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Space Shuttle teleprinter reverse engineering

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Re: Space Shuttle teleprinter reverse engineering

#71

Post by walrus01 »

beerandt wrote: post #14
generj wrote: post #2

I am fascinated they used 60 pounds and a large amount of space for this teleprinter. At 30K per pound of payload that is $1.8 million per flight. Really shows how important reliable printed updates were considered. And all the flaws of the printer that were managed around - turning it off to save power and prevent it overheating with specific tones.

The thing that immediately jumped into my head is coded military use. Especially since they mention the printer being based on a military design. It's still rather obscure, if not still secret, just to what extent we were actually using the shuttles in their intended military capacity. But when designed, the military use was expected to be much much higher than what panned out. This printer would be high on the list…

> The thing that immediately jumped into my head is coded military use. Especially since they mention the printer being based on a military design.

a significant portion of the funding for the shuttle came from the USAF, and one of its capabilities (to capture and return a large satellite) was a USAF requirement. They even went as far as building an entire launch pad for it at Vandenberg, which came very close to being used.

Re: Space Shuttle teleprinter reverse engineering

#72

Post by scionthefly »

johnklos wrote: post #62
perihelions wrote: post #11

Wait, do normal printers need gravity to work? If I were to find one and flip it upside-down, would it continue functioning normally?

An Apple ImageWriter II would work, no matter what. I bet it'd work if they were printing DURING a launch.

The only competition it would have would be a Microline ML184.

Re: Space Shuttle teleprinter reverse engineering

#73

Post by tyingq »

beerandt wrote: post #64
tyingq wrote: post #18

Earlier quoted context omitted.

Here's my guess. Government bureaucracy is probably very high for anything space related. So "based on the military's AN/UGC-74" could have helped get it through approvals. It would have ticked a lot of boxes for ruggedized parts, use in harsh environments, and so on.

I don't doubt that for a second- but I'm more curious about the requirement for some kind of printout in the first place. Especially since it ultimately ended up weighing what it did. Military/ Ruggedized is a smart choice for a printer that needs to go through that environment, no matter the why. I'm more interested in what it tells us about the underlying purpose (or what it might rule out, like the part about wire…

Oh, I didn't consider that, since I was a young person then. Sticking notes, directives, etc, everywhere was just really common. So if they get a note about extra daily checks on equipment X, they print/affix the note to the equipment. Or other similar needs. There would probably be limited screens, so anything you wanted to be known to everyone, becomes a note.

Re: Space Shuttle teleprinter reverse engineering

#74

Post by jcrawfordor »

beerandt wrote: post #64
tyingq wrote: post #18

Earlier quoted context omitted.

Here's my guess. Government bureaucracy is probably very high for anything space related. So "based on the military's AN/UGC-74" could have helped get it through approvals. It would have ticked a lot of boxes for ruggedized parts, use in harsh environments, and so on.

I don't doubt that for a second- but I'm more curious about the requirement for some kind of printout in the first place. Especially since it ultimately ended up weighing what it did. Military/ Ruggedized is a smart choice for a printer that needs to go through that environment, no matter the why. I'm more interested in what it tells us about the underlying purpose (or what it might rule out, like the part about wire…

I don't think the requirement for printed output requires any appeal to military applications. They would have been exchanging navigation information with mission control over the radio. That's all mission critical and needs to be read back. Anything they got via voice they would have to write down. Getting it by text in the first place would increase reliability and reduce cockpit workload.

You also get in-flight information like weather that you'll want to write down for later reference. Teleprinter writes it for you so you can review it at your leisure.

Airliners and ships at sea have both historically used teleprinters for the same reasons, although the modern navigation computers have mostly eliminated the need.

Re: Space Shuttle teleprinter reverse engineering

#75

Post by mandevil »

beerandt wrote: post #14
generj wrote: post #2

I am fascinated they used 60 pounds and a large amount of space for this teleprinter. At 30K per pound of payload that is $1.8 million per flight. Really shows how important reliable printed updates were considered. And all the flaws of the printer that were managed around - turning it off to save power and prevent it overheating with specific tones.

The thing that immediately jumped into my head is coded military use. Especially since they mention the printer being based on a military design. It's still rather obscure, if not still secret, just to what extent we were actually using the shuttles in their intended military capacity. But when designed, the military use was expected to be much much higher than what panned out. This printer would be high on the list…

STS definitely encrypted all comms- voice, data, telemetry, and printer for the classified portions of all missions (that would be STS-51C, STS-51J, STS-27, STS-28, STS-33, STS-36, and STS-38 along with parts of STS-39 and STS-53).

My assumption is that the decryption happened upstream of the teleprinter- the teleprinter was definitely chosen because they thought it would be useful to print things for all missions, not because it provided special encryption for military purposes. When they did classified stuff everything was encrypted.

Basically, printers are really useful. They are heavy and they can break, but are tremendously useful.

Re: Space Shuttle teleprinter reverse engineering

#76

Post by throwanem »

lsllc wrote: post #66
KineticLensman wrote: post #57

Earlier quoted context omitted.

