By Roshni Printer Photo credit: NASA GSFC/CIL/Adriana Manrique Gutierrez 詹姆斯．韋伯 太空望遠鏡 James Webb Space Telescope In the vast realm of space, a revolutionary tool has been geared up to propel our exploration of the cosmos – the James Webb Space Telescope. Set up as a successor to the Hubble Space Telescope, Webb was launched in December 2021 with the aim of uncovering the formation of galaxies, stars, and planets [1]. As an extremely long duration is needed for the light from a very distant object to reach us, the observation we make today is actually reflecting their appearance in the past, providing us a peek into the early universe. Observing the conditions during the formation of the first galaxies enables scientists to trace the origins of our own galaxy, along with the planets and stars it encompasses. Named after a prior administrator of NASA [2], Webb represents key advancements in the usage of space telescopes, and is the largest and most intricately designed observatories ever sent into space. The main component of the telescope, known as the primary mirror, functions to capture red and infrared light to facilitate the observation of far-off objects that are highly redshifted (footnote 1) [3, 4]. The mirror then reflects the light onto a smaller secondary mirror, where it is redirected to scientific instruments for interpretation. A large primary mirror can reveal more details of a far-off object by collecting more light signals from it. Webb has a light collecting area 6.25 times greater than that of the Hubble Space Telescope [4], but one of the biggest challenges was the technical restriction of launching such a large mirror into space. To overcome this hurdle, the telescope was innovatively designed to be a folding telescope – much like origami – where the mirror would unfold once they had detached from the launch vehicle. Webb is also an incredible feat of engineering that has the capability of adjusting its focus with very fine precision. The primary mirror is made up of 18 hexagonal segments of beryllium [3], whose position can be adjusted independently by the tiny mechanical motors called actuators behind each segment. Controlled by the team on the ground, adjustments as fine as about 1/10,000th of the width of a human hair can be made to produce focused, sharp images [5].
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