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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 109 records · Page 6
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NASA NTRS1977

Apollo-Soyuz O/3P/ and N/4S/ density measurement by UV spectroscopy

The densities of O(3P) and N(4S) at 225 km were determined during the Apollo-Soyuz Test Project by a resonance absorption-fluorescence technique in which O I and N I line radiation produced and collimated on board the Apollo was reflected from the Soyuz back to the Apollo for spectral analysis. The two spacecraft maneuvered so that a range of observation angles of plus or minus 25 deg with respect to the normal to the orbital velocity vector was scanned. The measurements described were made at night on two consecutive orbits at spacecraft separations of 150 and 500 m. The results indicate an O density of 1.15 billion per cu cm (plus or minus 30%), agreeing with mass-spectrometric measurements made under similar conditions, and an N density of 5.6 to 11.2 million per cu cm, in good agreement with recent measurements but suggesting a smaller diurnal variation than predicted by present models.

Donahue, T. M.↗
NASA NTRS1984

Optimal slewing maneuvers for flexible spacecraft using a closed form solution for the linear tracking problem

The problem of maneuvering a flexible spacecraft through a large angle while requiring the feedback control system to track a desired output state is considered. The desired output state is assumed to be provided by the corresponding open-loop maneuvering solution for the linear system model. Closed form solutions are provided for the Riccati and prefilter equations defining the optimal control. Example maneuvers are presented where control-rate penalties have been included in the performance index, in order to smooth both the open- and closed-loop control commands.

Turner, J. D.↗
NASA NTRS2014

Lunar Flashlight: Mapping Lunar Surface Volatiles Using a Cubesat

Lunar Flashlight is an exciting new mission concept in preformulation studies for NASA's Advanced Exploration Systems (AES) by a team from the Jet Propulsion Laboratory, UCLA, and Marshall Space Flight Center. This innovative, low-cost concept will map the lunar south pole for volatiles and demonstrate several technological firsts, including being the first CubeSat to reach the Moon, the first mission to use an 80 m2 solar sail, and the first mission to use a solar sail as a reflector for science observations. The Lunar Flashlight mission spacecraft maneuvers to its lunar polar orbit and uses its solar sail as a mirror to reflect 50 kW of sunlight down into shaded polar regions, while the on-board spectrometer measures surface reflection and composition. The Lunar Flashlight 6U spacecraft has heritage elements from multiple cubesat systems. The deployable solar sail/reflector is based on previous solar sail experiments, scaled up for this mission. The mission will demonstrate a path where 6U CubeSats could, at dramatically lower cost than previously thought possible, explore, locate and estimate size and composition of ice deposits on the Moon. Locating ice deposits in the Moon's permanently shadowed craters addresses one of NASA's Strategic Knowledge Gaps (SKGs) to detect composition, quantity, distribution, form of water/H species and other volatiles associated with lunar cold traps. Polar volatile data collected by Lunar Flashlight could then ensure that targets for more expensive lander- and rover-borne measurements would include volatiles in sufficient quantity and near enough to the surface to be operationally useful.

Cohen, Barbara A.↗
NASA NTRS1977

Thermal design of the IUE hydrazine auxiliary propulsion system

The International Ultraviolet Explorer is a large astronomical observatory scheduled to be placed in a three-axis stabilized synchronous orbit in the fourth quarter of 1977. The Hydrazine Auxiliary Propulsion System (HAPS) must perform a number of spacecraft maneuvers to achieve a successful mission. This paper describes the thermal design which accomplishes temperature control between 5 and 65 C for all orbital conditions by utilizing multilayer insulation and commandable component heaters. A primary design criteria was the minimization of spacecraft power by the selective use of the solar environment. The thermal design was carefully assessed and verified in both spacecraft thermal balance and subsystem solar simulation testing.

