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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Remotely manned systems: Exploration and operation in space; Proceedings of the First National Conference, California Institute of Technology, Pasadena, Calif., September 13-15, 1972.

Free-flying teleoperator systems are discussed, giving attention to earth-orbit mission considerations and Space Tug requirements, free-flying teleoperator requirements and conceptual design, system requirements for a free-flying teleoperator to despin, and the experimental evaluation of remote manipulator systems. Shuttle-Attached Manipulator Systems are considered, together with remote surface vehicle systems, manipulator systems technology, remote sensor and display technology, the man-machine interface, and control and machine intelligence. Nonspace applications are also explored, taking into account implications of nonspace applications, naval applications of remote manipulators, and hand tools and mechanical accessories for a deep submersible. Individual items are announced in this issue.

Heer, E.↗
NASA NTRS1973

Telescopic booms for the Hawkeye spacecraft

Several boom arrangements were proposed for the Hawkeye spacecraft. The design chosen to fly consists of one pair of stem roll-out booms and a set of telescopic booms. Some of the advantages of choosing this boom configuration were that the booms could be stored in the belt line area, which is near the center of gravity of the spacecraft, and also with the approach the telescopic booms could be extended at the spacecraft's initial spin rate (180 rpm). By being able to extend these booms at the initial spin rate of the spacecraft the need for a despin system was eliminated, thus weight saving to the spacecraft. With the method of storage and extension employed by the telescopic design, the desirable sensor distance from the spacecraft could also be attained.

Anderson, R. D.↗
NASA NTRS1975

Analysis of RAE-B attitude data

Attempts made to obtain a description of the in-orbit dynamic behavior of the RAE-B spacecraft and account for the discrepancies between predicted and actual in-orbit performance are reported. In particular, attitude dynamics during the final despin operations in lunar orbit, throughout all deployment operations, and into the final steady state mission mode were investigated. Attempts made to match computer simulation results to the observed equilibrium data are discussed. Due to a damaged antenna boom and the unavailability of sufficient attitude and dynamics data, most of the objectives were not realized.

Hedland, D. A.↗
NASA NTRS1974

The source of Neptune's internal heat and the value of Neptune's tidal dissipation factor

The suggestion is made that Neptune's observed internal heating is the action of tidal torques between Triton and Neptune in despinning the planet and causing the orbital decay of Triton's orbit. These result from the frictional dissipation of tides within Neptune. It is shown that the considered process implies a value of the tidal dissipation factor of approximately 170. The results of the investigation do not change the conclusion which follows from the lack of internal heating for Uranus that the interiors of Uranus and Neptune differ significantly.

Trafton, L.↗
NASA NTRS1975

Analytical stability and simulation response study for a coupled two-body system

An analytical stability study and a digital simulation response study of two connected rigid bodies are documented. Relative rotation of the bodies at the connection is allowed, thereby providing a model suitable for studying system stability and response during a soft-dock regime. Provisions are made of a docking port axes alignment torque and a despin torque capability for encountering spinning payloads. Although the stability analysis is based on linearized equations, the digital simulation is based on nonlinear models.

Tao, K. M.↗
NASA NTRS1976

Design principles of a rotating medium speed mechanism

Design principles of a medium speed mechanism (MSM) are presented, including discussion on the relative merits of beryllium and aluminium as structural materials. Rotating at a speed of 60 rpm, the application envisaged for the MSM was as a despin bearing for the despun platform or despun antenna of a spin stabilized satellite. The MSM was built and tested to qualification level and is currently undergoing real time life testing.

