The James Webb Telescope was launched on December 25, 2021. It took the telescope over a month to reach an orbit beyond the Moon, 1.5 million miles from planet Earth. In a spectacular launch and amazing high-tech origami deployment, the telescope unfolded its solar panels, heat shield, and mirrors successfully.
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The James Webb Telescope is now cooling its temperature thanks to the sun-shield and taking on a three-month long process of mirror alignment. Seven stages of fine-tuning are needed to get the telescope up and running. The iconic 18 golden mirrors, known as the primary mirrors, reflect light from the universe onto the secondary mirror that is extended by booms in the center. Light from the second mirror travels into the instruments where they are registered as data and visuals. But to get this right, all 18 mirrors must be aligned to create a unified image on the secondary mirror.
A Complex Game Of Mirrors And Light
Imagine a game where 18 people have to use a mirror to reflect the light of the sun onto a dot on the wall. The 18 people would have to move about their mirrors to get the sunbeam right on target. This is exactly what NASA engineers are doing, only that the light they are reflecting is that of the most distant objects of the observable universe, and mirrors are millions of miles away in deep space.
Out in deep space, each one of the 18 golden primary mirrors of the telescope has built-in actuators that allow them to move independently. The actuators are attached to the back of each mirror. Each mirror can adjust to an astonishing precision of up to 10 nanometers, that’s about 1/10,000th of the width of a human hair. Small adjustments to the secondary mirror and sensing instruments also take place during this process.
NASA has already achieved Segment Alignment and Image Stacking by focusing all dots reflected by each mirror and stacking them on top of each other on the secondary mirror. The photons of light have reached a specific location of the NIRCam’s sensor. However, until very fine adjustments are made, Webb is acting as 18 small telescopes and not as one large one. “We still have work to do, but we are increasingly pleased with the results we’re seeing,” Lee Feinberg, optical telescope element manager for Webb at NASA’s Goddard Space Flight Center says.