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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2013

Precise Truss Assembly using Commodity Parts and Low Precision Welding

We describe an Intelligent Precision Jigging Robot (IPJR), which allows high precision assembly of commodity parts with low-precision bonding. We present preliminary experiments in 2D that are motivated by the problem of assembling a space telescope optical bench on orbit using inexpensive, stock hardware and low-precision welding. An IPJR is a robot that acts as the precise "jigging", holding parts of a local assembly site in place while an external low precision assembly agent cuts and welds members. The prototype presented in this paper allows an assembly agent (in this case, a human using only low precision tools), to assemble a 2D truss made of wooden dowels to a precision on the order of millimeters over a span on the order of meters. We report the challenges of designing the IPJR hardware and software, analyze the error in assembly, document the test results over several experiments including a large-scale ring structure, and describe future work to implement the IPJR in 3D and with micron precision.

Komendera, Erik↗
NASA NTRS2014

Precise Truss Assembly Using Commodity Parts and Low Precision Welding

Hardware and software design and system integration for an intelligent precision jigging robot (IPJR), which allows high precision assembly using commodity parts and low-precision bonding, is described. Preliminary 2D experiments that are motivated by the problem of assembling space telescope optical benches and very large manipulators on orbit using inexpensive, stock hardware and low-precision welding are also described. An IPJR is a robot that acts as the precise "jigging", holding parts of a local structure assembly site in place, while an external low precision assembly agent cuts and welds members. The prototype presented in this paper allows an assembly agent (for this prototype, a human using only low precision tools), to assemble a 2D truss made of wooden dowels to a precision on the order of millimeters over a span on the order of meters. The analysis of the assembly error and the results of building a square structure and a ring structure are discussed. Options for future work, to extend the IPJR paradigm to building in 3D structures at micron precision are also summarized.

Komendera, Erik↗
NASA NTRS1986

High precision low resolution spectrophotometry of Comets Giacobini-Zinner and Halley

Optical window (300 to 1000 nm) observations were made of Comet Halley during 12 to 14 Mar. 1986 by a scanning spectrometer. The results provide accurate spectrophotometric measurements of the principal molecular bands from the 308 nm OH through the 918 nm CN emissions. The observations can be used to tie space derived ultraviolet and groundbased infrared observations to the optical observations and to one another. Additional observations were made of comet Giacobini-Zinner on 30 September 1985 of the same OH band and the 388 nm band of CN. The Swan band sequence ratios are used to test the best models of C2, with different ratios favoring different models, calling into question the assumptions of these very complete models.

Odell, C. R.↗
NASA NTRS1990

Precise Hinge Has Low Friction

Precise hinge rotates with minimal friction and without "slop". Axis of rotation at central axis of concentric, self-retaining assembly. Blades in same plane, and both edges of blades and apexes of grooves lie along same line, allowing free rotation without either binding or slop. Blades on rotor engage grooves on stator. Blades pivot about edges through arc defined by slotted openings in stator housing.

Collins, Earl R., Jr.↗
NASA NTRS1990

Indexing system for optical beam steering

This paper describes the design and testing of an indexing system for optical-beam steering. The cryogenic beam-steering mechanism is a 360-degree rotation device capable of discrete, high-precision alignment positions. It uses low-precision components for its rough alignment and kinematic design to meet its stringent repeatability and stability requirements (of about 5 arcsec). The principal advantages of this design include a decoupling of the low-precision, large angular motion from the high-precision alignment, and a power-off alignment position that potentially extends the life or hold time of cryogenic systems. An alternate design, which takes advantage of these attributes while reducing overall motion, is also presented. Preliminary test results show the kinematic mount capable of sub-arc second repeatability.

