Cogger L.,University of Calgary |
Howarth A.,University of Calgary |
Yau A.,University of Calgary |
White A.,University of Calgary |
And 9 more authors.
Space Science Reviews | Year: 2015
The Fast Auroral Imager (FAI) consists of two charge-coupled device (CCD) cameras: one to measure the 630 nm emission of atomic oxygen in aurora and enhanced night airglow; and the other to observe the prompt auroral emissions in the 650 to 1100 nm range. High sensitivity is realized through the combination of fast lens systems (f/0.8) and CCDs of high quantum efficiency (>90 % max). The cameras have a common 26 degree field-of-view to provide nighttime images of about 650 km diameter from apogee at 1500 km. The near infrared camera provides up to two images of 0.1 s exposure per second with a spatial resolution of a few km when the camera is pointing in the nadir direction, making it suitable for studies of dynamic auroral phenomena. The 630-nm camera has been designed to provide one image of 0.5 s exposure every 30 seconds. Launch of the satellite occurred on September 29, 2013. Following a description of the instrument, sample auroral images are presented. © 2014, The Author(s).
Vigneron A.C.,Carleton University |
De Ruiter A.H.J.,Ryerson University |
Burlton B.V.,Carleton University |
Soh W.K.H.,Magellan Aerospace
Acta Astronautica | Year: 2016
In support of Canada's proposed Polar Communication and Weather mission, this study examined the accuracy to which GPS-based autonomous navigation might be realized for spacecraft in a Molniya orbit. A navigation algorithm based on the Extended Kalman Filter was demonstrated to achieve a three-dimensional root-mean-square accuracy of 58.9 m over a Molniya orbit with 500 km and 40,000 km perigee and apogee altitudes, respectively. Despite the inclusion of biased and non-white error models in the generated GPS pseudorange measurements - a first for navigation studies in this orbital regime - algorithms based on the Unscented Kalman Filter and the Cubature Kalman Filter were not found to improve this result; their benefits were eclipsed due to the accurate pseudorange measurements which were available during periods of highly nonlinear dynamics. This study revealed receiver clock bias error to be a significant source of navigation solution error. For reasons of geometry, the navigation algorithm is not able to differentiate between this error and a radial position error. A novel dual-mode dynamic clock model was proposed and implemented as a means to minimize receiver clock bias error over the entire orbital regime. © 2016 IAA. Published by Elsevier Ltd. All rights reserved.
Soh W.,Magellan Aerospace |
Michels J.,Magellan Aerospace |
Asquin D.,Magellan Aerospace |
Vigneron A.,Carleton University |
And 2 more authors.
Proceedings of the International Astronautical Congress, IAC | Year: 2014
Geosynchronous communications and meteorological satellites have limited northern latitude coverage, specifically above 65° N. The lack of secure, highly reliable, high capacity communication services and insufficient meteorological data over the Arctic region has prompted Canada to investigate new satellite solutions. Since 2008, the Canadian Space Agency (CSA) has spearheaded the Polar Communication and Weather (PCW) mission, slated to operate in a Highly Elliptical Orbit (HEO). A 24-hour, 90° inclination, Tundra orbit is a strong candidate; able to fill the communication and weather coverage gaps, and in addition continuously monitor space weather in the Northern and Southern hemispheres. However, it is operationally challenging for GPS-based satellite orbit determination as the satellite is continuously above the GPS constellation, experiencing frequent signal outages, especially when passing over the poles and aggravated by the constellation's inclination of 55°. Magellan Aerospace, Winnipeg in collaboration with Carleton University, has successfully developed an onboard navigation technology for PCW within a CSA-funded Space Technology Development Program. The real-time navigation flight software is robust, capable of position determination to within 15 m (RMS) of uncertainty, and has been developed to Technology Readiness Level 5 (TRL-5) using the Magellan closed-loop attitude and orbit software simulator that qualified SCISAT (launched 2002), CASSIOPE (launched 2013), and the RADARSAT Constellation Mission (2018). The navigation technology uses a modified and optimally tuned covariance driven Extended Kalman Filter (EKF) to estimate the orbit, fusing a high-fidelity gravitational model (24×24 EGM96) and perturbation models with available raw GPS pseudo-range signals. The simulated 34dBHz threshold, 8-channel LI single frequency receiver with dual antenna demonstrated GPS side-lobe signals can be acquired in the Tundra orbit even in the presence of ionospheric attenuation. Hence the navigation solution maintains accuracy through non-Gaussian GPS signal outages, most notably at and around apogee, and converges to 130 m after experiencing unpredicted impulsive orbit accelerations. The technology was further verified by assessing the impact of specific perturbations and non-Gaussian pseudo-range measurement errors, particularly receiver clock errors modelled as steered or drifting depending on the current GPS visibility and geometry, and the inclusion of GPS Space Vehicle ephemeris errors (in the absence of global correction values). Finally, other nonlinear Bayesian filters (Unscented and Cubature) were developed and evaluated for the Tundra orbit but did not improve the navigation solution despite the retention of system nonlinearities. Copyright ©2014 by the International Astronautical Federation. All rights reserved.
