Keeping track of it all
When New Horizons passes Jupiter, it will be sending data home at 38 kbps, a little slower than most modems. When it gets to Pluto and begins gathering data, the satellite will only be able to send it back at between 300 and 600 bps. It will take almost 4.5 hr for those signals to reach Earth. At that rate, it would take 12 hr to download a single image from New Horizons' long-range imager, and nearly 40 days to send the entire 10 Gbits of data it will collect during the entire mission. And that's with sole access to NASA's Deep Space Network. But the Network, a triad of steerable, high-gain parabolic antenna sites located about 120° of longitude apart to ensure constant coverage of all areas of the sky, has other tasks. For example, it is receiving data from Martian rovers Spirit and Opportunity, getting information from the Cassini probe as it orbits Saturn and the Ulysses probe as it orbits the Sun, and still communicating with Voyager I and II.
To save time and resources, NASA scientists will make do with compressed (20:1) data sent to Earth starting 10 days after New Horizons' closest approach to Pluto. Some of the original data will be lost to compression, but if researchers determine they need more detail, they will command the probe to "losslessly compress" those files and retransmit them to Earth. This could take nine months.