Booster 4 (B4)

Booster 4 (B4) was the third full stacked Super Heavy booster prototype that was originally intended to fly on the first Orbital Flight together with S20, however, Elon Musk announced that a first orbital flight would involve Raptor 2 engines^[1] and that it would be with new prototypes.^[2]

Booster 4 was eventually decommissioned and stored at the Rocket Garden for 630 days,^[3] until it was finally rolled to Mega Bay 1 for scrapping on March 21, 2024. Scrapping began the next day and was completed on March 26.

History[]

It has been fully stacked in the High Bay and Raptor engines have been installed. On Tuesday, August 3 the booster was moved to the orbital launch site. One day later, B4 was lifted onto the orbital launch mount (OLM) by the LR11350 crane and on 6 August 2021, S20 was stacked onto the booster by the same crane - the first time the rocket was fully assembled! On the same day, the Ship was destacked and on 10 August 2021, B4 was removed from the OLM too.

On 11 August 2021, the booster rolled back to the launch site for some work in the High Bay and all engines have been removed. At the end of August, Raptor engine installation began again and on 7 September, it rolled back to the launch site. On 8 September 2021, B4 was lifted onto the OLM again by the LR11350 crane. Following outer Raptor engines have been identified on B4 during the lift: RB12, RB18, RB15, RB17, RB3, RB6, RB2 RB27?, RB4, RB20, RB5, RB9, [RB25?, RB26?], RB19, RB21, RB24, RB11, RB12

On 25 September 2021, B4 was lifted off from the OLM by the LR11350 crane once again. It was speculated that this was done to not damage the booster during the installation of the chopsticks. On 20 October 2021, new thermal protection framings have been spotted around the outer raptor engines. In October and November, SpaceX crews worked especially on the aft section.

On 13 December 2021, B4 was lifted on the OLM by the LR11000X crane for a third time. The following engines have been identified: RB28, RB29, RB30, RB31, RB32, RB13, RB16, RB12, RB18, RB15, RB17, RB3, RB6 RB33, RB14, RB4, RB20, RB5, RB7. On 17 December 2021, a first cryo test of B4 and the OLS tank farm systems has been conducted, followed by longer and more extensive testing on December 22 (two cycles) and December 23.

After this testing period, Booster 4 was once again lifted off the OLM by LR11000X on December 30. In mid January 2022, the aerocovers have been finally installed. On 6 February 2022, B4 was lifted onto the orbital launch mount for the fourth time. This came after Elon Musk announced a full stack for the Starship presentation on Thursday, February 10.

After well over a year of inactivity B4 began receiving attention on the 5th of March 2024 when man lifts were sent up to the Booster's grid fins. On the 6th, a grid fin was removed, signifying the beginning of scrapping for the prototype. On the 11th of March workers were spotted at B4's grid fins once again preparing for the removal of a second grid fin on the 12th. Workers began preparing to cut the vehicle into two pieces with scaffolding placed around the top of the LOX tank on March 20 and 21 and the vehicle was scrapped on March 22.

Timeline[]

