The key elements of the Starship Orbital Launch Pad are in place as the clarity of launch approaches

With Starship’s maiden flight approaching, Orbital Launch Pad A in Starbase, Texas, is being built to be ready for launch. Over a year of construction has brought the complex‚Äôs various elements to the brink of launch the most powerful rocket in history.

Timeline for collection

SpaceX started construction of the orbital launch pad on June 22, 2020, when teams began installing the concrete reinforcement bar for the six pillars of the orbital launch pad. After building reinforcing bars for reinforcement, a steel cylinder was muffled over the reinforcing bars, and each column was filled with concrete, covered and then allowed to harden.

When the columns were finished, there was not much progress on the Orbital Launch Pad (OLP) as the focus shifted to flying the SN8 and SN9 vehicles. While the test campaigns for SN9, SN10 and SN11 took place, SpaceX started working on OLP again by starting to lay the foundation for the tank farm and the associated GSE bunkers. Teams also began the installation of pipes for the tank farm.

An important milestone was reached on April 5, 2021, when GSE tank 1 was rolled out and then lifted up on its holder in the tank farm 3 days later.

So, during SN15’s test campaign, the construction work on OLP increased because SpaceX was reaching a point in the program where they had to test the entire stack and not just the ship. During this wave, GSE 2 was rolled out on April 19 and lifted up into its place in the tank farm.

On the same day, at the same time as the GSE tanks began to be installed, the foundation for the integration tower was built and the tower’s first steel column was added to the foundation. Eventually, the earth ridge between the landing site and the tank farm was being built before SN15 made its historic flight.

After the SN15 was restored and moved back to the construction site, SpaceX moved the pace up into yet another gear and quickly began building the OLP. Construction of the catch arms and Quick Disconnect arm began on the landing pad.

SpaceX leased the LR11350 with the name “Franken Crane” (FC) from employees due to its inconsistent color parts. This crane was then used to stack the Integration Tower using prefabricated truss sections built at the fuel production site. The first prefabricated section was lifted up on the tower on May 24th.

While the tower was being stacked, the first two pillar extensions were installed on May 31, and support beams were installed shortly thereafter on the foundations of the orbital launch mount in preparation for receiving the launch pad. On May 29, the first cryo shell rolled out to the launch pad. This shell was built to be the water tank for the water damping system. A GSE tank would not be sleeved until August 5, when Shell 1 was sleeved over GSE 5.

Another major milestone in construction was achieved when the Integration Tower’s roof section was installed on 28 July.

On July 31, when the tower was fully stacked, FC along with the LR11000 otherwise known as “Bucky” made a tandem lift of the Orbital Launch Table on the launch pad, and teams welded it into place. The roll-out and assembly of the launch table came after several months of work on the construction site.

Then, just three days after installing the launch pad, the SpaceX B4 rolled out and then 2 days later the S20 for alignment checks with the launch pad and booster space. After the alignment check was completed, the B4 was then taken off the OLP and rolled back to the construction site to be completed.

Ship 20 stacked on Booster 4 at OLP for fit check – via Jack Beyer for NSF

SpaceX then continued work on the OLP by starting to add pipes and wire to the integration tower, the orbital pad, and between the tank farm and the orbital pad. While all the necessary tubing was installed, the booster quick switch was installed on the launch pad on 26 August and the QD arm was installed on the integration tower on 29 August. On September 22, SpaceX tested the cryo GSE 5 on the tank farm.

After months of construction and speculation about how Mechazilla will work, we set up the collection system for installation. On October 6, the FC Wagon lifted up on the tool, which was designed to assemble the entire system on the ground before installation on the tower. On October 9, the first arm was lifted into place by FC, then Bucky lifted the second arm two days later.

LOX was first seen loaded into the tank farm on October 17th. The last Cryo shell was sleeved over GSE 2 on October 19, thus completing all the GSE tanks and grenades. The catching system was finally installed on the integration tower on October 20th.

The “chopsticks” catch arms are raised for mounting on the integration tower – via Mary (@bocachicagal) for NSF

Tank Farm

The tank facility consists of one water tank and seven tanks for other raw materials. There are three LOX (Liquid Oxygen) tanks, two CH4 (Liquid Methane) tanks and two LN2 (Liquid Nitrogen) tanks. There are also two horizontal CH4 tanks next to the main tank farm; their exact size is not known.

The water tank is just a large cylinder made up of stainless steel rings. The other seven tanks are double-walled with insulation between them, as they have to keep liquids at cryogenic temperatures. The inner tanks are built almost in the same way as SpaceX manufactures their 9 meter diameter ship and booster tanks using 304L stainless steel rollers. These tanks must be able to withstand constant pressure and pressure relief during their lifetime, so they have extra reinforcement.

