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JWST Solid State Recorder

jwst-docs.stsci.edu

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Re: JWST Solid State Recorder

#31

Post by shadowofneptune »

progbits wrote: post #21
osamagirl69 wrote: post #10

I am sure there are better presentations out there, but this conference proceedings has some great pictures of the control systems in JWST [1] I was also able to find a high resolution picture of the spacewire interface card with its glorious space grade asic packages [2] Sadly the SSR is not shown, I assume that it is basically a gigantic sheet of sram and a fpga. [1] https://www.researchgate.net/publication/2339621…

In [2], especially on the second picture z you can see some solder joints are not consistent or perfect: convex rather than concave fillets and differing amounts of solder. Now of course it still looks better than most commercial PCBs and far ahead of anything I ever made. But I was expecting a board flying to space to be "perfect", touched up by a gray haired wizard. How come? Is this actually plenty good, do they c…

Finished modules or even whole spacecraft are tested in giant ovens to make sure there are no issues with heat.

https://m.youtube.com/watch?v=5MG9Lof1m_o

Re: JWST Solid State Recorder

#33

Post by bschne »

> If a contact is missed, science observations can continue without filling the recorder, and the ground can catch up on the next contact.

Total noob question but how exactly does this part work? It seems like if you record close to the 4h transmission limit of data between contacts it wouldn't be possible to catch up on next contacts and not fill up the recorder. Is it not possible to record that much data in the timeframe between contacts, or is there some safety margin in the transmission limit they state for this reason?

Re: JWST Solid State Recorder

#34

Post by jacquesm »

kevin_thibedeau wrote: post #28
progbits wrote: post #21

Earlier quoted context omitted.

In [2], especially on the second picture z you can see some solder joints are not consistent or perfect: convex rather than concave fillets and differing amounts of solder. Now of course it still looks better than most commercial PCBs and far ahead of anything I ever made. But I was expecting a board flying to space to be "perfect", touched up by a gray haired wizard. How come? Is this actually plenty good, do they c…

These electronics tend to be hand soldered so there is less uniformity than reflow.

I looked at both boards in detail and I highly doubt they were hand soldered.

Re: JWST Solid State Recorder

#35

Post by mschuster91 »

hoseja wrote: post #30
mcnugget wrote: post #24

Earlier quoted context omitted.

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 m…

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

> 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...

Re: JWST Solid State Recorder

#36

Post by ragingrobot »

bschne wrote: post #33

> If a contact is missed, science observations can continue without filling the recorder, and the ground can catch up on the next contact. Total noob question but how exactly does this part work? It seems like if you record close to the 4h transmission limit of data between contacts it wouldn't be possible to catch up on next contacts and not fill up the recorder. Is it not possible to record that much data in the ti…

That's assuming they get close to the contact transfer limit. A lot of theoretical numbers are stated. Now that it's in use, maybe we'll get some practical numbers. Perhaps they never will get near the contact data limit, so it's not to be a concern.

It's possible they don't "catch up" for a while, getting a few extra bits and pieces over the next several contacts, not just at the contact following that missed.

Re: JWST Solid State Recorder

#37

Post by Cthulhu_ »

fnordpiglet wrote: post #16

Reading this stuff always makes me wish I did real computer stuff.

Alas, most of us are cursed to build CRUD applications in either old but reliable tech or the latest and greatest, which will be replaced with the next latest greatest in ~5 years when the next generation of over-excited devs rocks up. Sigh.

Re: JWST Solid State Recorder

#38

Post by privong »

green-salt wrote: post #15
spookthesunset wrote: post #9

One of the interesting things about this is all the tooling created around the JWST. Like there is even a downloadable app that you use to plan & book time. Plus all the documentation, etc.

This would be really cool to plan out a look at a specific galaxy or something to personally study if its not already on another queue

The Cycle 2 General Observer proposal deadline will probably be late this year or early next year (I forget exactly when). Anyone can apply, and proposals are reviewed by scientific panels after submission.

The Cycle 1 documentation, including the now-expired Call for Proposals is here: https://jwst-docs.stsci.edu/jwst-opportunities-and-policies

Re: JWST Solid State Recorder

#39

Post by fest »

fnordpiglet wrote: post #16

Reading this stuff always makes me wish I did real computer stuff.

Why don't you? 10 years ago I was getting tired of working on php crud apps, revived my electronics hobby, practiced on small contracting jobs, landed an interesting embedded software position which then lead to my current position job at a drone company. I had to pick up some new hobbies though, after I made a job out of my hobby- maybe that's what you're afraid of? :)

Re: JWST Solid State Recorder

#40

Post by fnordpiglet »

fest wrote: post #39
fnordpiglet wrote: post #16

Reading this stuff always makes me wish I did real computer stuff.

Why don't you? 10 years ago I was getting tired of working on php crud apps, revived my electronics hobby, practiced on small contracting jobs, landed an interesting embedded software position which then lead to my current position job at a drone company. I had to pick up some new hobbies though, after I made a job out of my hobby- maybe that's what you're afraid of? :)

Mostly money. It’s not a popular answer but doing what I do I make nearly 500% more than doing what I miss doing. I’ve got family and future to save for, and I can get to my goals faster doing this stuff. The upside is that I might be able to “retire” in a few years, which to my mind is doing what you want to do regardless of the compensation. So we will see :-) I may just join you soon.
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