[flagged]
Besides, everyone loves listening to his Scottish accent :D
The video is full of well edited historic footage so I don't buy your claim that text is just fine.
It's easier clicking that than making pronoun-filled replies that revolve around personal norms of commenting outside HN guidelines.
Thank you, I don't even bother to click on video links because usually the content bitrate is quite low. So I appreciate your inserting a transcript.
were more or less sitting around idle because of course business is happening during the day. So General Electric Network Internet Exchange, or Genie, was launched.
Priced at $6 per hour at night and $36 per hour during the day, Genie had all the best online games at the time and lots of sci-fi writers ended up using the service, including J. Michael Straczynski, who announced some TV show called Babylon 5 on there. And Babylon 5, one of my favorite TV shows, just celebrated its 30th anniversary of the series debuting.
Anyway, back to Apple Link and the shuttle email. On STS-43 the communications experiment was designated DTO-799, PGSD-slash-PADM Air Ground Communications Demonstration. So PGSC is the Payload General Support Computer, the aforementioned Grid Compass, and PADM was the Portable Audio Data Modem. And the modem was of course key in communication back then, right? This would be talking back to Earth. The space shuttle already had amazing communications capabilities compared to all previous space programs. It had been launching the Tracking Data and Relay Satellites, or TDRS. In fact, the primary payload on STS-43 was TDRS-5. These satellites sat out in geostationary orbit and they enabled communications with the shuttle when the shuttle didn't have a line of sight to the ground stations.
The shuttle actually supported digital communications protocols at bit rates that absolutely eclipsed the lowly dial-up connections that us earthbound plebs generally had to deal with. Like the telemetry and the voice communication, all that stuff would take up about 216 kilobits per second. But the shuttle could also send data like a real-time video as much as 50 megabits per second, so it was able to scream out data.
So yeah, there wasn't also an existing teletype communications system on board, so from the shuttle they could send up text to the teleprinter to provide written instructions and messages to the astronauts on their trip. And sometimes these printouts could be huge. They would spill out of the printer in zero-g, making for some comical sights as astronauts tried to make sense of the massive instructions flowing out of this device. So a big part of the air-to-ground communications experiment was to provide a two-way equivalent of this, and maybe one day eliminate the paper copy if it wasn't needed.
So now the question is, how do you connect a Mac to this space-age digital communication system so it can take advantage of all that bandwidth? Well, it turns out that modifying the digital communication system to support a data link to a device on the flight deck was not possible with resources they had on hand, right? So they just hooked up an old school modem, the portable audio data modem, to an audio channel. And let's be clear, the space channel communications were all digital, including the analog audio, which was converted to a digital format for transmission and then decoded and converted back to audio.
So the modem on the flight deck, it would convert the digital data on the computer to analog audio and vice versa. So the binary data on the computer was converted to an analog audio signal by the modem, fed into the shuttle's audio processor, which could convert it to a digital signal, and then beam that to the TDRS satellites, which would then send it back to the Earth at White Sands, and then that would be sent across the country on data links to the Johnson Space Center in Houston. And there, the data would be decoded, including the shuttle audio. And some lucky person at JSC could have picked up the wrong phone and, you know, sure, no doubt have listened into the modems screeching at them, right?
But anyway, according to the documents that I found, the protocol they used was V27TER, half-duplex. That's a fax protocol that uses 1200 symbols per second at 2 bits per symbol, making a total data rate of 2400 bits per second. And the half-duplex part is significant. It means that this is a one-directional transmission. And when a pair of modems share the line, only one can be transmitting while the other is receiving. And I think this may be down to the fact that shuttle audio was like a push-to-talk system, where you would push, talk, and then you would release and you would listen. And so running a modem over this had to run with the same constraints.
So, you know, you might think the obvious next step is just to plug that audio from
the shuttle into a phone line and point it at the AppleLink phone number. Well, it turns out that wouldn't work, because the servers running AppleLink's modems required full-duplex two-way communications. So instead, they connected that audio out to a Gateway Macintosh that was set up in JSC. On one side, it had a modem that was connected to the regular AppleLink services through, you know, regular phone line. And on the other side, which actually had to be connected to the printer port, because, you know, normally the modem takes the modem port, it would talk to the shuttle communications. And there was a special piece of software in there that would understand half-duplex signals, you know, tweak them around, repackage them. And on the other side, it would talk to the AppleLink services and make this whole thing possible.
So that's how it was supposed to work. But they did have a number of technical problems. The first time they tried to do this, there was some data switching system on the ground that was asleep. So they had to, like, power cycle their system decoding on the ground. The next time they tried, it failed because that hardware was still sort of in the process of waking up. Finally, the third time they hit send, it sent. And it worked and history was made. Now, an interesting side of this, on this, was that they used the standard AppleLink memo service, which was basically email. But the email addresses weren't protected in any way. So it was, they had to keep the shuttle email address secret. In fact, they registered STS-43 at AppleLink as an address so that curious people would be sending to that address rather than the actual shuttle address.
So anyway, after this flight, the Mac did fly again, but NASA elected to move the communication systems over to their tried and tested grid compass laptops. And I don't have any information on exactly how this operated beyond knowing that it used the same kind of modem. There might have been the same Mac at JSC for all I know, or they might have run their own bulletin board at NASA, right? NASA, BBS. There's very little information on this. There's a few references to the modem still being used and there's some photos of crew using it on later missions.
But I do know that by 1998, the email system was able to receive messages from the general internet because Bill Clinton sent an email to the crew of STS-95, which included Senator John Glenn. And he used a laptop that belonged to somebody that was in the right place at the right time. It wasn't a government laptop, it was like some doctor who was there and they used his AOL account to send a message to the space shuttle. And this is the first time, by the way, a sitting US president has sent an email. Bill was also the only president to attend a shuttle launch. Obama was actually supposed to see STS-134, which would include Mark Kelly, who of course is now a senator. That launch was scrubbed and Obama wasn't there when they retried again.
Incidentally, by the way, AOL also has its roots back in AppleLink because when Apple wanted to find an alternative to paying GE for their very expensive services, they approached quantum computer services, which had built a very similar online system for Commodore 64 users. From this, they produced AppleLink Personal Edition. It was launched in 1988. But because it wasn't using the GE backend, there was no way for the regular AppleLink users to interact with the AppleLink Personal users and the service didn't really go for long. The partnership was dissolved in 1989 and the service was rebranded, relaunched as America Online. So anyway, yeah, in 1998, I do know that on the shuttle, the computer that they were using now at that time to read the mail was an IBM ThinkPad running PC DOS.
And I'm not sure when they transitioned from the grid compass to the PCs, but I do know that at that point, they were still using a 2400 baud modem connection because there's a document from 1999 where NASA is looking for a replacement modem and this is part of the specification. Of course, these days, the space station has amazing communication capabilities and like the space station has Wi-Fi. Not only does it have Wi-Fi, it has Wi-Fi antennas on the outside so they can talk to space suits. And last year, there was actually a demonstration of a video link from an approaching cargo spacecraft from 600 meters away, more than half a kilometer away, they were able to get a Wi-Fi signal. And that's the kind of thing you can do when you don't have tons of other people with Wi-Fi networks clogging the airwaves.
I'm Scott Manley, fly safe.
As it stands it's not at all reader friendly .. which defeats your stated purpose.
For people who want it, transcription in SRT format is here: https://text.is/O6ZX
I also read SRT's in editors, it's a little different there to being broken up in a HN comment on a webpage on a device.