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Shi J.-F.,MDA Corporation | Ulrich S.,Carleton University
Proceedings of the International Astronautical Congress, IAC

A direct adaptive control law is developed for a robust International Space Station attitude regulation during robotic capture of a free-flyer by the Space Station Remote Manipulator System. The proposed output feedback direct adaptive controller is developed from the Simple Adaptive Control theory, and makes use of the Modified Rodrigues Parameters. The performance of the adaptive controller is examined in MacDonald, Dettwiler and Associates Space Station Portable Operations Training Simulator; a high-fidelity multibody flexible dynamic simulation facility. SPOTS simulafion results are provided for an ISS free-flyer capture of a SpaceX Dragon-like space vehicle with the flexible SSRMS manipulator. Simulation results highlight the improved performance and robustness to parametric and dynamics modeling uncertainties of the proposed novel attitude control approach when compared with an attitude Proportional-Derivative controller. Copyright © 2014 by MDA Corporation and Dr. Steve Ulrich. Source

Samsonov Sergey S.,Institute of Geological & Nuclear Sciences | Samsonov Sergey S.,European Center for Geodynamics and Seismology | van der Kooij M.,MDA Corporation | Tiampo K.,University of Western Ontario
Computers and Geosciences

We demonstrate here a computer code for calculation of time series and also mean and linear deformation rates from a set of coregistered unwrapped differential interferograms using a linear least-squares inversion technique based on the small baseline subset (SBAS) algorithm. The computer code is written in C and uses a singular value decomposition (SVD) routine from the LAPACK library and the fast Fourier transform for spatial filtering from the FFTW library. Various offset estimation and topographic correction algorithms are implemented, including simultaneous inversion for deformation rates and residual topographic error. This approach is particularly useful when applied to ALOS PALSAR interferograms that are coherent even at large perpendicular baselines and acquired with orbital parameters correlated with the time of acquisition. This methodology is applied to produce time series of ground deformation at Tauhara and Wairakei geothermal fields (Taupo Volcanic Zone, North Island, New Zealand) from 12 ALOS PALSAR images acquired between July 2007 and December 2009. We also present here a high-resolution deformation map of the ground subsidence caused by the extraction of geothermal groundwater for power generation, with maximum rates of subsidence of about 7. cm/y. © 2011 Elsevier Ltd. Source

Norman R.B.,NASA | Blattnig S.R.,NASA | De Angelis G.,MDA Corporation | Badavi F.F.,Christopher Newport University | Norbury J.W.,NASA
Advances in Space Research

An accurate understanding of the physical interactions and transport of space radiation is important for safe and efficient space operations. Secondary particles produced by primary particle interactions with intervening materials are an important contribution to radiation risk. Pions are copiously produced in the nuclear interactions typical of space radiations and can therefore be an important contribution to radiation exposure. Charged pions decay almost exclusively to muons. As a consequence, muons must also be considered in space radiation exposure studies. In this work, the NASA space radiation transport code HZETRN has been extended to include the transport of charged pions and muons. The relevant transport equation, solution method, and implemented cross sections are reviewed. Muon production in the Earth's upper atmosphere is then investigated, and comparisons with recent balloon flight measurements of differential muon flux are presented. Muon production from the updated version of HZETRN is found to match the experimental data well. © 2012 COSPAR. Published by Elsevier Ltd. All rights reserved. Source

D'Aliesio G.,MDA Corporation
Proceedings of the International Astronautical Congress, IAC

With the ever increasing need for high performance processing, high capacity and high performance mass memory along with a variety of data acquisition and control requirements in space, MDA's Earth Observation Data Management Systems line of products are enabling compact and highly integrated solutions for EO applications. From processor boards and data storage units to data acquisition and mechanism control electronics, this paper will overview a set of MDA's space qualified electronic products targeted towards earth observation payloads. The ESP750 enhanced space processor board is a high performance, radiation tolerant single board computer offered in a compact 3U form factor. The card is built around the IBM PowerPC 750FX processor operating at up to 700 MHz and includes Level 1 (LI) and Level 2 (L2) cache memory, on-board SDRAM, EEPROM, Built-in Test (BIT), a secure digital watchdog timer and a compliment of General Purpose I/O (GPIO), interrupt and timer functions. The Data Storage Unit (DSU) is being developed to provide earth observation satellites with cutting edge digital data storage technology for spaceflight. The DSU is a high speed mass memory used for storage and playback of data and can operate on multiple files concurrently. It contains high density non-volatile flash technology, a Leon3 fault tolerant processor, advanced FPGA technology and all the interface, control and memory functions required for operation in a compact, radiation tolerant and low power design. The DSU has the potential to perform certain data processing onboard, offers scalable storage capacity, and contains high reliability features, making it an ideal mass storage solution for next generation earth observation satellites. MDA's series of data acquisition electronics provide a variety of custom interfaces to acquire a multitude of signal types. Combined with command and control functionality, overall instrument or payload management can be achieved in a compact and integrated solution. MDA's long heritage in robotics has created an expertise in motor drive electronics for space applications. As a result, MDA's line of APMEs and MDEs can provide a low cost and compact off-the-shelf solution for antenna pointing, deployment or motor/mechanism control for instruments. MDA's series ofEO Data Management Systems line of products can be combined in order to achieve a highly integrated, cost effective, low mass/power solution for EO missions. Copyright © (2012) by the International Astronautical Federation. Source

Camelo L.M.,MDA Corporation
2010 14th International Symposium on Antenna Technology and Applied Electromagnetics and the American Electromagnetics Conference, ANTEM/AMEREM 2010

This paper describes the main RF design features, as well as the RF performance, of the Express AM4 Ku and Ka band top-floor steerable antennas. © 2010 IEEE. Source

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