When a SpaceX booster is landed, we are used to seeing soot deposited all over it, usually in a specific pattern.

You can read more about that in this question: Why the strange bands of soot of the landed F9 first stage?

Now that the first Falcon Heavy launch is complete, we see that the nosecone has quite a bit of soot on it as well.

You can see it in this image of one of the booster cores being moved into the HIF after landing.

Side Booster entering HIF

We do know from the question On the Falcon Heavy, why are the side boosters using Ti Grid fins, but not the center core? that there appears to be aerodynamic consequences to the use of a streamlined nose cone, as opposed to the larger/longer interstage that a single stick booster landing would have its end.

What is the cause of this soot pattern?

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    $\begingroup$ Nosecones got cooked medium-rare from the centre core on jettison. $\endgroup$ – ReactingToAngularVues Feb 15 '18 at 21:04

It was charred by the center core after separation:

Falcon Heavy side boosters seperate from the core in a three-camera view. One view from the center core shows one side booster falling away through the engine plume, being singed. Two views show the center from the perspective of the sides as they pass near the core's engines and flame dances around the cameras briefly.

Cropped and slowed detail

(Source: SpaceX FH launch webcast)

Looking at it I would expect one side to be charred too but it may not be - the nose cone is afaik composite (same as the interstage) and not metal.

  • $\begingroup$ Is that flame coming from the centre core though? From the gif it looks like it's the side booster own flame instead, coming back along the rocket while it start braking (I'm no expert, just asking) $\endgroup$ – redShadow Feb 16 '18 at 9:19
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    $\begingroup$ @redShadow I ser the center core flame "licking" the entire length of the booster. There is imho no way for the booster flame to get there - it is not braking at all and its engines just shut down before this. $\endgroup$ – jkavalik Feb 16 '18 at 9:23
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    $\begingroup$ @jkavalik you're right, engines should be off.. ok I might be making confusion between the three cameras. Top one is from the centre core, bottom two are from the two boosters, right? Looks like the flame in the top frame is coming from the bottom of the rocket that's detaching, but you're probably right, it's actually the other way round $\endgroup$ – redShadow Feb 16 '18 at 9:46
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    $\begingroup$ @redShadow you see the flame hit the side boosters on the other two cameras too. I will try to add a bigger version of the center core cam later when not on phone. $\endgroup$ – jkavalik Feb 16 '18 at 9:48
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    $\begingroup$ @redShadow It looks confusing because you only see the flame where it hits some surface. It looks to be transparent elsewhere. I guess the high temperature exhaust is not really burning at the point where it becomes visible in the center core camera, but then chars something when it hits the booster surface. $\endgroup$ – jpa Feb 16 '18 at 14:02

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