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I found the image below in a NASA image gallery for 2014. There, the text only says:

This unprecedented view of the space shuttle Atlantis, appearing like a bean sprout against clouds and city lights, on its way home, was photographed by the Expedition 28 crew of the International Space Station. Airglow over Earth can be seen in the background.

Image Credit: NASA, Last Updated: July 31, 2015, Editor: NASA Administrator

Tags: Expedition 28, Landings, Shuttle Atlantis, Space Shuttle, STS-135

Is the visible glow from a de-orbit burn, or heat from re-entry, or something else? Since it's moving away from the camera, why would the light be visible in either case? There's a bump or knee in the trail, highlighted in the second, annotated/cropped image. What probably caused it?

enter image description here

enter image description here

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  • $\begingroup$ It is the reentry. $\endgroup$ Jun 22, 2017 at 16:21
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    $\begingroup$ A de-orbit burn wouldn't be nearly that noticeable; hypergolics burn fairly faintly even in-atmosphere, and in vacuum the plume would diffuse very rapidly. The Proton first stage is about 200 times as powerful as OMS and looks like this: youtube.com/watch?v=LMwDASkWPJU $\endgroup$ Jun 22, 2017 at 18:47
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    $\begingroup$ Also the deorbit burn only lasted a few minutes - on STS-120, for example, it was 198 seconds. $\endgroup$ Jun 22, 2017 at 19:26
  • $\begingroup$ The term "airglow" hints on atmospheric effects which would not be present during deorbit burn. $\endgroup$
    – jkavalik
    Jun 23, 2017 at 4:54
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    $\begingroup$ @uhoh at 300-400km (at or a bit below ISS orbit which I believe should be where the deorbit burn usually happened) there is really no air. Sure it is far from perfect vacuum but not enough to create any significant pressure or cascading effects - my idea is that when you bump a molecule it goes long way before interacting with anything else whereas generating a glow requires each misplaced molecule to bump other quickly enough and in such numbers it sustains some kind of reaction (but I maybe wrong, intuition does not work well at those levels and I did not study anything closely related) $\endgroup$
    – jkavalik
    Jun 23, 2017 at 6:43

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Your picture shows the plasma trail behind STS-135, the last space shuttle entry in history.

The trail you’re seeing is therefore not actually the Orbiter streaking across the Earth! The plasma trail behind it fades with time, so the trail is brightest near the Orbiter’s position and fainter as you backtrack along its path. Think of it as an afterglow of the passing of Atlantis.

Why does this happen? The air gets heated by the Orbiter’s ramming the atmosphere at 20+ times the speed of sound. And contrary to popular belief, it’s not friction that heats the air, but compression. When you compress a gas it heats up (like when a bicycle pump gets hot when you use it a lot), and the Orbiter is screaming through the atmosphere at hypersonic speeds. That compresses the air a lot. A shock wave forms in front of the Orbiter, and the air begins to glow as it gets heated up to temperatures as high as 1260° C (2300° F).

That’s what you’re seeing above: the shocked, rammed, and glowing air as Atlantis pounded through it at several kilometers per second. And it did this many, many times over its life… until this one final time, caught on camera by astronauts high above the Earth.

source

Plasma trails were also visible from the ground if one was in the right place at the right time, as in this incredible picture of the STS-93 entry over Johnson Space Center. I was standing outside watching this in person, but I did not take this picture, sadly.

enter image description here

Here is a picture of the STS-107 plasma trail over California, before things went visibly wrong.

enter image description here

I do not know what caused the bump in the trail, but possible causes are:

  • a maneuver by the shuttle (roll reversal)
  • high altitude winds or other meteorology
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    $\begingroup$ The bump looks like the roll reversal to me, as the trail curves noticeably afterward. $\endgroup$
    – Tristan
    Jun 22, 2017 at 16:34
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    $\begingroup$ Yeah, agreed. Wind would be pretty diffuse up there. $\endgroup$ Jun 22, 2017 at 16:36
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    $\begingroup$ I guess it had to be a plasma trail. The exposure is fairly short (maybe a few seconds or so?) but the trail is fairly long, so it must be just sitting there glowing. That would explain the steady increase in brightness getting closer to the location of the shuttle itself. OK this makes a lot more sense now! $\endgroup$
    – uhoh
    Jun 22, 2017 at 16:49
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    $\begingroup$ To the (my) human eye, the STS-93 plasma trail looked just like the picture, a long meteor-like trail that slowly faded away at the end. $\endgroup$ Jun 22, 2017 at 17:06
  • $\begingroup$ What's the place with all the radio dishes in the foreground of the STS-107 photo? $\endgroup$
    – Vikki
    Jun 11, 2018 at 16:51

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