Starbase Pad 1 ends an era, enters preparations for the next phase

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After 11 Flights and many tests, the booster test stand turned launch mount has reached the end of its life. Pad 1 propelled the Starship program through the early years and now moves towards the new phase of operations.

Start of Construction and First Testing

Construction on Pad 1 began around July 2020, when crews started laying the foundation for the six legs of the launch mount. The legs would then be set up and poured, and the structure would remain in place for several months until January 2021, when the crews began construction of the fluids bunker and the concrete pad for the original vertical tanks.

Just before the completion of the suborbital hops with SN15, SpaceX started the construction of the launch tower. Once the hops were completed, the landing pad was turned into a construction zone as the chopsticks and the ship’s quick disconnect arm (SQD) were built.

Initially, SpaceX was going to have two vertical Liquid Nitrogen (LN2) tanks, three vertical Liquid Oxygen (LOX) tanks, and two vertical Liquid Methane (LCH4) tanks.

Launch Mount legs getting installed Aug 29, 2020 (Credit: BocaChicaGal for NSF)

However, during certification of the tanks, it was found that the LCH4 tanks didn’t meet the Texas state fire code, and SpaceX ended up moving to horizontal tanks instead. Eventually, the setup that was settled on for early testing and flights consisted of seven horizontal methane tanks, two medium and five small tanks. A sixth small tank was placed in the tank farm but was never hooked up, even to this day.

The mount itself was built at the production site, then rolled to the launch site and installed on the legs on July 31, 2021.

Then, just six days later, SpaceX rushed to get Booster 4 and Ship 20 to the pad shortly after their construction was completed. And, on Aug 6, 2021, the first-ever starship stack can be seen next to a tower that had no chopsticks, no SQD arm, and the tank farm was nowhere near completion.

This stack was accomplished using the Liebherr LR 11350 crane, which was used to stack the launch tower.

Lift of the launch mount ring on July 31, 2021. (Credit: BocaChicaGal for NSF)

The first stack was nothing more than a photo op, as the next stack wouldn’t occur until Feb 10, 2022, using the chopsticks. This stack was used as a test for the sticks and as a backdrop for SpaceX CEO Elon Musk’s Starship Update in February of 2022. The first full-stack testing was during the third and final stack of Booster 4 and Ship 20, where two cryogenic proof tests were completed on March 16 and 18, 2022.

As for pumps and subcoolers, the early testing and launches utilized three LOX pumps and four subcoolers, while the LCH4 side had three pumps and two subcoolers. The first-ever cryogenic test completed on Pad 1(A) was on Dec 17, 2021, with Booster 4, which was followed by another two over the next few days. These tests ruined any chance SpaceX ever had to test Booster 4’s engines, as tons of foreign object debris entered the booster’s tanks and damaged the internal plumbing and the already installed Raptor engines.

As a result, the first engine testing didn’t occur until July 11, 2022, with Booster 7, which would later become infamous as the spin boom, as SpaceX attempted a spin prime with all 33 engines.

The collection of oxygen and methane gas below the mount ignited, causing a detonation; luckily, this did not lead to the entire booster exploding.

After this incident, SpaceX had breakaway hoses going from the engines to a manifold to divert the LOX engine chill away from the launch mount. These hoses would stay during the entirety of the pad’s life.

The first-ever static fire on Pad 1 occurred on Aug 9, 2022, with a single engine test from Booster 7. This would culminate in a 31-engine static fire on February 9, 2023. This was due to two engines not igniting during a 33-engine attempt. A full-duration 10-second 33 engine static fire wouldn’t occur until Aug 25, 2023, with Booster 9.

Ship 24 stacked on Booster 7 on January 10, 2023 ahead of the first Wet Dress Rehearsal (Credit: Jack Beyer for NSF)

First Few Flights

The first stack of the first set of actual flight vehicles occurred on Oct 11, 2022, with Booster 7 and Ship 24. Following a few more stacks and testing, a Wet Dress Rehearsal was completed with Booster 7 and Ship 24 on Jan 23, 2023. Following this, the stack then launched on April 20, 2023. However, the engineers hoped that the concrete-only foundation would be enough for just one launch. 

