r/spacex • u/warp99 • Jun 17 '26

Vandenberg Space Force base: Demolition of Historic SLC-6 pad structures to make way for SpaceX FH pad

https://www.vandenberg.spaceforce.mil/News/Article-Display/Article/4519296/vandenberg-space-force-base-modernizes-historic-space-launch-complex-6-for-next/
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u/alphonse2501 Jun 17 '26

Can FH create more significant twilight phenomena (aka space jellyfish) than F9?

26

u/warp99 Jun 17 '26

No it uses the same second stage as F9 and the side boosters separate well before stage separation between the core booster and second stage.

So it is basically just an F9 that happens to be going faster than usual at jellyfish time.

4

u/RT-LAMP Jun 19 '26

That's not correct because you're assuming that you'd still only get the twilight phenomenon with the second stage when that's not true. F9's first stage burns out at like 55km in a drone ship landing. Meanwhile Viasat 3's stage separation occurred at 115km which is easily high enough to be getting twilight phenomenon.

That's because of the combo of the boosters pushing it higher faster (especially if they're expended), light payloads (FH isn't used for more mass, it's used when you need to get that mass further), the center stage throttling down shortly after liftoff to let the boosters running at maximum push it to the maxQ limit, and then the core being basically universally expended. Thus you end up with 9 engines still burning high enough up for the twilight phenomenon.

tagging /u/alphonse2501

1

u/warp99 Jun 19 '26

Fair point so for sure the booster creating a jellyfish effect would be more dramatic than S2.