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by tjohns
3543 days ago
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Nitpicking here, but I think even most modern satellites don't use IP for their downlinks. I suspect something like X.25 is used instead for digital data, if not something even more bespoke... and many satellites still send analog data. For example, this is the protocol used for NOAA weather satellites (and actually was developed in the 60s): https://en.wikipedia.org/wiki/Automatic_picture_transmission |
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I know little about space data transmission (though I vaguely recall some good discussion around the time of the New Horizons Pluto contact), but yes, it's been a mix of analog transmissions (initially) and digital, of various descriptions. I believe there is an IP-based transmission support for the ISS, though I wouldn't swear to that.
One of the zaniest image transmission protocols was for the early Soviet lunar missions, Luna 3. Again, film cameras, an in-spacecraft photo processing lab, and a TV camera to read off the film image and transmit it back to Earth. The image quality wasn't much, but it was the first imagery of the Lunar farside ever received.
https://en.m.wikipedia.org/wiki/Luna_3
A few years back there was a story of the National Geographic lunar map timed to coincide (well, a month late) with the December, 1968, Apollo 8 mission, the first manned flight around the Moon (though without a landing). This gave us the famous Earthrise photograph, and the Christmas Day broadcast from Apollo. The story of the map, and how rapidly the Lunar far side went from terra incognito (well, luna incognito) to mapped in detail was pretty staggering. I had that map as a kid, and just figured "we knew all that". Sometimes it takes growing up to see things with childlike wonder....
The story:
http://kelsocartography.com/blog/?p=1481
http://kelsocartography.com/blog/?p=1588
(Pretty sure that's made HN at some point.)