NASA’s next-generation observatory is entering the final stages of preparation before showing scientists an entirely new view of the universe.
Engineers are preparing to make final adjustments to instruments aboard the James Webb Space Telescope as the observatory prepares to operate this summer. NASA said the telescope has “calibrations and characterizations of instruments using a rich variety of astronomical sources” coming soon to make sure everything works before Webb is released to examine the early universe.
“We will measure the performance of the instruments: the amount of light entering the telescope reaches the detectors and is recorded,” said Scott Friedman, lead scientist for Webb commissioning at the Space Science Telescope Institute in Baltimore, in a NASA statement on Thursday (May 5). .
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While no telescope can accurately collect every photon that hits it, engineers will still want to know the performance at various wavelengths of light to assess Webb’s performance in collecting infrared light, Friedman said.
Friedman emphasized that the commissioning is “almost done” as the telescope is in the final two months of the process, which began after Webb’s launch on December 25, 2021. Once the instruments are properly evaluated, he said, “we will be ready to begin the great science programs that both astronomers and the public have been eagerly awaiting.”
The team has been posting some commissioning images along the way, and will soon be focusing on one notable commissioning target: the Large Magellanic Cloud. While Friedman wouldn’t say whether this Milky Way’s galactic neighbor will be included in the first release images, he did note that examining the galaxy will be useful to gauge any distortion.
The Webb telescope will also be further evaluated for its sharpness of stellar images, through the optics of all instruments. Each instrument works well with the optics tested so far, Friedman said, but additional filters and a tool called a “diffraction grating” (which spreads light into constituent colors) will also be tested.
The team will also certify the observatory’s target acquisition to make sure the telescope can point to an accuracy of up to one-hundredth of an arcsecond, which will be useful for exoplanet observations.
“The star must be placed behind a mask to block its light, which allows 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 components of the planet’s atmosphere.”
A final test activity will be the observation of moving targets such as planets, satellites, rings, asteroids and comets. “Observing this requires the observatory to change its pointing direction relative to 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.