SERT Credit - NASA

Electric ion engine tests.

Typical orbit: 1037 km x 1044 km at 99 degrees inclination. Mass: 1,404 kg (3,095 lb). Associated Launch Vehicle: Thorad Agena D SLV-2G.

• 1964 July 20 - SERT 1 Technology mission - Launch Site: Wallops Island. Launch Vehicle: Scout X-4. Apogee: 4,002 km (2,486 mi).

  Suborbital 30 minute test of NASA SERT ion engine. The early part of the flight was dedicated to attempts to operate the cesium engine. The cesium engine could not be started because of a high-voltage electrical short circuit. The mercury engine was started about 14 minutes into the flight. This engine was successfully operated for 31 minutes with 53 high-voltage recycle vents which were handled by the fault protection system. Each of the recycle events was only a few seconds duration. Major results from the test were the first demonstration of an ion engine in space, demonstration of effective ion beam neutralization, no EMI effects on other spacecraft systems, and effective recovery from electrical breakdowns. Thrust was measured using three independent measuring systems, and there were no major differences between in-space and ground test performance.

• 1970 February 4 - SERT 2 - Launch Site: Vandenberg. Launch Vehicle: Thorad Agena D SLV-2G. Mass: 1,404 kg (3,095 lb). Perigee: 1,039 km (645 mi). Apogee: 1,046 km (649 mi). Inclination: 99.20 deg. Period: 106.00 min.

  Space Electric Rocket Test; the ion engines aboard were operated until 1981. The SERT 2 development program started in 1966 and included thruster ground tests of 6742 hours and 5169 hours duration. A prototype version of the SERT 2 spacecraft was ground-tested for a period of 2400 hours with an operating ion engine. In addition to diagnostic equipment and related ion engine hardware, the spacecraft had two identical 15 cm diameter, mercury ion engines. 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. One power-processing unit accumulated nearly 17,900 hours during the course of the mission. Additionally, the ion propulsion system was electromagnetically compatible with all other spacecraft systems.

• NASA Report, Development and Flight History of SERT 2 Spacecraft, . Accessed at: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19920019740_1992019740.pdf. -right click to download pdfs!

• NASA Report, Comparative in-flight thrust measurements of the SERT 2 ion thruster, . Accessed at: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19700033381_1970033381.pdf. -right click to download pdfs!

• NASA Report, Results From SERT 1 Ion Rocket Flight Test, . Accessed at: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19700072262_1970072262.pdf. -right click to download pdfs!

• NASA Report, Development of The Sert I Spacecraft Summary Report, . Accessed at: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19660008296_1966008296.pdf. -right click to download pdfs!

• NASA Report, .

• WDC Rocket File (electronic version, supplied 2001) (via Jonathon McDowell).

• JPL Mission and Spacecraft Library, Jet Propulsion Laboratory, 1997. Accessed at: http://msl.jpl.nasa.gov/home.html.

• Krebs, Gunter, Gunter's Space Page, University of Frankfurt, 1996. Accessed at: http://www.skyrocket.de/space.

• McDowell, Jonathan, Jonathan's Space Home Page, Harvard University, 1997-present. Jonathan McDowell's complete on-line listing of all objects orbited and over 20,000 rocket launches Accessed at: http://www.planet4589.org/jsr.html.

• USAF Satellite Database, USAF Institute of Technology, 1995. Accessed at: ftp://archive.afit.af.mil/pub/space/.

• NASA Report, Thrust measurement of SERT I ion thrustors, . Accessed at: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19660013633_1966013633.pdf. -right click to download pdfs!