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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 649 records · Page 36

Mechanical design of SERT 2 thruster system

The mechanical design of the mercury bombardment thruster that was tested on SERT is described. The report shows how the structural, thermal, electrical, material compatibility, and neutral mercury coating considerations affected the design and integration of the subsystems and components. The SERT 2 spacecraft with two thrusters was launched on February 3, 1970. One thruster operated for 3782 hours and the other for 2011 hours. A high voltage short resulting from buildup of loose eroded material was believed to be the cause of failure.

Zavesky, R. J.↗

Electrostatic waves in the magnetosphere.

Electric dipole antennas on magnetospheric spacecraft measure E field components of many kinds of electromagnetic waves. In addition, lower hybrid resonance emissions are frequently observed well above the ionosphere. The Ogo 5 plasma wave experiment has also detected new forms of electrostatic emissions that appear to interact very strongly with the local plasma particles. Greatly enhanced wave amplitudes have been found during the expansion phases of substorms, and analysis indicates that these emissions produce strong pitch angle diffusion. Intense broadband electrostatic turbulence is also detected at current layers containing steep magnetic field gradients. This current-driven instability is operative at the bow shock and also at field null regions just within the magnetosheath, and at the magnetopause near the dayside polar cusp. The plasma turbulence appears to involve ion acoustic waves, and the wave particle scattering provides an important collisionless dissipation mechanism for field merging.

Scarf, F. L.↗

An approach to thermal-vacuum test optimization

An analytical model is presented that simulates failure rate characteristics of spacecraft equipment progressing through component and system level thermal-vacuum test programs and on into orbit. Costs for the test programs are part of the model as well as costs attributable to the mission. A lost value function combines the performance of the equipment with these costs and allows comparisons to be made among various test combinations and the resulting predicted mission performance. A minimum overall cost program is obtained by selecting that test program that yields the lowest lost value figure.

Kruger, R.↗

Space Shuttle payloads - An overview

A review is made of historical developments of NASA-launched payloads as a basis for projecting payload operations configured to fit the Shuttle's capabilities, and the impetus for new spacecraft and applications designs is discussed. Payloads have experienced a growth in size and weight, capacity and lifetime, and have increasingly featured more automation, microminiaturized circuitry, and data processing systems. Launches by the DoD and NASA have averaged about 20/yr. Spacecraft specifically configured for Shuttle launch have had to wait due to development schedule delays. Partial compensation has occurred by the use of the MMS, which fits into both the Delta nose cone and the Orbiter bay. The Landsat-4 and SMM are cited as examples. Successful demonstration of in-orbit servicing of satellites is required in order to attract spacecraft designers who will make full use of the Shuttle's capabilities. Finally, increased standardization of spacecraft shape, interfaces, and components is foreseeen.

Edgecombe, D. S.↗

Research in solar physics: Some techniques for analyzing data from the ultraviolet spectrometer and polarimeter

Useful information for certain aspects of the analysis of data obtained by the Ultraviolet Spectrometer and Polarimeter (UVSP) on the Solar Maximum Mission (SMM) are contained. The meaning of the UVSPCO-ordinate system and the SMM roll, pitch, and yaw are described and the process for overlaying UVSP images is explained. The various computer programs that calculate the line of sight component of the SMM spacecraft velocity from the spacecraft to the Sun is described. The spacecraft velocity is used to correct or interpret the signal observed in USVP dopplergrams. A method of using the spacecraft velocity to calibrate UVSP dopplergrams and magnetograms, i.e., determine the width of the observed emission line is applied. The UVSP polarization analysis procedures are described and the expressions for the statistical uncertainties in various quantities obtained from UVSP measurements are given.