30 June 2021: Potential B4 fwd dome sleeve (3-ring stack with fin attachment structures and thruster holes) spotted, moved outside tent
2 July 2021: B4? fwd dome section and S21? aft section near each other after stacking test
2 July 2021: B4 "comm dome" section (4-ring stack with some small holes in it) spotted
3 July 2021: Common dome on sleeving stand, sleeved with 4-ring stack ("CMN Dome Stiffend[?] Barrel")
4 July 2021: Booster fwd dome [B4?], Starship aft skirt, S21 aft dome in front of tents
5 July 2021: B4 aft tank #2 4-ring section with lead-ins moved between tents towards High Bay area [still labeled BN4][vid 06]
10 July 2021: New Superheavy [B4?] thrust puck (for nine engines) delivered
12 July 2021: Booster section attached to flipping jig inside High Bay [B4?]; later flipped [vid 13] [why booster; could it be SN20?]
14 July 2021: Fwd 2 section (3-ring stack with lead-ins) spotted
15 July 2021: Aft 3 section (4-ring stack with lead-ins) in front High Bay
15 July 2021: Common dome section stacked in High Bay [likely with aft #2?]
16 July 2021: B4 work in High Bay continued
16 July 2021: B4 aft 4 and B4 aft 5 (both 4-ring stacks with lead-ins) spotted
17 July 2021: GSE tank aft section (3-ring with dome) moved [GSE4/GSE6?]; label, likely outdated, mentioning B4: "BN4 aft dome stiffed panel"
17 July 2021: Potential B4? aft section (3-ring) hooked to flip rig and flipped; no dome installed yet inside!!
19 July 2021: Booster aft dome sleeve (3-ring section) spotted [B4?]
20 July 2021: B4? aft dome (3-ring stack or sleeve) spotted
20 July 2021: B4 aft 4 (4-ring with lead-ins), B4 aft 5 (4-ring with lead-ins), B4 fwd 4 (4-ring with lead-ins) ready
21 July 2021: Stacking progressed in High Bay, aft tank #2 has been stacked (at least 10 rings tall now)
23 July 2021: Aft 4 outside High Bay (4-ring with lead ins)
24 July 2021: B4 stacking continued in High Bay, now 16-rings tall
24 July 2021: B4? fwd dome placed on sleeving stand
24 July 2021: Fwd sleeve flipped at 3:35 pm
25 July 2021: Aft 5 (4-ring with lead-ins) outside High Bay
25 July 2021: B4? aft dome sleeve outside tent 1 (3-ring); later hooked to crane and flipping jig, flipped
25 July 2021: Aft dome/thrust dome placed on sleeving stand
26 July 2021: B4 stacked with fwd 5 section (4-ring), now 20 rings tall (~37m) at 12:50 am
26 July 2021: B4/B5? downcomer pipe spotted
27 July 2021: Methane transfer tube "downcomer" installed early in the morning
27 July 2021: LOX tank section inside High Bay ahead of stacking
27 July 2021: WAI internal SpaceX info: B4/S20 [SN20] ready on OLM by August 5 as internal goal!
28 July 2021: Thrust dome has been flipped
28 July 2021: Methane tank stacking: 6-ring fwd section attached to High Bay crane and stacked to another 3-ring stack (now 9 rings tall)
29 July 2021: Methane tank stacking continued with top 9-ring stack (fwd) stacked onto another section (fwd #4), methane tank section looks completed now
29 July 2021: Fwd #4 section ready for stacking (4-ring with lead-ins)
30 July 2021: Thrust section /aft dome section (3-ring with lead-ins) moved into High Bay; stacked with LOX section later
30 July 2021: Stacking continued in High Bay, methane tank section looks to be complete (13 rings) and LOX tank as well
30 July 2021: Grid fins spotted
30 July 2021: Methane tank moved out of High Bay; moved back later
30 July 2021: Grid fins installation on methane tank section began
30 July 2021: First grid fin installed on upper methane tank section [vid 31]; apparently they can't fold (confirmed by Elon Musk)
01 Aug 2021: B4 more grid fins installed
01 Aug 2021: Fit check of B4 on OLM NET Tuesday [Musk]
01 Aug 2021: LOX tank moved in High Bay and work platform installed ahead of final stacking
01 Aug 2021: CH4 tank lifted by High Bay crane and stacked onto LOX section; final stacking; met at 4:37 pm
01 Aug 2021: Raptor engines roll out in this order [where?]: RB7, RB2, RB3, RB15, RBxx, RBxx, RB9, RB21, RB19, RB18, RB4, RB6, RC74, RC79, RC58, RB8, RB11, RB14, RB20
01 Aug 2021: Raptors installed late night: RB7, RB2, RB3 pictured; at least 14 Raptors already installed as of 1:20 am of August 2 [?!]
02 Aug 2021: RC74,64, RCxx, RCxx, RCxx, RC65, RB22 installed on B4
02 Aug 2021: Work in High Bay continued on mating the two halves
02 Aug 2021: B4 had 29 Raptor engines installed in just one night [all engines installed]
03 Aug 2021: Detached from High Bay bridge crane
03 Aug 2021: B4 roll out to OLS
04 Aug 2021: CH4 tank condensation at 3am
04 Aug 2021: Attached to LR11350 load spreader
04 Aug 2021: GSE hoses detached ahead of lifting
04 Aug 2021: Lifted onto OLM by LR11350 in a very careful manoeuvre
05 Aug 2021: Detached from LR11350
06 Aug 2021: SN20/S20 stacked onto B4 by LR11350, fully assembled rocket for the first time ever!!
06 Aug 2021: SN20/S20 removed from B4 by LR11350 after first fit check for final construction, touch-down at 9:45 am
07 Aug 2021: Reattached to LR11350
08 Aug 2021: Work for preparing to remove it from OLM
08 Aug 2021: Attached to LR11350 [??]
10 Aug 2021: Prepared to be lifted from OLM
10 Aug 2021: Removed from OLM at 7:45 am by LR11350; detached from crane/load spreader at 3:06 pm
11 Aug 2021: Rolled back to build site on two SPMTs; during the transport, the booster was kept pressurized; moved into High Bay
11 Aug 2021: SN20/S20 moved out of the High Bay to prepare it for B4; positioned outside mid bay
11 Aug 2021: Raptor engines began to be removed
12 Aug 2021: Work in High Bay
12 Aug 2021: Raptor engine removal continued
13 Aug 2021: Work in High Bay continued
