Free Astronomy Magazine September-October 2024

Last segment blank of the ELT successfully delivered byESO − BárbaraFerreira oolargetobemadefromasin- glepieceofglass,M1willconsistof7 98hexagonalsegments, eachaboutfivecentimetresthickand 1.5metresacross,workingtogether tocollecttensofmillionsoftimesasmuc hlightasthehumaneye.Anad- ditional133segmentshavebeenpro- ducedtofacilitatethemaintenance andrecoatingofthesegmentsonce thetelescopeisoperational.ESOhas alsoprocured18sparesegments, bringing the total number to 949. TheM1blanks,shapedpiecesofma- terialthatarelaterpolishedtobe- comethemirrorsegments,aremade from ZERODUR®, a low-expansion glass-ceramic material developed bySCHOTT and optimised for the ex- tremetemperaturerangesatthe ELT’ssiteintheAtacamaDesert.Thisco mpanyhasalsomanufacturedtheblan ksofthreeotherELTmirrors— M2,M3,andM4—attheirfacilities in Mainz, Germany. “WhatESOorderedfromSCHOTTis more than just ZERODUR®,” says Marc Cayrel, Head of ELT Optome- chanicsatESO. “Inclosecollabora- tion with ESO, SCHOTT fine-tuned every single production step, tailor- ing the product to meet and often exceedtheELT’sverydemanding requirements.Theoutstandingqual- ityoftheblankswasmaintained throughoutthemassproductionof morethan230tonnesofthissuper- performingmaterial.ESOisthusvery thankfulfortheprofessionalismof theskilledteamsatSCHOTT,our trustedpartner.” ThomasWerner,ELT ProjectLeadatSCHOTT,says: “Ouren- tireteamisthrilledtoconcludewhat