Webb Telescope Snaps Stunning Selfie as Primary Mirror Alignment Progresses Well

Webb Telescope Snaps Stunning Selfie Progresses Primary Mirror Alignment
This “selfie” was created using a specialized pupil imaging lens inside of the NIRCam instrument that was designed to take images of the primary mirror segments instead of images of space. This configuration is not used during scientific operations and is used strictly for engineering and alignment purposes. In this case, the bright segment was pointed at a bright star, while the others aren’t currently in the same alignment. This image gave an early indication of the primary mirror alignment to the instrument. Credit: NASA

For SpaceUpClose.com & RocketSTEM

CAPE CANAVERAL, FL – The James Webb Space Telescope (JWST) snapped an absolutely stunning ‘selife’ of its 18 segment primary mirror as part of the initial alignment process in progress for the primary mirror – after the mammoth international observatory arrived at its final orbital destination at the L2 Lagrange Point on 24 Jan. 2022, sliding gently into its new home a million miles (1.5 million km) from Earth

The selfie image of the observatory’s 18 segment and 21.3-foot (6.5 m) wide gold-coated primary mirror was taken by the NIRCam instrument and unveiled by the NASA science and engineering team during a media briefing on Friday, Feb. 11 some 48 days after the Christmas Day launch – and constitutes the heart of the $10 Billion observatory which is an international collaboration of NASA, ESA and CSA.

The selfie is the first close up image of the primary mirror taken in deep space following its successful full deployment in mid-January.

The team also released the first actually images taken by Webb of the nondescript bright, isolated star in the constellation Ursa Major known HD 84406 which was chosen for the alignment work – the results of which are going well so far.

“These initial results closely match expectations and simulations,” said the NASA Webb team.

“This amazing telescope has not only spread its wings, but it has now opened its eyes,” said Lee Feinberg, Webb optical elements manager.

This image mosaic was created by pointing the telescope at a bright, isolated star in the constellation Ursa Major known as HD 84406. This star was chosen specifically because it is easily identifiable and not crowded by other stars of similar brightness, which helps to reduce background confusion. Each dot within the mosaic is labeled by the corresponding primary mirror segment that captured it. These initial results closely match expectations and simulations. Credit: NASA

The primary mirror alignment work thus far is the culmination of an arduous two decade long development and million mile journey since launching on Christmas Day, the massive international James Webb Space Telescope (JWST) finally arrived at its final orbital destination at the L2 Lagrange Point on 24 Jan. 2022, sliding gently into its new home a million miles from earth – after a minor course correction thruster firing.

 

 

This unannotated image mosaic was created by pointing the telescope at a bright, isolated star in the constellation Ursa Major known as HD 84406. This star was chosen specifically because it is easily identifiable and not crowded by other stars of similar brightness, which helps to reduce background confusion. These initial results closely match expectations and simulations. Credit: NASA

The  “selfie” image “was created using a specialized pupil imaging lens inside of the NIRCam instrument that was designed to take images of the primary mirror segments instead of images of space. This configuration is not used during scientific operations and is used strictly for engineering and alignment purposes. In this case, the bright segment was pointed at a bright star, while the others aren’t currently in the same alignment. This image gave an early indication of the primary mirror alignment to the instrument,” explained the Webb team.

The 18-segment gold coated primary mirror of NASA’s James Webb Space Telescope is raised into vertical alignment in the largest clean room at the agency’s Goddard Space Flight Center in Greenbelt, Maryland, on Nov. 2, 2016.The secondary mirror mount booms are folded down into stowed for launch configuration.  Credit: Ken Kremer/kenkremer.com/spaceupclose.com

Further details from NASA:

The team’s challenge was twofold: confirm that NIRCam was ready to collect light from celestial objects, and then identify starlight from the same star in each of the 18 primary mirror segments. The result is an image mosaic of 18 randomly organized dots of starlight, the product of Webb’s unaligned mirror segments all reflecting light from the same star back at Webb’s secondary mirror and into NIRCam’s detectors.

What looks like a simple image of blurry starlight now becomes the foundation to align and focus the telescope in order for Webb to deliver unprecedented views of the universe this summer. Over the next month or so, the team will gradually adjust the mirror segments until the 18 images become a single star.

“The entire Webb team is ecstatic at how well the first steps of taking images and aligning the telescope are proceeding. We were so happy to see that light makes its way into NIRCam,” said Marcia Rieke, principal investigator for the NIRCam instrument and regents professor of astronomy, University of Arizona.

During the image capturing process that began Feb. 2, Webb was repointed to 156 different positions around the predicted location of the star and generated 1,560 images using NIRCam’s 10 detectors, amounting to 54 gigabytes of raw data. The entire process lasted nearly 25 hours, but notedly the observatory was able to locate the target star in each of its mirror segments within the first six hours and 16 exposures. These images were then stitched together to produce a single, large mosaic that captures the signature of each primary mirror segment in one frame. The images shown here are only a center portion of that larger mosaic, a huge image with over 2 billion pixels.

