
Personal Observations on Reliability of Shuttle (1986) - michaelsbradley
https://history.nasa.gov/rogersrep/v2appf.htm
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flashmob
Quote "There is not enough room in the memory of the main line computers for
all the programs of ascent, descent, and payload programs in flight, so the
memory is loaded about four time from tapes, by the astronauts."

Woah. Did they do this right until 2011, or were their systems upgraded?

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joering2
I don't know that, but if it wasn't breaking at all then why would they be
upgrading solution than never failed?

Apollo 13 whole computer system had less power than the phone in your pocket;
yet that was perfectly enough to run the vehicle. Crazy times...

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flashmob
Agreed. Although in this case it would seem like it was increase on the
astronaut's workload, having to load each program from tape. Also the article
mentioned that they were using outdated software development methods and
tools, whatever they were it didn't mention.

Btw, found my answer after some googling, they were upgraded in the early 90's
then again in early 2000's [http://www.aviationtoday.com/1999/11/01/the-space-
shuttle-mo...](http://www.aviationtoday.com/1999/11/01/the-space-shuttle-
modernized/)

quote "In addition to 11 MDUs in the shuttle, MEDS has four integrated display
processors (IDPs) that contain 386DX computers and a 300-megabyte hard disc."

MDU - multiple display unit.

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pinewurst
It's interesting that (from the very interesting cited article) the processor
in each MDU, an R3000, is more powerful than all the legacy IBM 4Pis serving
as Shuttle main computers.

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questerzen
Funny, I just reread "What do you care what other people think?" yesterday.
The parallel of NASA's design process for avionics software to TDD is both
striking and revealing. People struggling with TDD could definitely benefit a
lot by thinking hard about the examples of the main engine design process and
avionics software. Thanks for posting!

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avian
Previous discussion:

[https://news.ycombinator.com/item?id=7201645](https://news.ycombinator.com/item?id=7201645)

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Kenji
> A mathematical model was made to calculate erosion. This was a model based
> not on physical understanding but on empirical curve fitting.

Very interesting point. A lot of today's "science" works like this, and it is
a deeply flawed approach.

