James Webb Space Telescope

Discussion in 'Astronomy, Exobiology, & Cosmology' started by geordief, Dec 24, 2021.

  1. DaveC426913 Valued Senior Member

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  3. James R Just this guy, you know? Staff Member

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    Hmm...

    What's the Rotating Libration Point frame?
     
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  5. James R Just this guy, you know? Staff Member

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    That makes sense. The effective gravitational potential around L2 is sort of saddle-shaped, as I understand it. So maybe the orbit is perpendicular to the ecliptic after all. I may well have misinterpreted a 2D projection of the 3D orbit in a video.
     
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  7. exchemist Valued Senior Member

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    That's what I thought at first too.

    However, the saddle is indeed a 2D representation, in the plane of the ecliptic. If you think in 3D, it seems to me the saddle becomes a 2D section through a doughnut-shaped ring of lower gravity. So the object tends to fall into the gravity well in the middle but also to slide out radially, down the flank of the doughnut, either in toward the earth or away from it. Hence the need for correction burns to the telescope from to time, once it is orbiting L2.

    But I may still have got it a bit wrong.........
     
  8. DaveC426913 Valued Senior Member

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    Objectively, the Earth/L system rotates 360 degrees around the sun over a year. As if we are standing on a record player, with the sun at the centre and we're standing on the surface of the rotating LP.

    All this is saying is that - for clarity - the diagram's frame is within that rotation.
     
  9. Michael 345 New year. PRESENT is 72 years oldl Valued Senior Member

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    Nearly 2am 16th January 2022 Australia and I have nothing to better to do (like sleep) than the check on progress of James Webb telescope

    Looks like about 85% there. Yah

    Let's try sleep

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  10. James R Just this guy, you know? Staff Member

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    Useful information. That makes a lot of sense. Thanks.
     
  11. exchemist Valued Senior Member

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    I've found a bit more on this. The orbit of the Webb telescope is evidently what is known as a "halo orbit": https://en.wikipedia.org/wiki/Halo_orbit. The diagrams shown in this article seem to be the same as those Dave posted in post 41.
     
  12. Michael 345 New year. PRESENT is 72 years oldl Valued Senior Member

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    This really is interesting stuff

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    I'm awe of the people who worked to put this sort of stuff together

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  13. geordief Valued Senior Member

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    I see the cruising speed is unchanged from yesterday at 0.1517ml/s.

    Thought it might be slowing down
    ...
     
  14. geordief Valued Senior Member

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    Think Lady Luck might have had a hand in it as well.
     
  15. Michael 345 New year. PRESENT is 72 years oldl Valued Senior Member

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    Didn't notice that

    Few distractions around

    Update - just looked at couple of seconds ago now 1515 ya still slowing

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    Last edited: Jan 19, 2022
  16. geordief Valued Senior Member

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    95% distance covered now.

    Slowing down ,about 600 mph (.1477 ms/s) now I think I calculated.
     
  17. Michael 345 New year. PRESENT is 72 years oldl Valued Senior Member

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    I made it 562 miles per hour, still a fair click

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  18. geordief Valued Senior Member

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    About 37 thousand miles to L2.

    That is about the same as going around the equator and half the way around again.

    They can almost see L2 now

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  19. Michael 345 New year. PRESENT is 72 years oldl Valued Senior Member

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    Spinoff
    The work performed on the telescope optics resulted in a NASA tech spinoff for diagnosing eye conditions and accurate mapping of the eye. This spinoff supports research in cataracts, keratoconus (an eye condition that causes reduced vision), and eye movement - and improvements in the LASIK procedure

    From one of the James Webb Telescope articles about spin offs from the research which went into building the telescope

    From research into building a artificial retina we get a spin-off to help diagnose problems in real retinas. NEAT

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  20. billvon Valued Senior Member

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    Down to 500, slower than your typical jet airliner at altitude.
     
  21. geordief Valued Senior Member

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    Is the trajectory to L2 a bit complicated ?

    I can see from the website that the distance to L2 has been actually be increasing over the past while.

    Just over 34,000 miles now.

    Is there something of a moving target here?

    Unless the website is incorrect why has the distance to L2 been actually increasing over the past while?
     
  22. billvon Valued Senior Member

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    I don't know. I imagine that since it is going to orbit L2, and not end up at L2, that it is now moving into position to intercept that orbit.

    However I looked at the "where is Webb" site and the distance listed to L2 orbit is now 33,900 miles and decreasing.
     
  23. geordief Valued Senior Member

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    Last edited: Jan 24, 2022

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