Sullivan, Mark T.↗
NASA NTRS2010

Characterization of Low Noise, Precision Voltage Reference REF5025-HT Under Extreme Temperatures

The performance of Texas Instruments precision voltage reference REF5025-HT was assessed under extreme temperatures. This low noise, 2.5 V output chip is suitable for use in high temperature down-hole drilling applications, but no data existed on its performance at cryogenic temperatures. The device was characterized in terms of output voltage and supply current at different input voltage levels as a function of temperature between +210 C and -190 C. Line and load regulation characteristics were also established at six load levels and at different temperatures. Restart capability at extreme temperatures and the effects of thermal cycling, covering the test temperature range, on its operation and stability were also investigated. Under no load condition, the voltage reference chip exhibited good stability in its output over the temperature range of -50 C to +200 C. Outside that temperature range, output voltage did change as temperature was changed. For example, at the extreme temperatures of +210 C and - 190 C, the output level dropped to 2.43 V and 2.32 V, respectively as compared to the nominal value of 2.5 V. At cryogenic test temperatures of -100 C and -150 C the output voltage dropped by about 20%. The quiescent supply current of the voltage reference varied slightly with temperature but remained close to its specified value. In terms of line regulation, the device exhibited excellent stability between -50 C and +150 C over the entire input voltage range and load levels. At the other test temperatures, however, while line regulation became poor at cryogenic temperatures of -100 C and below, it suffered slight degradation at the extreme high temperature but only at the high load level of 10 mA. The voltage reference also exhibited very good load regulation with temperature down to -100 C, but its output dropped sharply at +210 C only at the heavy load of 10 mA. The semiconductor chip was able restart at the extreme temperatures of -190 C and +210 C, and the limited thermal cycling did not influence its characteristics and had no impact on its packaging as no structural or physical damage was observed.

Patterson, Richard↗
NASA NTRS2004

Design Considerations for an Integrated Solar Sail Diagnostics System

Efforts are continuing under NASA support to improve the readiness level of solar sail technology. Solar sails have one of the best chances to be the next gossamer spacecraft flown in space. In the gossamer spacecraft community thus far, solar sails have always been considered a "low precision" application compared with, say, radar or optical devices. However, as this paper shows, even low precision gossamer applications put extraordinary demands on structural measurement systems if they are to be traceable to use in space.

Jenkins, Christopher H. M.↗
NASA NTRS2012

An Efficient and Versatile Means for Assembling and Manufacturing Systems in Space

Within NASA Space Science, Exploration and the Office of Chief Technologist, there are Grand Challenges and advanced future exploration, science and commercial mission applications that could benefit significantly from large-span and large-area structural systems. Of particular and persistent interest to the Space Science community is the desire for large (in the 10- 50 meter range for main aperture diameter) space telescopes that would revolutionize space astronomy. Achieving these systems will likely require on-orbit assembly, but previous approaches for assembling large-scale telescope truss structures and systems in space have been perceived as very costly because they require high precision and custom components. These components rely on a large number of mechanical connections and supporting infrastructure that are unique to each application. In this paper, a new assembly paradigm that mitigates these concerns is proposed and described. A new assembly approach, developed to implement the paradigm, is developed incorporating: Intelligent Precision Jigging Robots, Electron-Beam welding, robotic handling/manipulation, operations assembly sequence and path planning, and low precision weldable structural elements. Key advantages of the new assembly paradigm, as well as concept descriptions and ongoing research and technology development efforts for each of the major elements are summarized.

Dorsey, John T.↗
NASA NTRS1985

Investigation of outside visual cues required for low speed and hover

Knowledge of the visual cues required in the performance of stabilized hover in VTOL aircraft is a prerequisite for the development of both cockpit displays and ground-based simulation systems. Attention is presently given to the viability of experimental test flight techniques as the bases for the identification of essential external cues in aggressive and precise low speed and hovering tasks. The analysis and flight test program conducted employed a helicopter and a pilot wearing lenses that could be electronically fogged, where the primary variables were field-of-view, large object 'macrotexture', and fine detail 'microtexture', in six different fields-of-view. Fundamental metrics are proposed for the quantification of the visual field, to allow comparisons between tests, simulations, and aircraft displays.

