Hot Staging Troubles: What Really Happened To Booster 9?

In this episode we will examine the critical design considerations that had to be addressed to allow Starship to execute its hot stage maneuver without destroying both vehicles in the process! At the end you will hopefully gain an appreciation for the amount of work that went into being able to pull this off in a ridiculously short timeline.

After covering the upgrades that needed to be made for this to be successful, we will get deeper into the physics of hot staging. This isn't a unique mode of stage separation but the way it is executed is unlike any other rocket that has done this.

Lastly, we will address all of the speculative explanations about what caused Booster 9 to explode shortly after stage separation. The goal is not to come to a definite conclusion, but get a visual understanding of each theory, and then determine which ones actually seem feasible to the real cause of failure.

Please consider supporting CSI Starbase on:
Patreon: http://www.patreon.com/CSI_Starbase
PayPal: https://paypal.me/CSIstarbase
Twitter: https://twitter.com/CSI_Starbase

CSI Starbase Production : Geoff Allan
https://twitter.com/DeffGeff

The Ring Watchers - Super Heavy Propellant Distribution Article
https://ringwatchers.com/article/booster-prop-distribution

Huge thanks to the following photographers and content creators who make all of this possible!

Ryan Hansen Space
Patreon - https://patreon.com/ryanhansenspace
𝕏 - https://twitter.com/RyanHansenSpace
▶︎ https://www.youtube.com/@UCNxwUG0Vq8TztWdxL83FLHQ

Chameleon Circuit
Patreon - https://www.patreon.com/ChameleonCircuit
𝕏 - https://x.com/ChameleonCir

Andi Ashtorak - Starbase Simulator Video Game:
Download - https://ashtorak.itch.io/starbase-simulator
𝕏 - https://x.com/StarbaseSim

C-Bass Productions
𝕏 - https://twitter.com/C_Bass3d
▶︎ - https://www.youtube.com/c/CbassProduc...

📷Virtual Space 3D - Highbay & CSI Headquarters Renders
Patreon - https://patreon.com/VS_3D
𝕏 - https://twitter.com/Lolomatico3d

▶︎ RGVAerialPhotography
Patreon - http://patreon.com/RGVaerial
▶︎ https://www.youtube.com/@@UCQbKe0RZ62u47TZ8vmKNnRA

📷 Starship Gazer
Patreon - http://patreon.com/StarshipGazer
▶︎ https://youtu.be/@UCBVnapKtPTNYl4phaGXxYng

Randolph Visuals
Patreon - https://www.patreon.com/user?u=59915477
𝕏 - https://x.com/CosmicalChief

LabPadre - 24/7 Starbase Livestreams
▶︎ https://www.youtube.com/channel/@UCFwMITSkc1Fms6PoJoh1OUQ

NASASpaceflight
▶︎ https://www.youtube.com/NASASpaceflight

Cosmic Perspective w/Audio from Andrew Keating
▶︎ https://www.youtube.com/@UCh3jrub_0od3EFoUtiIG4jQ

Tim Dodd - The Everyday Astronaut
▶︎ https://www.youtube.com/@EverydayAstronaut

Timestamps

00:00 - Elon Starship Presentation
01:17 - Introduction
07:04 - HSR Design - Overpressure Prevention
10:05 - HSR Design - Max Q Durability
14:00 - HSR Structural Verification Testing
19:14 - HSR Design - Ignition Survivability
24:17 - S25 Aft Heat Shield Explained
29:40 - S27's Sudden Death
31:40 - S25 Aft Heat Shield Upgrade
33:47 - S27 Resurrection / Heat Shield Testing
37:00 - Falcon 9 v Starship Stage Separation
40:33 - Brilliant Sponsor Segment
42:00 - RVac Differential Thrust At Stage Sep
45:16 - Grid Fin Rotation During Hot Staging
49:30 - Raptor Relight Performance Issues?
51:50 - Booster Engine Plumbing - CH4
54:46 - CH4 Downcomer Collapse?
57:05 - Booster Engine Plumbing - LOX
58:04 - Fuel Slosh Intro
1:00:47 - RHS Fuel Slosh Simulation Explained
1:07:08 - Catastrophic Engine Cavitation Damage?
1:10:20 - B10 Upgraded Slosh Baffles
1:11:18 - Engine Plumbing Damage?
1:16:28 - Lessons Learned
1:17:08 - Outro

Music Credits

2:30 "Do You Remember" prod. by kochetkovv https://youtu.be/XXkND6MTJC8
7:03 https://www.youtube.com/watch?v=V-_44B2Ltyc
11:08 https://www.youtube.com/watch?v=Wr9kwih7its
14:21 https://youtu.be/TMIg0Q5FIQQ
19:28 https://youtu.be/yqhoDBaO6Zs
20:52 https://youtu.be/gpC1MN1CFSk
24:51 https://youtu.be/w-bLNAqQKVM
30:19 Collapse - @spaceflightmemories
31:40 Electric TVC - @spaceflightmemories
33:53 https://youtu.be/gutOF86rhgI
37:47 https://youtu.be/TpJfT3bF7DE
40:33 https://youtu.be/9YxwMetoPyM
41:53 https://youtu.be/Jt3fL3mbB7E
46:07 Saving Starship- @spaceflightmemories
53:04 https://youtu.be/68QeDAitSPo
57:00 https://youtu.be/DV3cKQJcqzE
1:07:04 https://youtu.be/odRL6ixtVkU
1:13:31 https://youtu.be/jfoquaHzZ9U
1:14:57 https://youtu.be/R76lIK0-SGQ
1:19:14 Beat from https://www.beatopia.com/ "The Last Song Produced by Ghost"

Last but not least I want to give HUGE SHOUTOUT to the entire CSI Starbase team on discord. This dedicated team of 200+ agents with specialties ranging all across the board, has been crucial in getting the most accurate info for these episodes. Couldn't do it without yal!