Ralph Girard

The RADARSAT-2&3 topographic mission: an overview

The Canadian Space Agency and MacDonald Dettwiler are jointly conducting a study to define the mission capabilities and the operational performance of a RADARSAT-2/3 tandem interferometric mission. The primary objective of the mission is to provide a global digital elevation model of the Earth with quality comparable to the emerging US National Imaging and Mapping Agency High Resolution Terrain Information Level 3 (HRTI-3) specification; approximately 2 m relative height accuracy (90% LE) and 10 m nominal post spacing. The initial phase of the study identified a set of required modifications to the RADARSAT-2 spacecraft to support the tandem interferometric mission. These modifications have already been included in the design of the RADARSAT-2 spacecraft that is currently in Phase C/D of development and is scheduled for launch by the end of 2003. The RADARSAT-3 spacecraft would be a copy of RADARSAT-2 and be launched two years after to maximize the window of opportunity for the tandem mission. The two spacecraft would be flown with a separation of a few kilometres to gather interferometric data in a simultaneous monostatic and bistatic (SiMB-static) mode. At the end of the interferometric mission, the two spacecraft would be set apart to maximize the coverage of the combined system. This paper gives an overview of the tandem mission, and presents a summary of technical investigations carried out by MacDonald Dettwiler on the operating mode, the performance assessment, the orbit definition and the interferometric processing.

A 94 GHz RF Electronics Subsystem for the CloudSat Cloud Profiling Radar

The CloudSat spacecraft, scheduled for launch in 2004, will carry the 94 GHz Cloud Profiling Radar (CPR) instrument. The design, assembly and test of the flight Radio Frequency Electronics Subsystem (RFES) for this instrument has been completed and is presented here. The RFES consists of an Upconverter (which includes an Exciter and two Drive Amplifiers (DAs)), a Receiver, and a Transmitter Calibrator assembly. Some key performance parameters of the RFES are as follows: dual 100 mW pulse-modulated drive outputs at 94 GHz, overall Receiver noise figure <5.0 dB, a highly stable W-band noise source to provide knowledge accuracy of Receiver gain of <0.4 dB over the 2 year mission life, and a W-band peak power detector to monitor the transmitter output power to within 0.5 dB over life. Some recent monolithic microwave integrated circuit (MMIC) designs were utilized which implement the DAs in 0.1 um GaAs high electron-mobility transistor (HEMT) technology and the Receiver low-noise amplifier (LNA) in 0.1 um InP HEMT technology.

The HYDROS radiometer/radar instrument

The science objectives of the Hydrosphere State Mission (HYDROS) are to provide frequent, global measurements of surface soil moisture and surface freeze/thaw state. In order to adequately measure these geophysical quantities, the key instrument requirements were determined by the HYDROS science team to be: (1) Dual-polarization L-Band radiometer measurements at 40 km resolution, (2) Dual-polarization L-Band radar measurements at 3 km resolution, and (3) A wide swath to insure global three-day refresh time for these measurements (1000 km swath at the selected orbit altitude of 670 km). As an optimal solution to this set of instrument requirements, a relatively large, 6-meter, conically-scanning reflector antenna architecture was selected for the instrument design. The deployable mesh antenna is shared by both the radiometer and radar instruments by using a single L-Band feed.

The RADARSAT Constellation Mission: Meeting the government of Canada'S needs and requirements

In this paper, we describe the high level RADARSAT Constellation Mission (RCM) concept and how it is being designed to meet Government of Canada user requirements. The constellation concept is designed primarily as a wide area monitoring system, offering medium resolution information on a daily basis, as well as high resolution imaging functionality. We briefly discuss the unique capabilities of the constellation particularly related to coverage and revisit as it pertains to meeting the needs of each of the three Core Use Area applications. Finally, we outline the approach and activities being undertaken in the development of a Data Utilization Plan to ensure that the Canadian user departments and agencies will be ready to use data from the RCM on Day 1 of the launch of the first satellite.