14 Aug 2021: Work continued in High Bay
15 Aug 2021: Work in High Bay continued; dents have appeared and disappeared again as the booster expands and contracts (normal)
16 Aug 2021: Work in High Bay continued
17 Aug 2021: Work continued in High Bay, external box has been added [?]
18 Aug 2021: Work in High Bay continued
19 Aug 2021: Work in High Bay continued
20 Aug 2021: RB24 engine delivered
23 Aug 2021: Three Raptor engines delivered in front of High Bay; RB17 and RB20 spotted; engines likely began to be installed
24 Aug 2021: Work in High Bay continued
24 Aug 2021: Raptor installation on B4 in High Bay continued; RB26, RB6, RB27 spotted
25 Aug 2021: Work continued; aerocover truss added on external COPVs, aerocovers will mount to these and protect the COPVs from aerodynamic forces during flight
25 Aug 2021: Raptor installation continued; RB4 spotted
26 Aug 2021: Work in High Bay continued
27 Aug 2021: Work, especially at the aft section, continued in High Bay; RB2, RB27 and RB4 spotted on B4; also some center Raptor [RC] engines have been spotted outside High Bay
28 Aug 2021: Raptor engines continued to be added
29 Aug 2021: Work in High Bay continued; engine RB5 moved into High Bay for installation
30 Aug 2021: Work in High Bay continued
31 Aug 2021: Work continued near interstage and grid fins
02 Sep 2021: Still in High Bay, work looks rather finished
03 Sep 2021: Work in High Bay continued
04 Sep 2021: B4 work at its aft area in High Bay
05 Sep 2021: Work in High Bay continued
06 Sep 2021: Work in High Bay continued
06 Sep 2021: SPMT moved towards High Bay/B4 for transporting it to launch site later
07 Sep 2021: B4 was removed from bridge crane in High Bay at 1:02 am
07 Sep 2021: B4 rolled back to launch site; (roll out started at 8:04 am, hwy4 at 8:18, arrived at launch site at 9:34 am)all 29 Raptor engines appear to have been installed; but there are no thermal insulation coverings around the engines
07 Sep 2021: Hooked to LR11350 crane
08 Sep 2021: Lifted onto OLM/platform by LR11350 (following outer engines identified: RB12, RB18, RB15, RB17, RB3, RB6, RB2 RB27?, RB4, RB20, RB5, RB9, [RB25?, RB26?], RB19, RB21, RB24, RB11, RB12); touch down at around 11:52 am; secured onto platform
09 Sep 2021: B4 and OLM work continued
09 Sep 2021: OLM: Quick disconnect extended towards booster at 10:11 am
10 Sep 2021: B4 and OLM work continued
11 Sep 2021: B4 and LR11350 detached
12 Sep 2021: B4 and OLM work continued, QD system has been retracted
15 Sep 2021: Prepared for testing
16 Sep 2021: B4 and OLM intense work continued
18 Sep 2021: Raptor engine RC67 removed
19 Sep 2021: RC67 continued to be removed (raptor installation platform has been used for first time); returned to production site
19 Sep 2021: RC64 delivered to launch site; installed on B4 via installation platform and Tesco Hi-Lift later (11.25am)
21 Sep 2021: B4/B5/B6?? fwd dome sleeve spotted (3-ring with strengthening/enforcement)
21 Sep 2021: B4/B5/B6?? aft tank #3 segment spotted (4-ring)
24 Sep 2021: Blue booster COPV cover [B4/B5?] spotted
24 Sep 2021: Workers at the top
24 Sep 2021: Booster stand rolled out to launch site for B4
24 Sep 2021: LR11350 lifted a loadspreader towards B4 ahead of destacking from OLM
25 Sep 2021: B4 lifted off from the OLM/pad by LR11350, likely not to damage the booster during installation of catch/stack arms on OLS, IT; carefully placed onto booster stand
24 Sep 2021: LR11350 detached from B4
25 Sep 2021: LR11350 and load spreader attached to B4
26 Sep 2021: Rolled away from OLM
27 Sep 2021: Work at upper LOX tank
29 Sep 2021: New future ship/booster test stand foundation spotted near the current location of B4
30 Sep 2021: Work around the skirt area continued and hull
02 Oct 2021: Work continued with man lifts up to the top; work on the center lines
03 Oct 2021: Worked on in several areas with man lift going up to the top, orange "AVI" bags near the top of the line
04 Oct 2021: Work continued; workers on top of the fwd dome; work on one of the long pipes (tightening screws); inspection
05 Oct 2021: Work continued, especially around the aft section with the QD ports and COPVs
11 Oct 2021: More Raptor engines removed from B4, e.g. RB27 visible; furthermore RB11 and RC79 and another with invisible SN
12 Oct 2021: Work on aft section
14 Oct 2021: Raptor engines removed from B4, 5 engines visible
15 Oct 2021: Work continued in different areas
17 Oct 2021: Work continued in several areas
18 Oct 2021: Work continued on its top; hydraulic power unit sled wrapped in plastic, possibly in preparation for installing aerocover
19 Oct 2021: Work on raceway
20 Oct 2021: New framing around the Raptor engines, possibly part of the new thermal protection system mentioned by Elon Musk
21 Oct 2021: Work at top continued, as well as in the engine sections (new thermal protection)
22 Oct 2021: Booster aft tank#5 and #3 spotted [B6?, signs look like B4 and B5]
22 Oct 2021: Work on aft section and engines continued; start of thermal protective cover installation
23 Oct 2021: B4 and SN20/S20 worked on
24 oct 2021: Work continued; TPS installation for Raptor engines continued; some work around COPVs
25 Oct 2021: Work continued
26 Oct 2021: Booster fwd section spotted outside tents [label B4/B6 fwd dome??]
26 Oct 2021: Insulating foam added around the COPVs and QD plate; work on raptor heat shield (TPS) continued; work con raceway
27 Oct 2021: RB33 delivered to launch site [for B4]
27 Oct 2021: B4 Raptor heat shield work continued, the big aerocovers now next to it [RGV]
