Comment by ChuckMcM | Hacker News Reader

Comment by ChuckMcM | Hacker News Reader

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I'm not sure describing the space shuttle as 'fragile' really does it justice. The ceramic tile system was fragile, but the requirement for the tiles came from the required re-entry mass, which included carrying down a full payload bay as well as the astronauts. That was imposed on the system as a military requirement (the rumor is that the Military wanted to be able to potentially snag a satellite and return it to earth). The X-37B has significantly less mass coming down, so much less energy to dissipate, and so less heat generated. Enough less that a spray on thermal coating over titanium is sufficient (at least according to the Air & Space article I read on it).

I thought the link to the x-37c was interesting but I can't find anything that suggests it is anything more than a proposal at this point.

The space shuttle Columbia was destroyed with all hands after it was hit by some insulating foam from its own external propellant tank [1]. The noise from its launch was also a serious threat [2]. I think it is fair to call it fragile. Of course, all space launch vehicles are fragile, but for a manned vehicle the shuttle sure had tight tolerances for safe operation.

Edit: I would argue that the huge mass of the (STS) oribiter was pretty much its greatest problem, and could be largely attributed to the requirement that the whole thing must be reusable. Not only was it problematic to bring all that mass down, but consider this: the system could bring almost as much mass to orbit as the Saturn V rocket [3], but almost all that capacity was consumed by the orbiter, leaving "just" 27,500 kg for payload. Of course, that is still a huge payload capacity, and the orbiter itself could, to an extent, be considered useful payload.

[1] https://en.wikipedia.org/wiki/Space_Shuttle_Columbia_disaste...

[2] https://www.nasa.gov/mission_pages/shuttle/launch/sound-supp...

[3] The maximum takeoff weight of a space shuttle orbiter was around 109,000 kg (https://en.wikipedia.org/wiki/Space_Shuttle_orbiter#Shuttle_...) while the maximum LEO payload of the Satrurn V was around 140,000 kg (https://en.wikipedia.org/wiki/Saturn_V).

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