9 ms·

Decoding James Webb Space Telescope

286 points by gaius_baltar 5y ago

gjsman-1000 5y ago
One would wish that for budget-exponentially-overrun taxpayer-funded infrastructure, there would be open-source decoding information available.
- andruby 5y ago
  I actually don’t know if they want to protect the data. I can imagine they might not want China or other countries listening in and potentially sending commands to the craft. Does anyone know if there is typically encryption on the downlink? How about uplink commands? I guess we want those to be secured so only authenticated control can send commands
  - gjsman-1000 5y ago
    There would have to be some sort of encryption or passkey or digital signature on commands, for sure. Otherwise some hobbyist in the middle of the Ocean on his yacht could be messing with the craft and taking pictures and there'd be no easy way to shut him down.
    - dylan604 5y ago
      "Torpedo in the water!" would probably be sufficient.
      - dividedbyzero 5y ago
        The US government being able to discreetly torpedo everyone everywhere within what would have to be a few minutes at most, that would be pretty pretty scary. Imagine the number of drones they'd need to have deployed and armed at all times, and the potential for abuse.
        dylan604 5y ago
        I think you might just be trying to make this threat a much bigger issue than it really is. How many people do you really think will be trying to attack the JWST?
    - manquer 5y ago
      It is not necessary really. There is unlikely any non-state actors[1] that has the ability to transmit signals to L2 . Just receiving signals even now (only 2 out of 30 days to l2) the OP used a 6 meter dish. Most of interplanetary mission signals are handled by the DSN. Any sort of encryption will add both b/w requirements and compute requirements . The CPU/network budgets on such missions are very very limited. Every bit and cycle counts. Finally standard encryption libraries, algorithms et al, are not likely suitable . I am no expert, but I have not read of any modern algorithms with very low network overhead + compute requirements designed for these kind of use cases, that is also secure from brute force or other attacks. Mission risk is also a factor, even handshake failures can jeopardize the mission. It is one thing a website did not load because of TLS negotiation failures and $10 B mission overshot its orbit because handshake failures on the encryption layer. [1] Threats from state actors for science missions is different category of concern, harder to quantify and with not much history of actual attacks. Collateral risks like from the ASAT Russian test to ISS, or in dual use missions would perhaps not apply here .Usually science teams collaborate well even if there is lot of tension in political sphere.
      - Sporktacular 5y ago
        "It is not necessary really." Authentication of commands to satellites is very, very necessary
        manquer 5y ago
        Encryption !=authentication. OP was talking about encryption. You could do authentication over plain text. For popular example http basic auth. It is not recommended for regular use cases, but is not out of realm of possibility in satelite given the constraints.
        Sporktacular 5y ago
        OP was talking about digital signatures and a hobbyist taking command of the spacecraft. In other words authentication. You said that was unnecessary and too taxing on constrained hardware. That is incorrect. Authentication is both necessary and not excessively taxing, when both considering the risk to the spacecraft's operation or even not considering it, since, as you said yourself, authentication schemes can be reasonably lightweight. "Not out of the realm of possibility in satellites" What are you talking about? Of course it isn't! Authentication to satellites is recommended and implemented all the time, for obvious reasons. You think they risk a multi million dollar investment to save some clock cycles? How many commandeered satellites do you read about daily? Do you have sources to back up any of this?
  - ixfo 5y ago
    Yes, CCSDS Magenta and Blue reference books mandate AES-256-GCM as a minimum for data encryption and mandate that encryption and authentication should be used, particularly for commands/uplink. Sliding scale of requirements based on application of course - your cubesat's imaging system is less critical than the flight termination system on a manned mission, for instance.
