B4

B4
--

B4 or booster 4 is the third fully stacked Super Heavy booster. After the pathfinder BN1, the test tank BN2.1 and the prototype BN3, according to Elon Musk. Booster 4 was planned to become the first booster to fly, together with S20, on a first orbital attempt. This plan however changed with Elon Musk anouncing that a first orbital flight would involve Raptor 2 engines and that it would be with new prototypes.

## History

It has been fully stacked in the high bay and Raptor engines have been installed. On Tuesday, August 03 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 06 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 07 September, it rolled back to the launch site. On 08 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 testings 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 06 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.

Video of a gimbal test by Elon Musk:

## Old info

Elon Musk has hinted towards a roll out and first fit check on the OLM as early as Tuesday, August 03.

## Timeline

* 30 June 2021: Potential B4 fwd dome sleeve (3-ring stack with fin attachment structures and thruster holes) spotted, moved outside tent
* 02 July 2021: B4? fwd dome section and S21? aft section near each other after stacking test
* 02 July 2021: B4 "comm dome" section (4-ring stack with some small holes in it) spotted
* 03 July 2021: Common dome on sleeving stand, sleeved with 4-ring stack ("CMN Dome Stiffend[?] Barrel")
* 04 July 2021: Booster fwd dome [B4?], Starship aft skirt, S21 aft dome infront of tents
* 05 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) infront 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 5th as internal goal!
* 28 July 2021: Thurst 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 stackign (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 02 [?!]
* 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 highbay 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 goint 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, eg 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 holddown 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 acces 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**
* 01 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]
* 02 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
* 07 March 2022: QD arm moved (retracted away from B4)
* 09 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 Stoped
* 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 infront 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 vaporizor? 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 intesity 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 fuelling pipes), venting right to the QD plate; ventin 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 thurst?), 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 announcment: "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 preassure relief with hissing noise.

Timeline according to LabPadre and NSF streams:

* 08:40 Sheriff at road block
* 08:50 Pad announcment
* 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 stoped
* 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 fastly (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 walve?) 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 significantl
* 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 nowg
* 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 downwart 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 frast 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 sectoin; 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 arount 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 hight 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 appeareing 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 halft
* 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 nerly 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 08-10, 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 veryfied):

* 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 veryfied):

* 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

Main article: Starship 4/20
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

Main article: Starship 4/20
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

Main article: Starship 4/20
On 19 March 2022, Ship 20 was destacked by the chopsicks. 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 loadwpreader
* 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 ventin (CH4 tanks vent stack)
* 17:23 Cars to pad
* 20:50 Road opened

## References

1. ↑ https://twitter.com/elonmusk/status/1410327121432657929
2. ↑ https://twitter.com/elonmusk/status/1505987581464367104
3. ↑ https://twitter.com/elonmusk/status/1506077232342581251
4. ↑ https://twitter.com/elonmusk/status/1472052839316963329