Engineering topics

Millard, Jerry M.

Publications and source records attributed to Millard, Jerry M..

7 records

NASA NTRS2010

Cassini Main Engine Assembly Cover Flight Management and Performance

The Cassini spacecraft has performed its four year Prime Mission at Saturn and is currently in orbit at Saturn performing a two year extended mission. 12Its main engine nozzles are susceptible to impact damage from micrometeoroids and on-orbit dust. The spacecraft has an articulating device known as the Main Engine Assembly (MEA) cover which can close and shield the main engines from these threats. The cover opens to allow for main engine burns that are necessary to maintain the trajectory. Periodically updated analyses of potential on-orbit dust hazard threats have resulted in the need to continue to use the MEA cover beyond its intended use and beyond its design life. This paper provides a detailed Systems-level overview of the flight management of the MEA cover device and its flight performance to date.

Somawardhana, Ruwan P.↗

NASA NTRS1992

Solar Probe thermal shield design and testing

This paper discusses the major thermal shield subsystem development activities in support of the Solar Probe study being conducted at JPL. The Solar Probe spacecraft will travel to within 4 solar radii of the sun's center to perform fundamental experiments in space physics. Exposure to 2900 earth suns at perihelion requires the spacecraft to be protected within the shadow envelope of a protective shield. In addition, the mass loss rate off of the shield at elevated temperature must comply with plasma instrument requirements and has become the driver of the shield design. This paper will focus on the analytical design work to size the shield and control the shield mass loss rate for the various spacecraft options under study, the application of carbon-carbon materials for shield components, development and preparation of carbon-carbon samples for materials testing, and a materials testing program for carbon-carbon and tungsten alloys to investigate thermal/optical properties, mass loss (carbon-carbon only), material integrity, and high velocity impact behavior.

Millard, Jerry M.↗

NASA NTRS1992

Hot rocket plume experiment - Survey and conceptual design

Attention is given to a space-borne engine plume experiment study to fly an experiment which will both verify and quantify the reduced contamination from advanced rhenium-iridium earth-storable bipropellant rockets (hot rockets) and provide a correlation between high-fidelity, in-space measurements and theoretical plume and surface contamination models. The experiment conceptual design is based on survey results from plume and contamination technologists throughout the U.S. With respect to shuttle use, cursory investigations validate Hitchhiker availability and adaptability, adequate remote manipulator system (RMS) articulation and dynamic capability, acceptable RMS attachment capability, adequate power and telemetry capability, and adequate flight altitude and attitude/orbital capability.

Millard, Jerry M.↗

NASA NTRS1991

Contamination Analysis Program

Contamination Analysis Program (CAP) generalized transient-executive-analysis computer code solving realistic mass-transport problems in free-molecular-flow environment. Involves mass fluxes from emission and reemission by sources on surfaces, venting, and emission by engines. Also solves problems including one-bounce mass reflections. Written in FORTRAN.

Millard, Jerry M.↗

NASA NTRS1991

A thermal shield concept for the Solar Probe mission

The Solar Probe spacecraft will travel to within 4 solar radii of the sun's center while performing a variety of fundamental experiments in space physics. Exposure to 2900 earth suns (400 W/sq cm) at perihelion imposes severe thermal and material demands on a solar shield system designed to protect the payload that will reside within the shield's shadow envelope or umbra. The design of the shield subsystem is a thermal/materials challenge requiring new technology development. While currently in the preproject study phase, anticipating a 1995 project start, shield preliminary design efforts are currently underway. This paper documents the current status of the mission concept, the materials issues, the configuration concept for the shield subsystem, the current configuration studies performed to date, and the required material testing to provide a database to support a design effort required to develop the shield subsystem.

Miyake, Robert N.↗

NASA NTRS1990

Modeling of internal contaminant deposition on a cold instrument sensor

A model is developed to predict the deposition of contaminants on the CCD sensors of the Wide Field Planetary Camera to determine expected performance parameters. Contaminant deposition due to internal instrument sources is considered as is the mechanism of transport to the CCDs themselves. The Contamination Analysis Program (CAP) model considers deposition and reemission kinetics, nodal containment sources, and internodal shape factors related to line-of-sight transport. Indirect transport is also accounted for in the CAP model by considering the effect of diffuse reflection at internodal exchanges. The effective total transport factors for each node-to-node exchange is precalculated to reduce the effective number of nodes and reducing run time of the CAP program. The method is applied to four distinct conditions and is found to be suitable for the analysis of internal self-contamination. Cold traps, venting, and vacuumlike design are factors which are found to be important for cold-sensitive sensors.

Barengoltz, Jack B.↗

NASA NTRS1987

Earth Observing System (EOS)/NOAA candidate propulsion system assessment and instrument contamination requirements

The instrumentation payloads of the Space Station polar platforms consist primarily of Earth Observing System (EOS) instruments and National Oceanic and Atmospheric Administration (NOAA) instruments. The accuracy, lifetime, and mission effectiveness of the instrumentation is adversely affected by the degradation of contamination sensitive surfaces. This paper describes the analysis and results of a study undertaken to select a propellant system for the polar platforms from a contamination standpoint, by evaluation of the potential contamination to three platforms, from three candidate propellant systems. In addition, this paper reports the results of a study which determined both the molecular and particulate contamination requirements for 37 EOS/NOAA instruments. These requirements provide an upper bound for acceptable levels of contamination.

Millard, Jerry M.↗