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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.

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At least 703 records · Page 39
All sourcesNASA NTRSDOE OSTI
NASA NTRS1997

Thrust Enhancement in Hypervelocity Nozzles by Chemical Catalysis

In the hypersonic flight regime, the air-breathing supersonic combustion ramjet (scramjet) has been shown to be a viable propulsion system. The current designs of scramjet engines provide performance benefits only up to a Mach number of 14. Performance losses increase rapidly as the Mach number increases. To extend the applicability of scram'jets beyond Mach 14, research is being conducted in the area of inlet and wave drag reduction, skin-friction and heat-transfer reduction, nozzle loss minimization, low-loss mixing, and combustion enhancement. For high Mach number applications, hydrogen is the obvious fuel choice because of its high energy content per unit mass in comparison with conventional fuels. These flight conditions require engines to operate at supersonic internal velocities, high combustor temperatures, and low static pressures. The high static temperature condition enhances the production of radicals such as H and OH, and the low-pressure condition slows the reaction rates, particularly the recombination reactions. High-temperature and low-pressure constraints, in combination with a small residence time, result in a radical-rich exhaust gas mixture exiting the combustor. At high Mach number conditions (due to low residence time), H and OH do not have enough time to recombine ; thus, a significant amount of energy is lost as these high-energy free radical are exhausted. The objective of the present study is to conduct a flowfield analysis for a typical nozzle geometry for NASP-type vehicle to assess for thrust enhancement in hypervelocity nozzles by substituting small amount of phosphine for hydrogen.

Singh, D. J.↗
NASA NTRS2003

Geoscience Laser Altimeter System: Characteristics and Performance of the Altimeter Receiver

The Geoscience Laser Altimeter System (GLAS) on board ICESat spacecraft measures the surface height (altimetry) via the time of flight of its 1064 nm laser pulse. The GLAS laser transmitter produces 6 ns wide pulses with 70 mJ energy at 1064 nm at a 40 Hz rate. The altimeter receiver consists of a telescope, aft optics, a silicon avalanche photodiode, and electronic amplifiers. The transmitted and echo pulse waveforms are digitized at 1 GHz rate. The laser pulse time of flight is determined on the ground from the two digitized pulse waveforms and their positions in the full waveform record (about 5.4 ms ong) by computing the pulse centroids or by curve fitting. The GLAS receiver algorithms in on board software selects the two waveform segments containing the transmitted and the echo pulses and sends them to ground. The probability of echo pulse detection and the accuracy of time of flight measurement depend on the received signal level, the background light within the receiver field of view, the inherent detector and amplifier noise, the quantization of the digitizer, and some times by cloud obscurations. A receiver model has been developed to calculate the probability of detection and accuracy of the altimeter measurements with these noise sources. From prelaunch testing, the minimum detectable echo pulse energy for 90% detection probability was about 0.1 fj/pulse onto the detector. Such a receiver sensitivity allows GLAS to measure the surface height through clouds with optical density less than 2. The echo pulse energy required to achieve 10 cm ranging accuracy was found to be about 3 times higher than the minimum detectable signal level. The smallest single shot range measurement error, which was determined by ranging to a fixed target with strong echo pulses and no background light, was 2 to 3cm. The maximum linear response echo pulse energy was 10 fJ/pulse for the strongest echo signals, assuming a Lambertian scattering snow surface, clear sky atmosphere transmission, and no pulse width spreading due to surface slopes. Results from the initial 38 days of GLAS operation on-orbit with Laser 1, showed the echo pulse energies varied, as expected, over a wide dynamic range due to the variability of atmosphere transmission and Earth surface characteristics. The receiver was able to reliably detect the ground surface echoes and measure time of flight under such dynamic conditions, except when there were dense clouds. When over Antarctica, the echo pulse energies were several times stronger than predicted. This suggests that the 1064 nm backscattering from the snow pack and ice-sheet &ce are not completely Lambertian but is somewhat peaked at opposit.ion. With Laser 1, the peak amplitude of the echo pulses from flat ice sheets under clear sky conditions exceeded the linear response range of the receiver, causing some pulse waveform distortion due to saturation. We have characterized the effects of receiver saturation on the time of flight, pulse width, and pulse energy measurements for flat surface by testing a night spare detector in the lab with simulated echo pulses. A data processing algorithm that minimizes the errors due to saturation for these measurements are described.

