Hacker News Reader

Comment by adt2bt | Hacker News Reader

Think of the word ‘reusable’ in this case as less a binary descriptor but more of a scale of reusability.

Yes, both systems are reusable, but there are key differences in the refurbishment of the systems that partly explains the cost difference. It took more labor, resources and time to refurbish the shuttle. Also consider rapid reusability was a stretch goal when it was being designed, but we have come a loooong way since, spacex in particular has had it as a driving competitive differentiator for years now.

Another big difference is that NASA post Cold War was a skilled jobs program, with an incentive to do distributed, high overhead work to appease their bosses (congress), while SpaceX has the opposite.

View on HN

> Yes, both systems are reusable, but there are key differences in the refurbishment of the systems that partly explains the cost difference. It took more labor, resources and time to refurbish the shuttle.

Starship uses essentially the same ceramic heat shield tiles as the Space Shuttle, so the fact the Shuttle had so much trouble with refurbishment doesn't mean that SpaceX has solved these refurbishment issues with the Starship upper stage.

Though the Starship lower stage, which contains the most expensive engines, doesn't have this problem. Since it doesn't need a heat shield. So partial reusability should be pretty realistic.

Shuttle's tiles were each unique. Starship is mostly clad with identical hexagonal tiles which can be mass produced and eventually refurbished by machine. A robot already welds on the tile fittings.

That was 24,300 unique parts rather than 1!

Now that's an exaggeration

More of an ignorant assumption. I asked ChatGPT now, and got this:

> In terms of shapes, the tiles were not uniform. In fact, there were over 17,000 different shapes used to fit specific areas of the shuttle's body. Each tile had to be individually manufactured and shaped to fit a precise location due to the complex curvature of the shuttle's surface. The unique shapes were necessary to ensure that every part of the shuttle received the proper protection against the extreme temperatures during re-entry.

Please don't cite LLMs for factual questions. They are prone to confabulation. Why not type the question "How many heat shield tiles did the Space Shuttle use?" into Google?

https://www.google.com/search?client=firefox-b&sca_esv=11e08...

This gives a direct answer (24,300) while citing a NASA source.

Since I mentioned I got the info from ChatGPT, people can decide for themselves how much they trust it.

Note that the question here is how many uniquely shaped tiles there was, not the total number.

This is interesting because if you have to manufacture and keep in stock 17,000 separate tile shapes, that will be vastly more expensive than SpaceX who, from what I hear, only uses a singe hex shaped tile everywhere.

SpaceX uses several different shapes for the nose and areas on and around the flap.

The tiles are very similar; the attachment system is very different (a big part of why Shuttle's were a pain to maintain) and Starship's simple shape means most of the tiles are the same (the ridiculous number of SKUs was another factor in Shuttle TPS costs).

Reply on news.ycombinator.com