    - xxpor 5y ago
      Fwiw, sat c&c is the one thing you're allowed to use encryption on the Amateur radio bands for.
      - adgjlsfhk1 5y ago
        how is that enforceable? you can't determine what the encrypted communication is.
        monocasa 5y ago
        Same as anything in amateur radio. There'll be a lot of hints at what you're doing from the shape of your broadcasts, and there's a lot of amateur radio enthusiasts that'll call the feds on you if they get a hint that you aren't following the rules.
        zemb 5y ago
        radio enthusiasts are fans of the fed?
        monocasa 5y ago
        They're generally very into enforcing the FCC rules, and calling the feds is one mechanism for doing that.
        8bitsrule 5y ago
        Here's an ARRL article from 11-2016 (re the shutdown of 11 FCC field stations) which details plans and motivations. https://www.arrl.org/news/fcc-special-counsel-laura-smith-says-amateur-enforcement-will-be-aggressive https://www.arrl.org/news/fcc-special-counsel-laura-smith-sa... In a more recent post (which includes good suggestions for experimenters): > The ham bands aren’t full of whacked-out haters looking to get rid of everybody else, but hams are very accustomed to people using the bands without a license or not following the band plans, causing interference problems. https://thesilicongraybeard.blogspot.com/2020/09/a-ham-radio-series-14-self-policing.html https://thesilicongraybeard.blogspot.com/2020/09/a-ham-radio... Usually the 'self-policing' by hams (it's usually very effective) is done gently. They get that the frequencies are free of $$cost, and don't want to lose (any more of) them.
  - jcims 5y ago
    I don't have any inside information but in my experience lurking in the amateur radio community the answer is 'it depends' and there is a lot of downlink that is not encrypted. This will get you into the graph: https://twitter.com/usa_satcom https://twitter.com/usa_satcom https://twitter.com/uhf_satcom https://twitter.com/uhf_satcom https://twitter.com/r2x0t https://twitter.com/r2x0t
  - cycomanic 5y ago
    I highly suspect that China (and almost every other country) are not the issue. Chinese and the whole international scientific community will profit immensely from the data coming from James Webb, so I don't think the Chinese have any interest in sabotaging the project. More dangerous would be some average joe, somewhere who would try to mess with it for the lulz.
    - TedDoesntTalk 5y ago
      Or terrorist organizations with tech skills
    - foobiekr 5y ago
      Embarrassing the US is high value.
      - wongarsu 5y ago
        If somebody like China is caught sabotaging JWST the fallout could be immense. They would be accused of trying to hold back human progress, and I could easily imagine high profile Chinese scientists leaving the country and science institutions boycotting China. It's not worth the risk.
        leephillips 5y ago
        I also don’t think they would want to do this, but I think you’re overestimating the risk. Genocide, stealing the entire South China Sea, and threatening the sovereignty of other nations haven’t inspired such boycotts.
        adventured 5y ago
        They actually understated the risk by incorrectly assessing where it would come from. The primary risk would be that the US would hit back and attempt to sabotage something important to China (and with China's sprawling global interests now, there are a vast number of soft, highly exposed targets). The US Government can be quite vindictive depending on the context, it will hit you back if it can. The responsible agency wouldn't seek publicity for any successful sabotage, but China would know who did it and what it was for.
- colechristensen 5y ago
  This is just telemetry data which doesn’t have much general or scientific interest, i guess they could publish the protocol spec (honestly it probably is aquirable) but most of the fun for the kinds of people who want this data is going to be doing this reverse engineering themselves. The real imaging data would require a much more significant dish to even receive (i can’t immediately find what it’s going to use, but I’m guessing something like a 40 meter dish) so there are approximately zero amateurs who could use such open source information.
  - dylan604 5y ago
    Aren't they using the Deep Space Network for this?
    - jacquesm 5y ago
      Yes, all communications are routed through DSN.
  - londons_explore 5y ago