28 Oct 2021: Work continued near common and forward dome, as well as on aft section
29 Oct 2021: Aft section work continued
30 Oct 2021: Work on Raptor engines shield (TPS) looks complete [?]
31 Oct 2021: Work continued
02 Nov 2021: Fwd section worked on
03 Nov 2021: RC74 delivered to launch site and unloaded; prepared for installation on B4
03 Nov 2021: Work on fwd section
04 Nov 2021: Aft section work continued
09 Nov 2021: Work at the fwd section
10 Nov 2021: COPV Covers installation finally began
17 Nov 2021: Inspection work
18 Nov 2021: Preparation work around aft section continued
20 Nov 2021: SN20/S20 and B4 (inspection) work
23 Nov 2021: Work on some areocovers
24 Nov 2021: Work on engines, raceway cover and aft section continued
27 Nov 2021: Work continued
28 Nov 2021: Work near the COPVs
30 Nov 2021: Work near COPVs, raceway covers continued to be installed
01 Dec 2021: COPV covers being installed
02 Dec 2021: Raceway cover continued to be added (Kevin Randolph)
03 Dec 2021: Aerocovers for both hydraulic power units were installed
04 Dec 2021: Work on aft section continued
06 Dec 2021: Connected to LR11000X
07 Dec 2021: Work continued
08 Dec 2021: Connected to load spreader [not two days ago? [yes]], work on COPVs
10 Dec 2021: Still hooked to LR11000X, not moved yet
11 Dec 2021: Unhooked from load spreader (without having moved), LR11000X moved
12 Dec 2021: Moved towards OLM, likely to be lifted soon
12 Dec 2021: Connected to LR11000X late in the night
13 Dec 2021: Work on aft section (QD plate) ahead of lifting
13 Dec 2021: B4 lifted onto OLM by LR11000X and installed carefully (engines spotted: RB28, RB29, RB30, RB31, RB32, RB13, RB16, RB12, RB18, RB15, RB17, RB3, RB6 RB33, RB14, RB4, RB20, RB5, RB7); all hold-down clamps extended one by one manually; RB engine disconnect spotted
14 Dec 2021: OLM work continued, booster QD hood closed; later opened and likely connected to B4, work around QD
14 Dec 2021: B4 work on OLM continued; ship QD arm likely to hold on booster
15 Dec 2021: Still attached to LR11000X; OLM and B4 work continued; later detached from crane
16 Dec 2021: Remained connected to QD; work on a cover attached to aft section
17 Dec 2021: B4 cryo proof test on OLM
17 Dec 2021: Elon Musk tweets; video of B4 gimbal test (center engines)
20 Dec 2021: Scrubbed testing
21 Dec 2021: B4 cryo proof test #2
22 Dec 2021: B4 cryo proof test #3
23 Dec 2021: B4/OLM igniter tests at 19:49 and 22:27
27 Dec 2021: LR11000X moved towards B4/OLM
27 Dec 2021: B4/OLM two ignitor tests [vid 28]
28 Dec 2021: B4/OLM igniter test #5?
28 Dec 2021: Hooked to LR11000X
30 Dec 2021: B4 prepared for lifting; QD disconnected (retracted and hatch closed); lifted by LR11000X and lowered onto a transport stand (engines spotted: RB28, RB29, RB30, RB 31, RB32, RB13, RB16, RB12, ... RB33, RB14, RB4, RB20, RB5, RB7, RB??, RB28); secured on stand
30 Dec 2021; Load spreader and LR11000X disconnected from B4; B4 moved towards landing pad
02 Jan 2022: B4 on landing pad
03 Jan 2022: LR11000X moved to landing pad and attached to B4 via loadspreader
04 Jan 2022: Work continued on several areas
05 Jan 2022: Work continued
06 Jan 2022: Attached to LR11000X
06 Jan 2022: Work through access hole
11 Jan 2022: Work continued around QD area
12 Jan 2022: Covers worked on
13 Jan 2022: Work continued; first aerocovers finally being added
14 Jan 2022: Work on engine section (work on aerocovers): engines have received side covers; three aerocovers are now installed
17 Jan 2022: Work on QD area; aerocover for QD panel installed
25 Jan 2022: Work continued
30 Jan 2022: Work on an aerocover
31 Jan 2022: Raptor nozzles have been painted grey [RGV]
01 Feb 2022: Grid fins unstrapped
02 Feb 2022: LR11000X moved to B4, load spreader picked up, hooked up
02 Feb 2022: Engine bells have been painted grey [not today]
04 Feb 2022: SPMT delivered ballast to launch site, possibly for B4 transport
05 Feb 2022: Unhooked from LR11000X at 9:56am
05 Feb 2022: B4 moved slightly with transport stand
05 Feb 2022: Moved to OLS after LR11000X on an SPMT (the one from yesterday); attached
06 Feb 2022: Work inside LOX tank; hatch closed at 5:30am
06 Feb 2022: Prepared for lifting (ropes attached), lifted off transport stand and onto OLM for the fourth time, by LR11000X [not chopsticks as suspected] without the help of the chopsticks; transport stand removed
06 Feb 2022: Secured on OLM, booster QD connected [great closeup]
06 Feb 2022: Ship QD arm work continued; rotated away from B4 after stacking
07 Feb 2022: Disconnected from LR11000X load spreader 2:54 am
07 Feb 2022: SPMT Coupler lifted; one of the two SPMTs moved away from under the B4 transport stand; stand moved away
07 Feb 2022: OLM/B4: booster QD work
08 Feb 2022: B4 grabbed by QD arm claws; work on the claws connectors
10 Feb 2022: Work around S20/B4 interface; chopsticks stabilization arms removed from S20
12 Feb 2022: OLM/B4 work on QD
14 Feb 2022: Starship 4/22: SN20/S20 destacked from B4 by chopsticks during road closure
18 Feb 2022: QD arm moved away from B4 (retracted)
18 Feb 2022: B4 cryo proof testing on OLM, LOX tank fully filled (frosty); methane subcoolers frosted up
1 March 2022: B4 cryo test, both tanks frosted up, whole OLS tank farm active; OLIT was venting as well (although ship QD not active) [cont. vid 02]
2 March 2022: B4 cryo test continued, LOX tank fully filled, CH4 partially, huge depress vents; loudspeaker vertical LN2 vent continued long in the morning; OLIT vented again
7 March 2022: QD arm moved (retracted away from B4)
9 March 2022: B4 vented (fwd dome depress vents)

