The Canadian Space Agency (CSA) today issued a request for proposals (RFP) for four priority technologies (PT) as part of the Space Technology Development Program.
The four priority technologies are;
- PT-1 Technologies for Terrestrial Snow Mass Mission ($750 000 contract).
- PT-2 Pointing Mirror Technology for the Atmospheric Imaging Mission of Northern Regions (AIM-North) ($750 000 contract).
- PT-3 Technology Development and Prototyping for Space- Based High-Performance, High-Density Signal Processing (LiteBIRD) ($750 000 contract).
- PT-4 Miniaturized blackbody technology development for onboard calibration of fire diagnosis sensor (WildFireSat) ($750 000 contract).
Proposals are due by October 4, 2019.
Terrestrial Snow Mass Mission background
Current Snow Water Equivalent (SWE) products are unable to deliver information at the spatial resolution and within the accuracy necessary to meet requirements for operational environmental monitoring, services, and prediction at Environment and Climate Change Canada (ECCC). Spaceborne measurements sensitive to SWE are required observational inputs to land surface data assimilation systems under development within the Meteorological Research Division of ECCC, for eventual operational implementation at the Meteorological Service of Canada. These modeling systems are fundamental to skilled numerical weather prediction and hydrological modeling. Enhanced snow information is also required to address priorities across Government departments (such as the Arctic and Northern Policy Framework) and to meet international obligations (for example the World Meteorological Organization Global Cryosphere Watch)
In order to provide the necessary data to improve SWE products and support land surface data assimilation, a dual-frequency Ku-band synthetic aperture radar, providing 250 m spatial resolution measurements with at least 4 looks across a wide swath was identified. After analyzing various configurations, a ScanSAR TOPS imaging mode with 500 km nominal swath width and sequential frequency operation at 13.5 GHz (Ku1) and 17.2 GHz (Ku2) was identified. In order to fit within a reasonable platform size, the antenna must be shared between the two frequencies.
Pointing Mirror Technology for the Atmospheric Imaging Mission of Northern Regions (AIM-North) background
The Atmospheric Imaging Mission of Northern Regions (AIM-North) [RD-1] is a concept to provide observations of unprecedented frequency, density, and precision for the monitoring of greenhouse gases (GHGs) and Air Quality (AQ) species in northern regions. AIM-North will improve our understanding of the carbon cycle of northern land regions, including both the biospheric and anthropogenic components, by performing observations over land from about 40- 80°N, with temporal revisits on the order of 60-180 minutes to capture diurnal variations. The observational needs, developed in partnership with Environment and Climate Change Canada (ECCC) [RD-2], driving the mission concept are derived, in part, from recommendations made by international organizations with respect to Essential Climate Variables (ECV) [RD-3] and global carbon monitoring [RD-4]. A feasibility study to meet these observational needs has led to a preliminary concept for the AIM-North mission, and a Phase 0 study is planned in 2019.
All land area north of 40°N is of interest. This includes all of Canada, along with these latitudes on other continents. Observing north of 50°N is intended to address the observational gap left by upcoming AQ and GHG missions in geosynchronous orbit (GEO), where overlapping coverage with GEO (between ~40-50°N) is also essential to enable inter-comparisons across the diurnal cycle. The current mission concept enables these observations through the use of a two satellite constellation in Highly Elliptical Orbit (HEO) and a suite of instruments, including an imaging Fourier Transform Spectrometer (iFTS) targeting GHG species, and a dispersive grating spectrometer targeting the AQ species.
The current concept of operations couples the optical input of these spectrometers to pointing mirrors to achieve the requisite revisit and coverage. For the iFTS the projection of the instrument field of view (FOV) is held at a fixed spatial region while compensating for satellite motion and earth rotation (to the extent possible) during image acquisition. Following image acquisition, the FOV is incrementally stepped across the accessible 40-80°N region of interest in a whiskbroom type fashion. It should be noted that the future mission concept may also potentially include a cloud imager to enable intelligent pointing, where the FOV is preferentially directed towards cloud free regions to increase the yield of usable data. Detailed considerations of intelligent pointing are beyond the scope of the technology development addressed by this Statement of Work (SOW).
