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Papers by William Deininger

This poster will discusses system concepts, architectures, and technology development work to mat... more This poster will discusses system concepts, architectures, and technology development work to mature critical components for low-cost surface probes for small solar system bodies.

The Kepler Discovery Mission has been developed to monitor a large star field for four years and ... more The Kepler Discovery Mission has been developed to monitor a large star field for four years and directly detect Earth-like planets through differential photometry. The mission is launched on a Delta II and flies in a heliocentric orbit. The 903-Kg flight segment consists of a CCD-based photometer instrument and a spacecraft bus. The spacecraft bus is at the base of the flight segment and provides structural support to the photometer. The spacecraft is 3-axis-stablized and uses fine guidance sensors to provide accurate pointing throughout the mission to better than 18.4 arcsec. Reaction wheels are used for attitude adjustments with a cold-gas reaction control system for wheel desaturations. Spacecraft thermal control is largely passive with some active heaters. The spacecraft avionics is based on redundant RAD 750 computers with a throughput of 119 MIPS. The power system produces 812 W EOL using a fixed solar array with a direct energy transfer architecture. Primary data downlink is via a Ka-band HGA to the DSN 34-m antennas.

2013 IEEE Aerospace Conference, 2013

ABSTRACT This paper describes an experimental platform that will demonstrate the major technologi... more ABSTRACT This paper describes an experimental platform that will demonstrate the major technologies required for the handling and storage of cryogenic propellants in a low-to-zero-g environment. In order to develop a cost-effective, high value-added demonstration mission, a review of the complete mission concept of operations (CONOPS) was performed. The overall cost of such a mission is driven not only by the spacecraft platform and on-orbit experiments themselves, but also by the complexities of handling cryogenic propellants during ground-processing operations. On-orbit storage methodologies were looked at for both passive and active systems. Passive systems rely purely on isolation of the stored propellant from environmental thermal loads, while active cooling employs cryocooler technologies. The benefit trade between active and passive systems is mission-dependent due to the mass, power, and system-level penalties associated with active cooling systems. The experimental platform described in this paper is capable of demonstrating multiple advanced micro-g cryogenic propellant management technologies. In addition to the requirements of demonstrating these technologies, the methodology of propellant transfer must be evaluated. The handling of multiphase liquids in micro-g is discussed using flight-heritage micro-g propellant management device technologies as well as accelerated tank stratification for access to vapor-free or liquid-free propellants. The mission concept presented shows the extensibility of the experimental platform to demonstrate advanced cryogenic components and technologies, propellant transfer methodologies, as well as the validation of thermal and fluidic models, from subscale tankage to an operational architecture.

$Research paper thumbnail of High temperature refractory member with radiation emissive overcoat$

The flow velocity of atomic hydrogen in the plume of an ammonia-propelled arcjet was measured usi... more The flow velocity of atomic hydrogen in the plume of an ammonia-propelled arcjet was measured using LIF. The velocity was obtained by the Doppler shift of the absorption peak of the Balmer alpha spectral line. Measurements were made at the nozzle exit, varying the distance from the plume centerline. Results are presented for arcjet operating conditions 13, 20 and 27 kW with a mass flow of 0.31 g/s. The on-axis H flow velocity varies from 14 km/s to 28 km/s over this range of input power. The axial velocity as a function of the distance from the axis is sharply peaked, dropping to almost zero at a radius of less than 5 mm.

2010 IEEE Aerospace Conference, 2010

... The ASPIRE Observatory has high mass and power margins and requires no technology development... more ... The ASPIRE Observatory has high mass and power margins and requires no technology development required ASPIRE is compatible with all EELV launch vehicles which can provide a C3 of +0.4 km2/s2. ... Table 3 ASPIRE has high heritage and large margins to minimize risk. ...