Re: JWST update :: Remember, remember, the velvet November


node:	Re: JWST update
template:	4
parent:	JWST update
owner:	ulkas
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created:	29.12.2021 - 23:39:43
updated:	29.12.2021 - 23:41:25

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akym sposobom bude brzdit na L2?

osobne by som si tipol, ze cca od polky letu ho zacne spolocna gravitacia slnka a zeme spomalovat, postupne az ostane trcat na L2, na konci este nejake tryskovanie na doladenie.
alebo to proste cele ubrzdia tryskami?

este, ta krycia plachta nebude sposobovat unasanie slnecnym vetrom?

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Nijak. Je to proste ako ked vyhodis kamen, ten spomaluje, az si v L2 do tej gravitacnej diery sadne :)

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Ak tomu dobre rozumiem, on vlastne brzdi cely cas - cely cas ho spomaluje ta gravitacia, ako pises. Popisuju to vlastne ako cestu "do kopca".

"Getting Webb to its orbit around L2 is like reaching the top of a hill by pedaling a bicycle vigorously only at the very beginning of the climb, generating enough energy and speed to spend most of the way coasting up the hill so as to slow to a stop and barely arrive at the top."
https://webb.nasa.gov/content/about/orbit.html

Su tam tri manevre, jeden na zaciatku, druhy po tyzdni, treti nakoniec.

Tu je nejake video k tomu.

Tu je info z redditu:

JWST has thrusters on it. Most of the work has been done already; it's coasting "uphill" now, slowing down as it goes. It won't stop right at L2. The coasting arc it's on will put it off to one side, and at the right time the thrusters will be used to nudge it into some flavor of a "halo" orbit. It will have to be nudged at regular intervals to stay in that orbit, which is sort of an oval centered on L2.

Dolezita vec, co som ani doteraz netusil je, ze on nebude "stat" na L2, ale pomaly kruzit okolo L2.
Tusim 6 mesiacov bude jeden "okruh". Cize za jeden rok sa dvakrat takto zakruti.
Tuto je vidiet.

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diky moc. som netusil, ze tam bude kruzit. taktiez haluz, ze musia pocas tych 6 mesiacov chladenia este dodatocne nakalibrovat tie zrkadla, kazde samostatne, pretoze to sa vlastne musi kalibrovat az po vychladeni a neda sa to uplne presne uz na zemi.

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Keby brzdil musel by sa otocit a vystavit optiku na slnko co nesmie. Takze to spravili tak ze ma o chlp nizsiu startovaciu rychlost nez treba na L2 a musi trochu "tryskovat" aby sa tam dostal. Rakete Ariane sa to podarilo velmi presne takze spotreba paliva na tieto manevre je optimalna a ostala vecsia rezerva.

L2 nie je stabilny orbit a korekcie su nutne co pokryje aj tlak slnecneho ziarenia/vetra. Ale je tam to gravitacne pole natolko vyvazene ze spotreba paliva na stabilizaciu je znesitelna.

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To unášanie podľa mňa musia nejako stabilizovať - takáto vec asi má stabilizačný systém, aby sa udržala na mieste presne pre také prípady? Tak si to predstavujem, že korekcie orbitu sa robia občas.