Henze, W., Jr.↗

The Capillary Pumped Loop (CPL) GAS experiment G-471

The Capillary Pumped Loop (CPL) experiment, 6-471 is a thermal control system with high density heat acquisition and transport capability. The CPL consists of two capillary pumped evaporators with integral heaters, a fluid loop charged with ammonia (NH3), a condenser plate (heat sink), and various control electronics. The purpose of the experiment is to demonstrate the capability of a capillary pumped system under zero gravity conditions for use in the thermal control of large scientific instruments, advanced orbiting spacecraft, and space station components. A unique feature of the CPL is the capillary pumps, which contain no moving parts. Each pump contains a wick of porous material which is saturated with the working fluid (anhydrous ammonia). As heat is added to the fluid, it evaporates and travels to the condenser, thus transporting the heat (via the latent heat of vaporization) from the heat source to its sink at nearly a constant temperature. The evaporation process produces the pressure gradient or pumping action that circulates the fluid. This is the same principal that plants and trees use to transport water and nutrients from their roots to their leaves against gravity. The difference is that the CPL employs a closed system to return the fluid directly to the pumps, whereas "Mother Nature'' has an open system where the fluid is indirectly returned to the roots by condensation of water from the clouds in the form of rain. It should be noted that the CPL experiment was the first flight of a thermal control system of this type. It was also the first shuttle experiment from the Space Station Advanced Development Program.

Dan Butler↗

LANDSAT-D program. Volume 2: Ground segment

Raw digital data, as received from the LANDSAT spacecraft, cannot generate images that meet specifications. Radiometric corrections must be made to compensate for aging and for differences in sensitivity among the instrument sensors. Geometric corrections must be made to compensate for off-nadir look angle, and to calculate spacecraft drift from its prescribed path. Corrections must also be made for look-angle jitter caused by vibrations induced by spacecraft equipment. The major components of the LANDSAT ground segment and their functions are discussed.

Source record↗

Planetary operations for the Pioneer Venus Orbiter mission

The Pioneer Venus Orbiter was inserted into Venus orbit on December 4, 1974 and is expected to operate until 1992. This paper discusses the scientific objectives of the Pioneer Venus Orbiter Project components, i.e., the Orbiter spacecraft, the atmosphere entry Probes, and the probe Bus, together with the design and operation characteristics of the Orbiter. Consideration is also given to the science instruments of the Orbiter, to their requirements with respect to pointing, orientation, and timing, and to the ground operations system. The Probes, the Bus, and the Orbiter were selected to study Venus in complementary ways: the Probes by sounding through most of the atmosphere at four locations, the probe Bus by sounding through the upper atmosphere during entry, and the Orbiter by in situ planet-wide observations of the ionosphere and the extreme upper atmosphere, and by examining the surface and interior remotely. In addition, the Orbiter also observes the interactions of Venus with the solar environment.

Jackson, Robert W.↗

Feasibility of vibration monitoring of small rotating machines for the environmental control and life support systems (ECLSS) of the NASA advanced space craft

The application of vibration monitoring to the rotating machinery typical of ECLSS components in advanced NASA spacecraft was studied. It is found that the weighted summation of the accelerometer power spectrum is the most successful detection scheme for a majority of problem types. Other detection schemes studied included high-frequency demodulation, cepstrum, clustering, and amplitude processing.

Milner, G. Martin↗

Putting Voyager together

The development of the Voyager missions is reviewed. The development of the technology is described, and the various components of the Voyager spacecraft are depicted and their functions identified. The budget pressures and their effects on the missions are discussed, and the problems experienced by the Voyager 2 spacecraft on its mission, and the way those were solved, are summarized.

Mclaughlin, William I.↗

Enhanced element-specific modal formulations for flexible multibody dynamics

The accuracy of current flexible multibody formalisms based on assumed modes is examined in the context of standard spacecraft motions involving structural components undergoing both slow and fast overall translational and rotational motions as well as small deformations. Limitations of current techniques in treating: (1) element-specific coupling behavior of large motion and small deformation, and (2) motion-induced structural stiffness variations, are noted. The roles of nonlinear and linear elastic structural theories in accurately predicting transient large-displacement dynamic behavior of flexible multibody systems are examined in detail. Coupling effects between deformation and overall motion are carefully scrutinized in the context of assumed-mode discretization techniques. Consistently linearized beam, plate, and shell formulations involving in-plane stretch variables are proposed and shown to yield very accurate simulation results and extremely fast modal convergence for most motions involving small strains. In some particular cases, however, in which membrane stiffness dominates bending stiffness, a nonlinear strain formulation is required in order to capture proper coupling between deformation and overall motion.