    But in a really open project, the design of the whole lot would be on the web, and the data sent back would be sitting on an FTP server somewhere for anyone to download and use. In many ways, an open project is cheaper to do than a behind-closed-doors project where every new contractor needs to get access to only the bits of the project they need access to, and misunderstandings happen because not everyone has enough of the big picture. The only bit that needs to be secret is one private key used to sign the commands sent to the satellite, just so one random Mallory can't 'steal' it.
    - semi-extrinsic 5y ago
      > the data sent back would be sitting on an FTP server somewhere for anyone to download and use I'm sure they could actually do that without too much fuss. But it would require significant amounts of scientist time to document those datasets to enable others to use them for any arbitrary dataset. I'm sure we'll see fully open data sets from JWST appear, but lots of the stuff it collects isn't going to be interesting enough that it's reasonable to spend scientist time documenting it.
- mhh__ 5y ago
  Science in general still basically operates on the "NASA invented xyz while going to the moon"-model from the 20th century. Things get developed and then trickle into industry via back-channels (or people moving) but the idea of open-source is still both culturally alien and legally suspect. Even in CS papers directly dealing with a piece of software there is no obligation to publish code.
  - ufmace 5y ago
    After seeing plenty of code and projects by people who weren't professional software engineers used to working on teams, part of the problem is likely that code written for this sort of thing often depends on a ton of dependencies and system-specific configuration bits that are documented poorly or not at all. Getting such projects to a state where a random person could git pull it and make sense of it and use it is a whole project unto itself that usually the core contributors are poorly equipped to take on. How many really understand the pain of onboarding into a poorly-documented repo and how to use the right tools to make it a smooth process?
    - Twisol 5y ago
      On top of that, missions are heavily incentivized (in an "our success depends on this" way) to solve only the problems they absolutely need to solve, due to constraints on time, budget, and manpower. It's an incredible feat to achieve what they do, but reuse and non-specialist use are non-goals.
    - mhh__ 5y ago
      (Argumentatively) I don't care. If I can't replicate your work you can't test it. If you make it clear it must be reproducible from the start and threaten to not publish if it can't be then they'll get in line - the kind of projects I'm thinking of are < 5k lines usually.
      - seoaeu 5y ago
        The only way to properly replicate a CS paper is to re-implement the code from scratch. Simply running someone's code again is most likely just going to give you the same buggy output they got (or just as likely a bunch of unrelated compile errors). But frequently, that isn't even what you want. Many CS papers are of the form "we were able to build software that does XYZ using this design", which isn't really a falsifiable statement in the first place. It just serves to give future researchers and practitioners data points they can use when building their own software
- pkaye 5y ago
  There are lots of interesting tools and information on the Space Telescope Institute website to browse through. I'm guessing you can get the decoded data as its received. https://www.stsci.edu/jwst/science-execution/data-analysis-toolbox https://www.stsci.edu/jwst/science-execution/data-analysis-t...
- stadium 5y ago
  This would certainly speed up the rate of discovery from the images and get more people interested in astronomy. Inside the project there must be an established data infrastructure running or ready to run. It probably has a raw layer and a transformed layer with well defined tabular schemas for the metadata of each image. It would be fun to see how both layers work and play around with the data. Would the instrument itself have a fixed set of metadata attributes assigned to all imaging, or is it programmable and changeable during the service life?
rodiger 5y ago
Does anyone know offhand when we should receive the first images?
- pacha-- 5y ago
  Six months if I recall correctly
- gjsman-1000 5y ago
  ~6 months. https://webbtelescope.org/quick-facts/mission-launch-quick-facts https://webbtelescope.org/quick-facts/mission-launch-quick-f...
