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.
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Decoding James Webb Space Telescope
71–80 of 98 posts
Re: Decoding James Webb Space Telescope
#72Earlier quoted context omitted.
"Torpedo in the water!" would probably be sufficient.
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.
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?
Re: Decoding James Webb Space Telescope
#73Earlier quoted context omitted.
About six months. 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…
(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 And so, the JWST is still considered near earth and can't use the deep space bands. https://deepspace.jpl…
why is the exact frequency used important? what's different about near space bands versus deep space? they look arbitrary to my idiot eyes.
(I'm asking why the band used is significant in any way)
Re: Decoding James Webb Space Telescope
#74I'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.
The instruments aren't really high bandwidth. If you take NIRCam as an example, it's 40 megapixels with an observation time per image that is from 4 minutes up to 3 hours.
Only the NIRcam has that many pixels, the other instruments have far fewer I believe.
They will make up for the smaller numbers of pixels per (long) exposure by running the thing constantly.
Check out the sort of images they produced with the 128x128 pixel sensor on spitzer: https://upload.wikimedia.org/wikipedia/commons/a/a5/Andromed...
Re: Decoding James Webb Space Telescope
#75Earlier quoted context omitted.
This is just the telemetry data. They deployed the high data rate antenna yesterday which can do many GB per day.
And to tag on, there's even a 6-second 4K video of that deployment step: https://svs.gsfc.nasa.gov/vis/a020000/a020300/a020339/WEBB_H... That's from this link: https://www.jwst.nasa.gov/content/webbLaunch/deploymentExplo... I feel so spoiled that NASA provides video clips of each specific deployment step.
I would feel more spoiled if it were actual video from the spacecraft.
Re: Decoding James Webb Space Telescope
#76I'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.
It's fairly typical for the S/L-band telemetry and command and control antenna (omnidirectional, in case of pointing/station keeping error) on a satellite to be a very low data rate, and narrow channel. The narrower the channel is, the easier it is to pick it out of noise, and aim medium sized earth station dishes at it.
Re: Decoding James Webb Space Telescope
#77Earlier quoted context omitted.
how is that enforceable? you can't determine what the encrypted communication is.
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.
radio enthusiasts are fans of the fed?
Re: Decoding James Webb Space Telescope
#78Earlier quoted context omitted.
(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 And so, the JWST is still considered near earth and can't use the deep space bands. https://deepspace.jpl…
why is the exact frequency used important? what's different about near space bands versus deep space? they look arbitrary to my idiot eyes. (I'm asking why the band used is significant in any way)
It's not a technical restriction, it's a regulatory one. Like how parts of the UHF spectrum are allocated to TV and parts to radio. They don't want near earth communication going on in the deep space band because it will swamp the weaker signal.
Re: Decoding James Webb Space Telescope
#79Earlier quoted context omitted.
why is the exact frequency used important? what's different about near space bands versus deep space? they look arbitrary to my idiot eyes. (I'm asking why the band used is significant in any way)
It's not a technical restriction, it's a regulatory one. Like how parts of the UHF spectrum are allocated to TV and parts to radio. They don't want near earth communication going on in the deep space band because it will swamp the weaker signal.
right but the bands are not far apart, and the comment I originally replied to seemed to imply that there was significance that it was in the near space category rather than deep space. like it enabled something or was important in some unmentioned way. it was the whole (unspoken) point of the comment and I'm not "in the know" enough to already know the unspoken part. I'm asking what the unspoken part is.
Re: Decoding James Webb Space Telescope
#80Earlier quoted context omitted.
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.
radio enthusiasts are fans of the fed?
They're generally very into enforcing the FCC rules, and calling the feds is one mechanism for doing that.