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.
Decoding James Webb Space Telescope
91–98 of 98 posts
Re: Decoding James Webb Space Telescope
#92Earlier quoted context omitted.
Gonna chime in here to comment that most NASA missions (and ESA too) provide the scientific data for download free of charge, under Public Domain or CC licenses. If it's for scientific purposes, it's not just good manners, but rather a requirement to cite the proper dataset (that also gives you the bonus of citing a respected source, so it's a win-win). Thing is that many people doesn't even know where to look for! A…
> Gonna chime in here to comment that most NASA missions (and ESA too) provide the scientific data for download free of charge I thought that was the case, but it's been so long since I've been on a mission proper (Cassini, student co-op) that I didn't want to say so without basis. Thanks!
Yes, I just explore these archives as a hobby and sometimes do a bit of amateur processing on the files. There tends to be some embargo period (a few months to a couple of years) where only the mission team has access to the data, and they decide how/to whom share it. But then again, they are all scientists and willing to share knowledge 99.9% of the time -- so a fellow researcher will probably be able to get a copy of the data if they are polite and ask for it accordingly.
As I'm just "playing" with the files, I don't mind waiting a few months/years to get access to full "scientific grade" readings from incredible complex machines and systems. And if the "raw" data is not easily available, they also usually do provide processed images as part of the missions public outreach campaigns (usually the ones that are found on Wikipedia).
Re: Decoding James Webb Space Telescope
#93Re: Decoding James Webb Space Telescope
#94Does anyone know offhand when we should receive the first images?
It would be 180 to 210 days from launch. There is a lot of calibration work for the mirrors along with cooling the telescope down.
Re: Decoding James Webb Space Telescope
#95Earlier quoted context omitted.
(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.
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 falsi…
That's true but it also allows me to look for selection bias in their data.
If I see a paper claiming remarkably good predictive capabilities of (say) the performance of a basic block, and no discussion of it's flaws you bet I'm assuming they didn't test it well enough.
Re: Decoding James Webb Space Telescope
#96Anyone 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.
The protocol is called SpaceWire[0][1]. Not sure about the details of where sensors are located.
[0]: https://en.wikipedia.org/wiki/SpaceWire [1]: https://ntrs.nasa.gov/api/citations/20030025278/downloads/20...
Re: Decoding James Webb Space Telescope
#97Earlier quoted context omitted.
Embarrassing the US is high value.
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.
Schemes like that would involve not taking credit for it - just another example of US failure, not a success by China.
Re: Decoding James Webb Space Telescope
#98Earlier quoted context omitted.
"It is not necessary really." Authentication of commands to satellites is very, very necessary
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.
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?