- deleted 5y ago
  [deleted]
- shagie 5y ago
  About six months. https://webbtelescope.org/quick-facts/mission-launch-quick-facts https://webbtelescope.org/quick-facts/mission-launch-quick-f... > After reaching its orbit, Webb undergoes science and calibration testing. Then, regular science operations and images will begin to arrive, approximately six months after launch. However, it is normal to also take a series of "first light" images that may arrive slightly earlier. It will take about a month for it to get out to the Sun-Earth L2 point which is 1.5M km (0.01 AU) from the Earth. For comparison, the Moon is 384k km away. The telescope will be 4x further away from the Earth than the Moon is.
  - monocasa 5y ago
    We'll probably get the calibration images before the six months from now when regular science missions start if they go according to plan as it's great press. Also there's a chance that there's a delay on the science mission images to allow for academic publishing.
  - shagie 5y ago
    (and too late for an edit) that 1.5M km thing is moderately important when it comes to communication with the JWST. The frequencies that can be used for communicating with a satellite or space probe are governed by how far away it is. The cut off for this is 2.0M km. https://en.wikipedia.org/wiki/Deep_space_bands https://en.wikipedia.org/wiki/Deep_space_bands And so, the JWST is still considered near earth and can't use the deep space bands. https://deepspace.jpl.nasa.gov/dsndocs/810-005/201/201C.pdf https://deepspace.jpl.nasa.gov/dsndocs/810-005/201/201C.pdf
Beltiras 5y ago
I'm a bit shocked at how low bandwith was allocated. 421 Megabytes per day is the theoretical upper limit. 16 Terabytes for the entire mission. I have more bulk storage in my desktop.
- TedDoesntTalk 5y ago
  That’s insane. Where did you read that?
  - jandrese 5y ago
    It's in the article, but the OP was confused because this isn't the imaging data. It's the telemetry, things like thruster temps, gyro speeds, etc... The metadata that NASA uses to make sure the spacecraft is healthy, not the mission payload.
  - smccully 5y ago
    Astronomical Images are calculated in Hours, and I have no idea how long the average image will be for NIRCam on JWST, but your average Space Photo from Ground Telescopes is usually a combination of 5 to 15 minutes images, with a total imaging time from 10 - 40 hours.
- boardwaalk 5y ago
  This is just the telemetry data. They deployed the high data rate antenna yesterday which can do many GB per day.
  - Animats 5y ago
    Oh, good, that unfolding worked. The amount of unpacking involved as this thing deploys is insane. On the data rate thing, satellites usually have a low data rate system with omnidirectional antennas, used for command and positioning. Then they have a high data rate system with directional antennas for whatever it is they do. (The USAF used to have a strict separation between the two. This reflects the USAF's pilot-oriented mentality. The USAF is pilots, and then everybody else. The low data rate system belonged to the piloting operation, which used to be in the Blue Cube in Sunnyvale CA and is now at Schriever Space Force Base, formerly Falcon AFB, in Colorado Springs CO. They "drive the bus", managing orbital insertion and station keeping. The high data rate system belonged to the payload, and once the piloting operation had it turned on and aimed, it was turned over to the agency that owned the payload. Private satellite operators usually don't make that distinction.)
datameta 5y ago
Would be cool to see a tracker displaying the status of deployed systems and instruments.
- pocketstar 5y ago
  There is one! https://jwst.nasa.gov/content/webbLaunch/whereIsWebb.html https://jwst.nasa.gov/content/webbLaunch/whereIsWebb.html
  - datameta 5y ago
    Thanks!
AYBABTME 5y ago
Anyone knows about the internal communication of the probe? What protocol does it use to talk between components, and what's the topology? Where and how do they locate sensors such as temperature probes, etc. It'd be cool to have more details about the "build" of the probe.
- alt219 5y ago
  The protocol is called SpaceWire[0][1]. Not sure about the details of where sensors are located. [0]: https://en.wikipedia.org/wiki/SpaceWire https://en.wikipedia.org/wiki/SpaceWire [1]: https://ntrs.nasa.gov/api/citations/20030025278/downloads/20030025278.pdf https://ntrs.nasa.gov/api/citations/20030025278/downloads/20...

