How dial-up modems used sound to talk to each other

Solar System on Instagram: "The math on this image is insane. New Horizons transmitted at 2,000 bits per second from 3 billion miles away. Slower than a 1990s dial-up modem. It took 16 months to download all the flyby data. The spacecraft had to hit a target box 100km wide, arriving within 150 seconds of schedule, after 9 years of flight. Miss it and the preloaded observation commands point at empty space. Ten days before arrival, the spacecraft crashed and went into safe mode. Engineers had 72