The Starship upper stage and Super Heavy booster stand on the launch pad in April 2023 ahead of the first integrated flight test for SpaceX’s Starship system. Credit: SpaceX
Rockets get all the glory and all the glamour. It’s just a fact. They’re tall, gleaming objects. They lift off from Earth standing atop columns of flame and generate thundering noise while they carry people and machines to the most distant reaches of outer space. It’s no wonder we love them.
Launch pads, however, are often overlooked even by spaceflight afficionados. Still, without a well-designed and properly constructed launch pad, rockets would never get off the ground.
When Elon Musk’s SpaceX group decided to both build and fly their massive Starship rocket from Boca Chica, Texas, one of the first things they needed to consider was how to design and build a launch pad that could handle the largest rocket humans have ever constructed in a region with a high water table that prevents digging more than a few feet below the surface.
The SpaceX team had to modify and fortify the ground below the launch pad site with more than 300,000 cubic yards of soil to bear the weight of the pad and the rocket. Once that was done, the company initiated construction of the steel-reinforced concrete Orbital Launch Mount (OLM)—a raised ring-shaped platform for the entire rocket stack to stand on, with space underneath for Starship’s 33 Raptor engines to vent their flames at ignition and during the launch. The OLM also includes enormous clamps that keep the rocket on the ground until all its engines ignite and produce enough thrust to send it spaceward.
Next to the OLM stands Starship’s tower, sometimes referred to as the Orbital Launch and Integration Tower (OLIT). The launch tower has several functions, including serving as a giant crane to help lift Starship and stack it on top of the Super Heavy Booster with two enormous movable robot “arms.” By comparison, NASA built the giant Saturn V moon rocket in the Vehicle Assembly Building (VAB) and then moved it to the launch pad atop an enormous movable transport, known as a “crawler.” SpaceX assembles the stack on the launch pad itself.
The SpaceX team hopes that in the future the arms on the tower, known as “chopsticks,” will be able to catch the Super Heavy Booster as it returns to the launch pad after each flight. The SpaceX group has not achieved this yet but remains optimistic that it will in the future. Musk himself has referred to the entire launch complex as “Mechazilla,” given its size, technical complexity, and robustness.
Critically, when SpaceX built the launch pad, engineers did not include a flame trench, also known as a flame diverter. Flame trenches have long been used in spaceflight to divert high-temperature exhaust gases away from the launch pad and tower to reduce the risk of damage to the rocket or the launch facilities. Ever the innovator, in October 2020, Musk famously tweeted “Aspiring to have no flame diverter in Boca, but this could turn out to be a mistake.” One argument for not building a flame trench in Boca Chica is that any place SpaceX landed on the Moon or even Mars would not have one either, so if SpaceX could build a rocket/launch pad that did not have or need one, they could also potentially launch from those future destinations as well.
However, this plan failed. During the first integrated Starship launch in April 2023, a downside of not incorporating a flame trench became very apparent. Although the launch was a partial success, Starship’s engines caused heavy damage to the OLM, stripping away much of its concrete and blowing the debris into the air and the surrounding area, possibly causing, or at least contributing to, the failure of several of the first stage’s Raptor engines. Huge, flying chunks of concrete were clearly seen in the video of the launch and debris was scattered over a wide area around the launch site. In addition, after the launch, the SpaceX team discovered that engine exhaust carved a deep crater below the OLM. The group quickly realized that the OLM would have to be redesigned and reconstructed.
The SpaceX team proposed, and subsequently implemented, a multi-layered, water-cooled steel plate that sits at the base of the OLM. The plate, which is perforated throughout, is deluged with a tremendous amount of water during the ignition of the engines that launch Starship from the pad, absorbing heat, sound, shockwaves, and the monstrous force of the liftoff. To date, this device has worked in practice several times and is being further reinforced given the number of planned Starship launches. SpaceX has also made other modifications to the Starship launch pad at Boca Chica based on lessons learned from the first Starship flights, most notably adding more protection to sensitive equipment.
SpaceX also wants to launch Starships from a second complex in Boca Chica and seeks to launch Starship from Cape Canaveral Space Force Station in Florida by 2026. It seems likely that any new facility will incorporate technology based on the lessons learned from the original Starship launch complex in Boca Chica.
A launch pad is analogous to the foundation under a house. Without a good foundation, the house will falter. Without a good launch pad, the rocket isn’t going anywhere. Musk and SpaceX appear to be working hard to build the best launch pad they can to help put Starship into orbit and beyond — and catch the returning first stage to boot. Given their ambitions, they are going to need it.
