Science

James Webb Space Telescope begins final checks before scientific observations

NASA’s Next Generation Observatory is entering its final stages of preparation before showing scientists a whole new way of looking at the universe.

Engineers are getting ready to make final changes to the instruments aboard the James Webb Space Telescope as the observatory gets ready to go live this summer. NASA said the telescope will soon have “calibrations and instrument characterizations using a rich variety of astronomical sources” to make sure everything works before Webb sets out to explore the early universe.

“We will be measuring instrument throughput — how much light that enters the telescope reaches the detectors and is recorded,” Scott Friedman, Webb Lead Scientist at the Baltimore Space Science Telescope Institute, said in a NASA statement Thursday (May 5). .

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While no telescope can accurately capture every photon that passes through it, Friedman says engineers will still want to know the throughput at multiple wavelengths of light to gauge Webb’s performance at collecting infrared light.

Friedman stressed that commissioning is “nearly complete” as the telescope is in the final two months of a process that began after Webb’s December 25, 2021 launch. Once the tools are properly assessed, he said, “we’ll be ready.” to launch the great scientific programs that both astronomers and the public have been eagerly awaiting.”

Along the way, the team releases several commissioning images, and an important commissioning target will soon be in the spotlight: the Large Magellanic Cloud. Although Friedman did not say whether this galactic neighbor of the Milky Way would be included in the early release images, he noted that studying the galaxy would be useful in calibrating any distortion.

The Webb telescope will also be appreciated even more for the clarity of stellar images through the entire optics of the instruments. Friedman noted that each tool works great with proven optics, but additional filters and a tool called a “diffraction grating” (which distributes light into component colors) will also be evaluated.

The team is also certifying the observatory’s target acquisition to ensure the telescope can point to within a hundredth of a second of arc, which would be useful for exoplanet observations.

“The star should be placed behind the mask so that its light is blocked, allowing the nearby exoplanet to shine through,” Friedman said. “In time series observations, we measure how an exoplanet’s atmosphere absorbs starlight during the hours it takes to pass in front of its star, allowing us to measure the properties and constituents of a planet’s atmosphere.”

The last stage of testing will be the observation of moving targets such as planets, satellites, rings, asteroids and comets. “Observing them requires the observatory to change its pointing direction relative to background reference stars during the observation,” Friedman said. “We will test this possibility by observing asteroids at different apparent speeds using each instrument.”

NASA plans to update the public on Webb’s progress on Monday (May 9) and a live stream of the discussion will be available online.

Follow Elizabeth Howell on Twitter @howellspace. Follow us on Twitter @Spacedotcom and on Facebook.

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