The outer shells, which are 12 meters wide, are made of stainless steel rings and painted white for thermal and corrosion protection. To insulate the inner tanks and keep the cryogenic liquids at just below the boiling point, fill the space between tank and shell with Perlite insulation. Perlite insulation is an inorganic material that has amazing thermal properties and does not support combustion.

Orbital launch site with tank farm visible to right – via Mary (@bocachicagal) for NSF

(The following figures are approximate calculations based on observations and current knowledge of how the tanks are built.)

The water tank has a capacity of about 1,000,000 liters of water. For reference, the water tower on the Kennedy Space Center’s LC-39A has a capacity of 300,000 gallons.

Each LOX tank has a volume of ~ 1,450 cubic meters and can hold ~ 1,650 tons of liquid oxygen for a total of ~ 4,950 tons of oxidant. Each CH4 tank has a volume of about ~ 1,680 cubic meters and can hold about ~ 710 tons of liquid methane for a total of ~ 1,420 tons of fuel. Finally, the LN2 tanks have a volume of ~ 1,680 cubic meters each and can hold about ~ 1,350 tons of liquid nitrogen for a total of ~ 2,710 tons.

So far, the orbital tank farm can store about ~ 4,950 tons of LOX, ~ 1,420 metric tons of CH4 and ~ 2,710 tons of LN2. The entire rocket needs about ~ 1,040 tons of CH4 (~ 780 on the booster, ~ 260 on the Starship) and ~ 3,760 metric tons of LOX (~ 2,820 on the booster and ~ 940 on the Starship). With these rough estimates, the orbital tank farm has enough propellant for only one orbital launch with margin left for a possible recycling.

The approximately 2,710 tons of liquid nitrogen allows SpaceX to cryo test a booster fully.

The propellants in these tanks will flow through subcoolers adjacent to the tank farm to supercool the propellants. These subcoolers use the temperature of liquid nitrogen to cool the propellants so that they are denser and thus pack more energy into the vehicle. After driving through the subcoolers, the propellants will be sent through the GSE bunker and then to the Launch Table and Integration Tower.

Start Mount

The launch pad is the place where the full Starship stack will sit before launch. It must be able to withstand a thrust of at least 74.4 MN (based on the booster configuration of the 33 Raptor 2 engine). The bracket includes important components such as the hold-down clamps, quick disconnect to the booster and the water flood system for sound attenuation.

The launch pad has 20 separate hold-down clamps that attach to the bottom of the booster for static fires and launches from the orbital pad. During launches, these hold-down terminals will be triggered when all the motors on the booster have nominal pressure.

The Orbital Launch Mount – via Mary (@bocachicagal) for NSF

To provide fuel to the booster before departure, the firing table must have a quick disconnect mount, which is on top of the table and will disconnect the booster around T-0. QD will help supply the booster with CH4, LOX and Helium, as well as supply external power before launch.

The river system will spray water on the bottom of the launch pad and on the ground to help reduce the sound waves from 29 and eventually 33 birds of prey shooting at full speed so the sound waves do not damage the rocket or pad.

Integration Tower (Mechazilla)

The integration tower will have a unique piece of hardware. Mechazilla, as named by Elon Musk, should be 145 meters high when completed, and it has the task of not only stacking the booster and Starship, but also capturing them when they land. Mechazilla will do this using two arms, which will lift / catch the booster from hard points between the grid fins, and the starship will be lifted / caught from hard points just below the front flaps.

The first booster capture attempt is not expected until at the earliest flight of Booster 5. Starship catches have also been suggested, but whether this will actually be attempted is less clear.

The arms are attached to a carriage that connects to the tower on the column just below the pulley at the top of the tower and wraps around to the two side columns for extra support. To be able to move easily up and down the tower, there are bearing skates to which the trolley is attached on the sides of each pillar at the top and bottom.

Integration tower with grab arms and QD arm visible – via Mary (@bocachicagal) for NSF

This carriage section will be attached to the pulley at the top via a cable that goes down into the tower and connects to a winch at the southern base of the tower and a coil at the western base of the tower. The game will be used to pull and push the arms up and down the tower so they can catch and pick up the booster and the ship. The arms themselves will be activated by a linear hydraulic actuator.

To ensure that the tower places the booster and the ship in the correct position, the catch arms will have tracks on the top so that the vehicle can be translated to the correct position.

The QD arm, like the booster QD, will supply the ship with CH4, LOX, Helium and external power before launching. The QD arm has a single activation point which is connected to the tower and allows the arm to move during launch and capture operations. The extension has a claw setup similar to the top of the Falcon 9 strongback. This claw setup is coupled to the booster for stabilization.

Work is still underway to complete the OLP to a level suitable for launch operations, but key elements are in place to support a maiden flight with Starship within the next year or so, pending vehicle readiness and regulatory approvals.

Assistance for this article was provided by NSF (L2 Level) Discord.

(Lead photo: SpaceX launch site in Starbase, Texas – via Mary (@bocachicagal) for NSF)

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