Joseph T. Skladany↗
NASA NTRS1990

Visions of visualization aids: Design philosophy and experimental results

Aids for the visualization of high-dimensional scientific or other data must be designed. Simply casting multidimensional data into a two- or three-dimensional spatial metaphor does not guarantee that the presentation will provide insight or parsimonious description of the phenomena underlying the data. Indeed, the communication of the essential meaning of some multidimensional data may be obscured by presentation in a spatially distributed format. Useful visualization is generally based on pre-existing theoretical beliefs concerning the underlying phenomena which guide selection and formatting of the plotted variables. Two examples from chaotic dynamics are used to illustrate how a visulaization may be an aid to insight. Two examples of displays to aid spatial maneuvering are described. The first, a perspective format for a commercial air traffic display, illustrates how geometric distortion may be introduced to insure that an operator can understand a depicted three-dimensional situation. The second, a display for planning small spacecraft maneuvers, illustrates how the complex counterintuitive character of orbital maneuvering may be made more tractable by removing higher-order nonlinear control dynamics, and allowing independent satisfaction of velocity and plume impingement constraints on orbital changes.

Ellis, Stephen R.↗
NASA NTRSDate not supplied

Spectral Properties of Dust on Asteroid (101955) Bennu with the OSIRIS-REx Visible and Infrared Spectrometer (OVIRS)

The Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) spacecraft successfully collected a sample of regolith from asteroid (101955) Bennu on October 20, 2020[1]. The Touch-and-Go (TAG) spacecraft maneuver used to collect the sample mobilized material, including very fine particles (dust),from up to ~1m in depth and ~10m in diameter from the point of contact with the asteroid [1,2].TAG created a dust plume that intercepted the spacecraft and accumulated on the instruments. As a result, all instruments show degradation in optical throughput, with the degree of degradation depending on their aperture size, orientation, and position on the spacecraft [1]. In this study, we analyzed OSIRIS-REx Visible and Infrared Spectrometer (OVIRS) from before and after TAG to assess the dust on the instrument with implications for Bennu’s dust composition and scattering properties, and future visible–near-infrared (VNIR)spectral observations with the OSIRIS-REx spacecraft. OVIRS is a point spectrometer that measures reflected light at VNIR wavelengths from 0.4 to 4.3 μm with a 4 mrad circular field of view(FOV) [3]. Previous observations with OVIRS revealed widespread hydrated minerals and carbon-bearing materials on Bennu [4,5]. A ~3 μm absorption feature is observed globally in OVIRS spectra, with a band position and depth that is consistent with Mg/Fe phyllosilicates and suggests a similar degree of aqueous alteration to that experienced by some carbonaceous chondrite meteorites[4,6]. A series of weak (<5%) VNIR spectral features, potentially associated with hydrated phyllosilicates and iron oxides, are also found in OVIRS spectra (Fig. 1), though not typically observed in meteorite spectra [7]. OSIRIS-REx Thermal Emission Spectrometer (OTES) spectra are consistent with a very thin accumulation (a few to ~ten microns) of fine particles (<~65–100 microns in size)across the surface of Bennu, and particularly on the roughest boulders, an interpretation that is supported by the dust plume seen during TAG [1,8]. An analysis of TAG contamination on the OTES optics revealed a 15% decrease in throughput, and OTES observations of space with and without that contamination allow a recreation of the thermal infrared spectrum [1]. The spectrum of the contamination lacks volume scattering features and exhibits a stronger Mg-OH absorption (~16.5 μm) than average Bennu, suggesting a Mg-rich phyllosilicate composition [1,6]. Here we present the first compositional analysis of Bennu dust at VNIR wavelengths by analyzing the contaminant on OVIRS.

H H Kaplan↗
NASA NTRS1984

Large-angle maneuvers of flexible spacecraft using a closed form solution for the terminal tracking problem

The problem of maneuvering a flexible spacecraft through a large-angle while requiring a sub-vector of the terminal state to exactly satisfy a set of terminal constraints is considered. The necessary conditions for this problem lead to three coupled nonlinear Riccati-like differential equations, which are solved in closed form. Example maneuvers are presented where control-rate penalties have been included in the performance index, in order to smooth the closed-loop control commands. Furthermore, example maneuvers are presented for both fixed and free and condition problem.