Sun, Xiao-Li↗
NASA NTRS1999

Preparing for Mars: the physiologic and medical challenges

As the twentieth century closes, retrospectives cite the Apollo moon missions as one of the important events of the past 100 years. A trip to Mars, however, would be even more challenging and significant. A round-trip Mars journey would require nearly three years away from Earth, a significant leap in complexity compared to the two week long Moon trips or the record-breaking fourteen-month flight on Mir. What would be the physiologic and medical challenges of a Mars flight? Two key areas of physiology present the greatest potential problems--calcium metabolism and radiation exposure. Data from Mir missions show that bone loss continues in space despite an aggressive countermeasure program. Average losses were 0.35% per month, but some load bearing areas lost >1% per month. A 1% loss rate, if it continued unabated for 30 months, could produce osteoporosis. Smaller losses could still increase fracture risk. Some bone loss can be well tolerated, particularly if the bone can be regained after the mission. But the effectiveness of post-flight rehabilitation to restore the density and quality of bone after spaceflight is not well known. Bone loss estimates are based on continuous weightlessness exposure, but this is not a requirement for a Mars trip. Most of the time on a Mars trip will be spent in the 1/3 Earth's gravity environment on Mars, and either intermittent or continuous artificial gravity can be provided for the transit between planets (although at an engineering cost). The dosing of the gravity exposure (e.g. the level and duration), however, has not been established. Radiation protection also requires a balance between engineering cost and human health. Excessive shielding could add billions of dollars to the cost of a mission. Trips in interplanetary space, however, expose the crew to heavy high-energy particles from cosmic rays (HZE particles), which have a high linear energy transfer. This high energy leads to significant biological damage (e.g. chromosomal aberrations, cancer induction). A recent report from the Committee on Space Biology and Medicine notes that only one systematic study of cancer induction from high-energy particles has been conducted (using the mouse Harderian gland). Predictions of cancer risk and acceptable radiation exposure in space are extrapolated from minimal data. Other areas of physiology also present problems, such as muscle loss, cardiovascular deconditioning, and vestibular adaptation. Despite all the issues, however, a focussed, aggressive research program that uses the resources of the International Space Station should pave the way for mankind's greatest adventure--a trip to Mars.

STS-90 Shuttle Project↗
NASA NTRS2005

Orbit Modification of Earth-Crossing Asteroids/Comets Using Rendezvous Spacecraft and Laser Ablation

This report describes the approach and results of an end-to-end simulation to deflect a long-period comet (LPC) by using a rapid rendezvous spacecraft and laser ablation system. The laser energy required for providing sufficient deflection DELTA V and an analysis of possible intercept/rendezvous spacecraft trajectories are studied in this analysis. These problems minimize a weighted sum of the flight time and required propellant by using an advanced propulsion system. The optimal thrust-vector history and propellant mass to use are found in order to transfer a spacecraft from the Earth to a targeted celestial object. One goal of this analysis is to formulate an optimization problem for intercept/rendezvous spacecraft trajectories. One approach to alter the trajectory of the object in a highly controlled manner is to use pulsed laser ablative propulsion. A sufficiently intense laser pulse ablates the surface of a near-Earth object (NEO) by causing plasma blowoff. The momentum change from a single laser pulse is very small. However, the cumulative effect is very effective because the laser can interact with the object over long periods of time. The laser ablation technique can overcome the mass penalties associated with other nondisruptive approaches because no propellant is required to generate the DELTA V (the material of the celestial object is the propellant source). Additionally, laser ablation is effective against a wide range of surface materials and does not require any landing or physical attachment to the object. For diverting distant asteroids and comets, the power and optical requirements of a laser ablation system on or near the Earth may be too extreme to contemplate in the next few decades. A hybrid solution would be for a spacecraft to carry a laser as a payload to a particular celestial body. The spacecraft would require an advanced propulsion system capable of rapid rendezvous with the object and an extremely powerful electrical generator, which is likely needed for the propulsion system as well. The spacecraft would station-keep with the object at a small standoff distance while the laser ablation is performed.

Park, Sang-Young↗
NASA NTRS2009

Altair Lunar Lander Consumables Management

The Altair lunar lander is scheduled to return humans to the moon in the year 2020. Keeping the crew of 4 and the vehicle functioning at their best while minimizing lander mass requires careful budgeting and management of consumables and cooperation with other constellation elements. Consumables discussed here include fluids, gasses, and energy. This paper presents the lander's missions and constraints as they relate to consumables and the design solutions that have been employed in recent Altair conceptual designs.

