listed on the spacex website is probably the lower bound of the possible costs for a mission.  (Think about automobile advertisements - generally the price for the base model is listed)

[ChrisWilson68]

About the higher perigee than the announced target: remember, SpaceX said they could have reserved first stage margin for recovery but chose to put it all toward the payload.  So they had margin to do better than the target orbit.  They could have chosen to use that margin to make the initial circular parking orbit higher.  If there had been a first-stage engine-out, or less performance than expected for any other reason, they could have fallen back to a lower parking orbit and still made their target GTO.  If they chose SECO to be triggered by a pre-set prop load in the upper stage that was sufficient to make the required GTO, then they could have just continued longer with the first burn to make the parking orbit higher.

By giving a higher perigee, SpaceX gave the payload a bit of extra boost toward GEO.

[ChrisWilson68]

You have to differentiate between cost and price. I am pretty sure that the actual launch costs are not the same as the launch price advertised on their web site. I might even go out on a limb and assume that the actually paid sum for a launch is not the same as the value given at the web site  8)

I'm going to go out on a limb and assume all of that is pure speculation on your part.  It's purely based on comparing SpaceX to other launch providers and not being able to believe SpaceX's costs could be lower.

SpaceX has, from the start, behaved differently from any other launch provider.  Why is it so hard to believe that different behavior can lead to different results?

According to this article, SES paid 'well under $60 million' for this launch:
http://www.spacenews.com/article/launch-report/37547ses-approves-satellite-shipment-for-falcon-9-launch-despite-questions
Granted, SES-8 is the first GEO mission of the Falcon 9, so the cost would naturally be somewhat lower.  Regardless of the advertised price on the spacex website, spacex's launch prices are significantly lower than other launchers.  Arianespace is reconsidering their launch prices as a result of spacex:
http://www.spacenews.com/article/launch-report/38331spacex-challenge-has-arianespace-rethinking-pricing-policies
Furthermore, I think that the 'sticker price' listed on the spacex website is more of a PR thing than an actual  cost listing, because other launch providers don't list costs on their website.  Additionally, the price listed on the spacex website is probably the lower bound of the possible costs for a mission.  (Think about automobile advertisements - generally the price for the base model is listed)

OK, let's take the automobile analogy.  Yes, they list the base model in their pricing, but it's a real price.  You can go in and pay that price and get that car if you want to.

But for a given model, the advertised price is generally more than what most people pay.  It's the upper bound in a bargaining game.  The last thing the auto dealer wants the buyer to know is how low they are willing to go with the price.

The same is true for airliners -- nobody pays the list price for a 747, and most customers get steep discounts.

Based on those analogies, the prices SpaceX lists should be upper bound on the prices customers pay, not lower bounds.

[Comga]

Brought over from the Updates thread:

view from 8K miles

https://twitter.com/elonmusk/status/408030622708678657/photo/1/large

They really need to clean that lense cover on that camera before launch!

;-)

But in truth, is there anything they could do on future missions to improve that camera image?  I know they got some amazingly clear images of staging on the cameras on the Saturn V's using 1960's tech.  Obivously the famous video of the S-1C being jettisoned, along with the interstage and the S-II lighting seemed much more clear without stuff all over the lens.

Anything? Of course there is something they could do. 

They could impliment a version of the system used on the Saturn V first stage engine monitors, which was another dirty environment.  Put a big window in front of the camera lens and spin it around.  Put a wiper blade on the other side so the window is wiped as it rotates.
 
Somehow I doubt that SpaceX would do this.

A simpler system might just route some venting gas by the lens.  If it is a cellphone camera sized system it wouldn't take much to blow away debris with heated vent gas.

I still doubt that SpaceX will do this, either.  The images are fine as they are for diagnostics.

What I wish they would do is to mosaic four images onto the live feed.  They show only one or two and keep switching back and forth between the different sources: wide angle fixed ground, close-up of the launch mount and engines, long range tracing from the ground, down-looking rocket cam, up-looking payload cam, Ground Thermal IR and onboard IR.  If they had four up at once there wouldn't be much switching and they wouldn't be any smaller than when they show two. 

[Lars_J]

This appears to be the first time on an F9 launch that the camera got so dirty - if there is a quick solution I have no doubt they will implement it.

[ChrisWilson68]

I hope they don't spending much, if any, time or resources making the camera picture look pretty.  They've been succeeding by focusing on the right things.  Every little bell and whistle you try to do adds complexity, costs engineering resources and focus, and risks failure from unintended consequences.