Juan, J.-N.↗
NASA NTRS2008

Modeling, Simulation, and Parameter Estimation of Lateral Spacecraft Fuel Slosh

Predicting the effect of fuel slosh on a spacecraft and/or launch vehicle attitude control system is a very important and a challenging task. Whether the spacecraft is under spinning or lateral moving conditions, the dynamic effect of the fuel slosh will help determine whether the spacecraft will remain on its chosen trajectory. There are three categories of slosh that can be caused by launch vehicle and/or spacecraft maneuvers when the fuel is in the presence of an acceleration field. These include bulk fluid motion, subsurface wave motion, and free surface slosh. Each of these slosh types have a periodic component that is defined by either a spinning or lateral motion. For spinning spacecraft, all three types of slosh can play a major role in determining stability. Bulk fluid motion and free surface slosh can affect the lateral slosh characteristics. For either condition, the possibility for an unpredicted coupled resonance between the spacecraft and its on board fuel can have mission threatening affects. This on-going research effort aims at improving the accuracy and efficiency of modeling techniques used to predict these types of lateral fluid motions. In particular, efforts will focus on analyzing the effects of viscoelastic diaphragms on slosh dynamics.

Chatman, Yadira↗
NASA NTRS2000

Optimization of Maneuver Execution for Landsat-7 Routine Operations

Multiple mission constraints were satisfied during a lengthy, strategic ascent phase. Once routine operations begin, the ongoing concern of maintaining mission requirements becomes an immediate priority. The Landsat-7 mission has tight longitude control box and Earth imaging that requires sub-satellite descending nodal equator crossing times to occur in a narrow 30minute range fifteen (15) times daily. Operationally, spacecraft maneuvers must'be executed properly to maintain mission requirements. The paper will discuss the importance of optimizing the altitude raising and plane change maneuvers, amidst known constraints, to satisfy requirements throughout mission lifetime. Emphasis will be placed not only on maneuver size and frequency but also on changes in orbital elements that impact maneuver execution decisions. Any associated trade-off arising from operations contingencies will be discussed as well. Results of actual altitude and plane change maneuvers are presented to clarify actions taken.

Cox, E. Lucien, Jr.↗
NASA NTRS2008

Parameter Estimation of Lateral Spacecraft Fuel Slosh

Predicting the effect of fuel slosh on the attitude control system of a spacecraft or launch vehicle is a very important and challenging task. Whether the spacecraft is spinning or moving laterally, the dynamic effect of the fuel slosh helps determine whether the spacecraft will remain on its intended trajectory. Three categories of slosh can be caused by launch vehicle or spacecraft maneuvers when the fuel is in the presence of an acceleration field. These are bulk-fluid motion, subsurface wave motion (currents), and free-surface slosh. Each of these slosh types has a periodic component defined by either a spinning or a lateral motion. For spinning spacecraft, all three types of slosh can greatly affect stability. Bulk-fluid motion and free-surface slosh can affect the lateral-slosh characteristics. For either condition, an unpredicted coupled resonance between the spacecraft and its onboard fuel could threaten a mission. This ongoing research effort seeks to improve the accuracy and efficiency of modeling techniques used to predict these types of fluid motions for lateral motion. Particular efforts focus on analyzing the effects of viscoelastic diaphragms on slosh dynamics.

Sudermann, James E.↗
NASA NTRS2008

1999-2003 Shortwave Characterizations of Earth Radiation Budget Satellite (ERBS)/Earth Radiation Budget Experiment (ERBE) Broadband Active Cavity Radiometer Sensors

From October 1984 through May 2005, the NASA Earth Radiation Budget Satellite (ERBS/ )/Earth Radiation Budget Experiment (ERBE)ERBE nonscanning active cavity radiometers (ACR) were used to monitor long-term changes in the earth radiation budget components of the incoming total solar irradiance (TSI), earth-reflected TSI, and earth-emitted outgoing longwave radiation (OLR). From September1984 through September 1999, using on-board calibration systems, the ERBS/ERBE ACR sensor response changes, in gains and offsets, were determined from on-orbit calibration sources and from direct observations of the incoming TSI through calibration solar ports at measurement precision levels approaching 0.5 W/sq m , at satellite altitudes. On October 6, 1999, the onboard radiometer calibration system elevation drive failed. Thereafter, special spacecraft maneuvers were performed to observe cold space and the sun in order to define the post-September 1999 geometry of the radiometer measurements, and to determine the October 1999-September 2003 ERBS sensor response changes. Analyses of these special solar and cold space observations indicate that the radiometers were pointing approximately 16 degrees away from the spacecraft nadir and on the anti-solar side of the spacecraft. The special observations indicated that the radiometers responses were stable at precision levels approaching 0.5 W/sq m . In this paper, the measurement geometry determinations and the determinations of the radiometers gain and offset are presented, which will permit the accurate processing of the October 1999 through September 2003 ERBE data products at satellite and top-of-the-atmosphere altitudes.

