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SPACE ELECTRIC ROCKET TEST
II (SERT II)
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The SERT II development
program which started in 1966 included
thruster ground tests of 6742 hours and 5169
hours duration. A prototype version of the
SERT II spacecraft was ground-tested for a
period of 2400 hours with an operating ion
engine. The spacecraft was launched into a
1000-km-high polar orbit on February 3,
1970. In addition to diagnostic equipment
and related IPS hardware, the spacecraft had
two identical 15 cm diameter, mercury ion
engines and two PPUs. Flight objectives
included in-space operation for a period of
6 months, measurement of thrust, and
demonstration of electromagnetic
compatibility. The thruster maximum power
level was 0.85 kW, and this provided
operation at a 28-mN thrust level at 4200 s
specific impulse. Flight data were obtained
from 1970 to 1981 with an ion engine
operating intermittently in one of three
different modes, namely, HV ion extraction,
discharge chamber operation only, or just
neutralizer operation.
Major results were that two mercury engines
thrusted for periods of 3781 hours and 2011
hours. Test duration was limited due to
shorts in the ion optical system. Thrust
measured in space and on the ground agreed
within the measurement uncertainties. Up to
300 thruster restarts were demonstrated. A
PPU accumulated nearly 17,900 hours during
the course of the mission. Additionally, the
IPS was electromagnetically compatible with
all other spacecraft systems.
Major results included, two mercury
thrusters operated for 2011 hrs and 3781
hrs. Test duration was limited due to shorts
in the ion optical system. Thrust measured
in space and on the ground agreed within
measurement uncertainties. Up to 300
thruster restarts were demonstrated. A PPU
accumulated nearly 17,900 hrs during the
mission. The IPS showed that it was EM
compatible with all other spacecraft
systems.
The preceding was an excerpt from:
Sovey, J. S., Rawlin, V. K., and Patterson,
M. J.: "Ion Propulsion Development
Projects in U. S.: Space Electric Rocket
Test 1 to Deep Space 1." Journal of
Propulsion and Power, Vol. 17, No. 3,
May-June 2001, pp. 517-526.
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