The propulsion subsystem features sets of two kinds of
small thrusters. The larger are used to make major trajectory
correction maneuvers, and the smaller to continually maintain
the spacecraft in its orbit.
Firing the thrusters changes the spacecraft's orientation.
Two clusters of four small hydrazine thrusters each are
mounted on the spacecraft, providing 0.88 newtons (0.2
pounds) of thrust each for small maneuvers to keep the
spacecraft in orbit and to increase or reduce the rotation
rate. Four more thrusters are also mounted on the spacecraft,
each providing 22.2 newtons (5 pounds of thrust) for major
trajectory correction maneuvers. These thrusters are only
used when the sample return capsule's lid is closed in
order to avoid contaminating the solar samples.
In addition to miscellaneous tubing, latch valves and
filters, the propulsion subsystem also includes two 55-centimeter-diameter
(22-inch) fuel tanks, each containing hydrazine, pressurized
with gaseous helium. The outlets of tanks are metered
together and will draw together equally.
The propulsion subsystem weighs 36.6 kilograms (80.7 pounds).