Διαστημικό τηλεσκόπιο James Webb (JWST) will specialise exclusively in infrared astronomy to study early σύμπαν. It will search for optical/infrared signals from the early αστέρια and galaxies formed in the Σύμπαν soon after the Big Bang for a better understanding of the formation and evolution of galaxies and the formation of αστέρια και πλανητικός συστήματα. Jwst will also study πλανητικός systems and the origins of life. The much-awaited Jwst is now scheduled to be launched on 18 December 2021.
Usually, one focusses a telescope at a target to observe. But at times you deliberately focus on nothing and that change the course of a field of study. Decision to focus Hubble χώρος telescope on nothing in the hitherto unexplored fields in the sky was one such incident that changed the course of astronomy.
Ανάμεσα σε πολλά επιτεύγματα ορόσημο του Hubble Χώρος Telescope (HST), the deep field images taken over the course of 10 days in 1995 when it captured about 3000 images of galaxies at different stages of stellar evolution has revolutionised astronomy and changed our understanding of the σύμπαν.
These deep field images were formed by the light that had travelled from the remotest locations of the σύμπαν for billions of light years through the expanding σύμπαν and had reached Earth now to be captured by the Hubble telescope after originally emanating from the early αστέρια and galaxies formed soon after Big Bang about 13 billion years ago. So, as such deep field images denoted early αστέρια and galaxies as they were then billions of years ago. This was truly remarkable feat.
But, this technique of capturing primordial optical signals for developing understanding of early σύμπαν could not be an effective methodological tool due to the fact discovered in 1929 by Edwin Hubble ότι η σύμπαν is expanding and all galaxies are moving away from each other as evidenced by the redshift of γαλαξίας’s spectrum to higher wavelengths in infrared (IR) region. But the Hubble telescope is equipped to observe in UV, visible and near-infrared region hence the need for an exclusive infrared αστεροσκοπείο in χώρος.
Η Διαστημικό τηλεσκόπιο James Webb (JWST) is thus a successor to the Hubble χώρος telescope (HST) in the sense that the Τζέιμς Γουέμπ telescope aims to carry forward the Hubble κληρονομιά του τηλεσκοπίου στην περιοχή μελέτης των πρώιμων σύμπαν. Jwst will operate exclusively in infrared astronomy and has following four key goals:
Για αυτούς τους λόγους, Jwst needed to be different from Hubble telescope in design and operation. It is a reflecting telescope designed to capture near-infrared radiations from ultra-deep fields with a large origami-style mirror that makes it 100 times more powerful than Hubble. Στην πραγματικότητα, Jwst είναι το μεγαλύτερο χώρος telescope ever. To maintain its unprecedented infrared sensitivity, Jwst has protection from infrared contamination from sun through a highly effective 5-layer sunshield. Further, to help maintain its very low operating temperature of 50 Kelvin (-223° C or -370° F), JWST will be placed in an τροχιά around the sun in the cold shadow of Earth all the time near the second Lagrange point (L2) of the Earth-Sun system at a distance of about 1.5 million km from Earth.
Η τοποθέτηση του Jwst near far off Sun-Earth system L2 τροχιά means, unlike Hubble telescope which received several repairs and maintenance in the χώρος, Jwst will be completely on its own after launch therefore there is no scope of any error at all. Perhaps this explains why launch of Jwst is almost eternally delayed.
Τώρα, Jwst is planned to be launched on 18 December 2021.
As on 02 November 2021, Jwst has already safely arrived at its launch site in French Guiana and the technical team is preparing for lift off on 18 December.
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Πηγές:
- NASA 2021. Webb telescope – The Road to Launch and Beyond for NASA’s James Webb Χώρος Telescope. Posted 02 November 2021. Available online at https://www.nasa.gov/feature/goddard/2021/the-road-to-launch-and-beyond-for-nasa-s-james-webb-space-telescope
- NASA. JWST – Γενικές ερωτήσεις για το Webb. Διαθέσιμο online στο https://www.jwst.nasa.gov/content/about/faqs/faq.html
- NASA. JWST – Βασικά στοιχεία. Διαθέσιμο online στο https://jwst.nasa.gov/content/features/keyFactsInternational/
- ESA. Επιστήμη & Εξερεύνηση. Webb – Βλέποντας περαιτέρω. Διαθέσιμο online στο https://www.esa.int/Science_Exploration/Space_Science/Webb
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