An assembly line…for rockets? It might seem like a crazy idea, but it is about to come to fruition in Boca Chica Texas. It is there that Spacex is developing a new generation of rocket to replace the groundbreaking Falcon series. This new rocket, called Starship, will have many times the payload capacity of its predecessor, and with 100% reusability, will offer vastly cheaper access to space…perhaps 10 times cheaper. But Spacex isn’t just building a new rocket, they also strive to build a whole production system, an assembly line for rockets, that allows for rapid design iteration. Getting here has been difficult, but the “assembly line” looks poised to kick into high gear this winter.
It all started over a year ago with the construction of the “Starhopper” prototype rocket, the first “Starship” test vehicle. This vehicle was essentially a proof-of-concept, performing three test hops, up to 150 meters in height. The vehicle used thick 12mm steel on its hull, and therefore was incredibly mass inefficient. Starshopper was followed by the “Mark 1” prototype late last year, a full size upper stage test vehicle using thinner and lighter 301 stainless steel. Unfortunately, the welding techniques used on Starhopper didn’t carry over well to this thinner steel, and Mark 1 was lost during pressure testing.
Undeterred, Spacex has been refining both the design of the vehicle and the production process with each successive iteration. SN1, the follow up vehicle to Mark 1, used even thinner 4mm steel and much improved welding techniques. Despite this, it too was lost during pressure testing. SN2 however, successfully demonstrated an ability to hold enough pressure for flight. SN3 was lost due to ground service equipment failure, but was the first to vehicle to feature landing legs. SN4 was further refined, featuring a methane header tank, and even lit its engines a few times. Sadly, SN4 exploded due to ground equipment failure before it could take to the skies.
Since then, Spacex has been more successful. SN5 took off and reached a height of 150 meter before landing softly on an adjacent landing pad. SN6 repeated this test with greater ease. SN7 and SN7.1 have tested out new construction methods and materials, all culminating in the latest prototype, SN8.
SN8 will be the first full-sized upper stage test vehicle since the ill-fated Mark 1…and what an improvement it is. It is significantly stronger and more robust, it is much lighter, while also being cheaper and faster to build. SN8 will attempt to fly to about 18km and perform a complex mid-air “flip” maneuver that is crucial to being able to land and reuse the rocket coming from orbit.
From there, Elon Musk’s vision of a Starship rocket factory comes into focus. SN9, which will utilize slightly revised materials and build on lessons learned from SN8, is already under construction. According to Musk’s recent tweets, the design will evolve less after SN9, with a number of Starships being built primarily to refine and improve the production methodology. In other words, beginning with SN9, the focus will be less on the rocket and more on getting the “rocket assembly line” up and running. That assembly line is already starting to churn, with SN9 under construction, SN10 a few weeks behind it, and SN11 a few weeks behind that.
Make no mistake, what is being attempted here is unprecedented on multiple levels and more failures are likely. But the technology behind Starship has come a long way in the past year. The design is maturing, and the production system is maturing alongside it, albeit a few weeks behind. The Starship factory is coming to life.