Ryan, Robert R.↗

Development and integration of the capillary pumped loop GAS and Hitchhiker flight experiments

The Capillary Pumped Loop (CPL) is a thermal control system with high density heat acquisition and transport capability. A small spaceflight version of the CPL was built and flown as a GAS experiment on STS 51-D in April 1985 and STS 51-G in June 1985, and as a Hitchhiker-G experiment on STS 61-C in January 1986. The purpose of the experiments was to demonstrate the capability of a capillary pumped system under microgravity conditions for use in the thermal control of large scientific instruments, advanced orbiting spacecraft, and space station components. The development, integration, and test activities of the CPL are described.

Butler, D.↗

Reusable Cryogenic-Liquid Tank With Replaceable Liner

Conceptual tank with replaceable liner holds liquid propellant and is suitable for reuse in spacecraft propulsion systems. Main components are: composite outer shell for containment of pressure, replaceable membrane liner, and foam-filled honeycomb sandwich bonded to inside of tank to insulate and stabilize wall of tank. Concept maximizes potential of filament-wound composite pressure shells with strength-to-density ratios five times those of comparable aluminum shells. Reduction in weight as much as 50 percent.

Freeman, William T., Jr.↗

Contamination of optical surfaces in Earth orbit

Glass and glass ceramic samples exposed to the low earth orbit environment for approximately 5.5 years on the Long Duration Exposure Facility (LDEF) were found to display limited degradation in optical transmission. Commercial optical quality fused silica samples display decreases in transmission in the 200 to 400 nm wavelength region, and this degradation appears to be a consequence of surface contamination. The contamination, found only on internal surfaces of samples, was measured by medium energy backscattering spectrometry and found to be primarily carbon. Additional thin film contamination by a species with atomic mass near 64, which was present at the level of about 8 x 10 exp 14/sq. cm has not been identified. These observations are consistent with the interpretation that organic binders used in the black absorbing paint (Chem Glaze Z-306) inside the sample holding tray were concentrated in the vicinity of the samples and photolytically cracked by solar UV radiation. The resulting decomposition products were deposited on the interior sample surface and gave rise to the optical transmission loss. No detectable contamination was observed on the external or space exposed surface of the samples. No measurable damage was detected which could be attributed to the direct action of gamma or UV radiation on the glass samples. These results emphasize the need for special precautions in the preparation of spacecraft carrying precision optical components on long duration missions.

Donald L Kinser↗

Spacecraft on-orbit coupled loads analysis

A method is presented for coupled loads analysis of on-orbit spacecraft systems. Discrete models are coupled then reduced using the Craig-Bampton technique. Coupled system transient response is determined as well as substructure interface forces and center-of-gravity accelerations. Typical results are presented for a spacecraft system having three components and being subjected to rocket motor thrust.

Tinker, Michael L.↗

Space Exploration Initiative

An overview of President Bush's Space Exploration Initiative (SEI) and it's three main components, Space Station Freedom, a Permanent Lunar Base, and a Manned Mission to Mars is provided. Computer simulations of the Space Station Freedom and Permanent Lunar Base are shown, and an animated sequence describes a Mars mission where heavy lift vehicle will bring components of a Mars Spacecraft into orbit, where it will be put together by astronauts using a robotic arm. The Mars spacecraft is shown orbiting Mars and discharging a lander to the surface, carrying human explorers. The video also details the SEI's Outreach Program, designed to garner interest in and ideas for Space Exploration.

Source record↗

Optical Chopper Assembly for the Mars Observer

This paper describes the Honeywell-developed Optical Chopper Assembly (OCA), a component of Mars Observer spacecraft's Pressure Modulator Infrared Radiometer (PMIRR) science experiment, which will map the Martian atmosphere during 1993 to 1995. The OCA is unique because of its constant accurate rotational speed, low electrical power consumption, and long-life requirements. These strict and demanding requirements were achieved by use of a number of novel approaches.

Allen, Terry↗