286 points by gaius_baltar 5y ago

One would wish that for budget-exponentially-overrun taxpayer-funded infrastructure, there would be open-source decoding information available.

andruby 5y ago
I actually don’t know if they want to protect the data. I can imagine they might not want China or other countries listening in and potentially sending commands to the craft. Does anyone know if there is typically encryption on the downlink? How about uplink commands? I guess we want those to be secured so only authenticated control can send commands
- gjsman-1000 5y ago
  There would have to be some sort of encryption or passkey or digital signature on commands, for sure. Otherwise some hobbyist in the middle of the Ocean on his yacht could be messing with the craft and taking pictures and there'd be no easy way to shut him down.
  - dylan604 5y ago
    "Torpedo in the water!" would probably be sufficient.
    - dividedbyzero 5y ago
      The US government being able to discreetly torpedo everyone everywhere within what would have to be a few minutes at most, that would be pretty pretty scary. Imagine the number of drones they'd need to have deployed and armed at all times, and the potential for abuse.
      - dylan604 5y ago
        I think you might just be trying to make this threat a much bigger issue than it really is. How many people do you really think will be trying to attack the JWST?
  - manquer 5y ago
    It is not necessary really. There is unlikely any non-state actors[1] that has the ability to transmit signals to L2 . Just receiving signals even now (only 2 out of 30 days to l2) the OP used a 6 meter dish. Most of interplanetary mission signals are handled by the DSN. Any sort of encryption will add both b/w requirements and compute requirements . The CPU/network budgets on such missions are very very limited. Every bit and cycle counts. Finally standard encryption libraries, algorithms et al, are not likely suitable . I am no expert, but I have not read of any modern algorithms with very low network overhead + compute requirements designed for these kind of use cases, that is also secure from brute force or other attacks. Mission risk is also a factor, even handshake failures can jeopardize the mission. It is one thing a website did not load because of TLS negotiation failures and $10 B mission overshot its orbit because handshake failures on the encryption layer. [1] Threats from state actors for science missions is different category of concern, harder to quantify and with not much history of actual attacks. Collateral risks like from the ASAT Russian test to ISS, or in dual use missions would perhaps not apply here .Usually science teams collaborate well even if there is lot of tension in political sphere.
    - Sporktacular 5y ago
      "It is not necessary really." Authentication of commands to satellites is very, very necessary
      - manquer 5y ago
        Encryption !=authentication. OP was talking about encryption. You could do authentication over plain text. For popular example http basic auth. It is not recommended for regular use cases, but is not out of realm of possibility in satelite given the constraints.
        Sporktacular 5y ago
        OP was talking about digital signatures and a hobbyist taking command of the spacecraft. In other words authentication. You said that was unnecessary and too taxing on constrained hardware. That is incorrect. Authentication is both necessary and not excessively taxing, when both considering the risk to the spacecraft's operation or even not considering it, since, as you said yourself, authentication schemes can be reasonably lightweight. "Not out of the realm of possibility in satellites" What are you talking about? Of course it isn't! Authentication to satellites is recommended and implemented all the time, for obvious reasons. You think they risk a multi million dollar investment to save some clock cycles? How many commandeered satellites do you read about daily? Do you have sources to back up any of this?
- ixfo 5y ago
  Yes, CCSDS Magenta and Blue reference books mandate AES-256-GCM as a minimum for data encryption and mandate that encryption and authentication should be used, particularly for commands/uplink. Sliding scale of requirements based on application of course - your cubesat's imaging system is less critical than the flight termination system on a manned mission, for instance.
  - xxpor 5y ago
    Fwiw, sat c&c is the one thing you're allowed to use encryption on the Amateur radio bands for.
    - adgjlsfhk1 5y ago
      how is that enforceable? you can't determine what the encrypted communication is.
      - monocasa 5y ago
        Same as anything in amateur radio. There'll be a lot of hints at what you're doing from the shape of your broadcasts, and there's a lot of amateur radio enthusiasts that'll call the feds on you if they get a hint that you aren't following the rules.
        zemb 5y ago
        radio enthusiasts are fans of the fed?
        monocasa 5y ago
        They're generally very into enforcing the FCC rules, and calling the feds is one mechanism for doing that.
        8bitsrule 5y ago
        Here's an ARRL article from 11-2016 (re the shutdown of 11 FCC field stations) which details plans and motivations. https://www.arrl.org/news/fcc-special-counsel-laura-smith-says-amateur-enforcement-will-be-aggressive https://www.arrl.org/news/fcc-special-counsel-laura-smith-sa... In a more recent post (which includes good suggestions for experimenters): > The ham bands aren’t full of whacked-out haters looking to get rid of everybody else, but hams are very accustomed to people using the bands without a license or not following the band plans, causing interference problems. https://thesilicongraybeard.blogspot.com/2020/09/a-ham-radio-series-14-self-policing.html https://thesilicongraybeard.blogspot.com/2020/09/a-ham-radio... Usually the 'self-policing' by hams (it's usually very effective) is done gently. They get that the frequencies are free of $$cost, and don't want to lose (any more of) them.
- jcims 5y ago
  I don't have any inside information but in my experience lurking in the amateur radio community the answer is 'it depends' and there is a lot of downlink that is not encrypted. This will get you into the graph: https://twitter.com/usa_satcom https://twitter.com/usa_satcom https://twitter.com/uhf_satcom https://twitter.com/uhf_satcom https://twitter.com/r2x0t https://twitter.com/r2x0t
- cycomanic 5y ago
