Special Coverage

Soft Robot “Walks” on Any Terrain
Defense Advanced Research Projects Agency
Using Microwaves to Produce High-Quality Graphene
Transducer-Actuator Systems for On-Machine Measurements and Automatic Part Alignment
Wide-Area Surveillance Using HD LWIR Uncooled Sensors
Heavy Lift Wing in Ground (WIG) Cargo Flying Boat
Technique Provides Security for Multi-Robot Systems
Bringing New Vision to Laser Material Processing Systems
NASA Tests Lasers’ Ability to Transmit Data from Space
Converting from Hydraulic Cylinders to Electric Actuators
Automating Optimization and Design Tasks Across Disciplines

Simulating the Phoenix Landing Radar System

Phoenix Mission Lander on Mars, artist’s concept.A computer program called “phxlrsim” simulates the behavior of the radar system used as an altimeter and vel - ocimeter during the entry, descent, and landing phases of the Phoenix lander spacecraft. The simulation includes modeling of internal functions of the radar system, the spacecraft trajectory, and the terrain. The computational models incorporate representations of nonideal hardware effects in the radar system and effects of radar speckle (coherent scatter of radar signals from terrain).

This program was written by Curtis W. Chen of Caltech for NASA’s Jet Propulsion Laboratory.

This software is available for commercial licensing. Please contact Karina Edmonds of the California Institute of Technology at (626) 395-2322. Refer to NPO-44431.

Posted in: Briefs, TSP, Software, Computer simulation, Radar, Radar, Entry, descent, and landing, Spacecraft

Injecting Artificial Memory Errors Into a Running Computer Program

Single-event upsets (SEUs) or “bitflips” are computer memory errors caused by radiation. BITFLIPS (Basic Instrumentation Tool for Fault Localized Injection of Probabilistic SEUs) is a computer program that deliberately injects SEUs into another computer program, while the latter is running, for the purpose of evaluating the fault tolerance of that program. BITFLIPS was written as a plug-in extension of the open-source Valgrind debugging and profiling software. BITFLIPS can inject SEUs into any program that can be run on the Linux operating system, without needing to modify the program’s source code. Further, if access to the original program source code is available, BITFLIPS offers fine-grained control over exactly when and which areas of memory (as specified via program variables) will be subjected to SEUs.

Posted in: Briefs, Software, Failure analysis, Computer software / hardware, Computer software and hardware, Computer software / hardware, Computer software and hardware, Radiation, Test equipment and instrumentation

Fault-Tolerant, Multiple-Zone Temperature Control

A computer program has been written as an essential part of an electronic temperature control system for a spaceborne instrument that contains several zones. The system was developed because the temperature and the rate of change of temperature in each zone are required to be maintained to within limits that amount to degrees of precision thought to be unattainable by use of simple bimetallic thermostats.

Posted in: Briefs, Software, Computer software / hardware, Computer software and hardware, Computer software / hardware, Computer software and hardware, Thermal management, Thermal management, Spacecraft

Implementing a Digital Phasemeter in an FPGA

Firmware for implementing a digital phasemeter within a field-programmable gate array (FPGA) has been devised. In the original application of this firmware, the phase that one seeks to measure is the difference between the phases of two nominally- equal-frequency heterodyne signals generated by two interferometers. In that application, zero-crossing detectors convert the heterodyne signals to trains of rectangular pulses (see figure), the two pulse trains are fed to a fringe counter (the major part of the phasemeter) controlled by a clock signal having a frequency greater than the heterodyne frequency, and the fringe counter computes a time-averaged estimate of the difference between the phases of the two pulse trains.

Posted in: Briefs, TSP, Software, Architecture, Computer software / hardware, Computer software and hardware, Integrated circuits, Architecture, Computer software / hardware, Computer software and hardware, Integrated circuits

Post-Flight Estimation of Motion of Space Structures: Part 1

A computer program estimates the relative positions and orientations of two space structures from data on the angular positions and distances of fiducial objects on one structure as measured by a targettracking electronic camera and laser range finders on another structure. The program is written specifically for determining the relative alignments of two antennas, connected by a long truss, deployed in outer space from a space shuttle.

