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0 pointsbigiain3y ago0 comments

> From articles I could find, it was installed in the JWST in 2012

I suspected something like that. I assumed there was a reason there was "only" 65GB of storage up there, when I can get a half terabyte microSD card for under $70 on PrimeDay. Lots of Moore's Law has happened in the last 10 years...

As a RaspberryPi enthusiast, I'm under no illusions about the reliability of microSD cards, but I wonder whether if they were building that data recorder today, that a huge raid 1 with perhaps 20 or 50 mirrors stored on 512GB SD cards might be able to compete on reliability and cost (including launch weight)?

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mcnugget3y ago

Bit flip probability is inversely proportional to density of the storage media so denser might have you run into issues. Also theres no point on building a recorder that's 10x larger than what you need if you're going to be limited by downlink availability. You could probably get away with all those SD cards in LEO though for a short missions, JWST falls into the category of missions where the price of that storage medium is going to be a rounding error vs the price it would incur if it randomly failed during qualification.

hoseja3y ago

It would still be better to have 10-100x in enterprise-grade storage with, say, quadruple redundancy. As Ingenuity has shown.

mschuster913y ago

> As Ingenuity has shown.

Bad comparison - Ingenuity was spec'd for five 90 seconds flights [1], JWST for up to ten years, depending on how much they have to use its rocket engines.

[1] https://en.wikipedia.org/wiki/Ingenuity_(helicopter)

[2] https://www.americanscientist.org/article/jwsts-limiting-fac...

pkaye3y ago

Another reason for the 65GB of storage is that storage is only used to buffer a day worth of transmitted data along with the previous days data till reception is confirmed.

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