7 ms·

JWST Solid State Recorder

115 points by orzi 4y ago

huhtenberg 4y 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 4y ago
  Surprisingly high IMO
  - Shared404 4y ago
    I know people who live within 30 minutes of me who get less than that - and I live in a college town.
    - jhgb 4y ago
      They didn't have a 70m sized parabolic dish, though.
      - Shared404 4y ago
        They don't, that is true. It's just highly impressive to me what we're able to accomplish when we actually focus effort on a task - including getting high-ish bandwidth back and forth between something in space.
    - semicolon_storm 4y ago
      Considering that's 2MB/s upload, I get less than that and I live in a major city with a major ISP.
  - jhgb 4y 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 4y 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?
- AaronFriel 4y 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-technology/space-nasa-recordings-deliver-images-from-the-dawn-of-time-2012-04/ https://www.electronicsweekly.com/news/business/information-... [2] https://www.seakr.com/our-technology/#products https://www.seakr.com/our-technology/#products
  - bigiain 4y 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)?
    - mcnugget 4y 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.
spookthesunset 4y 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.
- green-salt 4y 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
  - privong 4y 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 https://jwst-docs.stsci.edu/jwst-opportunities-and-policies
- bXVsbGVy 4y ago
  Some of the software are made available here: https://github.com/spacetelescope https://github.com/spacetelescope The Physical Optics Propagation in PYthon (Poppy) has some neat pictures: https://poppy-optics.readthedocs.io/en/latest/ https://poppy-optics.readthedocs.io/en/latest/
- privong 4y 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/astronomers-proposal-tool-apt/previous-apt-releases https://www.stsci.edu/scientific-community/software/astronom... [1] https://apst.stsci.edu/apt/documents/documentation/apt-project-plan-word.html https://apst.stsci.edu/apt/documents/documentation/apt-proje...
osamagirl69 4y 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_the_James_Webb_Space_Telescope_Integrated_Science_Instrument_Module_System https://www.researchgate.net/publication/233962152_Status_of... [2] https://www.nasa.gov/vision/universe/watchtheskies/jwst_spacewired.html https://www.nasa.gov/vision/universe/watchtheskies/jwst_spac...
- bXVsbGVy 4y 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 4y 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 4y 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 4y 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.
fnordpiglet 4y ago
Reading this stuff always makes me wish I did real computer stuff.
- I_Byte 4y 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_ 4y 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 4y 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? :)
  - fnordpiglet 4y 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 4y ago
Nice!!! It would be interesting to read more about shielding from radiation, data protection mechanisms, redundancy, MTBF and all the rest.
bschne 4y 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 4y 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.

115 points by orzi 4y 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 4y ago
Surprisingly high IMO
- Shared404 4y ago
  I know people who live within 30 minutes of me who get less than that - and I live in a college town.
  - jhgb 4y ago
    They didn't have a 70m sized parabolic dish, though.
    - Shared404 4y ago
      They don't, that is true. It's just highly impressive to me what we're able to accomplish when we actually focus effort on a task - including getting high-ish bandwidth back and forth between something in space.
  - semicolon_storm 4y ago
    Considering that's 2MB/s upload, I get less than that and I live in a major city with a major ISP.
- jhgb 4y 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 4y 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?

AaronFriel 4y 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-technology/space-nasa-recordings-deliver-images-from-the-dawn-of-time-2012-04/ https://www.electronicsweekly.com/news/business/information-... [2] https://www.seakr.com/our-technology/#products https://www.seakr.com/our-technology/#products
- bigiain 4y 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)?
  - mcnugget 4y 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.

spookthesunset 4y 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.

green-salt 4y 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
- privong 4y 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 https://jwst-docs.stsci.edu/jwst-opportunities-and-policies
bXVsbGVy 4y ago
Some of the software are made available here: https://github.com/spacetelescope https://github.com/spacetelescope The Physical Optics Propagation in PYthon (Poppy) has some neat pictures: https://poppy-optics.readthedocs.io/en/latest/ https://poppy-optics.readthedocs.io/en/latest/
privong 4y 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/astronomers-proposal-tool-apt/previous-apt-releases https://www.stsci.edu/scientific-community/software/astronom... [1] https://apst.stsci.edu/apt/documents/documentation/apt-project-plan-word.html https://apst.stsci.edu/apt/documents/documentation/apt-proje...

osamagirl69 4y 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_the_James_Webb_Space_Telescope_Integrated_Science_Instrument_Module_System https://www.researchgate.net/publication/233962152_Status_of... [2] https://www.nasa.gov/vision/universe/watchtheskies/jwst_spacewired.html https://www.nasa.gov/vision/universe/watchtheskies/jwst_spac...

bXVsbGVy 4y 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 4y 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 4y 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 4y 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.

fnordpiglet 4y ago

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

I_Byte 4y 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_ 4y 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 4y 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? :)
- fnordpiglet 4y 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 4y ago

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

bschne 4y 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 4y 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.