Orbiter Plasma/fire? at MECO

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arconin

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During the Discovery launch this past July 4th I noticed something I had not seen before on launches I had previously watched (not many admittedly, but several). <br /><br />As seen from the Main fuel tank camera just around the time of MECO and up to tank separation there were bands of Orange light arcing around the Orbiter and wisping away, looked like flame or plasma ribbons. <br /><br />It reminded me of the condensation bands that form around aircraft approaching and breaking the sound barrier or performing high G maneuvers, which form, maybe run the length of the body of the craft and wisp away.<br /><br />Anyhow, did anybody else see it and what was its cause?
 
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arconin

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Right, I didn't see it during the first RTF which I also watched right up to main tank separation, thats why it caught my attention this time. <br /><br />And yes, there was some aft of the vehicle as well.
 
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bushuser

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I vaguely remember seeing the same effect on last year's flight. A TV commentator described it as "normal." Remember, the exhaust plume spreads very wide in a vacuum. The image is also distorted by the wide-angle lense on that camera.
 
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vogon13

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From your description, I am thinking you saw the normal contracting plume edges from the SSMEs as they shut down, then the normal 'splutters' they seem to do, and then there was the firing of the RCS jets to move away from the external tank.<br /><br />The sun angle seemed to really highlight all this activity.<br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>
 
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nibb31

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It looked more like plasma than plume fire.<br /><br />I think it was plasma caused by the hypersonic air pressure on the leading edges of the orbiter wings. Correct?
 
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vogon13

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Big scorch marks on upper sides of ET are from the seperation rockets on the SRBs.<br /><br />Butt end of ET gets toasted pretty good from radiant heat of the engine exhaust.<br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>
 
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askold

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During the live commentary during the launch, the announcer said it was due to the thin but still present atmosphere at MECO, and the speed of the shuttle - which was near its final orbital velocity but not its final altitude.
 
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drwayne

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Side Note:<br /><br />In the infrared, the interaction between the shock layer, and the entrained hot exhaust gases, and the thin ambient atmosphere is quite noticable to very high altitudes.<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>
 
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drwayne

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Another side note on plume envelopment. If you go to the RocketCam gallery, there are good examples like this one that show the detachment of the shock layer and the movement of the plume up the vehicle.<br /><br />http://www.eclipticenterprises.com/video/gps-timelapse-mpeg-hi.mpg<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>
 
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drwayne

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Most notable after the last solids have been dropped off, from about the middle of the film on....<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>
 
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arconin

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thanks for the replys....I figured it was normal or at least a known phenomenon, but was just a little surprised to see it riding up around the body of the orbiter.
 
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