Innovation and imagery — Montreal team boldly goes

A team of Montreal-based researchers is responsible for a piece of advanced imaging technology on the pioneering James Webb Space Telescope, which, at 1.5 million kilometres, is now three times further away from the city than the moon. And from that high perch, this sophisticated instrument will be looking even further. Much further.

The Near Infrared Imager and Slitless Spectrograph (NIRISS) is one of four instruments on the telescope, which has now completed its final commissioning. That means the Montreal group can now begin taking a hard look at planets orbiting around other stars.

Led by David Lafrenière, a member of the Université de Montréal’s Institute for Research on Exoplanets, the Canadian contribution has guaranteed them precious telescope observation time for NIRISS to study the atmospheres of these distant worlds as they transit across their parent stars.

Such work led Lafrenière and fellow team to be named Radio-Canada scientists of the year in 2008, after they obtained the first direct image of exoplanet orbit motion in a planetary system other than our own. This milestone was announced via a prestigious publication in the journal Science.

“I’m very excited by the truly unprecedented view of exoplanetary atmospheres that Webb will provide, and I can’t wait to see what new and unexpected things we’ll learn,” Lafrenière told Canadian Space Agency (CSA) in mid-2021. “I’m hoping Webb will detect the atmospheres of habitable rocky planets.”

Lafrenière’s comments to the CSA suggested that Webb’s observations will extend a six-year NSERC research grant Lafrenière is already using, so that he and his colleagues can continue learning about the composition of Earth-sized exoplanets at least through the year 2024.

Webb’s deep-space location will provide observations of exoplanet atmospheric chemistry with unprecedented precision, which will in turn allow researchers to find clues as to how planets are born, evolve and grow to old age. NIRISS will thus allow us to put our own solar system in context.

In fact, Webb’s first science-quality images may include glamour shots of NIRISS-imaged exoplanets. That was hinted at during a June 29 NASA discussion about what the first operational images — still a tight secret — will contain.

“We will share Webb’s first exoplanet spectrum,” Thomas Zurbuchen, NASA’s associate administrator for the agency’s science mission directorate, told reporters during a livestreamed event from Baltimore’s Space Telescope Science Institute, which manages Webb’s observation schedule.

While Webb is optimized to look at huge gas giant planets, any hints of water, oxygen or other potentially life-friendly elements could one day help researchers in assessing the chances for life in much smaller rocky planets, like Earth.

Zurbuchen said one question researchers hope to determine is whether there “is life elsewhere”, other than Earth. Webb cannot answer that question on its own, but its observations will certainly help.

NIRISS and the Fine Guidance Sensor, a crucial pointing device for Webb, were both manufactured by Honeywell on behalf of CSA. The Canadian contribution provides Canadian researchers with a guaranteed share of observations on the $13 billion (US$10 billion) observatory, a valuable asset as Webb is already in high demand worldwide for telescope time.

Getting the instrument certified for observing in June was a milestone for NIRISS principal investigator René Doyon, another member of the Université de Montréal team. He is renowned for creating similar exoplanet-hunting spectrographs for Observatoire du Mont-Mégantic and the Canada-France-Hawaii Telescope.

“I’m so excited and thrilled to think that we’ve finally reached the end of this two-decade-long journey of Canada’s contribution to the mission,” Doyon said in a recent NASA blog post, adding he is “pinching himself” about the first images coming out soon.

His excitement is driven by the unique aspects of NIRISS, which include its deep-space vantage point, and a prioritization of infrared light — a part of the light spectrum largely filtered out in Earth’s atmosphere. While NIRISS can range into other celestial objects like galaxies and “failed” stars (brown dwarfs), its ability to capture high-precision spectra from a single bright object make it perfect for these exoplanet observers.

NIRISS has four modes, and it’s the SOSS (Single Object Slitless Spectroscopy) mode that will be especially helpful to gain information about exoplanet composition, Nathalie Ouellette, outreach scientist for Webb at Montréal, said in another NASA blog post.

“This mode is optimized to carry out time-series observations, which are ideal for studying a phenomenon that changes over the length of a typically hours-long observation, such as an exoplanet transiting in front of its host star.”

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