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Construction Starts on the World's Largest Optical Telescope

posted by n1 on Monday May 29 2017, @08:54PM   Printer-friendly
from the bigger-means-better dept.

Fnord666 writes:

After several years of planning and no shortage of financial anxiety, construction has officially started on the Extremely Large Telescope. Contractors are now building the main structure and dome of the Chile-based observer ahead of its initial service in 2024. That's a long time to wait, but this is no mean feat. With a 43-yard aperture, this promises to be the world's largest optical telescope for sometime, even compared to future or in-limbo projects like the Thirty Meter Telescope. Those gigantic dimensions will help it capture far more light, giving astronomers the chance to spot particularly distant galaxies, find small planets and capture more details of larger planets.

The ELT's full capabilities won't come until sometime after 2024, when the ESO starts a second construction phase. It could easily be another few years after that before the telescope lives up to its expectations.

Source: Engadget

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  • (Score: 0) by Anonymous Coward on Tuesday May 30 2017, @12:05AM (4 children)

    by Anonymous Coward on Tuesday May 30 2017, @12:05AM (#517383)

    Is it the cooling or the fuel? The whole point of that massive sunshade, that will make it a pig to slew onto new targets, is to make it possible to do all the cooling needed with an active refrigeration system ( https://jwst.nasa.gov/cryocooler.html [nasa.gov] ). Even if it did heat up, as WISE and Spitzer have shown, its HgCdTe detectors would run just fine. The problem is that the first three Lagrange points aren't stable, so you need station keeping thrusters to avoid slipping away into orbit around the Earth or Sun.

    Even if JWST isn't technically "servicable", I could see a robotic mission that goes out, grabs on to it, and provides station keeping services. It would be good practice for asteroid capture missions. Then, at least, it could be run until something breaks, like Kepler.

  • (Score: 2) by takyon on Tuesday May 30 2017, @12:34AM (2 children)

    by takyon (881) <takyonNO@SPAMsoylentnews.org> on Tuesday May 30 2017, @12:34AM (#517395) Journal

    I was sure it was the coolant that was the big deal, but the FAQ mentions fuel as well.

    Webb is designed to have a mission lifetime of not less than 5-1/2 years after launch, with the goal of having a lifetime greater than 10 years. The lifetime is ultimately limited by the amount of fuel used for maintaining the orbit, and by proper functioning in orbit of the spacecraft and instruments. Webb will carry fuel for a 10-year lifetime (with margin); the project will perform mission assurance testing of the flight system to guarantee 5 years of scientific operations starting at the end of the commissioning period 6 months after launch.

    It seems like they are definitely expecting it to last 10 years or even a little longer, which is good news.

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    • (Score: 1, Informative) by Anonymous Coward on Tuesday May 30 2017, @01:49AM (1 child)

      by Anonymous Coward on Tuesday May 30 2017, @01:49AM (#517412)

      The cooler is closed-cycle. But L2 orbits need fuel to maintain.

      • (Score: 2) by butthurt on Tuesday May 30 2017, @07:03PM

        by butthurt (6141) on Tuesday May 30 2017, @07:03PM (#517824) Journal

        Yes, ESA says that's true for L2:

        Orbits about L2 are dynamically unstable; small departures from equilibrium grow exponentially with a time constant of about 23 days.

        -- http://sci.esa.int/herschel/34699-orbit-navigation/ [esa.int]

        Wikipedia says without a citation:

        In contrast to L4 and L5, where stable equilibrium exists, the points L1, L2, and L3 are positions of unstable equilibrium. Any object orbiting at L1, L2, or L3 will tend to fall out of orbit; it is therefore rare to find natural objects there, and spacecraft inhabiting these areas must employ station keeping in order to maintain their position.

        -- https://en.wikipedia.org/wiki/Lagrangian_point [wikipedia.org]

  • (Score: 2) by kaszz on Tuesday May 30 2017, @12:56AM

    by kaszz (4211) on Tuesday May 30 2017, @12:56AM (#517405) Journal

    I wonder if one could buy it? Someone with enough cash could make use of a telescope already in space.