hasbeenthelargestsingleorderof ZERODUR®inthehistoryofourcom- pany.Forthisproject,wesuccessfully concludedtheserialproductionof hundredsofZERODUR®mirrorsub- strates,whenweusuallyhaveasin- gle-pieceoperation.It’sbeenan honourforallofustoplayapartin shapingthefutureofastronomy.” Oncecast,allsegmentsfollowa multi-step,internationaljourney. Afteraslowcoolingandheattreat- mentsequence,thesurfaceofeach blankisshapedbyultra-precision grindingatSCHOTT.Theblanksare thentransportedtoFrenchcompany SafranReosc,whereeachofthemis cut into an hexagon shape and pol- ishedtoaprecisionof10nanometres across the entire optical surface — meaningthesurfaceirregularitiesof themirrorwillbelessthanonethou- sandthofthewidthofahumanhair. ﻣﺠﻠﺔ FreeAstronomy ﺎﻟﻌﺮ ﺔ 38 ﺗﺴﻠ ﻢ آﺧﺮﻣ ﻮﻧﺎت اﻟﺘﻠﺴ ﻮب اﻟﻜﺒ ﻟﻠﻐﺎ ﺔ ﺄﻣﺎن : ﻘﻠﻢ ﺎر ﺮا ﻓ ﺮا - اﻟﻤﺮﺻﺪ اﻷوروﺑﻲ اﻟ ـ ﺠﻨﻮﺑﻲ ﺗﻌﺘـ ﻣﺮآة اﻟﺘﻠﺴﻜﻮب اﻟﻜﺒ ﻟﻠﻐﺎﻳﺔ ﻛﺒ ة ﻻ ﻳﻤﻜ و اً ﺟﺪ ﻦ ﺻﻨﻌﻬﺎ ﻣﻦ ﻗﻄﻌﺔ واﺣﺪة ﻣﻦ اﻟﺰﺟـﺎج ﺳـﺘﺘﻜﻮن M1 ﻣ ـﻦ 798 ﻗﻄﻌ ـﺔ ﺳﺪاﺳﻴﺔ ﻳﺒﻠﻎ ﺳﻤﻚ ﻛﻞ ﻣﻨﻬﺎ ﺣﻮاﱄ ﺧﻤﺴﺔ ﺳﻨﺘﻴﻤﱰات و ﻳﺒﻠﻎ ﻋﺮﺿ ﺎ ﻬ 1.5 ﻞﻌﻤﺗو ﻣﱰاً ﺎً ﻣﻌ ﻟﺠﻤﻊ ﻋـ ـ ﴩات ا ﻼﻳـ ﻣـﻦ اﻟﻀـﻮء ﺑ ﻣﻘﺎرﻧﺔ ﺎﻟﻌ اﻟﺒﴩﻳﺔ . ﺗـﻢ إﻧﺘـﺎج 133 ﻗﻄﻌـﺔ إﺿـﺎﻓﻴﺔ ﻟﺘﺴـﻬﻴﻞ ﺻﻴﺎﻧﺔ ﻫﺬه اﻷﺟﺰاء وإﻋﺎدة ﻃﻼءﻫﺎ ﺑﻤﺠﺮد ﺗﺸﻐﻴﻞ اﻟﺘﻠﺴﻜﻮب ﻗﺎم . ا ﺮﺻـﺪ اﻷوروﺑـﻲ اﻟﺠﻨﻮﺑﻲ أﻳﻀًﺎ ﺑﴩاء 18 ﻗﻄﻌﺔ اﺣﺘﻴﺎﻃﻴـﺔ ﻟﻴﺼﻞ اﻟﻌﺪد اﻹﺟﻤﺎﱄ إﱃ 949 . ﻗﻄﻊ اﻟﺰﺟﺎج اﻟﺨﺎم ﻟﻠﻤـﺮاة اﻟﺮﺋﻴﺴـﻴﺔ M1 وﻫﻲ ﻗﻄﻊ ﻣﻦ ا ﻮاد اﻟﺘﻲ ﺗﻢ ﺻ ﻘﻠﻬﺎ ﻟﺘﺼﺒﺢ أﺟﺰاء ا ﺮاﻳﺎ ﻣﺼﻨﻮﻋﺔ ﻣﻦ ( دور زﻳﺮو ) وﻫﻲ ﻣﺎدة ﺳ اﻣﻴﻚ زﺟﺎﺟﻴﺔ ﻣﻨﺨﻔﻀﺔ اﻟﺘﻤﺪد ﺗﻢ ﺗﻄﻮﻳﺮﻫﺎ ﺑﻮاﺳﻄﺔ ﺷﻮت ﴍﻛﺔ اﻷ ﺎﻧﻴﺔ وﺗﻢ ﺗﺤﺴﻴﻨﻬﺎ ﻟﻼﺳﺘﺨﺪام اﻷﻗﺼ ﺿﻤﻦ ﻰ ـ درﺟﺔ اﻟﺤﺮارة ا ة ﻮﺟﻮد ﰲ ﻣﻮﻗـﻊ اﻟﺘﻠﺴـﻜﻮب ﰲ . ﺻﺤﺮاء أﺗﺎﻛﺎﻣﺎ ﻗﺎﻣﺖ ﻫﺬه اﻟﴩﻛﺔ أﻳﻀـ ﺎً ﺑﺘﺼﻨﻴﻊ ﻗﻄﻊ اﻟﺰﺟﺎج اﻟﺨﺎم ﻟـﺜﻼث ﻣﺮاﻳـﺎ أﺧﺮى ﻟﻠﺘﻠﺴﻜﻮب اﻟﻜﺒ ﻟﻠﻐﺎﻳﺔ - M2 و M3 و M4 - ﰲ ﻣﻨﺸﺂﺗﻬﺎ ﰲ ﻣﺪﻳﻨﺔ ﰲ ﻣﺎﻳﻨﺰ أ ﺎﻧﻴﺎ . إن ﻪ ﻣﺎ ﻃﻠﺒ ا ﺮﺻﺪ اﻷوروﺑﻲ اﻟﺠﻨﻮﺑﻲ ﻣـﻦ ﴍﻛﺔ ﺷﻮت ﻫﻮ أﻛﺜﺮ ﻣﻦ ﻣﺠﺮد زﻳﺮو ) ﻣﺎدة ( دور ﻛﻤــﺎ ﻳﻘــﻮل ﻣــﺎ رك ﻛــﺎﻳﺮل رﺋــﻴﺲ ا ﻴﻜﺎﻧﻴﻜﺎ اﻟﻀﻮﺋﻴﺔ ﻋﲆ اﻟﺘﻠﺴـﻜﻮب اﻟﻜﺒـ ﰲ ﺟﺪاً ا ﺮﺻﺪ اﻷوروﺑﻲ اﻟﺠﻨﻮﺑﻲ . ﺑﺎﻟﺘﻌـﺎون اﻟﻮﺛﻴـﻖ ﻣـﻊ ا ﺮﺻـﺪ اﻻوروﺑـﻲ اﻟﺠﻨﻮﺑﻲ ﻗﺎﻣﺖ ﴍﻛﺔ ﺷـﻮت ﺑﻀـﺒﻂ ﻛـﻞ ﺧﻄﻮة ﻣـﻦ ﺧﻄـﻮات اﻹﻧﺘـﺎج وﺗﺨﺼـﻴﺺ ا ﻨﺘﺞ ﻟﺘﻠﺒﻴﺔ ﻣﺘﻄﻠﺒـﺎت اﻟﺘﻠﺴـﻜﻮب اﻟﻜﺒـ ﻟﻠﻐﺎﻳﺔ وﻫﻲ ﺎ ﻣﺎ ﺻﻌﺒﺔ وﻏﺎﻟﺒ ﻳﺘﻢ ﺗﺠﺎوزﻫﺎ . ﺗﻢ اﻟﺤﻔﺎظ ﻋـﲆ اﻟﺠـﻮدة ا ﺘﻤﻴـﺰة ﻟﻘﻄـﻊ اﻟﺰﺟﺎج اﻟﺨﺎم ﻃﻮال ﻓﱰة اﻹﻧﺘـﺎج اﻟﻀـﺨﻢ ﻷﻛﺜﺮ ﻣﻦ 230 ﻃﻨﺎ ﻣﻦ ﻫﺬه ا ـﺎدة ﻓﺎﺋﻘـﺔ اﻷداء وﻟﺬﻟﻚ ﻓـﺈن ﻣﻨﻈﻤـﺔ اﻟﺒﻴﺌـﺔ اﻟﻌﺎ ﻴـﺔ ﻣﻤﺘﻨﺔ ﺟﺪ اً ﻟﻼﺣﱰاﻓﻴـﺔ اﻟﺘـﻲ ﺗﺘﻤﺘـﻊ ﺑﻬـﺎ اﻟﻔـﺮق ا ـﺎﻫﺮة ﰲﴍﻛـﺔ ﺷـﻮت ﴍﻳﻜﻨـﺎ ا ﻮﺛــﻮق ﴍﻛــﺔ أور ﰲ ﺗــﺎرﻳﺦﴍﻛﺘﻨــﺎ ﺑﺎﻟﻨﺴﺒﺔ ﻟﻬﺬا ا ﴩوع ـ ﻧﺠﺤﻨـﺎ ﰲ اﻻﻧﺘﻬـﺎء ﻣﻦ اﻹﻧﺘﺎج اﻟ ﺘﺴﻠﺴﲇ ﺌﺎت ﻣﻦ رﻛﺎﺋﺰ ﻣﺮاﻳﺎ ( دور زﻳﺮو ) ﰲ ﺣ أﻧﻨـﺎ ﻋـﺎدة ﻣـﺎ ﻧﺠـﺮي ﻘﻄﻌ ﻟ ﻋﻤﻠﻴﺔ ﺔ واﺣﺪة . ﻟﻘﺪ ﻛﺎن ﴍﻓـﺎً ﻟﻨـﺎ ﺎً ﺟﻤﻴﻌ أن ﻧﺸﺎرك ﰲ ﺗﺸﻜﻴﻞ ﻣﺴﺘﻘﺒﻞ ﻋ ﻠـﻢ اﻟﻔﻠ ـﻚ . ﺑﻤﺠــﺮد اﻟﺘﺼ ـﻨﻴﻊ ﺗﺘﺒ ـﻊ ﺟﻤﻴ ـﻊ ـاﻟ ﻣﻌﺎﻳ ﴩاﺋﺢ دوﻟﻴﺔ ﻣﺘﻌﺪدة اﻟﺨﻄـﻮات ﺑﻤﺎ ﰲ ذﻟـﻚ اﻟﺘ ﱪﻳـﺪ ا ـﻨﺨﻔﺾ وا ﻌﺎﻟﺠـﺔ اﻟﺤﺮارﻳﺔ ﻳﺘﻢ و ﺗﺸﻜﻴﻞ ﺳﻄﺢ ﻛﻞ ﻗﻄﻌﺔ ﻣﻦ ﺧﻼل ﻃﺤﻦ ﻓﺎﺋﻖ اﻟﺪﻗـﺔ ﰲ ﴍﻛـﺔ ﺷـﻮت و ﺑﻌﺪ ذﻟﻚ ﻳﺘﻢ ﻧﻘﻞ ﻗﻄﻊ اﻟﺰﺟـﺎج اﻟﺨـﺎم إﱃ ﴍﻛﺔ ﺳﺎﻓﺮان رﻳﻮﺳﻚ اﻟﻔﺮﻧﺴﻴﺔ ﺣﻴﺚ ﻳﺘﻢ ﺗﻘﻄﻴﻌ ﻬﺎ إﱃ ﺷﻜﻞ ﺳﺪاﳼ وﺻـﻘﻠﻬﺎ ﺑﺪﻗـﺔ ﺗﺼﻞ إﱃ 10 ﻧﺎ ﻧﻮﻣﱰ ﻋﱪ اﻟﺴﻄﺢ ﺑﺄﻛﻤﻠﻪ ﻣﺎ ﻳﻌﻨﻲ أن ﻋﺪم اﻧﺘﻈﺎم ﺳﻄﺢ ا ﺮآة ﺳـﻴﻜﻮن أﻗﻞ ﻣﻦ أﻟﻒ ﻣﻦ ﻋﺮضﺷﻌﺮ ة اﻹﻧﺴﺎن .