JWST Solid State Recorder

https://jwst-docs.stsci.edu/jwst-observatory-hardware/jwst-solid-state-recorder

by orzi • 4 years ago

115 39 4 years ago

jwst-docs.stsci.edu

huhtenberg• 4 years ago

... JWST will downlink data in 4-hour contacts... In one contact, JWST can transmit at least 28.6 Gbytes

This works out to 2 MB/s.

worewood• 4 years ago

Surprisingly high IMO

Shared4042• 4 years ago

I know people who live within 30 minutes of me who get less than that - and I live in a college town.

jhgb2• 4 years ago

The DSN can receive data from MRO at Mars at up to 4 megabits per second, apparently. JWST is way closer, so it should be quite a bit faster.

xupybd• 4 years ago

How does this storage hold up over time?

I'm guessing that could be one of the limiting hardware elements. There must be some redundancy in that right?

AaronFriel2• 4 years ago

Given the capacity, I would be surprised if it wasn't single-level cell NAND (larger write capacity) or redundant. From articles I could find, it was installed in the JWST in 2012[1] and developed by a company called SEAKR which produces "Solid State Recorders"[2]. Certainly doesn't look like any commercial server storage I've seen.

I imagine the contracts could be FOIAed here and specs like anticipated write capacity obtained, would be very interesting to learn about radiation hardening and redundancy for SSDs - err, solid state recorders - in space.

[1] https://www.electronicsweekly.com/news/business/information-... [2] https://www.seakr.com/our-technology/#products

bigiain• 4 years ago

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)?

formerly_proven• 4 years ago

https://www.seakr.com/wp-content/uploads/2016/08/Flash_FMC-G...

Looks like any other SSD from a few years ago, just bigger and in a metal box.

The GEN3 FMC is a 192 GByte card designed for space applications. It is a standard 6U cPCI form factor composed of 3 cards: the main controller card and two memory mezzanine cards. It supports data and control transfers via the backplane cPCI bus.

mwcremer• 4 years ago

From the previously-posted IEEE article:

68-GB solid-state drive [...] by the end of JWST’s 10-year mission life, they expect to be down to about 60 GB because of deep-space radiation and wear and tear.

https://news.ycombinator.com/item?id=32067945

https://spectrum.ieee.org/james-webb-telescope-communication...

spookthesunset• 4 years ago

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.

bXVsbGVy2• 4 years ago

Some of the software are made available here:

https://github.com/spacetelescope

The Physical Optics Propagation in PYthon (Poppy) has some neat pictures: https://poppy-optics.readthedocs.io/en/latest/

green-salt• 4 years ago

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

privong2• 4 years ago

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

privong2• 4 years ago

Like there is even a downloadable app that you use to plan & book time

If you mean the APT (Astronomer's Proposal Tool) this tool was originally developed for Hubble Space Telescope proposals, and has been in use since at least least 2008[0]. A year or two ago, I found that parts of it are written in Common Lisp[1].

[0] https://www.stsci.edu/scientific-community/software/astronom...

[1] https://apst.stsci.edu/apt/documents/documentation/apt-proje...

jes• 4 years ago

Seems likely. Decades ago I had a discussion with someone about working at STSI, and the draw for me was that I would be working in CL.

osamagirl69• 4 years ago

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/233962152_Status_of...

[2] https://www.nasa.gov/vision/universe/watchtheskies/jwst_spac...

bXVsbGVy2• 4 years ago

The JWST ICDH team delivered the SpaceWire technology – which is packaged in a digital, low power (1.5W), high speed (66Mbps) Field-Programmable Gate Array (FPGA) computer chip

The concepts of "low power" and "high speed" has changed a lot since JWST was designed.

nine_k• 4 years ago

I think you're forgetting to factor in the distance.

Say, a low-power, high-speed interface which is USB 3.2 only works via good copper cables and at distances of a few meters.

justinjlynn• 4 years ago

Indeed.Given that the design process started almost 25 years ago, I'd be more surprised if it had changed less than it has.

progbits• 4 years ago

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 cover this in so much conformal coating there is no chance of joint breaking due to vibration and thermal cycling, or what?

Btw the large square packages in the first picture look amazing.

kevin_thibedeau• 4 years ago

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

shadowofneptune• 4 years ago

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

fnordpiglet2• 4 years ago

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

I_Byte• 4 years ago

I feel this. As a first year Computer Science student at university I am currently torn between staying as CS or switching to Computer Engineering. I am really interested in the low level aspects of computers from a software perspective (OS development, assembly, compilers) but I feel my education in my area of interest won’t be complete if I don’t also understand things from a hardware perspective.

Cthulhu_• 4 years ago

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.

fest• 4 years ago

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? :)

fnordpiglet2• 4 years ago

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.

NKosmatos• 4 years ago

Nice!!! It would be interesting to read more about shielding from radiation, data protection mechanisms, redundancy, MTBF and all the rest.

bschne• 4 years ago

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?

ragingrobot• 4 years ago

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.

JWST Solid State Recorder

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