Polsgrove, Tara↗
NASA NTRS2012

Demonstration of Time Domain Multiplexed Readout for Magnetically Coupled Calorimeters

Magnetically coupled calorimeters (MCC) have extremely high potential for x-ray applications due to the inherent high energy resolution capability and being non-dissipative. Although very high energy-resolution has been demonstrated, until now there has been no demonstration of multiplexed read-out. We report on the first realization of a time domain multiplexed (TDM) read-out. While this has many similarities with TDM of transition-edge-sensors (TES), for MGGs the energy resolution is limited by the SQUID read-out noise and requires the well established scheme to be altered in order to minimize degradation due to noise aliasing effects. In cur approach, each pixel is read out by a single first stage SQUID (SQ1) that is operated in open loop. The outputs of the SQ1 s are low-pass filtered with an array of low cross-talk inductors, then fed into a single-stage SQUID TD multiplexer. The multiplexer is addressed from room temperature and read out through a single amplifier channel. We present results achieved with a new detector platform. Noise performance is presented and compared to expectations. We have demonstrated multiplexed X-ray spectroscopy at 5.9keV with delta_FWHM=10eV. In an optimized setup, we show it is possible to multiplex 32 detectors without significantly degrading the Intrinsic detector resolution.

Porst, J.-P.↗
NASA NTRS2014

Investigation of Energetic Ions in a 100-A Hollow Cathode

The role of ion acoustic turbulence in the formation of high-energy ion tails in the plume of a 100-A LaB6 hollow cathode is experimentally and theoretically examined. At fixed flow rate and varying discharge current, single-point measurements of fluctuation intensity in the cathode plume are taken and compared to ion energy measurements. It is shown that for high discharge current the formation of energetic ions is correlated with the amplitude of the ion acoustic turbulence. Two-dimensional maps of background plasma parameters and wave turbulence are made at the highest discharge current investigated, 140 A. A simple, one-dimensional quasilinear model for the interaction of the ion energy distribution with the ion acoustic turbulence is employed, and it is shown that the energy in the measured wave turbulence is sufficiently large to explain the formation of ion tails in the cathode plume. Mitigation techniques for minimizing the amplitude of the turbulence are discussed.

ion acoustic turbulence↗
NASA NTRS2019

Local frustration around enzyme active sites

Conflicting biological goals often meet in the specification of protein sequences for structure and function. Overall, strong energetic conflicts are minimized in folded native states according to the principle of minimal frustration, so that a sequence can spontaneously fold, but local violations of this principle open up the possibility to encode the complex energy landscapes that are required for active biological functions. We survey the local energetic frustration patterns of all protein enzymes with known structures and experimentally annotated catalytic residues. In agreement with previous hypotheses, the catalytic sites themselves are often highly frustrated regardless of the protein oligomeric state, overall topology, and enzymatic class. At the same time a secondary shell of more weakly frustrated interactions surrounds the catalytic site itself. We evaluate the conservation of these energetic signatures in various family members of major enzyme classes, showing that local frustration is evolutionarily more conserved than the primary structure itself.

Maria I. Freiberger↗
NASA NTRS2010

Targeting Low-Energy Ballistic Lunar Transfers

Numerous low-energy ballistic transfers exist between the Earth and Moon that require less fuel than conventional transfers, but require three or more months of transfer time. An entirely ballistic lunar transfer departs the Earth from a particular declination at some time in order to arrive at the Moon at a given time along a desirable approach. Maneuvers may be added to the trajectory in order to adjust the Earth departure to meet mission requirements. In this paper, we characterize the (Delta)V cost required to adjust a low-energy ballistic lunar transfer such that a spacecraft may depart the Earth at a desirable declination, e.g., 28.5(white bullet), on a designated date. This study identifies the optimal locations to place one or two maneuvers along a transfer to minimize the (Delta)V cost of the transfer. One practical application of this study is to characterize the launch period for a mission that aims to launch from a particular launch site, such as Cape Canaveral, Florida, and arrive at a particular orbit at the Moon on a given date using a three-month low-energy transfer.