  I highly suspect that China (and almost every other country) are not the issue. Chinese and the whole international scientific community will profit immensely from the data coming from James Webb, so I don't think the Chinese have any interest in sabotaging the project. More dangerous would be some average joe, somewhere who would try to mess with it for the lulz.
  - TedDoesntTalk 5y ago
    Or terrorist organizations with tech skills
  - foobiekr 5y ago
    Embarrassing the US is high value.
    - wongarsu 5y ago
      If somebody like China is caught sabotaging JWST the fallout could be immense. They would be accused of trying to hold back human progress, and I could easily imagine high profile Chinese scientists leaving the country and science institutions boycotting China. It's not worth the risk.
      - leephillips 5y ago
        I also don’t think they would want to do this, but I think you’re overestimating the risk. Genocide, stealing the entire South China Sea, and threatening the sovereignty of other nations haven’t inspired such boycotts.
        adventured 5y ago
        They actually understated the risk by incorrectly assessing where it would come from. The primary risk would be that the US would hit back and attempt to sabotage something important to China (and with China's sprawling global interests now, there are a vast number of soft, highly exposed targets). The US Government can be quite vindictive depending on the context, it will hit you back if it can. The responsible agency wouldn't seek publicity for any successful sabotage, but China would know who did it and what it was for.
colechristensen 5y ago
This is just telemetry data which doesn’t have much general or scientific interest, i guess they could publish the protocol spec (honestly it probably is aquirable) but most of the fun for the kinds of people who want this data is going to be doing this reverse engineering themselves. The real imaging data would require a much more significant dish to even receive (i can’t immediately find what it’s going to use, but I’m guessing something like a 40 meter dish) so there are approximately zero amateurs who could use such open source information.
- dylan604 5y ago
  Aren't they using the Deep Space Network for this?
  - jacquesm 5y ago
    Yes, all communications are routed through DSN.
- londons_explore 5y ago
  But in a really open project, the design of the whole lot would be on the web, and the data sent back would be sitting on an FTP server somewhere for anyone to download and use. In many ways, an open project is cheaper to do than a behind-closed-doors project where every new contractor needs to get access to only the bits of the project they need access to, and misunderstandings happen because not everyone has enough of the big picture. The only bit that needs to be secret is one private key used to sign the commands sent to the satellite, just so one random Mallory can't 'steal' it.
  - semi-extrinsic 5y ago
    > the data sent back would be sitting on an FTP server somewhere for anyone to download and use I'm sure they could actually do that without too much fuss. But it would require significant amounts of scientist time to document those datasets to enable others to use them for any arbitrary dataset. I'm sure we'll see fully open data sets from JWST appear, but lots of the stuff it collects isn't going to be interesting enough that it's reasonable to spend scientist time documenting it.
mhh__ 5y ago
Science in general still basically operates on the "NASA invented xyz while going to the moon"-model from the 20th century. Things get developed and then trickle into industry via back-channels (or people moving) but the idea of open-source is still both culturally alien and legally suspect. Even in CS papers directly dealing with a piece of software there is no obligation to publish code.
- ufmace 5y ago
  After seeing plenty of code and projects by people who weren't professional software engineers used to working on teams, part of the problem is likely that code written for this sort of thing often depends on a ton of dependencies and system-specific configuration bits that are documented poorly or not at all. Getting such projects to a state where a random person could git pull it and make sense of it and use it is a whole project unto itself that usually the core contributors are poorly equipped to take on. How many really understand the pain of onboarding into a poorly-documented repo and how to use the right tools to make it a smooth process?
  - Twisol 5y ago
    On top of that, missions are heavily incentivized (in an "our success depends on this" way) to solve only the problems they absolutely need to solve, due to constraints on time, budget, and manpower. It's an incredible feat to achieve what they do, but reuse and non-specialist use are non-goals.
  - mhh__ 5y ago
    (Argumentatively) I don't care. If I can't replicate your work you can't test it. If you make it clear it must be reproducible from the start and threaten to not publish if it can't be then they'll get in line - the kind of projects I'm thinking of are < 5k lines usually.
    - seoaeu 5y ago
      The only way to properly replicate a CS paper is to re-implement the code from scratch. Simply running someone's code again is most likely just going to give you the same buggy output they got (or just as likely a bunch of unrelated compile errors). But frequently, that isn't even what you want. Many CS papers are of the form "we were able to build software that does XYZ using this design", which isn't really a falsifiable statement in the first place. It just serves to give future researchers and practitioners data points they can use when building their own software
pkaye 5y ago
There are lots of interesting tools and information on the Space Telescope Institute website to browse through. I'm guessing you can get the decoded data as its received. https://www.stsci.edu/jwst/science-execution/data-analysis-toolbox https://www.stsci.edu/jwst/science-execution/data-analysis-t...
stadium 5y ago
This would certainly speed up the rate of discovery from the images and get more people interested in astronomy. Inside the project there must be an established data infrastructure running or ready to run. It probably has a raw layer and a transformed layer with well defined tabular schemas for the metadata of each image. It would be fun to see how both layers work and play around with the data. Would the instrument itself have a fixed set of metadata attributes assigned to all imaging, or is it programmable and changeable during the service life?