In terms of relevance, I was amused that real and contemporary fictional spacecraft both had paper printers

The question is, would the craft now need help from reaction wheels to offset the inertia from the moving print head / paper feed? Or would there need to be a special version of the printer firmware that kept track of its movement so it could always impart equal but opposite inertia?

Since a thermal printer only needs as much pressure on the platen roller as required to keep the paper registered, the roller itself could be hollow and thus carry negligible inertia. The print head could be net neutral by operating boustrophedonically, which many printers already do - both of my inkjets, for example! - and that might actually count for more, considering the possible need for some thermal mass to dissipate waste heat from the printing elements. (I don't think modern thermal printers need that, but I suppose in the 80s they might have.) Worst case, the firmware might need to ensure the number of head passes is even, I think most simply by counting print passes and if needed performing a final "return" pass with a cold head - again a common behavior, and one also displayed by both my inkjets since that avoids the need for a parking station on either side of the paper path.

The line printer with its heavy drum would probably be more of a concern for the Shuttle, although I doubt a significant one. Reaction wheels function by change in angular momentum, and a line printer drum spins at a fixed rate in operation; as long as spinup and spindown take about the same time, which is easy enough to achieve, the net effect on attitude should be negligible, especially considering the entire printer constitutes only about 1/3000 of the orbiter's dry mass.

You might not want to run the thing during an OMS burn, but even if you did I doubt it'd matter; assuming constant thrust from spinup through spindown, your course would be displaced proportionally to the length of the print job, but given the minimal relative inertia and that line printers typically output in the tens of hundreds of lines per second I think it'd need quite a long job to make a noticeable difference, and you'd almost certainly run out of paper long before.

(Don't take any of this too seriously; I'm the wrong kind of engineer to give authoritative answers here, but the question is fun to think about anyway.)

Re: Space Shuttle teleprinter reverse engineering

#77

Post by omoikane »

bagels wrote: post #34
ghosty141 wrote: post #7

Earlier quoted context omitted.

Yeah somebody should mirror it. In general I dont understand why people post things like this on X. Its a horrible platform.

What are some better alternatives?

Current best answer seem to be Mastodon and Bluesky.

If we are going by the number of users, Facebook has more users than Twitter and Threads has about the same order of magnitude, but we still see a lot more Twitter submissions to HN compared to Facebook and Threads[1].

If users prefer the microblog format, Mastodon and Bluesky appear to be the most compelling alternatives, both have been steadily gaining users[2].

[1] Submissions from various sites:

https://news.ycombinator.com/from?site=twitter.com

https://news.ycombinator.com/from?site=threads.net

https://news.ycombinator.com/from?site=facebook.com

https://news.ycombinator.com/from?site=bsky.app

Not sure how we can find the number of Mastodon links since it has so many domains.

[2] Mastodon and Bluesky user counts:

https://mastodon.social/@mastodonusercount/11213120632905851...

https://bsky.app/profile/bsky.app/post/3klzrudt4uk2z

https://bsky.app/profile/bsky.app/post/3kkv3clm3su2h

Re: Space Shuttle teleprinter reverse engineering

#78

Post by lsllc »

throwanem wrote: post #76
lsllc wrote: post #66

Earlier quoted context omitted.

The question is, would the craft now need help from reaction wheels to offset the inertia from the moving print head / paper feed? Or would there need to be a special version of the printer firmware that kept track of its movement so it could always impart equal but opposite inertia?

Since a thermal printer only needs as much pressure on the platen roller as required to keep the paper registered, the roller itself could be hollow and thus carry negligible inertia. The print head could be net neutral by operating boustrophedonically, which many printers already do - both of my inkjets, for example! - and that might actually count for more, considering the possible need for some thermal mass to dis…

"boustrophedonically": now there's a word you don't get to use very often (possibly unless you're Indiana Jones). That's got to be worth something in Scrabble!

Re: Space Shuttle teleprinter reverse engineering

#79

Post by fragmede »

kens wrote: post #36
ghosty141 wrote: post #7

Earlier quoted context omitted.

Yeah somebody should mirror it. In general I dont understand why people post things like this on X. Its a horrible platform.

Serious answer: I post things on Twitter because it is easy, lets a huge number of people read my thread, and provides easy interaction. I post the same threads to Mastodon and get orders of magnitude less interest. I also write blog posts, which take a huge amount of time (a week versus an hour) and are hit-or-miss. Sometimes they are very popular and sometimes they disappear without a trace.

Why not Threads?

Re: Space Shuttle teleprinter reverse engineering

#80

Post by throwanem »

throwanem wrote: post #76
lsllc wrote: post #66

Earlier quoted context omitted.

The question is, would the craft now need help from reaction wheels to offset the inertia from the moving print head / paper feed? Or would there need to be a special version of the printer firmware that kept track of its movement so it could always impart equal but opposite inertia?

Since a thermal printer only needs as much pressure on the platen roller as required to keep the paper registered, the roller itself could be hollow and thus carry negligible inertia. The print head could be net neutral by operating boustrophedonically, which many printers already do - both of my inkjets, for example! - and that might actually count for more, considering the possible need for some thermal mass to dis…

Tens to hundreds of lines per minute, not second. Good grief, line printers are scary enough as is, without also feeding paper fast enough to start friction fires...
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