Generalized Propulsion System Model for NASA Manned Spacecraft Center, Houston, Texas Final Report
Digital computer program for studying transient performance of pressure fed rocket engines
Boehnlein, J. J.↗
SEARCH · Search NASA
Results for “SPACECRAFT MODEL”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
A guide to using meteoroid-environment models for experiment and spacecraft design applications
A method was derived for transforming a meteoroid flux, defined relative to the earth and expressed as a function of meteoroid mass, velocity, and mass density into a meteoroid flux expressed as a function of penetration thickness (or some other parameter) on a moving spacecraft at some particular distance from the earth. The procedure for performing the transformation is summarized and an example is discussed.
Kessler, D. J.↗
Modelling Atmospheric Scattering Using Spacecraft Observations
The period covered by this cooperative agreement included the analysis of data from the Voyager encounter with Neptune and Triton and the primary Galileo mission to Jupiter (including the Galileo Probe entry into Jupiter's atmosphere), as well as continued work on Uranus' seasonal variability using the Voyager encounter data as a baseline.
Rages, Kathy A.↗
Modelling Atmospheric Scatterers Using Spacecraft Observations
This project report reviews the analysis of data from the Voyager encounter with Neptune and Triton, and the primary Galileo mission to Jupiter. The project included analysis of the images from Voyager of the limb images from Neptune and Triton. Also included in the project was analysis of the Images from Galileo of Venus' and Jupiter's limb. The project work on the latitude bands and temporal variations on Uranus using the images from Voyager is summarized. Also, work on information from the Galileo Probe's Nephelometer is also covered
Rages, Kathy A.↗
Obliquity, Ice Sheets, and Layered Sediments on Mars: What Spacecraft Observations and Climate Models are Telling Us
The Mars Odyssey Gamma-Ray Spectrometer (GRS) data present a quandary: On the one hand, large deposits of (inferred) water ice are located where thermal models suggest they would form and best be protected, e.g., if deposited during periods of higher obliquity. On the other hand, the volume mixing ratios (approx. 70%) are so high that diffusive deposition of water in regolith pore space (which is the process assumed by these models) cannot be the primary formation mechanism. Furthermore, given that the water is inferred to be so close to the surface (less than a few 10's of cm's), it must be in communication with the atmosphere on time scales that are geologically relatively short (10(exp 3)-10(exp 6) years); therefore the water cannot be archaic. Considering the GRS data, images of mantled, fretted, and disaggregated terrain, and new climate modeling of Mars orbital cycles, we are led to an alternate conclusion about the ice deposits: that they form as subaerial ice sheets. This scenario not only provides a simple explanation for these observations, but may also help explain the formation of globally distributed, sedimentary layered deposits.
Richardson, M. I.↗
NASCAP Modeling of GEO Satellites--Spacecraft Charging is Back!
During the last few years of Solar Minimum, GEO spacecraft charging design practices may have become lax because of paucity of spacecraft charging events. Unfortunately, this has also been the time of great changes in spacecraft design, because of the new emphases on higher power arrays and lower costs. Also unfortunate is the fact that spacecraft charging may lead to failures of solar array strings, panels, or entire spacecraft. One way to prevent satellite failures die to spacecraft charging events is to simulate the effects with a charging code, such as the venerable NASCAP/GEO code. We will discuss the use of NASCAP on the ACTS satellite as well as a newer application dealing with typical recent spacecraft charging anomalies.
Chock, R.↗
Validation of spacecraft software cost estimation models for flight and ground systems
NASA's JPL managed by Cal Tech is currently investing ways to improve its ability to increase the cost estimation accuracy early in the project life cycle.
software cost model COCOMO SEER PRICE S↗
Some observations on modeling and simulation of spacecraft formations
In this paper, an investigation is made of the reconfiguration dynamics of spacecraft formations.
formation flying dynamics control reconfiguration↗
Spacecraft Internal Acoustic Environment Modeling
The objective of the project is to develop an acoustic modeling capability, based on commercial off-the-shelf software, to be used as a tool for oversight of the future manned Constellation vehicles to ensure compliance with acoustic requirements and thus provide a safe and habitable acoustic environment for the crews, and to validate developed models via building physical mockups and conducting acoustic measurements.
Allen, Christopher↗
Spacecraft Internal Acoustic Environment Modeling
The objective of the project is to develop an acoustic modeling capability, based on commercial off-the-shelf software, to be used as a tool for oversight of the future manned Constellation vehicles. The use of such a model will help ensure compliance with acoustic requirements. Also, this project includes modeling validation and development feedback via building physical mockups and conducting acoustic measurements to compare with the predictions.
