Canada's Contribution to the James Webb Space Telescope

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The Canadian Space Agency (CSA) is providing the Webb's Fine Guidance Sensor (FGS), as well as one of the telescope's four science instruments: the Near-InfraRed Imager and Slitless Spectrograph (NIRISS). Both were designed, built and tested for the CSA by COM DEV International in Ottawa and Cambridge, Ontario, with technical contributions from the Université de Montréal and National Research Council Canada and scientific guidance from the FGS science team. The CSA's contribution guarantees Canadian astronomers a share of observing time once the telescope launches in 2021.

The Fine Guidance Sensor: Keeping Webb on Target

The Fine Guidance Sensor consists of two identical cameras that are critical to Webb's ability to "see": their images will allow the Webb space telescope to determine its position, locate its celestial targets, and remain pointed so that the telescope can collect high-quality data. The FGS will guide the telescope with incredible precision, with an accuracy of one millionth of a degree.

Canada gained key knowledge in building pointing systems (specifically, the fine error sensor) on the FUSE mission, which contributed to Canada's expertise in designing Webb's FGS.


NIRISS will have unique capabilities for finding the earliest and most distant objects in the Universe's history. It will also peer through the glare of nearby young stars to unveil new Jupiter-like exoplanets. It will have the powerful capability of detecting the thin atmosphere of small, habitable, earth-like planets and determine its chemical composition to seek for water vapour, carbon dioxide and other potential biomarkers such as methane and oxygen.

The Canadian Science Team

The FGS-NIRISS science team is led by Professor René Doyon from the Université de Montréal, Director of the Mont-Mégantic Observatory, Director of the Institute for Research on Exoplanets (iRex), and member of the Centre de recherche en astrophysique du Québec (CRAQ). The team includes astronomers from: COM DEV; the National Research Council Canada; Saint Mary's University; the Space Telescope Science Institute (STScI); the Swiss Federal Institute of Technology Zurich (ETH Zurich); the Université de Montréal; York University; the University of Rochester; Cornell University; and the University of Toronto.

The Fine Guidance Sensor engineering test unit being prepared for cryogenic testing at the CSA's David Florida Lab in Ottawa (Credit: CSA/-COM DEV)

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Protoflight model of NIRISS's optical elements (Source: COM DEV)