After completing the key specular calibration steps, NASA's James Webb Space Telescope team expects Webb's optical performance to meet or exceed the scientific goals the telescope is expected to achieve.
On March 11, Webb's team completed a calibration phase called Fine Phasing, a critical phase in which every optical parameter that was inspected and tested met or exceeded expectations during this critical phase of debugging Webb's optical telescope components. This is the fifth crucial step in the calibration of the main mirror of the James Webb telescope: Segment Image Identification, Segment Alignment, Image Stacking, Coarse Phasing, Fine Phase, and Telescope Alignment Over Instrument Fields of View) and Iterate Alignment for Final Correction. So far, Webb's team hasn't identified any critical issues, nor has it found measurable contamination or blockages in Webb's optical path. Webb was able to successfully collect light from distant objects and accurately transmit it to the relevant instrument.
While the purpose of this image was to focus on the bright stars in the center of the image for alignment assessment, Webb's optics and NIRCam camera were so sensitive that galaxies and stars in the background of the image were revealed. During this phase of Webb's mirror calibration, the "fine phase" phase, each main lens segment is adjusted to produce a uniform image of the same star using only the NIRCam instrument, a near-infrared camera. The star in this image, named 2MASS J17554042+6551277, uses a red filter to optimize visual contrast.
Image source: NASA/Space Telescope Science Institute (STScI)
With webb still months away from finally presenting us with a whole new picture of the universe, that said, this milestone calibration meant that the telescope team confirmed that Webb's pioneering optical system was working as much as possible.
"More than 20 years ago, Webb's team began building the most powerful telescope ever built and came up with a bold optical design to meet the needs of scientific exploration," said Thomas Zurbuchen, deputy director of NASA's Science Mission Board. ”
On Earth, some of the largest ground-based telescopes also use segmented main mirrors, but Webb was the first telescope to use this design in space. The main mirror with a diameter of about 6.5 meters consists of 18 hexagonal beryllium segments, which are too large to fit directly into the rocket fairing, and it must be folded at launch, unfolded in space after liftoff, and then adjusted by the telescope team, the scale of the adjustment is in the nano range, until a single mirror is finally formed.
Lee Feinberg, director of components for the Webb Optical Telescope and nasa's Goddard Space Flight Center, said: "In addition to allowing Webb to achieve incredible scientific exploration goals, the team that designed, built, tested, launched and now operates this telescope has pioneered a new way to build a space telescope. ”
NASA's Webb telescope has completed the critical specular calibration steps, and the optics are working properly.
Video source: NASA Goddard Space Flight Center
Subtitle Production: Wow
With the completion of the fine phase modulation phase of the telescope calibration step, Webb's team has now completed Webb's main imager, the Near-Infrared Camera (NIRCam), fully calibrated with the telescope's mirror.
"We've fully aligned and focused our telescopes on a star, performing even better than expected, which means a lot to scientific observations, and we're so excited," said Ritva Keski-Kuha, deputy director of webb optical telescope components at NASA's Goddard Space Flight Center. ”
This new "selfie" from the Webb Telescope was created using a dedicated pupil imaging lens inside the NIRCam camera, which is specifically designed to take images of the main lens segment, rather than images of the sky, which will not be used during scientific operations, but only for engineering and calibration purposes. In the image above, all 18 of Webb's main mirror segments are neatly and uniformly collecting light from the same star.
Image credit: NASA/Space Telescope Science Institute
Over the next 6 weeks, Webb's team will continue to complete the remaining calibration steps, followed by the final scientific instrument preparations. Webb's team will make further adjustments to the telescope, including the Near-Infrared Spectrograph, mid-Infrared Instrument, Near InfraRed Imager, and Slitless Spectrograph. At this stage, the algorithm evaluates the performance of each instrument and then calculates the final correction required to achieve a well-aligned telescope on all scientific instruments. After that, Webb will begin its final alignment steps, and the telescope team will adjust for all the tiny residual positioning errors in the mirror segment.
The Webb telescope team is expected to complete all the work of calibrating the optical telescope components by early (and possibly earlier) before about two months of scientific instrument preparation. Webb's first full-resolution images and scientific data will be released during the summer.
Webb is the world's premier space science telescope, and once fully operational, it will help unravel mysteries in the solar system, leapfrog distant worlds around other stars, and explore the mysterious structure and origin of our universe, and Earth's place in it. Webb is an international program led by NASA's partners with the European Space Agency (ESA) and the Canadian Space Agency.
For more information on the Webb Mission, please visit:
https://www.nasa.gov/webb
References:
https://www.nasa.gov/press-release/nasa-s-webb-reaches-alignment-milestone-optics-working-successfully