Hoh, R. H.↗
NASA NTRS2009

Silicon Microleaks for Inlets of Mass Spectrometers

Microleaks for inlets of mass spectrometers used to analyze atmospheric gases can be fabricated in silicon wafers by means of photolithography, etching, and other techniques that are commonly used in the manufacture of integrated circuits and microelectromechanical systems. The microleaks serve to limit the flows of the gases into the mass-spectrometer vacuums to specified very small flow rates consistent with the capacities of the spectrometer vacuum pumps. There is a need to be able to precisely tailor the dimensions of each microleak so as to tailor its conductance to a precise low value. (As used here, "conductance" signifies the ratio between the rate of flow in the leak and the pressure drop from the upstream to the downstream end of the leak.) To date, microleaks have been made, variously, of crimped metal tubes, pulled glass tubes, or frits. Crimped-metal and pulled-glass-tube microleaks cannot readily be fabricated repeatably to precise dimensions and are susceptible to clogging with droplets or particles. Frits tend to be differentially chemically reactive with various gas constituents and, hence, to distort the gas mixtures to be analyzed. The present approach involving microfabrication in silicon largely overcomes the disadvantages of the prior approaches.

Harpold, Dan↗
NASA NTRS2014

3D Printing In Zero-G ISS Technology Demonstration

The National Aeronautics and Space Administration (NASA) has a long term strategy to fabricate components and equipment on‐demand for manned missions to the Moon, Mars, and beyond. To support this strategy, NASA and Made in Space, Inc. are developing the 3D Printing In Zero‐G payload as a Technology Demonstration for the International Space Station (ISS). The 3D Printing In Zero‐G experiment ('3D Print') will be the first machine to perform 3D printing in space. The greater the distance from Earth and the longer the mission duration, the more difficult resupply becomes; this requires a change from the current spares, maintenance, repair, and hardware design model that has been used on the International Space Station (ISS) up until now. Given the extension of the ISS Program, which will inevitably result in replacement parts being required, the ISS is an ideal platform to begin changing the current model for resupply and repair to one that is more suitable for all exploration missions. 3D Printing, more formally known as Additive Manufacturing, is the method of building parts/objects/tools layer‐by‐layer. The 3D Print experiment will use extrusion‐based additive manufacturing, which involves building an object out of plastic deposited by a wire‐feed via an extruder head. Parts can be printed from data files loaded on the device at launch, as well as additional files uplinked to the device while on‐orbit. The plastic extrusion additive manufacturing process is a low‐energy, low‐mass solution to many common needs on board the ISS. The 3D Print payload will serve as the ideal first step to proving that process in space. It is unreasonable to expect NASA to launch large blocks of material from which parts or tools can be traditionally machined, and even more unreasonable to fly up multiple drill bits that would be required to machine parts from aerospace‐grade materials such as titanium 6‐4 alloy and Inconel. The technology to produce parts on demand, in space, offers unique design options that are not possible through traditional manufacturing methods while offering cost-effective, high‐precision, low‐unit on‐demand manufacturing. Thus, Additive Manufacturing capabilities are the foundation of an advanced manufacturing in space roadmap. The 3D Printing In Zero‐G experiment will demonstrate the capability of utilizing Additive Manufacturing technology in space. This will serve as the enabling first step to realizing an additive manufacturing, print‐on‐demand "machine shop" for long‐duration missions and sustaining human exploration of other planets, where there is extremely limited ability and availability of Earth‐based logistics support. Simply put, Additive Manufacturing in space is a critical enabling technology for NASA. It will provide the capability to produce hardware on‐demand, directly lowering cost and decreasing risk by having the exact part or tool needed in the time it takes to print. This capability will also provide the much‐needed solution to the cost, volume, and up‐mass constraints that prohibit launching everything needed for long‐duration or long‐distance missions from Earth, including spare parts and replacement systems. A successful mission for the 3D Printing In Zero‐G payload is the first step to demonstrate the capability of printing on orbit. The data gathered and lessons learned from this demonstration will be applied to the next generation of additive manufacturing technology on orbit. It is expected that Additive Manufacturing technology will quickly become a critical part of any mission's infrastructure.