Development of Canadian hyperspectral imager onboard micro-satellites

In order to meet the needs of Canadian government departments for operational land and ocean applications the Canadian Space Agency in collaboration with its industry has carried out activities and initiated early phase studies to investigate the feasibility of hyperspectral imager that is compatible with a microsatellite platform. Feasibility studies on two different concepts of microsatellite hyperspectral imagers are ongoing. A user evaluation study that assesses the key parameters of the microsatellite has completed. This paper briefly summarizes the development and early results of the feasibility studies and user assessment.

Concept study of Canadian hyperspectral mission

The Canadian Space Agency (CSA) has initiated several studies on possible missions addressing the needs of Canadian government departments for operational land and ocean applications. Three parallel studies have been completed that reviewed the requirements with an objective to identify microsatellite mission concepts. The CSA has further awarded two contracts to the Canadian industry teams to investigate the feasibility of hyperspectral imagers that are compatible with a microsatellite platform. Two different concepts of low-mass imaging systems have been proposed and studied. In order to address to the main challenges identified, the CSA has extended the two feasibility studies. This paper briefly reports the updates of the feasibility studies in the extension period and new development in the ongoing concept study of a Canadian hyperspectral mission.

The RADARSAT constellation payload design

The Canadian Space Agency completed the definition phase of the RADARSAT Constellation, a constellation of three satellites that will ensure C-band data continuity with RADARSAT-2. The first satellite is scheduled to enter in operation toward the end of the RADARSAT-2 mission, for a full implementation of the constellation in 2014-15. The RADARSAT Constellation is designed to improve significantly the availability of SAR data for main Canadian Government departments, the main applications areas being maritime surveillance, ecosystem monitoring and disaster management. An important constraint on the mission was to reduce significantly the cost of SAR data, which forced the use of new approaches in the payload design. The paper presents the initial payload design process and three techniques investigated to improve its performance.

The hydrosphere state mission: an overview

The Hydrosphere State Mission (HYDROS) has been selected as a possible mission for the NASAs Earth System Science Pathfinder program (ESSP). The objective of the mission is to provide the first global scale measurement of Earths soil moisture and land surface freeze/thaw conditions. The new data will lead to breakthroughs in weather and climate prediction and in the understanding of water, energy and carbon cycles. HYDROS is an alternative mission to OCO and AQUARIUS and is currently in a risk mitigation phase. It may be approved for a full formulation phase if it closes a list of risks that have been identified by ESSP. These risks include technical, science and partnering issues that are being addressed in a series of activities by organizations in the US and Canada. The paper gives an overview of the HYDROS mission and instruments and presents results of activities carried out as part of the risk mitigation phase. If the current activities are successful, HYDROS will be launched in 2008-2009 for a minimum mission duration of two years.

A wide-swath frequent revisit Canadian Hyperspectral Mission - concept study outcomes

The goal of the Canadian Hyperspectral Mission (CHM) is to provide a new and powerful space-based tool for delivering frequently updated hyperspectral remote sensing information products for a broad range of operational users in governments and industries worldwide. The resulting CHM concept includes a relatively low cost constellation of three microsatellites and a supporting ground segment which, together, would be capable of imaging the entire land mass and coastal areas of Canada, USA and Europe every 3 days.

Design of a light–weight digital beam forming antenna for future sar applications

The CSA has been working actively during the past decade on developing various technologies for improving the capabilities of SAR antennas. Various techniques have been investigated for decreasing the mass per unit of area as well as improving the electronic capabilities of the radar. These efforts were combined to form a new concept that is presented here. The concept was defined for C-band applications but could also be applied at lower frequency. The radar antenna has a total area of 38 m2. The central aperture (∼10 m2) is used on transmit and receive while the wings are receive only phased arrays spanning a total area of 28 m2. The central aperture transmits a large beam and the receive aperture captures the echo simultaneously from various directions through a digital beam synthesis.