Gyro noise measurement and analysis

Noise measurements were performed on two identical space qualified gyroscopes of the floated rate integrating type (Perranti Type I25) in an analog rehalance loop configuration of selectable loop bandwidth, running under space representative conditions. The noise frequency range of interest was O.OO5 Hz to 50 Hz. The noise results were processed...

Experimental and system study of Reaction Wheels. Part I: Measurement and statistical analysis of force and torque irregularities

Torque and force irregularities of running reaction wheels were studied. In this first part of the study report results from noise measurements at constant wheel speeds on various types of current technology European reaction wheels, both with ball- and magnet bearings and with DC or AC drive motor, are presented. The measured noise in radial...

Preliminary experiments with an electro-osmotic heat pipe laboratory model

Preliminary experiments have been performed with a laboratory model of an electro-osmotic heat pipe filled with ethanol. With dismounted electro-osmotic pump, the heat transport through the pipe and the temperature distribution along the pipe wall have been measured. The measurements have been performed as a function of the temperature...

Testing of spacecraft attitude and orbit control systems

The testing of Spacecraft Attitude and Orbit Control Subsystems is described from the early design up to in-flight, inclusive. Main topics dealt with are: description of three generic AOCS test classes, model philosophy, standardization, subsystem static test methods, subsystem dynamic test methods, generic test equipment and test facilities....

Image data reduction with splines and segmentation with emphasis on earth observation

This report describes the results of a feasibility study on image data compression using spline approximation and image segmentation, with emphasis on earth observation applications. The main subjects dealt with, are: the data compression method, implementation aspects, the test software and test results. It appears that a reduction factor of 5...

Development of a multi-component internal strain-gauge balance for model tests in a cryogenic wind tunnel

A three-component internal strain-gauge balance for use in a cryogenic wind tunnel has been developed by NLR. With this balance model tests were performed in the NASA 0.3-m Transonic Cryogenic Tunnel. The results are discussed with a view to the development of strain-gauge balances for the ETW.

CAESAR, a CCD airborne experimental scanner for applications in remote sensing radiometric and geometric calibration

Within the framework of the National Remote Sensing Programme, an airborne push-broom scanner was developed in The Netherlands by the National Aerospace Laboratory NLR and the Institute for Applied Physics TNO-TH (TPD). With the development of this scanner, named CAESAR, two objectives were fulfilled: technical knowledge about CCD detectors and...

Test loops for two-phase thermal management system components

Two mechanically pumped two-phase test rigs were built at NLR in order to experimentally study critical issues of spacecraft two-phase thermal management systems: - a 5 kW, 31 mm ID, freon loop, focusing on the critical components of the ESA Two-Phase Heat Transport System. - a 30000 W, 4.93 mm ID, ammonia loop, to support the development of the...

Experiences with two GPS SPS receivers in northern Europe

Results are given of measurements with two hand-held GPS C/A- code SPS (Standard Positioning Service) receivers at thirty locations in Finland, Norway and Sweden. Comparison is made between computed positions by the receivers and positions on geographic maps. It is concluded that both receivers have pros en cons. A combination of the...

Performance Testing of Data Delivery Techniques for AJAX Applications

Preprint of paper published in: Journal of Web Engineering (Rinton Press), 8 (4), 2009 AJAX applications are designed to have high user interactivity and low user-perceived latency. Real-time dynamic web data such as news headlines, stock tickers, and auction updates need to be propagated to the users as soon as possible. However, AJAX still...

Blockchain verification and validation: Techniques, challenges, and research directions

As blockchain technology is gaining popularity in industry and society, solutions for Verification and Validation (V&V) of blockchain-based software applications (BC-Apps) have started gaining equal attention. To ensure that BC-Apps are properly developed before deployment, it is paramount to apply systematic V&V to verify their...