On 2023-11-17, Marcus House posted the first part of this week’s space report, covering pre-launch preparations and licensing for the second Starship test flight and other news of the week.
Failure of one or two engines out of 30 or so doesn’t significantly impact the economics but, as we saw in the shuttle, resorting to a gazillion tiles where even one could render the system unusable on subsequent flights, would impact the economics. In the case of the shuttle, it terminated the program. Are there any comparable engineering trade offs in other systems that were able to overcome the tyranny of number of failure points?
In the original presentation of the stainless steel Starship, Elon Musk said they planned to use transpiration cooling for re-entry, releasing methane through pores in the outer hull of the ship. Here is a Business Insider article from February 2019 describing the design at that time.
Not long after, he said they’d switched to ceramic tiles, as noted in this July 2019 Next Big Future article with some comments from a certain James Bowery.
I haven’t seen an authoritative statement of why they abandoned transpiration cooling.
Hey! The answer is obvious – methane is a “Global Warming Gas” (in scientific terms, a Radiatively Active Gas), much more active than harmless CO2 or even deadly water vapor. Clearly it would be unacceptable to the usual suspects in the Regulatory Regime to allow anyone to bleed methane into the atmosphere as part of a spaceship return procedure. Think about the children!