Lee, Robert B., III↗
NASA NTRS1991

Validating system-level error recovery for spacecraft

The system-level software onboard a spacecraft is responsible for recovery from communication, thermal, power, and computer-health anomalies that may occur. The recovery must occur without disrupting any critical scientific or engineering activity that is executing at the time of the error. Thus, the error-recovery software may have to execute concurrently with the ongoing acquisition of scientific data or with spacecraft maneuvers. This paper provides a technique by which the rules that constrain the concurrent execution of these processes can be modeled in a graph. An algorithm is described that uses this model to validate that the constraints hold for all concurrent executions of the error-recovery softwave with the softwave that controls the science and engineering events on the spacecraft.

Lutz, Robyn R.↗
NASA NTRS1993

Constraint checking during error recovery

The system-level software onboard a spacecraft is responsible for recovery from communication, power, thermal, and computer-health anomalies that may occur. The recovery must occur without disrupting any critical scientific or engineering activity that is executing at the time of the error. Thus, the error-recovery software may have to execute concurrently with the ongoing acquisition of scientific data or with spacecraft maneuvers. This work provides a technique by which the rules that constrain the concurrent execution of these processes can be modeled in a graph. An algorithm is described that uses this model to validate that the constraints hold for all concurrent executions of the error-recovery software with the software that controls the science and engineering activities of the spacecraft. The results are applicable to a variety of control systems with critical constraints on the timing and ordering of the events they control.

Lutz, Robyn R.↗
NASA NTRS1990

Spacecraft preliminary orbit determination using tracking measurements obtained from the Tracking and Data Relay Satellite System (TDRSS) and the Ground Spaceflight Tracking and Data Network (GSTDN)

In order to validate the operational and computational capabilities of the Preliminary Orbit Determination System (PODS), tests were performed using tracking measurements for several systems including the ERB satellite, the SMM, the STS and Landsat-4. POD procedures are utilized to generate a state vector following an unplanned orbital perturbation or spacecraft maneuver, when an estimation process such as a differential correction orbit determination cannot obtain a solution. Results are presented to demonstrate POD for several situations involving different qualities of a priori target state vectors, data type combinations, data arc lengths, and mixtures of single-TDRS, dual-TDRS, and GSTDN measurements. The system's ability to determine accurately the state vector for the spacecraft and the effectiveness of the solution screening process are discussed. It is shown that PODS is capable of determining a spacecraft vector when differential correction orbit determination processes fail.

Kirschner, S. M.↗
NASA NTRS1994

SCL: An off-the-shelf system for spacecraft control

In this age of shrinking military, civil, and commercial space budgets, an off-the-shelf solution is needed to provide a multimission approach to spacecraft control. A standard operational interface which can be applied to multiple spacecraft allows a common approach to ground and space operations. A trend for many space programs has been to reduce operational staff by applying autonomy to the spacecraft and to the ground stations. The Spacecraft Command Language (SCL) system developed by Interface and Control Systems, Inc. (ICS) provides an off-the-shelf solution for spacecraft operations. The SCL system is designed to provide a hyper-scripting interface which remains standard from program to program. The spacecraft and ground station hardware specifics are isolated to provide the maximum amount of portability from system to system. Uplink and downlink interfaces are also isolated to allow the system to perform independent of the communications protocols chosen. The SCL system can be used for both the ground stations and the spacecraft, or as a value added package for existing ground station environments. The SCL system provides an expanded stored commanding capability as well as a rule-based expert system on-board. The expert system allows reactive control on-board the spacecraft for functions such as electrical power systems (EPS), thermal control, etc. which have traditionally been performed on the ground. The SCL rule and scripting capability share a common syntax allowing control of scripts from rules and rules from scripts. Rather than telemeter over sampled data to the ground, the SCL system maintains a database on-board which is available for interrogation by the scripts and rules. The SCL knowledge base is constructed on the ground and uploaded to the spacecraft. The SCL system follows an open-systems approach allowing other tasks to communicate with SCL on the ground and in space. The SCL system was used on the Clementine program (launched January 25, 1994) and is required to have bidirectional communications with the guidance, navigation, and control (GNC) algorithms which were written as another task. Sequencing of the spacecraft maneuvers are handled by SCL, but the low-level thruster pulse commands are handled by the GNC software. Attitude information is reported back as telemetry, allowing the SCL expert system to inference on the changing data. The Clementine SCL flight software was largely reused from another Naval Center for Space Technology (NCST) satellite program. This paper details the SCL architecture and how an off-the-shelf solution makes sense for multimission spacecraft programs. The Clementine mission will be used as a case study in the application of the SCL to a 'fast track' program. The benefits of such a system in a 'better, cheaper, faster' climate will be discussed.