rodiger 5y ago

Does anyone know offhand when we should receive the first images?

pacha-- 5y ago
Six months if I recall correctly
gjsman-1000 5y ago
~6 months. https://webbtelescope.org/quick-facts/mission-launch-quick-facts https://webbtelescope.org/quick-facts/mission-launch-quick-f...
deleted 5y ago
[deleted]
shagie 5y ago
About six months. https://webbtelescope.org/quick-facts/mission-launch-quick-facts https://webbtelescope.org/quick-facts/mission-launch-quick-f... > After reaching its orbit, Webb undergoes science and calibration testing. Then, regular science operations and images will begin to arrive, approximately six months after launch. However, it is normal to also take a series of "first light" images that may arrive slightly earlier. It will take about a month for it to get out to the Sun-Earth L2 point which is 1.5M km (0.01 AU) from the Earth. For comparison, the Moon is 384k km away. The telescope will be 4x further away from the Earth than the Moon is.
- monocasa 5y ago
  We'll probably get the calibration images before the six months from now when regular science missions start if they go according to plan as it's great press. Also there's a chance that there's a delay on the science mission images to allow for academic publishing.
- shagie 5y ago
  (and too late for an edit) that 1.5M km thing is moderately important when it comes to communication with the JWST. The frequencies that can be used for communicating with a satellite or space probe are governed by how far away it is. The cut off for this is 2.0M km. https://en.wikipedia.org/wiki/Deep_space_bands https://en.wikipedia.org/wiki/Deep_space_bands And so, the JWST is still considered near earth and can't use the deep space bands. https://deepspace.jpl.nasa.gov/dsndocs/810-005/201/201C.pdf https://deepspace.jpl.nasa.gov/dsndocs/810-005/201/201C.pdf

Beltiras 5y ago

I'm a bit shocked at how low bandwith was allocated. 421 Megabytes per day is the theoretical upper limit. 16 Terabytes for the entire mission. I have more bulk storage in my desktop.

TedDoesntTalk 5y ago
That’s insane. Where did you read that?
- jandrese 5y ago
  It's in the article, but the OP was confused because this isn't the imaging data. It's the telemetry, things like thruster temps, gyro speeds, etc... The metadata that NASA uses to make sure the spacecraft is healthy, not the mission payload.
- smccully 5y ago
  Astronomical Images are calculated in Hours, and I have no idea how long the average image will be for NIRCam on JWST, but your average Space Photo from Ground Telescopes is usually a combination of 5 to 15 minutes images, with a total imaging time from 10 - 40 hours.
boardwaalk 5y ago
This is just the telemetry data. They deployed the high data rate antenna yesterday which can do many GB per day.
- Animats 5y ago
  Oh, good, that unfolding worked. The amount of unpacking involved as this thing deploys is insane. On the data rate thing, satellites usually have a low data rate system with omnidirectional antennas, used for command and positioning. Then they have a high data rate system with directional antennas for whatever it is they do. (The USAF used to have a strict separation between the two. This reflects the USAF's pilot-oriented mentality. The USAF is pilots, and then everybody else. The low data rate system belonged to the piloting operation, which used to be in the Blue Cube in Sunnyvale CA and is now at Schriever Space Force Base, formerly Falcon AFB, in Colorado Springs CO. They "drive the bus", managing orbital insertion and station keeping. The high data rate system belonged to the payload, and once the piloting operation had it turned on and aimed, it was turned over to the agency that owned the payload. Private satellite operators usually don't make that distinction.)

datameta 5y ago

Would be cool to see a tracker displaying the status of deployed systems and instruments.

pocketstar 5y ago
There is one! https://jwst.nasa.gov/content/webbLaunch/whereIsWebb.html https://jwst.nasa.gov/content/webbLaunch/whereIsWebb.html
- datameta 5y ago
  Thanks!

AYBABTME 5y ago

Anyone knows about the internal communication of the probe? What protocol does it use to talk between components, and what's the topology? Where and how do they locate sensors such as temperature probes, etc. It'd be cool to have more details about the "build" of the probe.

alt219 5y ago
The protocol is called SpaceWire[0][1]. Not sure about the details of where sensors are located. [0]: https://en.wikipedia.org/wiki/SpaceWire https://en.wikipedia.org/wiki/SpaceWire [1]: https://ntrs.nasa.gov/api/citations/20030025278/downloads/20030025278.pdf https://ntrs.nasa.gov/api/citations/20030025278/downloads/20...