61–70 of 98 posts
One would wish that for budget-exponentially-overrun taxpayer-funded infrastructure, there would be open-source decoding information available.
https://www.stsci.edu/jwst/science-execution/data-analysis-t...
Earlier quoted context omitted.
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. Eve…
"It is not necessary really." Authentication of commands to satellites is very, very necessary
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.
Does anyone know offhand when we should receive the first images?
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…
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.
Earlier quoted context omitted.
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.
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…
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.
Earlier quoted context omitted.
Most of the public specifications are distributed freely by the CCSDS (Consultative Committee for Space Data Systems): https://public.ccsds.org/Publications/BlueBooks.aspx The mission-specific parameters ("managed parameters") used by any given mission are usually more tightly controlled, as are the payload specifications for each telemetry channel. > This is just telemetry data which doesn’t have much general or sci…
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…
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!
One would wish that for budget-exponentially-overrun taxpayer-funded infrastructure, there would be open-source decoding information available.
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?
Earlier quoted context omitted.
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…
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…
This was to prevent others from also getting the data and publishing before the requesting scientist.
Assuming this continues to be true, they probably wouldn't want to handle the data by publishing it to a FTP server immediately on receipt.
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.
Yes, please provide a source! Based on this [0], with the High-Gain antenna (Ka-band), they can do 3.5 Mbyte/sec (28 Mbit/sec), which is about 295 Gbyte/day. Even if only assuming 16 hours/downlink/day, that is ~200 Gbytes/day. Also, with the S-Band Medium gain antenna, JWST is capable of accomplishing true duplex communication, which means they can uplink on the S-band and simultaneously downlink on Ka-band. For ref…
In Reed-Solomon only mode, MRO can transmit about 6.6 Mbps but at typical Mars-Earth range the data rate is much lower.
Earlier quoted context omitted.
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.
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.
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.
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.
This is just the telemetry data. They deployed the high data rate antenna yesterday which can do many GB per day.
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.