Buckley, Brian↗
NASA NTRS1988

Maneuvering strategies using CMGs

This paper considers control strategies for maneuvering spacecraft using Single-Gimbal Control Momentum Gyros (CMGs). A pyramid configuration using four gyros is utilized. Preferred initial gimbal angles for maximum utilization of CMG momentum are obtained for some known torque commands. Feedback control laws are derived from the stability point of view by using the Liapunov's Second Theorem. The gyro rates are obtained by the pseudo-inverse technique. The effect of gimbal rate bounds on controllability are studied for an example maneuver. Singularity avoidance is based on limiting the gyro rates depending on a singularity index.

Oh, H. S.↗
NASA NTRS1972

A Monte Carlo error analysis program for near-Mars, finite-burn, orbital transfer maneuvers

A computer program was developed which performs an error analysis of a minimum-fuel, finite-thrust, transfer maneuver between two Keplerian orbits in the vicinity of Mars. The method of analysis is the Monte Carlo approach where each off-nominal initial orbit is targeted to the desired final orbit. The errors in the initial orbit are described by two covariance matrices of state deviations and tracking errors. The function of the program is to relate these errors to the resulting errors in the final orbit. The equations of motion for the transfer trajectory are those of a spacecraft maneuvering with constant thrust and mass-flow rate in the neighborhood of a single body. The thrust vector is allowed to rotate in a plane with a constant pitch rate. The transfer trajectory is characterized by six control parameters and the final orbit is defined, or partially defined, by the desired target parameters. The program is applicable to the deboost maneuver (hyperbola to ellipse), orbital trim maneuver (ellipse to ellipse), fly-by maneuver (hyperbola to hyperbola), escape maneuvers (ellipse to hyperbola), and deorbit maneuver.

Green, R. N.↗
NASA NTRS2004

NASA Tech Briefs, December 2004

opics include: High-Rate Digital Receiver Board; Signal Design for Improved Ranging Among Multiple Transceivers; Automated Analysis, Classification, and Display of Waveforms; Fast-Acquisition/Weak-Signal-Tracking GPS Receiver for HEO; Format for Interchange and Display of 3D Terrain Data; Program Analyzes Radar Altimeter Data; Indoor Navigation using Direction Sensor and Beacons; Software Assists in Responding to Anomalous Conditions; Software for Autonomous Spacecraft Maneuvers; WinPlot; Software for Automated Testing of Mission-Control Displays; Nanocarpets for Trapping Microscopic Particles; Precious-Metal Salt Coatings for Detecting Hydrazines; Amplifying Electrochemical Indicators; Better End-Cap Processing for Oxidation-Resistant Polyimides; Carbon-Fiber Brush Heat Exchangers; Solar-Powered Airplane with Cameras and WLAN; A Resonator for Low-Threshold Frequency Conversion; Masked Proportional Routing; Algorithm Determines Wind Speed and Direction from Venturi-Sensor Data; Feature-Identification and Data-Compression Software; Alternative Attitude Commanding and Control for Precise Spacecraft Landing; Inspecting Friction Stir Welding using Electromagnetic Probes; and Helicity in Supercritical O2/H2 and C7H16/N2 Mixing Layers.

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