“This initial search covered an area about the size of the full Moon because the segment dots could potentially have been that spread out on the sky,” said Marshall Perrin, deputy telescope scientist for Webb and astronomer at the Space Telescope Science Institute. “Taking so much data right on the first day required all of Webb’s science operations and data processing systems here on Earth working smoothly with the observatory in space right from the start. And we found light from all 18 segments very near the center early in that search! This is a great starting point for mirror alignment.”

Lee Feinberg, Webb optical telescope element manager at NASA’s Goddard Space Flight Center, explains the early stages of the mirror alignment process. 

Each unique dot visible in the image mosaic is the same star as imaged by each of Webb’s 18 primary mirror segments, a treasure trove of detail that optics experts and engineers will use to align the entire telescope. This activity determined the post-deployment alignment positions of every mirror segment, which is the critical first step in bringing the entire observatory into a functional alignment for scientific operations.

NIRCam is the observatory’s wavefront sensor and a key imager. It was intentionally selected to be used for Webb’s initial alignment steps because it has a wide field of view and the unique capability to safely operate at higher temperatures than the other instruments. It is also packed with customized components that were designed to specifically aid in the process. NIRCam will be used throughout nearly the entire alignment of the telescope’s mirrors. It is, however, important to note that NIRCam is operating far above its ideal temperature while capturing these initial engineering images, and visual artifacts can be seen in the mosaic. The impact of these artifacts will lessen significantly as Webb draws closer to its ideal cryogenic operating temperatures.

“Launching Webb to space was of course an exciting event, but for scientists and optical engineers, this is a pinnacle moment, when light from a star is successfully making its way through the system down onto a detector,” said Michael McElwain, Webb observatory project scientist, NASA’s Goddard Space Flight Center.

Moving forward, Webb’s images will only become clearer, more detail-laden, and more intricate as its other three instruments arrive at their intended cryogenic operating temperatures and begin capturing data. The first scientific images are expected to be delivered to the world in the summer. Though this is a big moment, confirming that Webb is a functional telescope, there is much ahead to be done in the coming months to prepare the observatory for full scientific operations using all four of its instruments.

Webb orbital animation at L2 Lagrange point

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Webb is in many respects a time machine looking back to the formation of the Universe over 13.5 Billion years ago and how we came to be and evolve over the eons.

Watch Ken’s BBC World TV interview about Webb achieving final orbit and the goals ahead:

Video Caption: Dr. Ken Kremer of Space UpClose live interview on BBC World News TV on Jan. 24, 2022 ET (Jan. 25 GMT) about NASA James Webb Space Telescope (JWST) just hours after achieving orbit at its final destination, why at L2, what’s ahead with spacecraft checkouts, what are the science goals and when are first pictures expected

Watch this space for my ongoing reports on JWST mission and science.

Watch Ken’s continuing reports about JWST, IXPE, DART, SpaceX Crew and Cargo Dragons, Artemis, SLS, Orion and NASA missions, Lucy Asteroid mission, SpaceX Starlink, Blue Origin and Space Tourism, Commercial Crew and Starliner and Crew Dragon and onsite for live reporting of upcoming and recent SpaceX and ULA launches including Crew 1 & 2 & 3, ISS, Solar Orbiter, Mars 2020 Perseverance and Curiosity rovers, NRO spysats and national security missions and more at the Kennedy Space Center and Cape Canaveral Space Force Station.

Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news: www.kenkremer.com –www.spaceupclose.com – twitter @ken_kremer – email: ken at kenkremer.com

Dr. Kremer is a research scientist and journalist based in the KSC area, active in outreach and interviewed regularly on TV and radio about space topics.
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Artists concept of James Webb Space Telescope (JWST). It achieved orbit at final destination at L2 on 24 Jan. 2022. The James Webb Space Telescope is the next great space science observatory following Hubble, designed to answer outstanding questions about the Universe and to make breakthrough discoveries in all fields of astronomy. Webb will see farther into our origins: from the formation of stars and planets, to the birth of the first galaxies in the early Universe. Webb is an international partnership between NASA, ESA and CSA. Credit: NASA/ESA/CSA

 

Webb trajectory diagram shows a conceptual view of Webb’s trajectory and halo orbit. Webb launched on the sun-facing side of the earth and travelled a slightly curved trajectory for the ~1,609,344 km to enter its L2 halo orbit on 24 Jan. 2022. A halo orbit is one which rather than follow a single path, is an orbit that periodically varies through a series of paths. The ‘Earth/L2 frame’ orbits the Sun while Webb orbits L2 as shown in this animation of Webb’s orbit. Also note Webb’s orientation; the sunshield is perpendicular to the Sun so Webb’s mirrors and instruments are in cold complete darkness. Credit: NASA/ESA/CSA

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Ken Kremer

Watch for Ken’s continuing onsite coverage of NASA, SpaceX, ULA, Boeing, Lockheed Martin, Northrop Grumman and more space and mission reports direct from Kennedy Space Center and Cape Canaveral Air Force Station in Florida and Wallops Flight Facility in Virginia. Stay tuned here for Ken's continuing Earth and Planetary science and human spaceflight news. Dr. Kremer is a research scientist and journalist based in the KSC area, active in outreach and interviewed regularly on TV and radio about space topics. Ken’s photos are for sale and he is available for lectures and outreach events.

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