NASA’s next-generation observatory is entering the final stages of preparation before showing scientists a whole new view of the universe.
Engineers are preparing to make final adjustments to the instruments aboard the James Webb Space Telescope as the observatory prepares for operation this summer. NASA said the telescope has “calibrations and characterizations of instruments using a rich variety of astronomical sources” coming up to make sure everything is working before Webb is released to examine the early universe.
“We’re going to be measuring instrument throughput — how much light that enters the telescope hits the detectors and gets registered,” said Scott Friedman, Webb’s lead commissioning scientist at the Space Science Telescope Institute in Baltimore, USA. a statement from NASA Thursday, May 5. .
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While no telescope can accurately collect every photon that comes in, engineers will still want to know the throughput at multiple wavelengths of light to gauge Webb’s performance in collecting infrared light, Friedman said.
Friedman stressed that commissioning is “almost there,” as the telescope is in the final two months of the process, which began after Webb launched on Dec. 25, 2021. Once the instruments have been properly evaluated, a he said, “we will be ready to begin the major science programs that astronomers and the public have been eagerly awaiting.”
The team released some commissioning images along the way, and one notable commissioning target will soon be in focus: the Large Magellanic Cloud. Although Friedman didn’t specify whether this galactic neighbor of the Milky Way would be included in the first images released, he noted that examining the galaxy would be helpful in calibrating any distortion.
The Webb Telescope will also be evaluated even further for its sharpness of stellar images, through all the optics of the instruments. Each instrument works well with the optics tested so far, Friedman noted, but additional filters and a tool called a “diffraction grating” (which scatters light into constituent colors) will also be evaluated.
The team will also certify the observatory’s target acquisition to ensure the telescope can point with precision down to hundredths of an arcsecond, which will be useful for exoplanet observations.
“The star must be placed behind a 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 the atmosphere. of the planet.”
A final final testing activity will be observing moving targets such as planets, satellites, rings, asteroids and comets. “Observing them requires the observatory to change its pointing direction relative to the background guide stars during the observation,” Friedman said. “We will test this capability by observing asteroids of different apparent velocities 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.