WASHINGTON — The James Webb Space Telescope has seen its first star – 18 times. The NASA images, released on Feb. 11, show light from the same star as the brand-new telescope works on aligning its 18 mirrors for deep space exploration.
These are the first pictures coming from the revolutionary orbiting space probe, which is designed to observe some of the oldest and most distant objects and events in the universe. NASA explains that the telescope is nearing completion of the first phase in a months-long process to properly align the satellite’s primary mirror — using the Near Infrared Camera (NIRCam) instrument.
Officials at NASA say their challenge in completing this is two-fold. First, they have to confirm that NIRCam is ready to collect light from celestial objects. Next, James Webb must 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,” which is a product of the telescope’s unaligned mirror segments all reflecting the light of that one star back at James Webb’s secondary mirror and into the 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 starting in the summer of 2022. Over the next month or so, the team will gradually adjust the mirror segments until the 18 images become a single image of that distant star.
The telescope is gathering gigabytes of data just in tests
Moving forward, Webb’s images will only become clearer, more detailed, and more intricate as its other three instruments reach their intended cryogenic operating temperatures and begin capturing data.
“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,” says Marcia Rieke, principal investigator for the NIRCam instrument and regents professor of astronomy at the University of Arizona, in a media release.
During the image capturing process that began on Feb. 2, astronomers repointed James Webb towards 156 different positions around the predicted location of the star and generated 1,560 images using NIRCam’s 10 detectors — compiling 54 gigabytes of raw data.
The entire process lasted nearly 25 hours, but the telescope 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 sent to Earth are only a center portion of that larger mosaic — producing a huge image with over two 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,” explains 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.”
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.
The telescope needs time to cool down in space
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.
NASA adds that NIRCam is the observatory’s “wavefront sensor and a key imager.” Scientists selected it for use during the James Webb telescope’s initial alignment because it has a wide field of view and the unique ability to safely operate at higher temperatures than other high-tech instruments.
NIRCam also contains customized components designed to specifically aid in the process. The device will be used throughout nearly the entire alignment of the telescope’s mirrors.
The NASA team notes, however, that NIRCam is still operating well beyond its ideal running temperature while it captures these initial engineering images, leaving “visual artifacts” in the mosaic. Luckily, researchers say the impact of these artifacts will lessen significantly as James Webb reaches its ideal operating temperature.
“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,” says Michael McElwain, a Webb observatory project scientist at NASA’s Goddard Space Flight Center.
Though this is a big moment, confirming that Webb is a functional telescope, there is still much to do in the coming months as the state-of-the-art probe prepares for full scientific operations using all four of its instruments.
South West News Service contributed to this report.