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posted by CoolHand on Monday June 20 2016, @09:42PM   Printer-friendly
from the better-than-our-pocket-telescope dept.

The James Webb Space Telescope (what could maybe be called a 'better Hubble telescope') is due to be launched in 2018.

Its primary mirror spans 6.5 metres, compared to Hubble's 2.5, giving it seven times more light-gathering power. It will also gather from the infrared spectrum instead of gathering visible light: this will allow it to 'see' past clouds of dust, to gather more information about the beginning of the universe.

It will NOT be fixable like the Hubble, though. It is going to be sitting out at L2 (Lagrange point 2 of the Earth-Sun system) which is 1,500,000 kilometers (930,000 mi) from Earth, directly opposite to the Sun. At this point, with the Earth, moon and sun behind it, the spacecraft can get a clear view of deep space.

Where exactly is L2 for the Earth-Sun system? You can work it out for yourself (https://en.wikipedia.org/wiki/Lagrangian_point#L2)

or look at pretty pictures
1. http://webbtelescope.org/webb_telescope/technology_at_the_extremes/graphics/fig-4-webb-orbit-big.jpg
2. http://www.stsci.edu/jwst/overview/design/orbit1.jpg

Why do you have to state 'L2 for the Earth-Sun system'?

[Continues...]

In celestial mechanics, the Lagrangian points (/ləˈɡrɑːndʒiən/; also Lagrange points, L-points, or libration points) are positions in an orbital configuration of two large bodies where a small object affected only by gravity can maintain a stable position relative to the two large bodies. The Lagrange points mark positions where the combined gravitational pull of the two large masses provides precisely the centripetal force required to orbit with them. There are five such points, labeled L1 to L5, all in the orbital plane of the two large bodies. The first three are on the line connecting the two large bodies and the last two, L4 and L5, each form an equilateral triangle with the two large bodies. The two latter points are stable, which implies that objects can orbit around them in a rotating coordinate system tied to the two large bodies.

ANY 3 body system will have 5 Lagrange points! (I did not know that).

http://www.cbc.ca/news/technology/james-webb-space-telescope-hubble-1.3557887


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JWST Launch Christmas Morning 55 comments

James Webb Space Telescope reaches launch pad for Christmas liftoff

The James Webb Space Telescope is due to launch on Saturday (Dec. 25) during a 32-minute window that opens at 7:20 a.m. EST (1220 GMT). The massive observatory will blast off from Kourou, French Guiana, atop an Ariane 5 rocket operated by European launch provider Arianespace. You can watch launch coverage live at Space.com beginning at 6 a.m. EST (1100 GMT) courtesy of NASA or you can watch directly at the agency's website.

ESA launch kit (PDF).

Previously:


Original Submission

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  • (Score: 1, Insightful) by Anonymous Coward on Monday June 20 2016, @10:11PM

    by Anonymous Coward on Monday June 20 2016, @10:11PM (#363073)

    ANY 3 body system will have 5 Lagrange points! (I did not know that).

    Yo mama's ass has 5 Lagrange points!

    • (Score: 2) by bob_super on Tuesday June 21 2016, @12:29AM

      by bob_super (1357) on Tuesday June 21 2016, @12:29AM (#363098)

      "It's not what it looks like, officer. This is a science experiment designed to find the influence of a metallic unibody on the 5 Lagrange points"
      (back seat, or trunk?)

  • (Score: -1, Troll) by Anonymous Coward on Monday June 20 2016, @10:12PM

    by Anonymous Coward on Monday June 20 2016, @10:12PM (#363074)

    If it's not pointed at the earth then it's useless for spying on brown people to make sure they're obeying their American masters.

  • (Score: 1) by khallow on Monday June 20 2016, @10:16PM

    by khallow (3766) Subscriber Badge on Monday June 20 2016, @10:16PM (#363076) Journal

    ANY 3 body system will have 5 Lagrange points! (I did not know that).

    The third body has to have considerably less mass than the other two and the Lagrange points are relative to the position of the third body. So putting another Earth-sized planet at one of the Earth-Moon Lagrange points will change the dynamics (the Moon becomes the third body relative to the other two).

    • (Score: 3, Informative) by BsAtHome on Monday June 20 2016, @10:34PM

      by BsAtHome (889) on Monday June 20 2016, @10:34PM (#363080)

      Hm, Earth mass 5.9e24 kg, Moon mass 7.3e22 kg, Sun mass 2e30 kg, Telescope mass 1e4 (probably less).

      I guess they have their asses covered on the mass issue by 18 orders of magnitude.

      It would be quite a feat to launch a telescope with a significant mass to change the Lagrange points, considering that the mass has to be subtracted from the Earth's mass. But then again, we could all have some fun when our bellies are not feeling so heavy anymore (please fund the space agencies for a project of that kind).

      • (Score: 1) by khallow on Monday June 20 2016, @11:01PM

        by khallow (3766) Subscriber Badge on Monday June 20 2016, @11:01PM (#363085) Journal
        Well, given that I just pulled an Earth-massed object out of my ass, we could just launch my ass. For science!
        • (Score: 2) by BsAtHome on Monday June 20 2016, @11:11PM

          by BsAtHome (889) on Monday June 20 2016, @11:11PM (#363087)

          Yes, please. Your volcanic ass is clouding my window. You might also consider temperature control. The glow is not good for my beauty sleep.

  • (Score: 0) by Anonymous Coward on Tuesday June 21 2016, @12:11AM

    by Anonymous Coward on Tuesday June 21 2016, @12:11AM (#363097)

    That's a funny looking probe. It looks like a raft with a satellite dish on it. It even surpasses the Apollo lander, which looked like 4 pins stuck into a wad of foil. What's your candidate for funniest-looking spacecraft?

    On a more serious note, it's scary that it's not designed to be repaired, like Hubble is. Then again, most spacecraft aren't. Hubble was lucky in that regard, especially since they fouled up the original optics. Cross your rafts, I mean fingers.

    • (Score: 0) by Anonymous Coward on Tuesday June 21 2016, @11:32PM

      by Anonymous Coward on Tuesday June 21 2016, @11:32PM (#363592)

      it was designed as such since it will be located at a distance too far for manned crews to reach

      unless we get our shit together and have manned capability beyond LEO then we'll have to settle with robust sattelites

  • (Score: 0) by Anonymous Coward on Tuesday June 21 2016, @01:14AM

    by Anonymous Coward on Tuesday June 21 2016, @01:14AM (#363104)

    SpaceX can do it.

    Make a grabber. Go. Grab. Spacewalk. Return.

  • (Score: 4, Funny) by Snotnose on Tuesday June 21 2016, @01:37AM

    by Snotnose (1623) on Tuesday June 21 2016, @01:37AM (#363113)

    Guy likes to start his bike and rev it a good 2-3 minutes before he actually leaves, or 2-3 minutes after coming home and turning the damn thing off. Think this mirror can find his penis for him?

    --
    The Word Of the Day (WOD) is finicky. As in, "sharks avoid the sewage discharge pipe because they make their finicky".
    • (Score: 2) by Absolutely.Geek on Tuesday June 21 2016, @02:46AM

      by Absolutely.Geek (5328) on Tuesday June 21 2016, @02:46AM (#363131)

      Unlikely; it will be in his wife's purse; along with his balls. Hence the need for a vestigial penis.

      --
      Don't trust the police or the government - Shihad: My mind's sedate.
    • (Score: 0) by Anonymous Coward on Tuesday June 21 2016, @03:30AM

      by Anonymous Coward on Tuesday June 21 2016, @03:30AM (#363144)

      Probably not [xkcd.com].