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Showing content with the highest reputation on 01/01/22 in all areas

  1. I don't see why a satellite can't just sit at L2, albeit with occasional nudges to keep it there and stop it starting to slide either in towards, or out away from, earth, which is what would otherwise happen, given that L1, 2 and 3 are only metastable locations. There was some information posted earlier in the thread explaining that the the telescope will be put into an orbit so as to keep it out of the shadows of the earth and the moon. I'm not sure why this is necessary, but evidently it is.
    1 point
  2. "Are Vegan's, a help or a hindrance to, our future?" Vegans may well be less of a problem than people who misuse apostrophes.
    1 point
  3. Yes thanks. Partly because I was allowed to go out into the street to listen + watch. I'd just spent 10 days isolating due to covid. Quarantine ended at 1 minute to midnight.
    1 point
  4. Some of them them are points of stable equilibrium, but the others are not. https://en.wikipedia.org/wiki/Lagrange_point L1, L2, and L3 are on the line through the centres of the two large bodies, while L4 and L5 each act as the third vertex of an equilateral triangle formed with the centres of the two large bodies. L4 and L5 are stable, which implies that objects can orbit around them in a rotating coordinate system tied to the two large bodies. The L4 and L5 points are stable points and have a tendency to pull objects into them. Several planets have trojan asteroids near their L4 and L5 points with respect to the Sun; Jupiter has more than one million of these trojans.
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  5. https://webb.nasa.gov/content/about/orbit.html Some Technical Details: It is easy for an object (like a spacecraft) at one of these five points to stay in place relative to the other two bodies (e.g., the Sun and the Earth). In fact, L4 and L5 are stable in that objects there will orbit L4 and L5 with no assistance. Some small asteroids are known to be orbiting the Sun-Earth L4 and L5 points. However, L1, L2, and L3 are metastable so objects around these points slowly drift away into their own orbits around the Sun unless they maintain their positions, for example by using small periodic rocket thrust. This is why L1, L2, and L3 don't "collect" objects like L4 and L5 do. Webb At L2 If Webb is orbiting the Sun further out than Earth, shouldn't it take more than a year to orbit the Sun? Normally yes, but the balance of the combined gravitational pull of the Sun and the Earth at the L2 point means that Webb will keep up with the Earth as it goes around the Sun. The gravitational forces of the Sun and the Earth can nearly hold a spacecraft at this point, so that it takes relatively little rocket thrust to keep the spacecraft in orbit around L2. And Webb will orbit around L2, not sit stationary precisely at L2. Webb's orbit is represented in this screenshot from our deployment video (below), roughly to scale; it is actually similar in size to the Moon's orbit around the Earth! This orbit (which takes Webb about 6 months to complete once) keeps the telescope out of the shadows of both the Earth and Moon. Unlike Hubble, which goes in and out of Earth shadow every 90 minutes, Webb will have an unimpeded view that will allow science operations 24/7. ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: In summing, L2 is actually only semi stable and still needs some rocket thrust to keep it in orbit around L2. https://solarsystem.nasa.gov/resources/754/what-is-a-lagrange-point/ "L4 and L5 correspond to hilltops and L1, L2 and L3 correspond to saddles (i.e. points where the potential is curving up in one direction and down in the other). This suggests that satellites placed at the Lagrange points will have a tendency to wander off (try sitting a marble on top of a watermelon or on top of a real saddle and you get the idea). But when a satellite parked at L4 or L5 starts to roll off the hill it picks up speed. At this point the Coriolis force comes into play - the same force that causes hurricanes to spin up on the earth - and sends the satellite into a stable orbit around the Lagrange point".
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  6. There you go. That doesn't mean Claudio must be wrong. It's mostly a problem of it being or not being enough for other scientists to drop what they're doing and focus their attention on the idea. I can guarantee you that if you're a scientist, and they present you with a theory that really cuts it, you'll be paying outmost attention to it. In the meantime, nice words to your friends --maybe a little over-the-top encouragement-- doesn't do much harm.
    -1 points
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