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Callens, R. A.

Publications and source records attributed to Callens, R. A..

7 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

Ion propulsion for shared Shuttle, sun-synchronous missions

The configuration of an ion propulsion module (IPM) for use in the deployment and retrieval of sun-synchronous satellites on shared Shuttle flights is described. In addition to enabling shared Shuttle payloads requiring large orbital plane changes for achieving desired viewing conditions, the IPM makes over 10 kw available for payload power-sharing on orbit. The IPM also affords a large on-orbit propulsion capability. It has 2.8 x 10 to the 7th N-sec available at full propellant loading, of which less than half was needed for deploying and retrieving the representative spacecraft studied. Its remaining propulsion capability can be used for increasing payload or for additional propulsive functions on orbit.

Zafran, S.↗
NASA NTRS1979

Ion propulsion cost effectivity

Ion propulsion modules employing 8 cm thrusters and 30 cm thrusters were studied for Multimission Modular Spacecraft (MMS) applications. Recurring and non-recurring cost elements were generated for these modules. As a result, ion propulsion cost drivers were identified to be Shuttle charges, solar array, power processing, and thruster costs. Cost effective design approaches included short length module configurations, array power sharing, operation at reduced thruster input power (reduced solar array size), simplified power processing units, and power processor output switching.

Zafran, S.↗
NASA NTRS1976

Noncatalytic hydrazine thruster development - 0.050 to 5.0 pounds thrust

Noncatalytic (thermal-decompositon) hydrazine thrusters can operate in both the pulsing and steady-state modes to meet the propulsive requirements of long-life spacecraft. The thermal decomposition mode yields higher specific impulse than is characteristic of catalytic thrusters at similar thrust levels. This performance gain is the result of higher temperature operation and a lower fraction of ammonia dissociation. Some life limiting factors of catalytic thrusters are eliminated.

Murch, C. K.↗
NASA NTRS1972

Performance testing of a solid propellant pulsed plasma microthruster.

Extensive performance testing has been carried out on a solid propellant, pulsed plasma microthruster essentially identical to the four units aboard the DOD, Lincoln Experimental Satellite (LES)-6. Tests include measurements of thrust, specific impulse, thrust vector, impulse bit repeatability, intermittency and endurance. The results show good impulse bit repeatability and a well defined thrust vector. The impulse bit, with a 1.85-joule input, was found to be approximately 26 micronewton-seconds at 190 seconds specific impulse. Based upon the results of the intermittency tests, a better understanding of the intermittency mechanism has been achieved.

Williams, T. E.↗