SpaceX Doubles Down From Starship Failure
The loss of the Starship Mark 1 (Mk 1) prototype was, as I have written earlier, quite a setback to SpaceX's ambitions. I also predicted that it would not be catastrophic to the company or its Mars aspirations, but perhaps be a proverbial speed bump on the way to success. The CEO of SpaceX, Elon Musk, has now confirmed this to be true; work on the next Starship prototype is already underway and a slew of improvements are being introduced in this iteration.
The next prototype, originally called Mk 3 (now called SN1 or Serial Number 1) is already under construction. Musk says that the prototype would be ready for flight in 2–3 months. While I do expect that this craft would be built quickly, I do not believe that we will see it flying in 2–3 months time. As always, timelines for Musk are aspirational.
Nonetheless, the revised nomenclature “SN1” appears to imply that this prototype is indeed intended to go to orbit. This suggests that the project’s scope is wider than Mk 3 was ever intended to be. Mk 3, as you may recall, was only intended to fly as high as 20,000 meters. Even if this inference turns out to be incorrect, it is clear that SN1 will have a number of changes compared to Mark 1.
Single Weld Rings
Mark 1 was built using off-the-shelf sheets of steel that were bent into curves and manually welded at the ends to form rings. These rings were then stacked on top of each other and again welded horizontally. As we now know, the manual welds, done outside in full exposure of the elements, turned out not to be as strong as originally hoped. SN1 will solve this problem by using longer sheets of steel that are curved into a complete ring and welded at one end using an automated welder. This helps ensure the weld quality while also reducing the number of welds required to build the craft. The steel used on the craft will also be of a thinner gauge, making the rings lighter and cheaper to build.
The bulkheads of Mk 1 were bump-formed. This construction method also turned out to not be as strong as required. The new bulkheads for SN1 are built of stamped steel plates and welded together with a revised welding technique. According to Musk, this makes the bulkheads stronger but also 20% lighter.
SN1 will be moving to a direct all-electric motor-driven flight control system to control its “brakerons.” These will, unsurprisingly, be using electric motors developed at Tesla. This new control system is more fault-tolerant and lighter when compared to the prior pump-driven design.
Conformal Header Tank
The header tank in the Mk1 prototype was a simple off-the-shelf component. Mk3 was intended to have a conformal tank that would be fitted into the nose of the craft. This would ostensibly make it lighter and free up a bit more room inside the spacecraft for payloads. Musk didn’t mention if this would still be the plan for SN1, but I think it is likely the case.
Despite the loss of Mk 1, it looks like SpaceX is taking this opportunity to speed up work on Mark 3/SN1 and it looks like they intend on rolling out new technologies on this prototype more quickly than was originally intended. I do not think that we will see SN1 flying in March, but a flight in summer 2020 seems plausible. If all goes well, Starship may be orbital before 2020 is out.