The geometry of HEO coupled with the required coverage, and spatial/temporal sampling of the intended observations implies stringent and challenging requirements for the enabling pointing mirror technology. For example, the Observational Requirements [RD-2] call for a relatively high spatial resolution, over the large aforementioned area of interest, from a reference altitude of 37700 km. Ignoring at present additional system level contributions, the spatial resolution coupled with the reference altitude immediately imply the minimum required angular resolution and knowledge of the pointing mirror subsystem, while the altitude and coverage imply the necessary angular swath of the mirror. Additionally, the angular stability/jitter of the sub-system must be on sub-pixel angular dimensions over the estimated image acquisition times. These timescales are governed, in part, by the frame rates of available and appropriate detector technologies and the necessary sampling to properly resolve the spectral bands of interest in a Michelson interferometer. Further, the species of interest and requisite precision imply the need for observations in the visible and short wave infrared, from which one can infer optical performance specifications related to reflectivity, clear aperture, tolerable wavefront error (WFE), and surface roughness. More details on the impact that the Observational Requirements and concept of operations have on the pointing mirror subsystem requirements can be found in the subsequent sections which explicitly discuss the Scope of Work as well as the Functional Characteristics and Performance Requirements.
Technology Development and Prototyping for Space-Based High-Performance, High-Density Signal Processing objective
On-board digital signal processing (DSP) is a rapidly advancing technology development trend that is expected to significantly expand for applications in payloads of all types: from communications to science instruments, and earth observation. Canadian readout systems combining on-board DSP techniques with innovative technologies, such as the FPGA-based data compression are currently deployed in nearly all ground-based Cosmic Microwave Background (CMB) telescopes including South Pole Telescope that use most sensitive cryogenic Transition Edge Sensors (TES) detectors.
This technology development project is aimed at further enhancement of Canadian leadership in the field of digital data processing using demanding requirements of the JAXA LiteBIRD space telescope as the target mission, which is aiming at a launch date in 2027 with 3 years of operations in L2 orbit. In addition to developing Canada’s space astronomy technology, this project would advance Canadian expertise in designing radiation-tolerant Digital Signal Processing and FPGA electronics.
Miniaturized blackbody technology development for onboard calibration of fire diagnosis sensor background
Multispectral imaging radiometers are widely used in thermal remote sensing. To minimize their measurement errors, the complement of an on-board calibration source, such as a cavity blackbody, is desirable. This type of source is typically designed with a cavity length exceeding the opening diameter so as to achieve high emissivity. Because the emissive surface needs to be large enough to match the instrument FOV, the resulting volume of such a source may make its use on small spacecrafts prohibitive. The present document defines the scope for an investigation of space qualifiable high emissivity plates as a smaller size alternative to cavity blackbody. The purpose is to evaluate, in light of the results, if this is a viable solution for the in-orbit calibration of a multispectral imaging radiometer recently designed for wildfire diagnosis.
On average, Canadian wildfires consume 2.4 million hectares of forest and release 20 million tonnes of carbon into the atmosphere annually. Because firefighting resources are limited and not all fires are equal in severity, it is important for fire managers to have adequate tools to compare fires and manage priorities. Lately, the CSA has initiated the development of a multispectral imaging radiometer designed for this purpose. The baseline instrument consists of an assembly of three nadir viewing cameras providing co-registered visible, MWIR, and LWIR image data. Data retrievals are intended to be made from the low earth orbit in pushbroom scanning mode. At the heart of the infrared cameras is a new array of 512×3 VOx resistive microbolometers [RD-1], selected for its low demand for spacecraft resources and its ability to retrieve fire characteristics. The wide swath of observation, essential to achieve high rates of revisit, is made possible by staggering two 512×3 arrays to form an effective 1017×3 microbolometer array in the detector assembly. The technical details of the multispectral imaging radiometer are provided in [RD-2].
This Statement of Work addresses the design, construction, and characterization of plate platforms for the in-orbit calibration of the infrared cameras of the above instrument. Each platform would include a launch-lock mechanism and rely on a fail-safe actuation mechanism to reposition itself into the cameras FOV during periods of in-orbit calibration. This work targets the resistively heated plates; the passively heated devices are excluded. The elements to be reviewed and assessed in the bid must include, but are not limited to, the following:
- Radiometric modeling and methods for validating modeling results
- Launch-lock subsystems and actuation mechanisms
- Fail-safe mechanisms that allow the plate to be moved away from the camera FOV in case of actuation mechanism failure
- Methods for high emissivity surface coating with adequate uniformity and reproducibility
- Design of high strength, low mass structural plate platform with minimal thermal gradient across the emissive surface
- Redundant precision temperature sensors with minimal drift over mission lifetime
- Methods for calibration and temperature control of the temperature sensor
- Distribution of resistive heaters and temperature sensors over the plate area
- Methods for validating motor system longevity and launch survival
- Measurement setup to characterize, in a representative environment: (i) variation of temperature and emissivity over the plate surface area; and (ii) effects of the thermal background and instrument temperature gradients on emission uniformity and stability
It should be noted that, unlike in the illustration shown in RD-2, it is possible to place the infrared cameras side by side so that their shared calibration plate (if it is the selected arrangement) does not encompass the FOV of the visible channel camera. Note also that it remains a possibility that each infrared camera has its own calibration plate.