Low-energy transfers↗
NASA NTRS2020

OSA Spotlight Summary: Designing Miniature X-ray Optics for the SmallSat Lunar Science Mission Concept CubeX

The scientific demand for extended field X-Ray remote sensing for mapping of planetary bodies has produced the CubeSat X-ray Telescope (CubeX) lunar mission concept. Orbiting the Moon at 6,000 km for 1 year sometime during the mid-decade solar maximum, the primary objectives of CubeX are to map lunar surface elemental abundances and to assess feasibility of x-ray pulsar timing navigation. CubeX’s Miniature X-ray Optics (MiXO) design builds on heritage of existing X-ray imaging designs using new electroformed NiCo alloy replication (ENR) to create shells of 1 mm thickness. MiXO will provide 1 arcmin resolution X-Ray imaging for an extended instantaneous field of view, at various energy range sensitivities. Based on the classic Wolter-Type I design (using a paraboloid/hyperboloid grazing mirror pair), mirror parameters were expanded to allow both shell length and focal-plane offsets to vary independently. The design was optimized with a merit function that factored together four sub-merits: PSF sharpness (measured as half-power diameter), consistency across the field, minimized scattering, and maximized effective area. Monte Carlo analysis was used to predict final performance, including surface scatter effects. The demonstrated configurations include a compact 34 shell design with a diameter of 105 mm more efficient at higher energies, and a larger 130 mm/24 shell version with a larger overall effective area at lower energies. The compact design carries more expensive fabrication and assembly cost (with more shells) as well as a more challenging alignment (with denser packing). Both have overall resolution <1’ up to 26’ off-axis and <1.5’ up to 33’ off-axis, whereas a conventional design’s image quality degrades quickly beyond 15’ off-axis. This opens up new possibilities for future SmallSat missions that could use two different configurations for wide energy ranges or midsized instruments using multiple identical modules for larger collecting area.

x-ray↗
NASA NTRS2007

Development of Multifunctional Radiation Shielding Materials for Long Duration Human Exploration Beyond the Low Earth Orbit

One of the major challenges for long duration human exploration beyond the low Earth orbit and sustained human presence on planetary surfaces would be development of materials that would help minimize the radiation exposure to crew and equipment from the interplanetary radiation environment, This radiation environment consists primarily of a continuous flux of galactic cosmic rays (GCR) and transient but intense fluxes of solar energetic particles (SEP). The potential for biological damage by the relatively low percentage of high-energy heavy-ions in the GCR spectrum far outweigh that due to lighter particles because of their ionizing-power and the quality of the resulting biological damage. Although the SEP spectrum does not contain heavy ions and their energy range is much lower than that for GCRs, they however pose serious risks to astronaut health particularly in the event of a bad solar storm The primary purpose of this paper is to discuss our recent efforts in development and evaluation of materials for minimizing the hazards from the interplanetary radiation environment. Traditionally, addition of shielding materials to spacecrafts has invariably resulted in paying a penalty in terms of additional weight. It would therefore be of great benefit if materials could be developed not only with superior shielding effectiveness but also sufficient structural integrity. Such a multifunctional material could then be considered as an integral part of spacecraft structures. Any proposed radiation shielding material for use in outer space should be composed of nuclei that maximize the likelihood of projectile fragmentation while producing the minimum number of target fragments. A modeling based approach will be presented to show that composite materials using hydrogen-rich epoxy matrices reinforced with polyethylene fibers and/or fabrics could effectively meet this requirement. This paper will discuss the fabrication of such a material for a crewed vehicle. Ln addition, the capability of synthesizing radiation shielding materials for habitat structures primarily from Lunar or Martian in-situ resources will also be presented. Such an approach would significantly _reduce the cost associated with transportation of such materials and structures from earth. Results from radiation exposure measurements will be presented demonstrating the shielding effectiveness of the developed materials. Mechanical testing data will be discussed to illustrate that the specific mechanical properties of the developed composites are comparable to structural aluminum based alloys currently used for the space shuttle and space station.

Sen, S.↗
NASA NTRS1981

Antenna optimization and cost consideration for the Solar Power Satellite microwave system

The sizing, criteria, cost analysis, and optimized taper of the Solar Power Satellite (SPS) transmitting antenna are discussed. The sizing parameters considered were a thermal limit of 23 kW/sq m in the antenna, a peak power density of 23 mW/sq cm in the ionosphere, and cost effectiveness. Cost schedules and equations are presented for the SPS, and four antenna tapers are analyzed and compared, including the reference 10 dB Gaussian taper. An even powered quadratic series is formulated to minimize electricity cost and stay within thermal and ionospheric power level limits. The optimized Johnson Space Center taper is found to display the lowest energy costs, 4% below the 10 dB Gaussian, and can deliver 5.69 GW at 45.4 mills/kWh to the grid. Further studies are indicated for the optimal antenna and rectenna sizes

