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    ztracené heslo?
    COMMANCHEDobyvani vesmiru a kosmonautika 🚀🛰️👩🏼‍🚀
    XCHAOS
    XCHAOS --- ---
    First contact with VZLUSAT-2 reported | VZLÚ... partner průmyslu
    https://www.vzlu.cz/first-contact-with-vzlusat-2-reported/?lang=en
    HOWKING
    HOWKING --- ---
    BLACKHEAD: jj, už jsem si to spočítal.
    BLACKHEAD
    BLACKHEAD --- ---
    HOWKING, HOWKING: Podle ATOMIKS ta obezna rychlost vychazi kolem 600km/h..
    (zaokrouhleno: 1M3 km * 2 / 182 * 24 = cca 600km/h)

    Ale zalezi jak to je s tema sesti mesici a samzorejme beru drahu po ty elipse jen jako 2x apogee, ne skutecnej obvod elipsy...
    JIMIQ
    JIMIQ --- ---
    -211 a něco začne fungovat už od -224, ne? To je tak měsíc tops a pak teda tři měsíce na ten zbytek
    HOWKING
    HOWKING --- ---
    NASA Science Live: What’s Next for the James Webb Space Telescope?
    https://www.youtube.com/watch?v=pWklR2PBfQU
    ATOMIKS
    ATOMIKS --- ---
    HOWKING: jsem si musel vymazat cookies
    HOWKING
    HOWKING --- ---
    U mě to ukazuje dobře - ale reload trvá 5 minut
    ATOMIKS
    ATOMIKS --- ---
    Y2k problem...
    ATOMIKS
    ATOMIKS --- ---
    NaN

    VOYTEX
    VOYTEX --- ---
    ATOMIKS: "it would require Webb to turn 180 degrees in order to thrust toward the Sun, which would have exposed its telescope optics and instruments directly to the Sun, thus overheating their structures and literally melting the glue that holds them together"

    Prileti takhle Soyuz s Naukou na L2 a Nauka povida...
    ARCHIMEDES
    ARCHIMEDES --- ---
    HOWKING: Chci vidět setiny sekundy v čase příspěvku!
    ARCHIMEDES
    ARCHIMEDES --- ---
    Michal Václavík, FB před hodinou: "Pár novinek k dnešnímu MCC-2 Kosmického dalekohledu Jamese Webba. Motorický manévr by měl trvat 4 minuty a 58 sekund při Δv 1,5 m/s a spotřebě pohonných látek 2,3 kg. Vše je předběžné a oficiálně neověřené."
    HOWKING
    HOWKING --- ---
    Tak asi to bude fakt ta oběžná rychlost. (ale tak vysokou jsem nečekal)
    ATOMIKS
    ATOMIKS --- ---
    takže i kdyby to přešvihli, tak on se tam stejně vrátí .o) ...
    ATOMIKS
    ATOMIKS --- ---
    tak oni spíš zatáčí než brzdí, ne?
    Generally speaking, getting a spacecraft to Sun-Earth L2 is fairly straightforward, but Webb’s architecture added a wrinkle. Karen Richon, Webb’s Flight Dynamics lead engineer, describes getting Webb to L2 and keeping it there:

    “Think about throwing a ball straight up in the air, as hard as you can; it starts out very fast, but slows down as gravity pulls it back towards Earth, eventually stopping at its peak and then returning to the ground. Similar to your arm giving the ball energy to go up a few meters from the Earth’s surface, the Ariane 5 rocket gave Webb energy to go the great distance of 1.1 million kilometers, but not quite enough energy to escape Earth’s gravity. Just like the ball, Webb is slowing down, and, if we allowed it, would eventually stop and fall back towards Earth. Unlike the ball, Webb wouldn’t return to the Earth’s surface, but would be in an extremely elliptical orbit, with a perigee altitude of 300 kilometers and an apogee altitude of 1,300,000 kilometers. Utilizing thrust every three weeks or so from small rocket engines aboard Webb will keep it orbiting L2, looping around it in a halo orbit once every six months.

    “So, why did the Ariane not give Webb more energy and why did Webb need course correction? If the Ariane had given Webb even a little bit too much energy than needed to get it to L2, it would be going too fast when it got there and would overshoot its desired science orbit. Webb would have to do a significant braking maneuver by thrusting toward the Sun to slow down. Not only would that big burn cost a lot of propellant, it would be impossible because it would require Webb to turn 180 degrees in order to thrust toward the Sun, which would have exposed its telescope optics and instruments directly to the Sun, thus overheating their structures and literally melting the glue that holds them together. Mounting thrusters on the telescope as a way to direct braking thrust was infeasible for a number of reasons and was never a design option.

    “Therefore, Webb requested just enough energy from the Ariane rocket to ensure that we would never have to do a retro burn, but would always require a burn from the observatory to precisely make up the difference and place it in the desired orbit. The Ariane 5 targeted Webb so accurately that our first and most critical burn was smaller than we had to plan and design for, leaving more fuel for an extended mission!”

    —Karen Richon, Webb Flight Dynamics lead engineer, NASA’s Goddard Space Flight Center
    HOWKING
    HOWKING --- ---
    JIMIQ: Nad tím jsem přemýšlel, ale mají ji nazvanou cruising, nikoli orbital.
    HOWKING
    HOWKING --- ---
    JIMIQ: Bez brždění by tam letěli půl roku, kdyby to mělo vyjít tak, že se radiální rychlost od Slunce sníží k nule jen gravitací Země a Slunce.
    JIMIQ
    JIMIQ --- ---
    A nemuze ta rychlost nejt uz zhruba to jak se bude pohybovat po halo orbite? Protoze podle toho obrazku je jakoby dost vychylenej od samotneho L2 (aby ne, kdyz ta orbita ma prumer jak vzdalenost L2 od Zeme)

    Kazdopadne na where is webb to pise ze zbejva necelych 500km
    HOWKING
    HOWKING --- ---
    Stále 730 km/h a nebrzdí. Co když mají průser. Přece nebudou brzdit na fleku - na tak silné namáhání to rozbalené není stavěno.
    Kliknutím sem můžete změnit nastavení reklam