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I think it may be related to the sun, but I don't understand the "tooth" shape in the GIF - is this a shadow of something? Is the spacecraft already spinning for the satellite deployment?

What are the sources of light. Possibly some combination of Sun, Earthshine, infrared/red thermal radiation from the nozzle, but is there also artificial illumination from the spacecraft for the camera?

I can't understand exactly what I'm looking at here (the mechanism making this pattern of light on the nozzle).

Full video shown here - use the launch time code T+ 00:26:30 to 00:28:30 for reference.

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above: Early illustration of a 2nd stage, shown without a large communications satellite payload from the Spaceflight 101 article Falcon 9 v1.1 & F9R Launch Vehicle Overview. The dimension listed there as about 3.7m x 13.8m without payload adapter. This is for reference only.

The second stage looks much shorter in the images in this question but it is described as an "incomplete stage". It seems it might be from 2010.

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uhoh
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  • also - can someone suggest a better way to make a GIF? I use ImageJ but occasionally (like here) changing to 8-bit color looks horrible. Either a nice Python or on-line solution (no software downloads). Thanks! – uhoh Aug 14 '16 at 06:29
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    It looks to me like the aft end of the nozzle is illuminated by the Sun, the foward end is in shadow and glowing from heat, and the jagged boundary is a shadow casr by the end of the stage and its various appurtenances. – Organic Marble Aug 14 '16 at 11:44
  • @OrganicMarble so in the GIF (T+ 00:26:30 to 00:27:30 roughly) the sun is behind us (from the camera's point of view)? Is the nozzle metal or ceramic - opaque or translucent? – uhoh Aug 14 '16 at 11:47
  • The nozzle is metal, opaque, but fairly thin; while the engine is burning, it glows red-hot -- the nozzle extension is cooled by that radiation. Pic of the extension here: http://space.stackexchange.com/questions/8806/what-are-the-differences-between-a-standard-merlin-engine-and-the-merlin-vacuum – Russell Borogove Aug 14 '16 at 18:42
  • This is sunlight and a shadow from the payload, which has a lot of square corners, if you look at its photographs. – kkm -still wary of SE promises Aug 14 '16 at 18:54
  • @kkm I never thought about the payload - I'm thinking the 2nd stage is a (relatively) smooth 3.7m diameter cylinder maybe ~8m (?) long, so it's hard to see how those shadows make it all the way to the nozzle. Have you seen any pics - drawings are fine - of the whole system at this point? – uhoh Aug 15 '16 at 01:18
  • I think the shadow shape is more likely projected off the aft end of the stage rather than from the payload. – Russell Borogove Aug 15 '16 at 04:05
  • @RussellBorogove ah! You have a very nice photo of it - quite a work of art! – uhoh Aug 15 '16 at 04:43
  • @uhoh, the fairing is long gone by this time, and the satellite that is jettisoned off by springs at the very end of the timeline in the video is rather square with square folded attachments (https://youtu.be/QZTCEO0gvLo?t=49m5s). It could be responsible for the jagged shadow. Maybe something else; nothing under the fairing needs to be aerodynamic. In any case, the dark area where you can see the glow is indeed a shadow. I do not hazard writing a documentally corroborated answer, sorry--the case seems too obvious for that. :) – kkm -still wary of SE promises Aug 15 '16 at 18:46
  • @uhoh, if you want to go deeper into that, look no further that the Falcon 9 User Manual (http://www.spacex.com/sites/spacex/files/falcon_9_users_guide_rev_2.0.pdf). The overall vehicle layout cutoff is on p. 10, the PAF is photographed on p. 15, and overall payload shape is defined on p. 31. – kkm -still wary of SE promises Aug 15 '16 at 18:55
  • @kkm Thanks! Users guides are designed not to be deep in areas that can distract users - like detailed dimensions outside of the immediate payload area. Can you help me find the approximate distance in meters from the bottom of the PAF to the bottom of the 3.66m stage body, and to the bottom of the nozzle? That's the deep I need to find, not a drawing with everything in place. Also, do you mean page 36, not page 31? – uhoh Aug 15 '16 at 22:50
  • @kkm If I take total height of 70m, subtract 11.5 m for fairing, 43 m for 1st stage (an old value of 41 I remember from an older SpaceX webpage plus 2m guess for recent upgrades), and then allow a gap of 0.5m between the first stage and the bottom of the 2nd stage nozzle (inside the interstage) I get a rough guesstimate of 15 m from the bottom of the 2nd stage nozzle to the top of the PAF, but I'd rather have the real numbers. – uhoh Aug 15 '16 at 23:29
  • @uhoh, sorry, I have no idea where to obtain the dimensions with the 1% precision. Also, I think that deviates quite far from the topic of the question. And you are right, I meant page 36. – kkm -still wary of SE promises Aug 15 '16 at 23:45

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