6 August 2021 - First Stack Of B4 And Ship 20 Then Destacked[]

On Friday, August, 2021: Ship 20 Was Stacked On Booster 4 Using a Crane.

Timeline Based On NSF Stream:

23:21 Lifting Up Started
44:40 Lifting Up Stopped
45:05 The Crane Started Moving Towards The Booster
59:40 The Crane Started Lowering The Ship Towards The Booster
1:20:44 Stacking Completed
2:25:32 Destacking
2:55:44 Destacking Completed

17 December 2021 - Cryo Proof Test and OLS System Check[]

Testing timeline of the first test on the orbital launch mount (OLM) according to LabPadre and NSF streams:

07:28 or earlier road closed; venting of GSE lines in front of OLS tank farm already began
8:54 Pad cleared but two cars went down on 8:57 again (likely closing beach)
9:11 Tank farm venting (possibly from somewhere around CH4 condenser)
9:48 GSE vent between subcooler and large detanked CH4 buffer
9:53 CH4 subcooler vent until 10:06
10:18 Venting from behind bunker (LN2 vaporizer? or/and LOX coolers?), SoLS tank farm ground vent spotted, some more vents from SoLS tanks
10:22 CH4 subcooler started again
10:25 White car left
10:51 OLM venting from below QD pipes, decreased a bit in intensity at 10:56, increased a lot again at 11:01
10:54 Black car left, pad definitively clear
11:04 SoLS tank farm venting stopped
11:18 Venting from behind tank farm (LOX subcooler area) decreased
11:33 Vent from GSE equipment between GSE2 and GSE7
11:54 Lot of venting north of tank farm
12:11 OLM vent decreased a lot and stopped a minute later
12:15 OLM vent again for less than a minute, started at 12:17 again, stopped at 12:24 nearly completely
12:30 Cryo loading began (venting from one of the two big QD fueling pipes), venting right to the QD plate; venting from below of OLM started soon after
12:40 Condensation started on bottom of B4 LOX tank, soon getting frosty
12:45 Lot of venting from below OLM
12:48 OLM lower QD vent started again
13:04 B4 venting
13:20 LOX tank frost about half a ring high, CH4 tank condensation is currently forming
13:28 CH4 tank condensation/frost 1.5-2 rings high
13:30 CH4 tank frost reached 2 rings, began to decrease
13:38 Tank farm venting increased from several areas (CH4 subcooleers, GSE bunker area/buffer tanks)
13:46 CH4 subcooler and OLM venting decreased
14:00 CH4tank condensation nearly fully disappeared, LOX at a high
14:32 Tank farm venting decreased a lot
14:47 OLM venting from below decreased a lot again
14:52 OLM lower QD vent depressing for 2 minutes, CH4 tank fwd dome vent a bit later
12:53 B4 depress vents continued both near fwd and common dome. common dome vent facing downward! (ullage thrust?), fwd dome vent in 4 directions; depress continued several minutes
15:00 Venting from QD line nearly fully disappeared
15:10 GSE1 outer pipe venting increased, LOX tank frost disappeared
15:16 Cars to pad
15:17 Road opened
15:21 Vertical LN2 tank near bunker began venting
15:41 Vertical CH4 condenser tank venting started
16:15 Venting on OLS tank farm nearly fully disappeared (some venting on GSE1 tank pipe continued, as well as puffs from below OLM)

20 December 2021 - Scrubbed Testing[]

Timeline according to LabPadre and NSF streams:

08:55 Sheriff at road block
09:13 Soft closure
09:33 Pad announcement: "Attention on the pad, all personal exit the pad now, we are closing the pad for B4 cryo proof"
09:48 Road closed
10:05 Satellite dish lowered, most cars left
10:10 or earlier: Venting spotted at OLS tank farm from the filling lines north of GSE tanks
12:20 LOX subcoolers getting frosty, some venting?
13:37 Pad clear
14:22 Road opened
14:31 Vertical LN2 tank venting started

Started to load, actuator on the valves on the LOX site might not have worked; they worked on it during the night [according to LabPadre stream].

21 December 2021 - Cryo Proof Testing #2a and #2b[]

During this test, after some tank farm activity, testing was interrupted for some inspection or work on the OLM. After that, SpaceX likely did a systems check on the OLS and B4 with what appeared to be two cryo proof cycles. Interesting: Vent between GSE2 and GSE7 has two forms: constant boil-off vs fast upward pressure relief with hissing noise.

Timeline according to LabPadre and NSF streams:

