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posted by martyb on Sunday February 07 2016, @06:10AM   Printer-friendly
from the coming-together dept.

Ars Technica is reporting With its mirror complete, giant space telescope on track for 2018 launch:

After years of delays and cost overruns, the James Webb Space Telescope is finally coming together. This week the 18th and final primary mirror segment of the telescope was installed onto the support structure at Goddard Space Flight Center. From here, additional optics must be installed, and the telescope requires testing to ensure it can withstand the forces of a rocket launch anticipated in late 2018.

Each of the hexagon-shaped mirrors weighs 40 kg and spans 1.3 meters. After launch, the telescope will be flown to the second Lagrange point of the Earth-Sun system, about 1.5 million kilometers from Earth. From there, it will begin observations. When deployed in space, the telescope will have a 6.5-meter diameter.

[...] Significantly larger than the 2.4-meter Hubble telescope, the Webb will observe primarily in the near-infrared region of the spectrum. Its primary goals include searching for light from the universe's first stars and better understanding the formation of galaxies and planetary systems.

We have all probably heard about this project, but I had not heard (or maybe I had forgotten) the part about being "flown to the second Lagrange point of the Earth-Sun system." I guess that means that corrective surgery will be out of the question, as that's farther than any human has been from Earth. I hope they get it right the first time.


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  • (Score: 0) by Anonymous Coward on Sunday February 07 2016, @06:42AM

    by Anonymous Coward on Sunday February 07 2016, @06:42AM (#300092)

    Great. So now the aliens have a giant mirror to snort dope on and dance with alien hookers.

    No wonder astronauts are often filmed "flying", they're addicted to alien dope!

  • (Score: 0) by Anonymous Coward on Sunday February 07 2016, @09:01AM

    by Anonymous Coward on Sunday February 07 2016, @09:01AM (#300122)

    Don't forget to check the mirror. Can haz Nobbel prize?

  • (Score: 2, Disagree) by Gravis on Sunday February 07 2016, @10:36AM

    by Gravis (4596) on Sunday February 07 2016, @10:36AM (#300141)

    with the Hubble we learned a very important lesson about manufacturing: gravity matters. since then, we have made better tools that take gravity into consideration when manufacturing things for space. Hubble's gravitational deformation was an important lesson that we needed to learn.

    • (Score: 0) by Anonymous Coward on Sunday February 07 2016, @01:16PM

      by Anonymous Coward on Sunday February 07 2016, @01:16PM (#300175)

      It was a good lesson. But it was also probably not the last one. Let's hope we learned enough. I certainly hope we have because the JWST is one of the more exciting things we have going to me.

    • (Score: 3, Informative) by tonyPick on Sunday February 07 2016, @03:21PM

      by tonyPick (1237) on Sunday February 07 2016, @03:21PM (#300200) Homepage Journal

      with the Hubble we learned a very important lesson about manufacturing: gravity matters

      You mean the spherical aberration issue (the one fixed with the "corrective" WFPC2 upgrade?) mentioned here http://www.spacetelescope.org/about/history/aberration_problem/ [spacetelescope.org]

      AIUI although it was initially thought (and the news reported) that it was down to gravity sag, it turned out to be an instrument defect at the subcontractor: From the HST Optical Failure Report:

      The critical optics used as a template in shaping the mirror, the reflective null corrector (RNC), consisted of two small mirrors and a lens. The RNC was designed and built by the Perkin-Elmer Corporation for the HST Project.

      This unit had been preserved by the manufacturer exactly as it was during the manufacture of the mirror. When the Board measured the RNC, the lens was incorrectly spaced from the mirrors. Calculations of the effect of such displacement on the primary mirror show that the measured amount, 1.3 mm, accounts in detail for the amount and character of the observed image blurring.

      In fact people were aware of the whole gravity sag thing, and as a result didn't run some simpler cross checks that they might have done, since they figured gravity would throw off the results anyway...

      You can get the full report as a pdf from http://ntrs.nasa.gov/search.jsp?R=19910003124 [nasa.gov]

      (Of course, if you mean something else.... then ignore all that).