Emmanuel A.,University of Manitoba |
Raghavan J.,University of Manitoba |
Harris R.,Magellan Aerospace |
Ferguson P.,Magellan Aerospace
Advances in Space Research | Year: 2014
The Canadian Space Agency (CSA) has proposed a Polar Communications and Weather (PCW) satellite mission, in conjunction with other partners. The PCW will provide essential communications and meteorological services to the Canadian Arctic, as well as space weather observations of in situ ionizing radiation along the orbit. The CSA has identified three potential Highly Elliptical Orbits (HEOs) for a PCW satellite constellation, Molniya, Modified Tundra and Triple Apogee (TAP), each having specific merits, which would directly benefit the performance/longevity of a PCW spacecraft. Radiation shielding effectiveness of various materials was studied for the three PCW orbit options to determine the feasibility of employing materials other than conventional aluminium to achieve a specified spacecraft shielding level with weight savings over aluminium. It was found that, depending on the orbit-specific radiation environment characteristics, the benefits of using polyethylene based materials is significant enough (e.g.; 22% in Molniya for PE at 50 krad TID) to merit further investigation. © 2013 Published by Elsevier Ltd. on behalf of COSPAR. All rights reserved.
Wickramasinghe V.,NRC Institute for Aerospace Research |
Chen Y.,NRC Institute for Aerospace Research |
Zimcik D.,NRC Institute for Aerospace Research |
Tremblay P.,MAYA HTT |
And 2 more authors.
Conference Proceedings of the Society for Experimental Mechanics Series | Year: 2011
A comprehensive modal survey test based on multi-input multi-output experimental modal analysis techniques was conducted on the CASSIOPE spacecraft. This paper describes the details of the methodology used to perform the successful experimental modal test to efficiently extract the critical modes of the spacecraft. Results from the modal test have been used to validate the analytical finite element model and to provide confidence in the structural integrity of the spacecraft design. The test was performed on the flight model of the CASSIOPE spacecraft in the final stages of integration, which included all of the payload and bus instruments and electronics boxes. The multiple-input excitation for the spacecraft was generated using two portable electrodynamic modal shakers installed on the top and bottom of the spacecraft to distribute the excitation energy and the response was measured using 81 miniature accelerometers. A digital multi-channel data acquisition system was used to record the time domain data and calculate the frequency domain spectra. Advanced modal analysis software was used to extract modal parameters from the measured data and critical modes were compared with predictions from the finite element model. Most modes identified through the experimental data compared favorably with the predictions. Nevertheless, some differences were large enough to require iterative update of the finite elelement model. The structural dynamics information from the updated finite element model was used to plan the mechanical vibration qualification test and predict the response of the spacecraft to the launch vehicle environmental loads through coupled loads analysis. ©2010 Society for Experimental Mechanics Inc.