Instead, the Raptor engines on Booster 7 obliterated the fondag and superheated the groundwater below, causing a volcanic-like eruption at the base of Pad 1. During static fire testing, SpaceX realized that using fondag concrete alone would not be sufficient to protect the launch pad. So, before Flight 1, crews had already started work on the steel water plate that has been on every flight and static fire since Flight 1.

Following the concrete and dirt cloud of Flight 1, SpaceX upgraded the launch pad’s foundation and added the water-cooled steel plate. This plate shoots out high-pressure water to counteract the high-pressure exhaust of the raptor engines, which in turn dampens sound and dust, and protects the launch pad. 

Additionally, before Flight 2, SpaceX had to modify the SQD arm to accommodate the increased height from the hotstage ring, so it was moved up an additional 1.82 meters. It had already been moved up once before when the SQD plate on Ship was moved up a ring between Ship 20 and Ship 24.

Following the more successful Flight 2 of Starship, SpaceX started to add nine LN2 and LOX horizontal tanks as well as expand the number of pumps and subcoolers for the launch pad. SpaceX added two more LOX pumps and four additional subcoolers, along with one more LCH4 pump and two more subcoolers. This brought the propellant load time from 1 hour and 30 minutes to 50 minutes.

Booster 9 on the Launch Mount July 31, 2023, ahead of its first set of engine testing (Credit: Jack Beyer for NSF)

Following Flight 3 and before Flight 4, the new horizontal LOX and LN2 tanks were commissioned into the tank farm, and the vertical tanks began to be scrapped.

Flight 5 and Beyond

After Flight 4 crews began to modify the tower and the chopsticks to prepare for a booster catch. This involved adding reinforcements to the arms and larger gusset plates to the top of the tower to enhance its strength. Crews also finished destroying the vertical tanks as they were no longer needed for the tank farm.

Flight 5 was a pivotal flight for the Starship Program, as SpaceX successfully brought a Super Heavy Booster back, and the launch pad infrastructure worked perfectly, allowing teams to catch Booster 12. The catch arms would go on to catch Boosters 14 and 15, and the launch pad would even help refly both boosters on later flights. 

Booster 12 About to be caught by the tower (Credit: Max Evans for NSF)

The configuration of Pad 1during Flight 5 and all the way up to Flight 11 wouldn’t change much. There were two instances where SpaceX put a ship on the pad to conduct a static fire test because Ship 36 had decided to blow up Masseys. The two ships were Ship 37 and Ship 38. SpaceX made modifications to the pad to minimize disruptions to flight operations.

The quickest turnaround time for Pad 1 was 37 days between Flight 5 and Flight 6. Over its lifetime, Pad 1 performed 28 cryogenic proof and tanking tests, 15 spin primes, 34 static fires, six wet dress rehearsals, four aborted launch attempts, and 11 Full Stack flight tests.

In their long original configuration, the chopsticks performed over 100 lifts, which included boosters being mounted and demounted from the pad, as well as stacking and destacking of ships.

Ship 37 and Booster 16 Lifting off from Pad 1 as the exhaust scorches the BQD (Credit: Jack Beyer for NSF)

The quickest stack in its history was the second-to-last stack of Flight 2 with Ship 25, which, from leaving the transport stand to being placed on Booster 9, was 33 minutes.

After all of the testing and hardships, SpaceX will lay this pad to rest and begin the conversion to the new design, but without the lessons learned from Pad 1, that would not have been possible. Thank you for your service, Pad 1.

Featured Image: Booster 15 about to be caught by Pad 1 (Credit: BocaChicaGal for NSF)

The post Starbase Pad 1 ends an era, enters preparations for the next phase appeared first on NASASpaceFlight.com.



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