Kerwin, E. M.↗
NASA NTRS1983

Radiation protection for manned space activities

The Earth's natural radiation environment poses a hazard to manned space activities directly through biological effects and indirectly through effects on materials and electronics. The following standard practices are indicated that address: (1) environment models for all radiation species including uncertainties and temporal variations; (2) upper bound and nominal quality factors for biological radiation effects that include dose, dose rate, critical organ, and linear energy transfer variations; (3) particle transport and shielding methodology including system and man modeling and uncertainty analysis; (4) mission planning that includes active dosimetry, minimizes exposure during extravehicular activities, subjects every mission to a radiation review, and specifies operational procedures for forecasting, recognizing, and dealing with large solar flaes.

Jordan, T. M.↗
NASA NTRS1992

Alteration of hydrovolcanic basaltic ash - Observations with visible and near-infrared spectrometry

Altered basaltic tephras from tuff rings and tuff cones across the Basin and Range were examined using visible and NIR (Vis/IR) reflectance spectrometry and a variety of other techniques. It was found that Vis/IR spectrometry is sensitive to subtle changes in the hydration and oxidation state of these tephras. In the tuffs examined, ferrous and ferric iron minerals produce one composite absorption feature rather than two resolvable bands. Different styles of alteration were noted between thinly bedded tuff ring deposits emplaced by high energy, largely dry, pyroclastic surge and massively bedded tuff cone deposits emplaced by wetter, lower energy pyroclastic flow. The former class of tephras become hydrated and only moderately oxidized with some limited development of dioctehedral smectite clay minerals and minimal palagomitization. The latter class of tephras are highly palagonitized which implies a high degree of hydration and oxidation. In the most of highly altered tephras, all the Fe(2+) that is initially in the volcanic glass is converted to Fe(3+) within nanophase and bulk ferric oxide phases in the palagonite. There is also more extensive development in tuff cone beds of zeolite and phyllosilicate minerals. The differences in reflectance spectra of altered basaltic tephras can be traced to initial differences in the water/magma ratio extant at the volcanic vent.

Farrand, William H.↗
NASA NTRS2003

Atmospheric Ionizing Radiation (AIR): Analysis, Results, and Lessons Learned From the June 1997 ER-2 Campaign

The United States initiated a program to assess the technology required for an environmentally safe and operationally efficient High Speed Civil Transport (HSCT) for entrance on the world market after the turn of the century. Due to the changing regulations on radiation exposures and the growing concerns over uncertainty in our knowledge of atmospheric radiations, the NASA High Speed Research Project Office (HSRPO) commissioned a review of "Radiation Exposure and High-Altitude Flight" by the National Council on Radiation Protection and Measurements (NCRP). On the basis of the NCRP recommendations, the HSRPO funded a flight experiment to resolve the environmental uncertainty in the atmospheric ionizing radiation levels as a step in developing an approach to minimize the radiation impact on HSCT operations. To minimize costs in this project, an international investigator approach was taken to assure coverage with instrument sensitivity across the range of particle types and energies to allow unique characterization of the diverse radiation components. The present workshop is a result of the flight measurements made at the maximum intensity of the solar cycle modulated background radiation levels during the month of June 1997.

Wilson, J. W.↗
NASA NTRS2021

Microsphere Plutonium-238 Oxide Fuel to Revolutionize New Radioisotope Power Systems and Heat Sources for Planetary Exploration

Microsphere 238PuO2 fuels have potential to provide performance and safety enhancements for future radioisotope heat and power systems (RPS) as well as enable more flexible and compact RPS designs. Improvements in RPS specific power and more flexible geometries were recently investigated by JPL and PNNL as part of a study on cryobot devices for exploring Ocean Worlds. Missions to penetrate ice and explore oceans, such as on Europa, will require RPS with high specific power within the vehicle to provide both heat and power. Such missions will be mass-constrained, and the energy required to penetrate the ice is highly dependent on cryobot size. Therefore, compact RPS geometries are needed to maximize heat and power while minimizing 238Pu inventory. Microsphere-based heat sources are an attractive way to obtain flexible geometries and high volumetric power loadings because they can fill a region of any size and shape provided fuel temperatures are kept below a threshold and launch/re-entry safety are not compromised. The sol-gel technique to produce 238PuO2 microsphere particles for heat sources has the benefit of preventing dust generation, as opposed to the current 238PuO2 powder/pellet processing method, reducing hazards in the fuel fabrication line. Microspheres can also be individually coated to enhance thermal conductivity, and/or reduce the likelihood of 238PuO2 fuel dispersal in an accident. Although PNNL has produced 238PuO2 microspheres using the sol-gel method, the application of coatings and their integrity over time has yet to be investigated. Continued R&D could demonstrate the feasibility of advanced, microspherebased heat sources and provide baseline data for planning future missions requiring new RPS with different heat source configurations.

