What will the James Webb Space Telescope look at first?


James Webb Space Telescope Primary Mirror in Space
(Image Credit: NASA’s Goddard Space Flight Cente)

As the 18 main mirror components of the James Webb Space Telescope begin their lengthy alignment procedure, the astronomy world wonders: What will the massive telescope gaze at first?

Webb soared into space successfully on December 25December 25 and successfully completed its significant deployments about two weeks later while speeding toward its ultimate destination: the Earth-sun Lagrange Point 2 (L2), a gravitationally stable spot in space about 930,000 miles (1.5 million kilometers) away from our planet.

It is necessary to progressively align the telescope's 18 hexagonal mirror segments into a single, practically flawless light-collection surface. A vital part of that process is capturing photos of the sky to monitor how well the alignment is progressing. Still, Jane Rigby, Webb operations project scientist, urged everyone not to anticipate much from Webb's "first light."

"The first photographs will be unattractive. It is going to be hazy. We'll have a total of 18 of these specks dotting the sky. "When asked about the successful deployment of Webb's 21.3-foot-wide (6.3 meters) primary mirror on Saturday (January 8January 8), Rigby informed reporters at a live-streamed press conference. Rigby spoke from NASA's Goddard Space Flight Center in Maryland, where telescope operations are based.

During the press briefing, members of the Webb team did not specify whether or not they wanted to disclose those early, "ugly" photographs. The primary mirror segments will first be off by millimeters, which is a huge degree of imprecision when focusing on a distant exoplanet or viewing the stars in a faraway galaxy.

But by around Day 120 of the mission, which is about April 24April 24, engineers estimate that the telescope will be viewing significantly more accurately, with the alignment phase complete.

For Rigby, the mirrors act as miniature prima donna prima donnas doing their own thing and singing to themselves in whatever key they want. "We have to make them operate like a chorus, and that is a deliberate, arduous process."

The next significant issue is what Webb will initially put its attention on. The observatory, promoted as a successor to the breakthrough Hubble Space Telescope that debuted in 1990, has received numerous "telescope time" requests among scientists. The great majority of them had to be turned down. NASA's website lists a few "early science" initiatives, although it is unknown which of these Webb would investigate first.


Related: James Webb Space Telescope vs. Hubble: How will their images compare?

However, we know a few of the observatory's early commissioning engineering alignment objectives.

"To test the detectors, "Rigby remarked, "we have several sources that are [of] good and uniform brightness"... A number of those objects are in the Large Magellanic Cloud since we can always view the north and south ecliptic poles. It doesn't matter when you need them."

As a result, regardless of when Webb launched, the team chose many commissioning period targets in the Large Magellanic Cloud, a dwarf galaxy near the Milky Way. "We knew we didn't have to continually replanning if the launch date altered," she added.

That consistency was, in retrospect, a sensible option since Webb's launch date was delayed thrice in the final few weeks alone owing to last-minute difficulties, including a defective data connection and an unforeseen clamp band release during launch preparations. All problems were satisfactorily rectified before launch.


Related: NASA’s James Webb Telescope Successfully Completes Deployment in Space.So what's next for the biggest observatory off Earth?


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