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

[Sohl]

Second stage is on site. And yes, fix is being implemented

(-padrat from Update thread: http://forum.nasaspaceflight.com/index.php?topic=32783.msg1112335#msg1112335)

Speculating here, but it seems to me that if a "fix is being implemented" onsite, then it likely involves more than a simple re-calibration of software parameters or small software algorithm/logic change.  Those kinds of things, once prepared, should be able to be loaded into the flight avionics and confirmed in a software test in a matter of hours or a couple of days.  The push-out of the NET launch date by ten seven extra days also suggests to me that some upper-stage hardware needed to be swapped out or at least manipulated to implement the fix.

Not that it matters really if it was just software, or hardware, or some combination.  I just hope they zeroed in on the correct issue, designed the right fix, and can implement it properly before the flight. 

Edit: fixed typo and changed amount of slip in the NET launch date

[butters]

I speculate that the fix involves adding insulation and/or an electric heater.

[aero]

I speculate that the fix involves adding insulation and/or an electric heater.

And fixed the LOX leak that we saw on some of the video. That (what looked to me to be) mass of LOX ice around the top of the engine could alter the temperature of the metal, hence the readings made by the engine controllers. May or may not have been a factor in the failed restart.

[AndyX]

Chris included the updates from L2 on this.

http://www.nasaspaceflight.com/2013/10/spacex-press-abort-test-raptor-engine/

[Garrett]

Second stage is on site. And yes, fix is being implemented

(-padrat from Update thread: http://forum.nasaspaceflight.com/index.php?topic=32783.msg1112335#msg1112335)

Speculating here, but it seems to me that if a "fix is being implemented" onsite, then it likely involves more than a simple re-calibration of software parameters or small software algorithm/logic change.  Those kinds of things, once prepared, should be able to be loaded into the flight avionics and confirmed in a software test in a matter of hours or a couple of days. 

I'd imagine that even a "simple" software parameter change could result in several days, weeks even, of simulations and analyses to reassure both SpaceX and their customer that the change would have the desired effect. But yeah, I also get the impression that a little bit of hardware needed to be modified/added.

[edkyle99]

And fixed the LOX leak that we saw on some of the video. That (what looked to me to be) mass of LOX ice around the top of the engine could alter the temperature of the metal, hence the readings made by the engine controllers. May or may not have been a factor in the failed restart.

I still don't see a LOX leak there.  I see a purge.

 - Ed Kyle

[mlindner]

And fixed the LOX leak that we saw on some of the video. That (what looked to me to be) mass of LOX ice around the top of the engine could alter the temperature of the metal, hence the readings made by the engine controllers. May or may not have been a factor in the failed restart.

I still don't see a LOX leak there.  I see a purge.

 - Ed Kyle

Yes, looked like the venting was coming from a valve of some sort. So probably not a leak.

[Sohl]

I'd imagine that even a "simple" software parameter change could result in several days, weeks even, of simulations and analyses

Garrett, I'm sure it could, but there has already been several weeks since the flight, so I'd expect that simulation and perhaps hardware-in-the-loop testing would probably not be a critical path item at this point, assuming they knew what to change.

I could be wrong, but the impression I got during comments by Elon and Gwynne was that the likely problem was something they had seen signs of before and/or had reason to suspect from earlier design and development work, and that it was not too significant to fix.  Maybe they hoped to not have to address the likely problem in the real rocket and the problem happened anyway, perhaps worse then any prior simulation or analysis had shown. But I'm really starting to head into irresponsible speculation here.    Let's hope it is quickly fixed and they get on-track for regular flights.

[Salo]

 
http://www.ses.com/4233127/upcoming-launches

[Robotbeat]

Looks like they aren't putting it on their manifest unless and until the things are straightened out.

[Jason1701]

The first Ariane 5 launch from CCAFS!

[ww2planes1]

Hmm... Their fleet coverage map already has it listed as "operational."
http://www.ses.com/fleet-coverage

The main SES-8 page still shows a Q4 2013 launch from Falcon 9.  Looks like some website admin just got a little ahead of themselves.

[Jarnis]

Hmm... Their fleet coverage map already has it listed as "operational."
http://www.ses.com/fleet-coverage

The main SES-8 page still shows a Q4 2013 launch from Falcon 9.  Looks like some website admin just got a little ahead of themselves.

They sure are confident it'll work out! 

[smoliarm]

The same thing already happened at SES website, it was in June:
SES-8 disappeared from the list of upcoming launches, but at the same time the Fleet Map showed SES-8 as functional sat in orbit.
This was noted earlier in this thread:
http://forum.nasaspaceflight.com/index.php?topic=24469.msg1059573#msg1059573
Later, SES-8 reappeared in upcoming launches - rescheduled.

As I understand, this means that this launch just has been postponed. It will show up on the list as they approve the new launch date.

[Roy_H]

I hope this isn't a stupid idea, cause I'm not a rocket scientist. But...
As I understand it, the second burn of the upper stage is to align the orbit with the equator, then accelerate to transfer orbit which is an ellipse with the apogee near GEO. There is an option to keep the initial burn to gain the same height, but not aligned with the equator. This second option would require significant fuel usage by the satellite to get to the correct orbit.

The second burn could be postponed until the GEO height is achieved, if all goes well, the satellite gets delivered into the proper GTO, but if it fails then all is not lost. Presumably this is more wasteful in terms of fuel for the upper stage, but I believe SpaceX has lots of spare capacity. Would this work? Would the customer feel better?

Another question, is there a de-orbit burn after the satellite is released to insure the upper stage burns up in earths atmosphere instead of becoming space junk? Again I think there is spare fuel capacity to do this.

Thirdly, would there be enough spare fuel capacity to deliver the satellite closer to its intended circular orbit than typically provided by GTO and thus provide superior service vs competing launchers and save the satellites' fuel?

[Jim]

The mission doesn't have excess performance, it requires near the max capability of the F9

[Comga]

The optimum division of the plane change between the perigee and apogee is a classical exercise in Orbital Mechanics 101. (Been there. Done that.)  A first out-of-plane burn is done at the first crossing of the equator, and the second is done when the satellite again crosses the equator at apogee. There is a solution for optimum, departure from which increases the required delta-V and, conversely, reduce the payload capability. 

If Jim is correct, and there is no excess performance to lose, there is no room for adjustment of the division of plane change.  Delaying the plane change until apogee after a direct injection would increase the delta-V required of the satellite and reduce its lifetime.  If there is any excess performance, the satellite lifetime is maximized by increasing the plane change at perigee so the apogee plane change requires less delta-V.

[mr. mark]

Any ideas on how long the approval process will take before launch ok is given? Seems less likely for late November launch. Who is the secondary launch provider if any?

[kevin-rf]

Any ideas on how long the approval process will take before launch ok is given? Seems less likely for late November launch. Who is the secondary launch provider if any?

You really think they can get a ride from someone else faster than SpaceX can clear the restart problem? It is a little late in the game to change the vehicle.

[mr. mark]

Never stated that. I just asked if there was a secondary launch provider and who it was. I did state that it may be getting late in the day and SpaceX may miss a late November approx. launch date. Guess we will see.