Hostenkamp, R. G.↗
NASA NTRS1976

Large Diameter Shuttle Launched-AEM (LDSL-AEM) study

A technical description of a Large Diameter Shuttle Launched-AEM (LDSL-AEM), an AEM base module adapted to carry 5 ft diameter payloads in the shuttle with propulsion for carrying payloads to higher altitude orbits from a 150 NM shuttle orbit, is described. The AEM is designed for launch on the scout launch vehicle. Onboard equipment provides capability to despin, acquire the earth, and control the vehicle in an earth pointing mode using reaction wheels for torque with magnets for all attitude acquisition, wheel desaturation, and nutation damping. Earth sensors in the wheels provide pitch and roll attitude. This system provides autonomous control capability to 1 degree in pitch and roll and 2 degrees in yaw. The attitude can be determined to .5 degrees in pitch and roll and 2 degrees in yaw.

Source record↗
NASA NTRS1977

Global tectonics of Mercury and the moon

Lobate scarps on Mercury have been studied to determine the nature of the surface stress history and implications for the planet's early tectonic history. Morphologic and transection relations indicate that most Mercurian scarps are tectonic in nature and are due to compressive stresses in the surface layer. The azimuthal distribution of lobate-scarp trends is compatible with an early predominantly compressive global stress field due to thermal shrinkage of the planet. Superposition relations indicate that the contractive phase was largely a pre-Caloris process. The effects of stresses due to planetary despinning were either negligible, predate the scarps, or were largely obscured by cratering or volcanism. The tectonic history of Mercury as recorded in the lobate scarps is different from that which caused the system of lineaments on the moon.

Cordell, B. M.↗
NASA NTRS1978

Design and evaluation of a rotating variable conductance heat pipe system

Analysis of the Dynamics Explorer high orbiter spacecraft showed that the proposed louver system, along with existing radiator heat rejection areas on the S/C surface were insufficient to safely control the S/C's thermal excursions caused by highly varying internal power levels and solar input angles. A variable conductance heat pipe system in conjunction with a conventional radial heat pipe system was designed, built, tested, and shown to resolve this problem. The conventional pipes, radial, spinning at 10 rpm were required to carry 35 watts each after experiencing despin from 80 rpm. The VCHPs attached to the radial pipes at the S/C perimeter distributed the excess energy via a finned radiator attached around the S/C's center.

Marshburn, J. P.↗
NASA NTRS1978

Attitude control algorithms for the Solar Maximum Mission

Algorithms for onboard attitude control of the Solar Maximum Mission (SMM) are discussed and test results are presented. The algorithms include: despin and sun acquisition, control of pitch and yaw (sun pointing) to 5 arc-sec accuracy and roll (around the sun line) to 0.1 deg, time-optimal and constant-rate slew sequences, attitude maintenance during orbit night and sun reacquisition at orbit dawn, momentum unloading, and gyro drift calibration. The tests were performed on the SMM Software Development and Validation Facility at the NASA Goddard Space Flight Center with a FORTRAN prototype version of the onboard software.

Markley, F. L.↗
NASA NTRS1978

Galileo dual-spin attitude and articulation control system

Galileo, the first outer planet explorer to be configured as a dual spinner, will conduct intensive investigation of Jupiter's atmosphere, satellites, and magnetosphere. The exacting mission, coupled with the inherently complex spin and flexible body dynamics of the vehicle, demands careful design of the Galileo Attitude and Articulation Control System (AACS). A brief overview of the Galileo mission and spacecraft is presented, followed by a detailed discussion on the mechanization of the AACS and the many factors that influence its design. Included are discussions on attitude determination and control, high-gain antenna pointing, science scan platform pointing, nutation damping, wobble compensation, spin and despin control, and propellant migration and boom flexibility effects.

Ward, R. S.↗
NASA NTRS1979

Pioneer Venus Star Sensor

The design predictions and orbital performance verification of the solid state star scanner used in the Onboard Attitude Control of the Pioneer Venus Orbiter and Multiprobe are presented. The star sensor extended the scanner use to active despin control, and it differs from previous sensors in solid state detection, redundant electronics for reliability, larger field of view, and large dynamic spin range. The star scanner hardware and design performance based on the ability to predict all noise sources, signal magnitudes, and expected detection probability are discussed. In-flight data collected to verify sensor ground calibration are tabulated and plotted in predicted accuracy curves. It is concluded that the Pioneer Venus Star Sensor has demonstrated predictable star calibration in the range of .1 magnitude uncertainties and usable star catalogs of 100 stars with very high probabilities of detection, which were much better than expected and well within the mission requirements.