08:40 Sheriff at road block
08:50 Pad announcement
08:53 Minor GSE fill line venting spotted
08:56 Soft closure?
09:42 Road closed
09:53 or earlier: Venting from between GSE2 and GSE7 [noises started at 09:48 on Rover 2.0]
10:05 or so: Pad cleared [10:09 last cars arrived Sentinel]
11:01 Venting between GSE2 and GSE7 stopped
11:09 LOX subcoolers ("hippos") started to vent
11:17 Minor GSE fill line venting started again
11:21 Venting from south of OLS tank farm berm/near GSE bunker
11:30 Venting between GSE2 and GSE7 started again
11:32 Venting from between CH4 subcooler and CH4 buffer (only sporadically)
11:33 CH4 suboolers venting (only sporadically)
12:06 Venting between GSEs stopped; other two continued sporadically; LOX subcoolers vent continuously
12:04 Sporadical venting from vertical LN2 tank
12:08 GSE fill line venting started again
12:09 Cars to pad
12:27 Venting on vertical LN2 tank increased
12:30 Man lift near OLM; later workers spotted on OLM
12:55 Last workers climbing down OLM; LOX subcoolers venting during whole time
13:02 Pad cleared; full frost on LOX sub coolers shown [Rover]
13:09 OLM vent started and picked up quickly (the one below QD pipes)
13:11 Venting from CH4 subcooler started again sporadically
13:14:55 OLM vent increased a lot
13:21 OLM vent decreased
13:27 OLM vent increased again; increased a lot until 13:35
13:40 OLM vent stopped abruptly
13:42/43 "Fuel load" venting/condensation from one of the fill lines of the QD
13;45-13:50 Venting from below OLM (likely from the center engines, some release valve?) increased
13:57 OLM vent started again
14:00 B4 vent?
14:02 OLM vent decreased; LOX tank frost starting slowly
14:03 Venting from between CH4 buffer and subcoolers started again
14:05 Engine vents have increased a lot
14:06 LOX subcooler area venting decreased significantly
14:11 CH4 subcoolers started again
14:20 Condensation on CH4 tank started
14:25 CH4 frost two rings
14:35 CH4 tank 4 rings frost
14:38 Drone spotted
14:40 Venting from QD filling lines decreased
14:50 Frost decreased to around 3 rings
15:02 LOX tank venting (common dome, facing downwards and a bit upwards; aerocovers might not be strong enough to redirect the whole the whole vent)
15:06 LOX tank condensation started
15:08 Frost lower than one ring on CH4 tank; LOX tank vent spooled down
15:13 Short 3secs CH4 vent (fwd dome)
15:15 LOX tank one third to one half condensation (likely due to the venting); engine area vent decreased
15:17 OLM vent stopped
15:26 CH4 tank frost nearly completely gone
15:40, 15:50 Short 2sec CH4 tank vent
15:50 QD lines venting increased again; CH4 tank frost increasing again
15:55 CH4 frost remaining constant now
16:00 CH4 tank short vent
16:10 GSE1 vent from outside pipe
16:18, 21 CH4 tank short vent
16:25 CH4 tank frost increased slightly (2 rings now)
16:26, 34, 39, 44, 49 CH4 tank short vent
16:28 QD lines venting stopped
16:30 GSE1 tank vent decreased
16:34 GSE1 tank increased again
16:38 2secs LOX tank vent
16:40 QD vents venting again
16:48 CH4 tank frost 2.5 rings tall
16:50 Venting between GSE2 and GSE7 began
16:52 LOX tank downward vent started for about 1 minute
16:53 CH4 tank short vent
16:54 Short LOX and CH4 tank vents
16:56 Short LOX vent
16:59 Lot of venting from engine section; CH4 condensation (not frost) up to 4 rings
17:00 CH4 tank condensation and frost started to decrease
17:04 GSE5 (LOX tank) venting from outside pipe (!); stopped at 17:07 for about half a minute and then started again
Road closure extended to 8pm
17:07 Engine vents decreased again
17:10 CH4 tank short vent
17:15 QD line venting stopped
17:16 LOX (continuous) and CH4 (in intervals) tank vents started
17:18 LOX tank vent stopped, later CH4 tank vent as well; CH4 tank frost significantly decreased
17:19, 21, 23, 26 CH4 tank vent short
17:20 LOX tank vent about 30 secs; GSE5 vent decreased a lot and Vent between GSE2 and GSE7 stopped
17:28 LOX subcoolers started up again
17:32 Road opened
17:33 LOX subcoolers stopped venting
17:38 CH4 tank short vent
17:42 Vertical LN2 tank near GSE bunker started venting (typical finishing sign)
Timeline stopped, some minor puffs from engine area continued; CH4 tank condensation continued to decrease

The difficulty with timelines of testing at the OLS is that cameras not always point directly to the location where something is going to happen and the start of some tank farm venting is for example not shown on any camera view. Therefore, the time indications are often estimates.

22 December 2021 - Cryo proof testing #3[]

Testing yesterday took longer to spool up. Today, frost appeared much earlier in the timeline. While during yesterdays testing the tanks were only partially filled, today, the LOX tank was fully filled. Timeline according to LabPadre and NSF streams:

