Physical Sciences

Biomorphic Gliders

Miniature robotic microflyers would gather scientific data to enable reconnaissance missions and deploy payloads on landing. Biomorphic gliders are small robotic microflyers proposed for use in scientific exploration of planetary atmospheres and terrains that capture some key features of insect and bird flight. Biomorphic gliders as biomorphic flight systems are a subset of biomorphic explorers. The multidisciplinary system concept of "Biomorphic Explorers" represents small, dedicated, low-cost explorers that possess some of the key features of biological systems, not easily captured by conventional robotic systems. Such features particularly include versatile mobility, adaptive controls, bioinspired sensor mechanisms, biomorphic sensor fusion, biomorphic communications, biomorphic cooperative behavior, distributed operations, and biomorphic energy generation/conversion. Significant scientific and technological payoff at a low cost is realizable by using the potential offered by a large number of such cooperatively operating biomorphic explorer units in concert with the traditional exploration platforms such as the lander/rover, orbiter, etc., for example.

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High-Heat-Flux Thermogravimetric Analysis With Radiography

A process and a laboratory setup to implement the process (see figure) have been devised to enable the acquisition of time-resolved data on the thermal decomposition of a specimen of a solid material exposed to a heat flux comparable to the heat flux in a typical rocket engine. The process is called "RTR-TGA" because it includes a combination of real-time radiography (RTR) and thermogravimetric analysis (TGA). In the process, one specimen surface (e.g., representing a surface exposed to flames in a rocket engine) is heated by a continuous-wave CO2-laser beam while the interior temperature of the specimen is measured and the specimen is observed by an x-ray apparatus that produces video images that can be recorded. The major advantage of this process over older processes for observing thermal decomposition of material specimens is that the environment to which the specimen is exposed approximates more closely the heating environment in a full-scale rocket engine.

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Thermogravimetric Analysis With Laser Heating

A thin specimen is radiantly heated from both sides.Laser thermogravimetric analysis (laser TGA) is a technique that yields time-resolved data on the thermal decomposition of a specimen of a solid material exposed to a heat flux comparable to the heat flux in a typical rocket engine. Like the technique described in the preceding article, laser TGA involves heating the specimen with a continuous-wave laser beam to obtain the required high heat flux. The utility of laser TGA is not restricted to rocket-engine materials; laser TGA could be used to study high-heating-rate thermal decomposition of almost any high-temperature insulating material.

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Ultralight Balloon Systems for Exploring Uranus and Neptune

A report proposes ultralight balloon systems to carry a 10-kg payload, including scientific instruments for exploring the atmospheres of Uranus and Neptune. The system masses to be transported to those planets would be kept low by not transporting balloon-inflating gases. Each system would include an upper balloon about 4 m in diameter (0.5 kg) connected via a small port (about 0.25 m in diameter) to a lower balloon about 15 m in diameter (6.4 kg). Through an opening in the lower balloon, the balloons would become filled with low-molecular-weight atmospheric gas (which has little methane content) during initial descent through the upper atmosphere. At some point in the descent, the opening would be closed. Thereafter, the collected gas would provide buoyancy in the higher-molecular-weight atmosphere (methane content ≈2 percent) in the exploration altitude range below the methane-cloud tops, and the lower balloon (used for collection only) would be dropped. The altitude could be held constant or could be regulated by alternately venting gas and dropping ballast, as is done on balloons in the terrestrial atmosphere.

Posted in: Briefs, TSP, Physical Sciences

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Field-Reversed Magnetic Mirrors for Confinement of Plasmas

The mirror magnetic-flux density needed for confinement would be reduced. A field-reversed configuration (FRC) has been proposed for a magnetic mirror — a solenoidal electromagnet configured and operated in such a way as to effect at least partial confinement of a plasma. Magnetic mirrors had been investigated for potential use as plasma-confinement devices in nuclear fusion reactors, and had been largely rejected for that use because, as explained below, they allow too much plasma to escape. The proposed FRC is intended to increase the degree of confinement achievable by a mirror magnetic field of a given flux density and/or to reduce the flux density needed to obtain a given degree of confinement. (Whether the increase in effectiveness of confinement would be sufficient to justify the use of magnetic mirrors in fusion reactors remains to be seen.)

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Updated Multidisciplinary Optical-System-Analysis Software

Version 5.0 of the Integrated Modeling of Optical Systems (IMOS) software has been released. A previous version was described in "Software for Multidisciplinary Analysis of Optical Systems" (NPO-20536), NASA Tech Briefs, Vol. 24, No. 11 (November 2000), page 36. In both versions, IMOS is a MATLAB™ computer program that provides many functions for analysis of a system represented by mathematical models of its thermal, structural, control, and/or optical aspects. IMOS is unique in making it possible to perform the entire multidisciplinary analysis in one program. The new features incorporated into version 5.0 include a capability for calculating stresses in rods and beams, a utility subprogram that generates equivalent properties of laminates, a three-dimensional-viewing subprogram, a provision for temperature-dependent heat input for thermal analyses, a provision for a simulated stiffness for the drilling degree of freedom of a plate structural element, a provision for a lumped-mass formulation for a beam, a capability to orient properties of materials with respect to plate structural elements, plate-to-acoustic and beam-to-acoustic connections for statistical energy analysis, geometric stiffnesses for plate elements (for buckling analysis), subprograms for translation from the SINDA program to IMOS and from IMOS to the NASTRAN program, and greatly improved subprograms for translation from IMOS to SINDA and from NASTRAN to IMOS.

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RVSM Certification of Dryden DC-8 Airborne Laboratory

A required pressure-altitude accuracy of ±160 ft (±49 m) has been achieved. The NASA Dryden DC-8 Airborne Science Laboratory (see Figure 1) performs research around the globe, recently in support of the SAGE III Ozone Loss and Validation Experiment (SOLVE). This experiment operated in the North Atlantic airspace region, which is subject to reduced vertical separation minimum (RVSM) requirements (see Figure 2). These requirements allow aircraft traffic to be separated vertically by a minimum of 1,000 ft (304.8 m) at altitudes between 29,000 and 41,000 ft (between 8.84 and 12.50 km) above mean sea level, in contradistinction to the usual vertical separation of 2,000 ft (0.61 km). RVSM non-group aircraft compliance requires a pressure-altitude accuracy within ±160 ft (±49 m). RVSM allows greater traffic density while maintaining safe aircraft separation.

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