Various footage of the IFT-2 of SpaceX's Starship show intriguing pattern of, presumably, exhaust gases illuminated by the Ship's 3+3 engines (attached below). While this may be an optical illusion, it does appear that some of the gases are present even in front of the Ship. What are the main components/pathways of the flow of the exhaust gases during such hot staging? Could it be that either back-scattering (off the super heavy booster) or just the (initial) thermal distribution of velocities lead to significant part of the gases actually overtaking the Ship, and leading to the beautiful picture we have seen on Nov 18th?

Note: Both the exhaust velocity and the mean thermal velocities of particles at, say 3500K are of the order of few km/s, and we are dealing with expansion of gas in vacuum.
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  • $\begingroup$ Those gases are not in front of the ship. They expand out from behind the ship. The camera angle is the only reason it can appear otherwise. $\endgroup$
    – Rory Alsop
    Nov 19 at 22:34
  • 1
    $\begingroup$ Here's an image of the top of the booster and the structure between the booster and the Starship upper stage (called the interstage). The top of the booster is going to deflect the Starship engine exhaust out through the gaps in the interstage. The exhaust is going to mostly go sideways with respect to the stack's long axis. With several engines firing at once, the exhaust will form an expanding ring, and that's what the images show. It's not continuous because of turbulence (and maybe some rapid thrust changes at first). teslarati.com/wp-content/uploads/2023/08/F31cK_SWwAAjJmA.jpg $\endgroup$ Nov 20 at 4:28


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