How is the New Horizons spacecraft propelled?
There are 16 thrusters on New Horizons: four 1 lbf (4.4 N) and twelve 0.2 lbf (0.9 N) plumbed into redundant branches. The larger thrusters are used primarily for trajectory corrections, and the small ones (previously used on Cassini and the Voyager spacecraft) are used primarily for attitude control and spinup/spindown maneuvers. Two star cameras (from Galileo Avionica) are used for fine attitude control. They are mounted on the face of the spacecraft and provide attitude information while in spinning or in 3-axis mode. Between star camera readings, knowledge is provided by dual redundant Miniature Inertial Measurement Unit (MIMU) from Honeywell. Each unit contains three solid-state gyroscopes and three accelerometers. Two Adcole Sun sensors provide coarse attitude control. One detects angle to the Sun, while the other measures spin rate and clocking.
