During the Jupiter flyby in February 2007, New Horizons sent data home at about 38 kilobits per second (kbps), which is slightly slower than the transmission speed for most computer modems. The average downlink rate after New Horizons passes Pluto (and sends the bulk of its encounter data back to Earth) is approximately 2,000 bits per second, a rate the spacecraft achieves by downlinking with both of its transmitters through NASA’s largest antennas. Even then, it will take until late 2016 to bring down all the encounter data stored on the spacecraft’s recorders.
Since NASA’s Deep Space Network has to track other missions besides New Horizons, the team plans to produce a lossy compressed browse data set that can be sent down more quickly. The browse dataset will be downlinked before the end of 2015; the complete dataset will be downlinked after the browse dataset.
New Horizons (via iamdanw)