Maggio 23, 2022

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Accensione! Il telescopio spaziale Webb accende gli strumenti

Telescopio spaziale James Webb della NASA. Credito: NASA Goddard Space Flight Center e Northrup Grumman

Ora inizia il processo di allineamento di tutti i 18 segmenti speculari in modo che lavorino insieme come uno.

Dall’arrivo di[{” attribute=””>NASA’s James Webb Space Telescope at its orbital destination January 24, the mission operations team has successfully powered on all of the telescope’s science instruments, including its primary camera, the Near Infrared Camera, or NIRCam, built by a team of researchers and engineers led by University of Arizona astronomer Marcia Rieke.

Turning the instruments on is the first in a series of critical steps that also includes turning off heaters to begin a long cool-down process for the instruments and aligning the telescope’s mirrors over a period of months.

Launched on December 25, Webb is NASA’s top science priority, and UArizona astronomers played key roles in designing and developing the telescope’s infrared eyes. NIRCam and MIRI, which stands for Mid-Infrared Instrument, will allow Webb to peer deeper into the cosmos than ever before and collect light from the earliest stars, galaxies, nebulous stellar nurseries, planetary atmospheres, and more.

Artist Conception of the James Webb Space Telescope

The James Webb Space Telescope has reached it’s parking spot in space and has successfully powered up all of it’s instruments. Within the week, the UArizona-led NIRCam will be used to align the 18 gold-plated mirror segments to work together as one giant mirror.. Credit: NASA GSFC/CIL/Adriana Manrique Gutierrez

Marcia Rieke, a University of Arizona Regents Professor of Astronomy, is principal investigator for NIRCam. Her husband, George Rieke, also a Regents Professor of Astronomy, is the science team lead for MIRI.

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While MIRI and some components of the telescope’s other instruments were powered on in the weeks after Webb’s December 25 launch, the final three instruments – including NIRCam – turned on in the past few days.

After the powered-on instruments undergo initial checks, the mission operations team’s next major step is to turn off instrument heaters. The heaters keep critical optics warm to protect them from water and ice condensation. As the instruments meet predefined criteria for overall temperatures, the team will shut off the heaters to allow the instruments to cool to final temperatures that will allow the infrared detectors to see faint objects in the night sky.

NIRCam Sensor Array

A sensor array for the NIRCam instrument, designed and tested by Marcia Rieke’s research group at Steward Observatory. For the sensors to detect infrared light without too much noise in the data, Webb and its instruments must be kept as cool as possible. Credit: Marcia Rieke

When NIRCam reaches about minus 244 degrees Fahrenheit, likely later this week, Webb’s optics team will be ready to begin meticulously aligning the telescope’s 18 primary mirror segments to work together as a single mirror surface. NASA is targeting star HD84406 to begin this process. It will be the first object NIRCam sees when photons of light hit the instrument’s powered-on detectors. However, it won’t be the first image that is shared with the public. That object has not been chosen yet, and NASA will likely release the image this summer.

NIRCam was assigned the task of aligning the telescope because it was built to observe shorter wavelengths of light than the other onboard instruments. Because of this, it can discern the most detail and is the most sensitive to misalignment.

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“These first photos mean that we finally get starlight moving through the system and detected by NIRCam,” Marcia Rieke said. “NIRCam has not been turned on since before launch; this will prove the launch didn’t introduce issues for how it can work.”

Poiché i 18 segmenti dello specchio non funzionano ancora in tandem, il processo di allineamento creerà prima un’immagine di 18 punti di luce sfocati casuali mentre il telescopio punta sulla stella HD84406.

Per le prime settimane di allineamento dello specchio, il team manterrà il NIRCam addestrato sulla stella mentre eseguirà aggiustamenti microscopici ai segmenti dello specchio di Webb. Alla fine, quella raccolta di 18 punti sfocati diventerà un’immagine focalizzata di una singola stella.

Il raffreddamento del telescopio e degli strumenti continuerà nel prossimo mese, con NIRCam che alla fine raggiungerà quasi meno 400 gradi Fahrenheit.

La NASA ha assegnato il 13% del tempo totale di osservazione di Webb agli astronomi dell’UArizona. Ciò offre all’università più tempo di visione rispetto a qualsiasi altro centro di astronomia al mondo. La National Science Foundation ha classificato l’Università dell’Arizona n. 1 nelle spese di ricerca di astrofisica e astrofisica ogni anno dal 1988.