Werkheiser, Niki↗
NASA NTRS2011

Bonding Thin Mirror Segments Without Distortion for the International X-Ray Observatory

The International X-Ray Observatory (IXO) uses thin glass optics to maximize large effective area and precise low angular resolution. The thin glass mirror segments must be transferred from their fabricated state to a permanent structure without imparting distortion. IXO will incorporate about fourteen thousand thin mirror segments to achieve the mission goal of 3.0 square meters of effective area at 1.25 keV with an angular resolution of five arcseconds. To preserve figure and alignment, the mirror segment must be bonded with sub-micron movement at each corner. Recent advances in technology development have produced significant x-ray test results of a bonded pair of mirrors. Three specific bonding cycles will be described highlighting the improvements in procedure, temperature control, and precision bonding. This paper will highlight the recent advances in alignment and permanent bonding as well as the results they have produced.

Evans, Tyler C.↗
NASA NTRS1986

Baseline experiments in teleoperator control

Studies have been conducted at the NASA Langley Research Center (LaRC) to establish baseline human teleoperator interface data and to assess the influence of some of the interface parameters on human performance in teleoperation. As baseline data, the results will be used to assess future interface improvements resulting from this research in basic teleoperator human factors. In addition, the data have been used to validate LaRC's basic teleoperator hardware setup and to compare initial teleoperator study results. Four subjects controlled a modified industrial manipulator to perform a simple task involving both high and low precision. Two different schemes for controlling the manipulator were studied along with both direct and indirect viewing of the task. Performance of the task was measured as the length of time required to complete the task along with the number of errors made in the process. Analyses of variance were computed to determine the significance of the influences of each of the independent variables. Comparisons were also made between the LaRC data and data taken earlier by Grumman Aerospace Corp. at their facilities.

Hankins, W. W., III↗
NASA NTRS1989

Error-Compensated Telescope

Proposed reflecting telescope includes large, low-precision primary mirror stage and small, precise correcting mirror. Correcting mirror machined under computer control to compensate for error in primary mirror. Correcting mirror machined by diamond cutting tool. Computer analyzes interferometric measurements of primary mirror to determine shape of surface of correcting mirror needed to compensate for errors in wave front reflected from primary mirror and commands position and movement of cutting tool accordingly.

Meinel, Aden B.↗
NASA NTRS1989

Closed loop navigation and guidance for gravity probe B orbit insertion

This paper addresses the problem of guiding the Gravity Probe B (GP-B) spacecraft from its location after initial insertion to a very precise low earth orbit. Specifically, the satellite orbit is required to be circular to within 0.001 eccentricity, polar to within 0.001 deg inclination, and aligned with the direction of the star Rigel to within 0.001 deg. Navigation data supplied by an on-board GPS receiver is used as feedback to a control algorithm designed to minimize the time to achieve the desired orbit. Translational control is provided by the proportional helium thrusters, which are used for drag-free and attitude control during the remainder of the science mission. Simulations of the guidance system are presented which give an indication of performance characteristics for several types of orbit injection errors. This research is the first reported effort to use GPS as a sensor for a closed loop space guidance system.

Axelrad, P.↗
NASA NTRS1989

Thermal design for the Comet Rendezvous Asteroid Flyby spacecraft

The mission overview of the Comet Rendezvous Asteroid Flyby (CRAF) spacecraft, which is planned to rendezvous with Comet Kopff in 1998, is presented, together with the CRAF mission trajectory. The preliminary thermal design of the CRAF spacecraft is discussed, with emphasis placed on the Low Precision Pointing Platform, Bus, Propulsion Module, and Comet Penetrator, the thermal design of which was impacted most by the comet environment. Model simulations showed the design of the bus and the propulsion module subsystems to be adequate. Configuration diagrams are included.

Tsuyuki, G. T.↗