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Simulator for Testing Spacecraft Separation Devices

A report describes the main features of a system for testing pyrotechnic and mechanical devices used to separate spacecraft and modules of spacecraft during flight. The system includes a spacecraft simulator [also denoted a large mobility base (LMB)] equipped with air thrusters, sensors, and data-acquisition equipment. The spacecraft simulator floats on air bearings over an epoxy-covered concrete floor. This free-flotation arrangement enables simulation of motion in outer space in three degrees of freedom: translation along two orthogonal horizontal axes and rotation about a vertical axis. The system also includes a static stand. In one application, the system was used to test a boltretraction system (BRS) intended for separation of the lifting-body and deorbitpropulsion stages of the X-38 spacecraft. The LMB was connected via the BRS to the static stand, then pyrotechnic devices that actuate the BRS were fired. The separation distance and acceleration were measured. The report cites a document, not yet published at the time of reporting the information for this article, that is said to present additional detailed information.

Posted in: Test & Measurement, Briefs

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Deformable Mirror to Help NASA Search for New Planets

Boston Micromachines, a provider of MEMS-based deformable mirror products for adaptive optics systems, is developing a deformable mirror that will aid NASA in the search for extra-solar planets. The mirror comprises a micromirror array consisting of 331 closely packed ultra-flat hexagonal mirror elements. Each element is capable of tip, tilt, and piston motion with nanometer precision as required for a space-based, hyper-contrast coronagraph imaging telescope.

Posted in: Application Briefs

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Update on EMD and Hilbert-Spectra Analysis of Time Series

U.S. Patent 6,381,559 presents further information about the method described in "Analyzing Time Series Using EMD and Hilbert Spectra" (GSC-13817), NASA Tech Briefs, Vol. 24, No. 10 (October 2000), page 63. To recapitulate: The method is especially well suited for analyzing time-series data that represent nonstationary and nonlinear physical phenomena. The method is based principally on the concept of empirical mode decomposition (EMD), according to which any complicated signal (as represented by digital samples) can be decomposed into a finite number of functions, called "intrinsic mode functions" (IMFs), that admit well-behaved Hilbert transforms. The local energies and the instantaneous frequencies derived from the IMFs through Hilbert transforms can be used to construct an energy-frequency-time distribution, denoted a Hilbert spectrum. The patent expands on the description in the cited prior article by explaining underlying mathematical principles and describing details of implementation. The patent also describes, as major elements of the method, the options of (1) filtering the original signal by combining a subset of IMFs and (2) fitting a curve to the filtered signal — something that it may not be possible to do with the original signal.

Posted in: Information Sciences, Briefs, TSP

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Quad-Tree Visual-Calculus Analysis of Satellite Coverage

The computational burden is less than in a pixel representation. An improved method of analysis of coverage of areas of the Earth by a constellation of radio-communication or scientific-observation satellites has been developed. This method is intended to supplant an older method in which the global-coverage- analysis problem is solved from a ground-to-satellite perspective. The older method is suitable for coarse-grained analysis of coverage of a constellation of a few satellites, but the algorithms of the older method are too slow and cumbersome for the large scope of the problem of analysis of coverage of a modern constellation of many satellites intended to provide global coverage all the time. In contrast, the present method provides for rapid and efficient analysis. This method is derived from a satellite-to-ground perspective and involves a unique combination of two techniques for multiresolution representation of map features on the surface of a sphere.

Posted in: Information Sciences, Briefs, TSP

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UEILogger

United Electronics Industries, Canton, MA, has introduced the UEILogger series of data loggers and recorders. The logger "Cube" contains the logger engine and either three or six I/O slots. The logger is matched to the user's application by installing the appropriate I/O boards from more than 20 different available boards. A single 4 x 4.1 x 5.8" logger cube can provide up to 150 A/D channels or 288 digital I/O. The logger requires no programming, and the logging application is configured using a Windows-based application that sets up the logger and extracts data from the logger's memory. The software allows users to set input and output ranges, sample/update rates, and signal conditioning from pull-down menus. The program may be downloaded via the unit's standard Ethernet port or stored on the SD card. The logger supports sample rates up to 100 samples per second on each I/O channel or port. Data is logged onto standard SD cards; a 2-Gig SD card is included that holds more than 500 million 16-bit A/D readings.

Posted in: Products

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Ginger N. Flores, LOCAD Project Manager, NASA Marshall Space Flight Center, Huntsville, AL

Diagnosis on Earth is a fairly simple procedure, done at any hospital or medical center. In space flight, however, where doctors and even basic medical equipment may be lacking, falling ill is a serious matter for both astronaut and ground control. Using horseshoe crab blood as a reactive agent, the Lab-On-a-Chip Application Development-Portable Test System (LOCAD-PTS) is a handheld device developed by NASA researchers to help identify microorganisms. Ginger N. Flores is the LOCAD project manager.

Posted in: Who's Who

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More About Software for No-Loss Computing

A document presents some additional information on the subject matter of “Integrated Hardware and Software for No-Loss Computing” (NPO-42554), which appears elsewhere in this issue of NASA Tech Briefs. To recapitulate: The hardware and software designs of a developmental parallel computing system are integrated to effectuate a concept of noloss computing (NLC). The system is designed to reconfigure an application program such that it can be monitored in real time and further reconfigured to continue a computation in the event of failure of one of the computers. The design provides for (1) a distributed class of NLC computation agents, denoted introspection agents, that effects hierarchical detection of anomalies; (2) enhancement of the compiler of the parallel computing system to cause generation of state vectors that can be used to continue a computation in the event of a failure; and (3) activation of a recovery component when an anomaly is detected.

Posted in: Information Sciences, Briefs, TSP

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