07:00 or earlier: Vertical LN2 vent began
07:47 GSE1 tank vent began
07:59 Pad announcement "Attention on the pad, pad clear in 1 hour"
08:34 GSE1 tank vent decreased a lot
08:42 or earlier: Road closed
09:08 Pad cleared
09:10 Or so: GSE filling lines vent
09:28 Horizontal CH4 buffer tank venting began very slightly
09:36 LOX subcooler area started venting
09:42 OLM lower QD vent started, picked up over time
09:50 CH4 subcooler venting started
09:56-57 OLM lower QD vent decreased significantly
09:58 GSE1 tank vent stopped after having decreased a lot
09:59:45 OLM vent increased a lot again
10:09 OLM vent decreased; increased at 10:19:48 again
10:35 OLM vent stopped
10:36 QD line (north) started venting
10.38 Venting from engine section started; has increased a lot by 10:45
10:48 Venting from B4 aft section opposite of QD
10:50 Some venting from B4 aft section; condensation and frost on LOX tank started
11:00 LOX frost up to second ring
11:04 Vent between GSE7 and GSE2 started
11:22 Frost on LOX tank reached ring 6
11:27 Frost on LOX tank reached ring 7; ring 8 at 32, ring 9 at 38, ring 10 at 43, ring 11 at around 49 (slower and stagnating), ring 12 at around 54
12:03 Frost on LOX tank reached ring 14
12:05 CH4 tank condensation started; 15 rings at 08; Vent between GSE7 and GSE2 stopped
12:06 Short LOX tank (common dome) vents started
12:10 15 rings frost on LOX tank
12:11 OLM vent started; CH4 tank 6.5 rings frost
12:14 or so: short CH4 tank (fwd dome) vents started
12:16 OLM vent decreased
12:19 Frost height holding at 16 rings / 8 rings; venting from OLM QD lines decreased; Vent between GSE7 and GSE2 started again
12:22 CH4 tank frost began to decrease; continuous short CH4 tank vents, but no LOX tank vents
12:27 Vertical LN2 tank started a bit and picked up over the next minutes
12:28 Vent between GSE7 and GSE2 stopped again
12:34 OLM vent increased again, but not so much as earlier
12:43 CH4 subcoolers started again
12:46 Common dome downward vent started for some seconds, continued sporadically over next few minutes; LOX subcoolers area vent increased and extended south of berm
12:50 LOX frost started to increase towards ring 16 and QD line venting again, while CH4 frost decreased significantly
13:00 CH4 tank nearly fully disappeared
13:01 Vertical LN2 tank sporadical venting stopped
13:08 Condensation on LOX tank reached the top on the shadowy side (sunny side stayed at about 16 rings)
13:11 CH4 tank frost slowly appearing again for some minutes, later stopped at about 1 ring
13:15 QD line venting decreased a bit
13:22 or earlier CH4 subcooler vent decreased a lot
13:23 OLM vent increased a bit for a short time
13:25 LOX tank fully frosty (sun lit top a bit less)
13:31 Whistling noise
13:37 CH4 tank frost increased to 1.5 rings
13:45 Short CH4 tank vent; LOX tank frost likely on its peak, no more frost possible; GSE1 tank started
13:46 QD line venting started to pick up again, OLM vent stopped; LOX subcoolers vent stopped
15:49 Some frost on shadowy side of CH4 tank began to fall off [?]
13:54, 57: 14:00, 04, 06, 11, 19, 24, 26, 28, 30, 32, 34, 36, 38, 41, 44, 47, 51, 55, 15:00, 14, 25 Short CH4 tank vent
14:07 LOX frost at sunny side slowly began to decrease
14:15 GSE5 started venting for about one minute; LOX tank frost continued to decrease
14:17 GSE5 venting started again
14:20 QD line venting has decreased
14:36 GSE1 venting decreased
14:43 CH4 frost now clearly disappearing as well
15:01, 09, 10 Pad announcement [?] "Attention this is a test, please..."
15:05 LOX frost decreased to about one half
15:07 or so: Venting from GSE fill lines started
15:15 CH4 tank frost fully disappeared
15:55 Short venting noise
16:08 OLM vent started; engine area venting decreased
16:09 Double depress vent from both tanks in all directions (upper in intervals, lower continuous); upper stopped at 16:11, lower at 16:12
16:10 OLM vent stopped; frost on LOX tank nearly completely disappeared
16:13 GSE5 vent decrease, some more depress venting; bike motor noise
16:16 LOX subcooler area venting started
16:17 More CH4 depress
16:18 GSE5 increased venting for half a minute, then decreased again; LOX subcooler area vent decreased a bit
16:21 SpaceX cars to pad
16:22 Road opened
16:25 Vertical LN2 tank "tankenstein?" venting began
16:29 LOX subcooler vents slowly fading out

5–7 February 2022 - Lift[]

Timeline according to LabPadre discord:

09:56 B4 unhooked from LR11000X
17:08 Chopsticks moved up
18:01 B4 moved towards OLS
19:28 B4 attached to LR11000X
---
05:30 Aft hatch closed
10:28 Lift started
11:25 Installed on OLM, hold down clamps extended
14:59 Attached to booster QD on OLM
---
2:54 Detached from LR11000X

On February 8–10, Ship 20 was stacked on B4 for the Starship presentation [see: SN20/Ship 20#08-10 February 2022 - Stacking].

18 February 2022 - Cryo proof test[]

Timeline according to LabPadre (not independently verified):

05:46 Road closed
06:21 Pad cleared
06:30 Farm venting on both sides of OLS tank farm
08:20 Cryo load started
08:37 Frost formed
10:26 Frost started to form on LCH4 tank
12:10 Road opened

01 March 2022 - Cryo proof test[]

Timeline according to LabPadre (not independently verified):

08:35 PA: "Attention Starbase, Pad closure less than 1 hour."
08:56 Road closed
13:10 Chopsticks moved
14:31 Pad clear per Cameron County
15:04 Tank farm venting (LOX subcoolers, LN2 area)
15:29 Venting from OLIT spotted at a new location (first time this vent was spotted, interesting because QD arm was not in use)
15:35 OLM vent started
18:30 Frost on LOX tank
19:25 Frost on B4 methane tank, heavy venting from OLIT
00:10 Road opened

Both tanks frosted up, whole OLS tank farm active; OLIT was venting as well (although ship QD not active)LOX tank fully filled, CH4 partially, huge depress vents; loudspeaker vertical LN2 vent continued long in the morning; OLIT vented again

15 March 2022 - S20 Lift & Full stack[]

On March 15, 2022, Ship 20 was lifted onto B4 for the third time. For the second time, this operation was done by the chopsticks in a much faster process than previously.

16 March 2022 - Starship 4/20 Cryo test[]

On March 16, 2022, SpaceX conducted a cryo proof test with liquid nitrogen on the full stack. It was the first time the ship QD was active with cryogenics. B4 tanks frosted up partially and S20 tanks got condensation.

18 March 2022 - Starship 4/20 Propellant load test[]

On 18 March 2022, a propellant load test was conducted on the full stack for the first time. Unlike a cryo proof test, where only LN2 is used, here the tanks got filled with propellant (CH4/LOX). The booster 4 LOX and CH4 tanks got frosty, followed by S20 tanks, but only partially. A drone observed the test.