Gutshall, R. L.↗
NASA NTRS1980

Atmospheric tides and the rotation of Venus. I - Tidal theory and the balance of torques

Insolation absorbed by the surface of Venus is quickly redeposited at the bottom of the atmosphere. This periodic heating causes mass to flow away from the warm afternoon side of the planet and into the cooler morning region. The Sun's gravitational field exerts a torque on this atmospheric tide tending to accelerate the retrograde zonal circulation. When this torque is transmitted to the crust, it can balance the despinning effect of tides in the body of Venus. The slow retrograde rotation of Venus may be a steady state among tides in the atmosphere, tides in the solid body, and possibly the influence of the Earth.

Dobrovolskis, A. R.↗
NASA NTRS1981

Ejecta patterns diagnostic of planetary rotations

A new scheme for determining a body's rotational history from the geological record is presented. Trajectories of ejecta on a rotating object are affected by the Coriolis effect in a manner characteristic of the direction and speed of the object's spin. This information is registered on the surface in the form of debris deposits and ray patterns, and can be interpreted by comparing photographs of the planet's surface with specified paradigms. This approach has the advantage of being independent of the body's internal structure and of relating its rotational history directly to its cratering chronology. This approach could be used, for example, to date the despinning of Mercury relative to its latest bombardment.

Dobrovolskis, A.↗
NASA NTRS1983

Integrated Power/Attitude Control System (IPACS)

During orbit day, solar energy collected by the solar cell arrays and transformed into electrical energy is used to power the spacecraft subsystems, including the control system. In conventional spacecraft designs, a portion of the energy collected during the light portion of the orbit is stored in a set of batteries for use during orbit night. In the Integrated Power/Attitude Control System (IPACS) approach, that energy is stored in the rotating flywheel in the form of kinetic energy. Umbra electrical power demands are satisfied by attaching a generator to the wheel shaft and despinning the rotor. Through this approach, the battery system is no longer required and thus is eliminated.

Keckler, C. R.↗
NASA NTRS1983

The magnetic-field investigation on ISPM

The International Solar Polar Mission (ISPM) onboard instrumentation for the magnetic field experiment to establish, on the basis of in-situ observations, the heliolatitude dependence of the interplanetary magnetic field, is described. The prime output consists of vector measurements, made by two triaxial magnetometers, of the ambient magnetic field along the orbit of the spacecraft. The onboard data processor generates two data streams to be transmitted through the spacecraft telemetry. The low speed, analog data stream consists of averaged and despun vector measurements, digitized in the spacecraft analog to digital converter (ADC). The despinning algorithm used in the analog processor is described. The high speed, digital data stream consists of vector measurements digitized in the instrument ADCs, generating up to two vector samples per sec. Multiple data-path switching is used to increase system reliability and to allow cross calibration of the ADCs. On board facilities for inflight calibration are described.

Balogh, A.↗
NASA NTRS1984

An attitude reorientation algorithm for the Galileo spacecraft

This paper presents an onboard closed loop attitude reorientation algorithm for a dual-spin spacecraft, Galileo. The basic concept for the design uses the despun stator as a reference and fires a sequence of fixed duration thruster pulses to precess the angular momentum vector to its commanded orientation. The error signals used to despin the stator and to perform the turn are derived from the stator error quaternion which is computed using gyro outputs. Constraints considered in the design include gyro rate saturation, plume impingement effects, system parameter variations, as well as software reliability and flexibility. The performance of the algorithm was predicted by analysis and confirmed by computer simulation results. It was concluded that a reorientation accuracy of better than 1 milliradian with a nutation angle of less than 1 degree during the turn can be achieved.

Lin, H.-S.↗