| Summary
The New Millennium Program's Earth Observing-1 (EO-1)
mission provides for the first on-orbit demonstration
of a low mass, low cost, dependable electromagnetic Pulse
Plasma Thruster (PPT) propulsion unit designed for precision
attitude control. The PPT uses solid Teflon propellant
and is capable of delivering high specific impulse (650
- 1400 sec), very fine impulse bits (90 — 860 µN-s)
at low power (12 — 70 W), and an estimated total
impulse of 460 N-sec. The total mass is ~5 kg.
The PPT consists of a coiled spring to feed the Teflon
propellant, an igniter plug to initiate a small trigger
discharge and an energy storage capacitor and electrodes.
Plasma is created by the ablation of the Teflon propellant
from discharge of the storage capacitor across the electrodes.
The plasma is accelerated by Lorenz force in the induced
magnetic field to generate thrust. The thrust is modulated
by varying the magnitude of the impulse bit. The impulse
bit is varied by changing the charge time of the main
capacitor. When commanded, the PPT replaces the function
of the pitch axis reaction wheel and maintains fine
pitch attitude control pointing requirements for EO-1
while meeting stringent electromagnetic and contamination
constraints for the mission. |
