The SpaceX Starship is a very big deal

[Andrew Lockley]

Poster's note: $35/kg =  $35bn/MT. Postulating that aerosols (spaceosols?) could be placed in LEO, this would be cost competitive with a sustained stratospheric SRM programme, assuming approx 10y particle life. There would also be an order of magnitude lower mass flux, so likely reduced chemistry effect. In practical terms, a higher orbit would be needed, as drag would be functionally infinite for isolated nano scale particles in LEO. However, more efficient particle designs may be possible (eg absorption-based black carbon), which have undesirable properties if used at bulk in the stratosphere. This approach could offset the cost of reaching a higher orbit. 

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The SpaceX Starship is a very big deal

 cjhandmer

31 mins ago

Part of my series on common misconceptions in space journalism.

SpaceX has been working on some variant of the Big Falcon Rocket for almost a decade, with a publicly announced architecture for three years. The target performance figures are on the Starship website, endlessly dissected on Twitter, Reddit, and NASA spaceflight forums, and there’s even a livestream of construction.

Yet none of the oft-published mainstream articles seem to capture the magnitude of the vision that Starship embodies. Starship prompts superlatives, but by the end of this post the reader will understand not only how big Starship is, but also that it’s as small as it can possibly be.

Image result for starship

Since Starship was first unveiled as BFR/BFS at the IAC in 2016, the rocket has undergone a number of design changes. Together with Elon’s rather cryptic statement that the hardest part of the Starship design process was understanding exactly what question it would answer, we have a golden opportunity to employ reasoning backwards from design to implicit requirements.

Let’s start with a quick recap of the essential numbers.

Starship is the upper stage vehicle. It has a dry mass of 200 T, a fuel/ox mass of 1200 T, and a nominal payload of 150 T. Combined with high performance methane-oxygen vacuum engines, Starship is capable of over 7 km/s of Δv, which is very important.

Starship is boosted for Earth launch by Super Heavy, which is capable of lifting Starship to about 4 km/s before returning to the launch pad.

Both stages are designed to be fully reusable, enabling both high reliability and very cheap launch cost. Indeed, the marginal cost per flight could fall to $5m or below, reducing launch costs to the neighborhood of $35/kg, or 1000x less than Shuttle.