Posted in: Briefs, Software, Measurements, Antennas, Computer software / hardware, Computer software and hardware, Antennas, Computer software / hardware, Computer software and hardware, Spacecraft

Post-Flight Estimation of Motion of Space Structures: Part 2

A computer program related to the one described in the immediately preceding article estimates the relative position of two space structures that are hinged to each other. The input to the program consists of time-series data on distances, measured by two range finders at different positions on one structure, to a corner-cube retroreflector on the other structure. Given a Cartesian (x,y,z) coordinate system and the known x coordinate of the retroreflector relative to the y,z plane that contains the range finders, the program estimates the y and z coordinates of the retroreflector.

Posted in: Briefs, Software, Mathematical models, Antennas, Computer software / hardware, Computer software and hardware, Antennas, Computer software / hardware, Computer software and hardware, Spacecraft

Simulating Operation of a Large Turbofan Engine

The Commercial Modular Aero- Propulsion System Simulation (CMAPSS) is a computer program for simulating transient operation of a commercial turbofan engine that can generate as much as 90,000 lb (≈0.4 MN) of thrust. It includes a power-management system that enables simulation of openor closed-loop engine operation over a wide range of thrust levels throughout the full range of flight conditions.

Posted in: Briefs, TSP, Software, Computer simulation, Turboprop engines

Automated Assistance for Designing Active Magnetic Bearings

MagBear12 is a computer code (see figure) that assists in the design of radial, heteropolar active magnetic bearings (AMBs). MagBear12 was developed to help in designing the system described in “Advanced Active-Magnetic-Bearing Thrust-Measurement System” (SSC- 00177-1), which appears in NASA Tech Briefs, Vol. 32, No. 9 (September 2008), p. 61. (See the Mechanics/Machinery section in the accompanying issue of NASA Tech Briefs). Beyond this initial application, MagBear12 is expected to be useful for designing AMBs for a variety of rotating machinery. This program incorporates design rules and governing equations that are also implemented in other, proprietary design software used by AMB manufacturers. In addition, this program incorporates an advanced unpublished fringing-magnetic- field model that increases accuracy beyond that offered by the other AMB-design software.

Posted in: Briefs, Software, CAD / CAM / CAE, CAD, CAM, and CAE, Magnetic materials, Bearings

Computational Simulation of a Water-Cooled Heat Pump

A Fortran-language computer program for simulating the operation of a water-cooled vapor-compression heat pump in any orientation with respect to gravity has been developed by modifying a prior general-purpose heat-pump design code used at Oak Ridge National Laboratory (ORNL). Al - though it is specific to the design of a high-temperature-lift heat pump for the International Space Station, this program could serve as a basis for development of general-purpose computational software for designing and analyzing liquid-cooled heat-pumps. The ORNL program contained models of refrigerant-fluid-to-air heat exchangers; the main modification consisted in replacing those models with models of plate-type heat exchangers utilizing water as both the cooling and the heating source liquid.

Posted in: Briefs, TSP, Software, Computer simulation, Water, Heat exchangers, Heat exchangers, Cooling

Computational Model of Heat Transfer on the ISS

SCRAM Lite (“SCRAM” signifies “Station Compact Radiator Analysis Model”) is a computer program for analyzing convective and radiative heat transfer and heat-rejection performance of coolant loops and radiators, respectively, in the active thermal-control systems of the International Space Station (ISS). SCRAM Lite is a derivative of prior versions of SCRAM but is more robust.

Posted in: Briefs, TSP, Software, Computer simulation, Heat transfer, Thermodynamics, Heat transfer, Thermodynamics, Performance upgrades, Spacecraft

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