19 March 2022 - S20 destacked[]

On 19 March 2022, Ship 20 was destacked by the chopsticks. It was the first operation of the chopsticks during which the road remained open.

21 March 2022 - Propellant/cryo test[]

Late night test with fog and limited visibility; orbital tank farm methane side was active. Timeline according to LabPadre discord:

09:22 Road closed
10:38 Pad cleared
11:12 Cars to pad
12:00 Pad cleared again
23:27 Road opened

24 March 2022 - Lifted off OLM[]

Timeline according to LabPadre discord:

PA: "Clear the orbital launch mount for booster 4 lift"
12:00 Stabilization clamps on booster transport stand extended
13:00 Lift started off OLM
14:16 Touched down on transport stand, aligned with hold down clamps
21:29 Disconnected from LR11000X and loadspreader
22:16 Started to move away from OLS

30 June 2022 - Roll back[]

Timeline according to LabPadre discord:

11:07 B4 started to move
11:30 PA: "Attention Starbase personnel, Pad closure in 1.5 hours"
11:33 B4 left launch site
11:41 or earlier Road closed
12:38 Arrived at build site
13:18 B4 arrived at rocket garden at the place where B5 was before
13:58 Pad cleared
14:29 OLS tank farm venting (CH4 tanks vent stack)
17:23 Cars to pad
20:50 Road opened

21 March 2024 - Roll to Mega bay[]

Timeline according to LabPadre discord:

19:09 Started to roll away from rocket garden
21:14 Entered hwy 4
21:50 Entered mega bay 1

Gallery[]

Video of a gimbal test by Elon Musk:^[4]

Stacking in High Bay[]

Raptor engines being installed on B4 in high bay

Raptor engines installed on B4 in high bay

Engine section details[]

"Completing feed system for 29 Raptor rocket engines on Super Heavy Booster" [B4]

Roll out[]

B4 being rolled out to OLS by two SPMTs; launch site visible in the background; S20 in front of mid bay

Lift[]

B4 being lifted onto OLM for first fit check; visible on B4 are the 9 Raptor Center engines and the 20 outer Raptor Boost engines; on the OLM the hold down clamps are visible

B4 being lifted onto OLM by LR11350 crane for fit check

B4 being lifted onto OLM by LR11350 for fit check

B4 being lifted onto OLM for first fit check; visible on B4 are the 9 Raptor Center engines and the 20 outer Raptor Boost engines; on the OLM the hold down clamps are visible

S20 stacking[]

See: SN20#Stacking on B4

First full stack on OLM[]

S20 stacked on B4 for short fit check befor removing it again

S20 being stacked onto B4 for a first, short fit check at the orbital launch site

S20 stacked onto B4 by LR11350 crane for a short fit check

S20 stacked onto B4 for a short fit check

S20 stacked on B4 for short fit check befor removing it again

S20 being stacked onto B4 for a first, short fit check at the orbital launch site

S20 stacked onto B4 by LR11350 crane for a short fit check

S20 stacked onto B4 for a short fit check

References[]

[1] ttps://twitter.com/elonmusk/status/1505987581464367104

[2] ttps://twitter.com/elonmusk/status/1506077232342581251

[3] ttps://discord.com/channels/892037187095380008/1014696055125856337/1220576094957342850

[4] ttps://twitter.com/elonmusk/status/1472052839316963329

[1]

[2]

[3]

[4]

Booster 4 (B4)

History[]

Timeline[]

6 August 2021 - First Stack Of B4 And Ship 20 Then Destacked[]

17 December 2021 - Cryo Proof Test and OLS System Check[]

20 December 2021 - Scrubbed Testing[]

21 December 2021 - Cryo Proof Testing #2a and #2b[]

22 December 2021 - Cryo proof testing #3[]

5–7 February 2022 - Lift[]

18 February 2022 - Cryo proof test[]

01 March 2022 - Cryo proof test[]

15 March 2022 - S20 Lift & Full stack[]

16 March 2022 - Starship 4/20 Cryo test[]

18 March 2022 - Starship 4/20 Propellant load test[]

19 March 2022 - S20 destacked[]

21 March 2022 - Propellant/cryo test[]

24 March 2022 - Lifted off OLM[]

30 June 2022 - Roll back[]

21 March 2024 - Roll to Mega bay[]

Gallery[]

Stacking in High Bay[]

B4 grid fins installed in Highbay

Raptor engines being installed on B4 in high bay

Raptor engines installed on B4 in high bay

Engine section details[]

"Completing feed system for 29 Raptor rocket engines on Super Heavy Booster" [B4]

29 Raptor engines installed on B4

Roll out[]

B4 being rolled out to OLS by two SPMTs; launch site visible in the background; S20 in front of mid bay

B4 roll out to OLS; CH4 fwd dome and grid fins visible

Lift[]

B4 being lifted onto OLM by LR11350 crane for fit check

B4 being lifted onto OLM by LR11350 for fit check

B4 being lifted onto OLM for first fit check; visible on B4 are the 9 Raptor Center engines and the 20 outer Raptor Boost engines; on the OLM the hold down clamps are visible

S20 stacking[]

First full stack on OLM[]

S20 stacked on B4 for short fit check befor removing it again

S20 being stacked onto B4 for a first, short fit check at the orbital launch site

S20 stacked onto B4 by LR11350 crane for a short fit check

S20 stacked onto B4 for a short fit check

References[]