Canada's Contribution to the Webb Telescope

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 by COM DEV International in Ottawa and Cambridge, Ontario, for the CSA, with technical contributions from the Université de Montréal and National Research Council Canada and scientific guidance of the FGS science team. The CSA's contribution guarantees Canadian astronomers a share of observing time once the telescope launches in 2018.

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.

What's one-millionth of a degree?

In terms of the human eye, a person's field of view is almost 180°(try spreading your arms on either side of your body until you no longer see your hands—this is approximately 180°). One millionth of a degree is the angle formed by someone holding up a quarter at a distance of 1500 km away from you (the distance from Montreal to St John's, Newfoundland!).

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 FGS-NIRISS science team is jointly led by Dr John Hutchings of the National Research Council Canada and Professor René Doyon from the Université de Montréal, Director of the Mont-Mégantic Observatory 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; the University of Rochester; and the University of Toronto.

Contribution du canada

Slated for launch in 2018, the James Webb Space Telescope is a joint project between NASA, the European Space Agency and the CSA.
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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)

james Webb

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