Fleurial, Jean-Pierre↗
NASA NTRSDate not supplied

Novel Hourly-Resolved Global Cloud Property Composite from Operational Satellites Imagers

Numerous applications in satellite remote sensing of surface properties, atmospheric state, composition, and radiation require accurate knowledge of the location and characteristics of clouds. Operational satellite imager radiances are valuable for cloud detection and for deriving many different physical parameters that can be used for a variety of weather, aviation, and energy applications. The NASA Satellite ClOud and Radiation Property retrieval System (SatCORPS) applies a suite of algorithms to meteorological satellite data to provide cloud properties, radiative fluxes and other parameters on a global scale. This paper describes a new global high-resolution dataset of cloud properties made available for community use that is constructed from analyses of a constellation of meteorological satellite imagers. Data taken from Meteosat-8/9 and -11, Himawari-8/9, GOES-16, and -17/-18, Aqua, Terra, Suomi-NPP and NOAA-20 are processed and composited on a 3-km grid to provide hourly global coverage. A historical multi-year dataset is available to serve various needs including modeling challenges related to cloud evaluations and parameterizations. Near real-time data products are also currently available between 60N and 60S. Efforts are underway to operationalize polar orbiting satellite cloud detection methods for low-latency applications over polar regions. The cloud detection and retrieval algorithms have been developed over many years to support NASA weather and climate programs such as the Clouds and Earth’s Radiant Energy System (CERES). To improve the utility of the data products, machine learning and other innovative methods are applied in various ways to help minimize data product uncertainties under the most challenging conditions and to improve their consistency at all times of day. A brief description of the methods highlighting the unique aspects of the SatCORPS data products will be presented along with information on their status and availability.

SatCORPS↗
NASA NTRS1993

Space Shuttle Main Engine performance analysis

For a number of years, NASA has relied primarily upon periodically updated versions of Rocketdyne's power balance model (PBM) to provide space shuttle main engine (SSME) steady-state performance prediction. A recent computational study indicated that PBM predictions do not satisfy fundamental energy conservation principles. More recently, SSME test results provided by the Technology Test Bed (TTB) program have indicated significant discrepancies between PBM flow and temperature predictions and TTB observations. Results of these investigations have diminished confidence in the predictions provided by PBM, and motivated the development of new computational tools for supporting SSME performance analysis. A multivariate least squares regression algorithm was developed and implemented during this effort in order to efficiently characterize TTB data. This procedure, called the 'gains model,' was used to approximate the variation of SSME performance parameters such as flow rate, pressure, temperature, speed, and assorted hardware characteristics in terms of six assumed independent influences. These six influences were engine power level, mixture ratio, fuel inlet pressure and temperature, and oxidizer inlet pressure and temperature. A BFGS optimization algorithm provided the base procedure for determining regression coefficients for both linear and full quadratic approximations of parameter variation. Statistical information relative to data deviation from regression derived relations was also computed. A new strategy for integrating test data with theoretical performance prediction was also investigated. The current integration procedure employed by PBM treats test data as pristine and adjusts hardware characteristics in a heuristic manner to achieve engine balance. Within PBM, this integration procedure is called 'data reduction.' By contrast, the new data integration procedure, termed 'reconciliation,' uses mathematical optimization techniques, and requires both measurement and balance uncertainty estimates. The reconciler attempts to select operational parameters that minimize the difference between theoretical prediction and observation. Selected values are further constrained to fall within measurement uncertainty limits and to satisfy fundamental physical relations (mass conservation, energy conservation, pressure drop relations, etc.) within uncertainty estimates for all SSME subsystems. The parameter selection problem described above is a traditional nonlinear programming problem. The reconciler employs a mixed penalty method to determine optimum values of SSME operating parameters associated with this problem formulation.

Santi, L. Michael↗