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Cambridge, Canada

De Ruiter A.,Carleton University | Lee J.,Canadian Space Agency | Lee J.,Control and Analysis Group | Ng A.,Canadian Space Agency | And 6 more authors.
AIAA Guidance, Navigation, and Control Conference | Year: 2010

The Japan Canada Joint Collaboration Satellites - Formation Flight (JC2Sat-FF) project is a joint project between the Canadian Space Agency (CSA) and the Japan Aerospace Exploration Agency (JAXA). This paper presents an overview of JC2Sat mission and discusses unique GNC challenges and solutions with focus on attitude control subsystem (ACS) and relative navigation subsystem (RNS). Preliminary simulations are presented to validate that the design requirements are satisfied by proposed design techniques. Copyright © 2010 by Government of Canada. Source

Srivastava V.K.,A+ Network | Srivastava V.K.,Indian School of Mines | Kumar J.,Mission Development Group | Kulshrestha S.,Jai Narain Vyas University | Kushvah B.S.,Indian School of Mines
Acta Astronautica | Year: 2016

During the Mars solar conjunction, telecommunication and tracking between the spacecraft and the Earth degrades significantly. The radio signal degradation depends on the angular separation between the Sun, Earth and probe (SEP), the signal frequency band and the solar activity. All radiometric tracking data types display increased noise and signatures for smaller SEP angles. Due to scintillation, telemetry frame errors increase significantly when solar elongation becomes small enough. This degradation in telemetry data return starts at solar elongation angles of around 5° at S-band, around 2° at X-band and about 1° at Ka-band. This paper presents a mathematical model for predicting Mars superior solar conjunction for any Mars orbiting spacecraft. The described model is simulated for the Mars Orbiter Mission which experienced Mars solar conjunction during May-July 2015. Such a model may be useful to flight projects and design engineers in the planning of Mars solar conjunction operational scenarios. © 2015 IAA. Source

Vijayasree P.,Mission Development Group | Kumar N.,Mission Development Group | Karidhal R.,Mission Development Group | Harendranath K.,Flight Dynamics Group | And 2 more authors.
International Journal of Remote Sensing | Year: 2014

Climate in the tropics is primarily influenced by variations in energy and water budget exchanges in the land/ocean/atmosphere systems. The interaction of these systems with the general atmospheric circulation is still not fully understood - one of the reasons why weather forecasts and predictions of climatic events are less accurate. The Megha-Tropiques mission, an ISRO-CNES (Indian Space Research Organisation-Centre National d'Etudes Spatiales) collaborative programme, aims to study water cycle and energy exchanges in the tropics, and use the data in climate and meteorology models. Megha-Tropiques is part of the Global Precipitation Measurement Mission, which is an international network of satellites. Of the four payloads on board, MADRAS is jointly developed by ISRO and the French space agency, CNES; SAPHIR and SCARAB completely by CNES; and GPS-ROSA is obtained from TAS-I (Thales Alenia Space Italia, Milan, Italy). GPS-ROSA supplements the geophysical parameters of the other payloads for atmosphere modelling. Mission planning involved integrating and interrelating the efforts of space and ground systems in realizing the operational system that provides the satellite-based science data meeting the turnaround time (TAT). Pre-launch simulations involved usage of a software simulator as a tool for network tests, training of spacecraft operation personnel, and validating the spacecraft health-monitoring software. The required operations were performed to characterize the payloads as well as to calibrate the various attitude sensors of the spacecraft. This paper summarizes mission planning and analysis aiding spacecraft configuration, pre-launch mission simulations, launch and early-orbit operations, and the on-orbit operational guidelines for Megha-Tropiques. © 2014 Taylor & Francis. Source

Karidhal R.,Mission Development Group | Subbarao K.,Mission Development Group | Kesavaraju V.,Mission Development Group | Pandiyan R.,Flight Dynamics Group
Advances in the Astronautical Sciences | Year: 2012

The computation of time varying image-motion plane and derivation of reference attitude is the main requirement of high resolution optical imaging for driving the spacecraft platform motion. In this paper, two types of imaging modes are considered. In Type-I imaging, the Image Plane is constructed perpendicular to the direction of imaging while in Type-II imaging the Image Plane is made parallel to the direction of imaging. Type-I imaging mode is applicable to a camera system where linear CCDs are used and the platform attitude should need to be controlled such that the projection of the linear CCD on ground is always maintained perpendicular to the imaging direction. Type-II imaging is applicable to a camera system wherein an area array CCD (e.g. TDI - Time Delay and Integration device) is used to improve overall Signal to Noise ratio. In such a case, the earth rotation compensation becomes a must in order to allow all the stages of the array to capture the signal from the same ground region before getting integrated. Spherical geometry is used to define the trajectory of imaging using two points in the desired direction on the earth surface where the earth model is built as an ellipsoid. Once the trajectory is defined, the image plane is constructed depending on the type of imaging. Using the image plane definition at each time and vector coordinate transform methods the platform attitude is derived. The paper has been arranged in four Sections viz., Section 1 describing the trajectory formation, Section 2 describing the image plane definition, Section 3 discussing about the attitude derivation at each time and the Section 4 focusing on the various ways of acquiring images using the defined attitude in the context of multi-strip imaging during a payload pass for a cartographic satellite, Cartosat-2. Source

Tarun T.L.,Mission Development Group | Padmakar J.P.,Mission Development Group | Eswafa Prakash W.V.,Mission Development Group
Journal of Spacecraft Technology | Year: 2014

Spacecraft health monitoring is a mission critical activity that spans the entire life of the spacecraft. Precise and efficient software tools are required to realize this task and one such tool developed at ISAC is SCHEMACS (Spacecraft Health Monitoring, Analysis and Control Software). SCHEMACS enables the processing of real-time and offline spacecraft telemetry data into subsystem parameters that indicate the health of the subsystem as well as the spacecraft. In general, real-time and offline processing has been evolved around table-driven and code-driven architectures with the former being superior in view of the long term maintenance. Parameter definition table was constituted by the commonly used processing schemes; however sparingly used schemes were written using special processing software. Over the time with technology development, many special processing algorithms and 64-bit data formats became common for spacecraft subsystems. The increased number of special processing schemes led to the identification of schemes with common behaviour and normalize them befitting into the parameter definition table. Different methods used to achieve normalization include the extensive use of arithmetic expressions (AEXP), 64 bit data processing (IEEE-64) and Look-up Table (LUT). The normalized schemes were deployed for missions including YouthSat, Megha Tropiques and Risat-1 with considerable saving in special processing software. Source

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