Chu, S. Reynold↗
Spacecraft Internal Acoustic Environment Modeling
Acoustic modeling can be used to identify key noise sources, determine/analyze sub-allocated requirements, keep track of the accumulation of minor noise sources, and to predict vehicle noise levels at various stages in vehicle development, first with estimates of noise sources, later with experimental data. In FY09, the physical mockup developed in FY08, with interior geometric shape similar to Orion CM (Crew Module) IML (Interior Mode Line), was used to validate SEA (Statistical Energy Analysis) acoustic model development with realistic ventilation fan sources. The sound power levels of these sources were unknown a priori, as opposed to previous studies that RSS (Reference Sound Source) with known sound power level was used. The modeling results were evaluated based on comparisons to measurements of sound pressure levels over a wide frequency range, including the frequency range where SEA gives good results. Sound intensity measurement was performed over a rectangular-shaped grid system enclosing the ventilation fan source. Sound intensities were measured at the top, front, back, right, and left surfaces of the and system. Sound intensity at the bottom surface was not measured, but sound blocking material was placed tinder the bottom surface to reflect most of the incident sound energy back to the remaining measured surfaces. Integrating measured sound intensities over measured surfaces renders estimated sound power of the source. The reverberation time T6o of the mockup interior had been modified to match reverberation levels of ISS US Lab interior for speech frequency bands, i.e., 0.5k, 1k, 2k, 4 kHz, by attaching appropriately sized Thinsulate sound absorption material to the interior wall of the mockup. Sound absorption of Thinsulate was modeled in three methods: Sabine equation with measured mockup interior reverberation time T60, layup model based on past impedance tube testing, and layup model plus air absorption correction. The evaluation/validation was carried out by acquiring octave band microphone data simultaneously at ten fixed locations throughout the mockup. SPLs (Sound Pressure Levels) predicted by our SEA model match well with measurements for our CM mockup, with a more complicated shape. Additionally in FY09, background NC noise (Noise Criterion) simulation and MRT (Modified Rhyme Test) were developed and performed in the mockup to determine the maximum noise level in CM habitable volume for fair crew voice communications. Numerous demonstrations of simulated noise environment in the mockup and associated SIL (Speech Interference Level) via MRT were performed for various communities, including members from NASA and Orion prime-/sub-contractors. Also, a new HSIR (Human-Systems Integration Requirement) for limiting pre- and post-landing SIL was proposed.
Chu, SShao-sheng R.↗
Spacecraft Internal Acoustic Environment Modeling
Acoustic modeling can be used to identify key noise sources, determine/analyze sub-allocated requirements, keep track of the accumulation of minor noise sources, and to predict vehicle noise levels at various stages in vehicle development, first with estimates of noise sources, later with experimental data. This paper describes the implementation of acoustic modeling for design purposes by incrementally increasing model fidelity and validating the accuracy of the model while predicting the noise of sources under various conditions. During FY 07, a simple-geometry Statistical Energy Analysis (SEA) model was developed and validated using a physical mockup and acoustic measurements. A process for modeling the effects of absorptive wall treatments and the resulting reverberation environment were developed. During FY 08, a model with more complex and representative geometry of the Orion Crew Module (CM) interior was built, and noise predictions based on input noise sources were made. A corresponding physical mockup was also built. Measurements were made inside this mockup, and comparisons were made with the model and showed excellent agreement. During FY 09, the fidelity of the mockup and corresponding model were increased incrementally by including a simple ventilation system. The airborne noise contribution of the fans was measured using a sound intensity technique, since the sound power levels were not known beforehand. This is opposed to earlier studies where Reference Sound Sources (RSS) with known sound power level were used. Comparisons of the modeling result with the measurements in the mockup showed excellent results. During FY 10, the fidelity of the mockup and the model were further increased by including an ECLSS (Environmental Control and Life Support System) wall, associated closeout panels, and the gap between ECLSS wall and mockup wall. The effect of sealing the gap and adding sound absorptive treatment to ECLSS wall were also modeled and validated.
Chu, Shao-Sheng R.↗
Modeling the Effects of Spacecraft Venting on Instrument Measurements of the Martian Atmosphere for an Elliptical Orbit
Analysis has been performed for MAVEN mission. Due to the elliptical orbit, large pressure variations in orbit will be experienced, there is a need to understand how internal pressures change and the flux of gas from vents could potentially bias instrument measurements. Goal of this analysis is to predict the effect that atmospheric gases trapped and vented from spacecraft volumes could have on instrument measurements.
Petro, Elaine↗
Spacecraft Charging Current Balance Model Applied to High Voltage Solar Array Operations
No abstract available
Willis, Emily M.↗
Modeling Meteoroid Densities for Spacecraft Risk Assessment
Densities are a key driver of risk posed to spacecraft by the meteoroid environment. MEM 3 has incorporated a density distribution that utilizes measurements of 92 events. Densities are extremely difficult to measure. Greater need than ever for high resolution meteor imagery to break degeneracies.
Ehlert, Steven↗
State modeling and pass automation in spacecraft control
The integrated monitoring and control commercial off-the-shelf system (IMACCS), which demonstrates the feasibility of automating spacecraft monitoring and control activities through the use of state modeling, is described together with its use. The use of the system for the control and ground support of the solar, anomalous and magnetic particle explorer (SAMPEX) spacecraft is considered. A key component of IMACCS is the Altair mission control system which implements finite state modeling as an element of its expert system capability. Using the finite state modeling and state transition capabilities of the Altair mission control system, IMACCS features automated monitoring, routine pass support, anomaly resolution and emergency 'lights on again' response. Automatic orbit determination and the production of typical flight dynamics products exists. These functionalities are described.
Klein, J.↗