This summer, the European Southern Observatory Council approved construction of the European Extremely Large Telescope. The E-ELT, to be sited on the Cerro Armazones mountain in the Atacama Desert of Chile, will be the largest optical/infrared telescope ever built. The primary diameter will be 39.3-meter (129-foot). Rather than a single mirror, the primary element will be an array of 798 1.4-meter (55-inch) mirrors.

The estimated cost for the mega-telescope, which is expected to see first light in 2022, is €1.055 billion ($1.36 billion at current exchanges rates).

American taxpayers should take note. That price is less than 1/6 the cost of NASA’s infrared James Webb Space Telescope (assuming JWST does not suffer any further cost overruns). Yet, the angular resolution of E-ELT at mid-infrared wavelengths will be six times better than JWST.

As we noted recently, advances in ground-based infrared astronomy are one reason why many astronomers are strangely unexcited about the JWST. The E-EELT is a good example of that.

The Europeans have also shown the willingness to sacrifice ultimate performance for the sake of cost-effectiveness. The size of the primary element was reduced from 42 meters, as originally planned, to save money and speed construction. This reduced the cost by 18%, from €1.275 billion to €1.055 billion, at the cost of 13% lower light sensitivity. Yet, astronomers are happy with the tradeoff because it enables the instrument to get built.

The construction plans for this telescope require almost 800 mirrors to be fabricated, then shipped separately to the top of the 3,064-meter (10,052-foot) peak.

There are risks in that plan, which will require a massive number of trucks. Perhaps one of the trucks will accidentally drive over a cliff, before the project is complete. With that many trucks, accidents are almost inevitable. Then, all of those mirrors must be assembled by workers under difficult conditions, at an altitude almost two miles above sea level. Working in parkas and mittens is uncomfortable. Studies show that workers in comfortable, air-conditioned factories at sea level are more efficient. Instead of trying to complete a massive construction project at that altitude, wouldn’t it be better to fabricate one huge monolithic mirror and develop a supertruck to transport it?  Of course, no one has proposed such silliness. Yet, that’s the same “logic” used to justify developing superheavy lift rockets for space telescopes and other large space structures. We know how to make tradeoffs and compromises for the sake of cost-effectiveness on Earth, but never seem to do it for space projects.

Written by Astro1 on October 10th, 2012 , Astronomy, Space Policy and Management

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    Buck Field commented

    Excellent treatment of the topic, emphasizing relative cost/benefit & ROI of different approaches, my favorite subject.

    Thanks for this!

    October 10, 2012 at 1:17 pm
    Rick Boozer commented

    Surprised that you didn’t note the analogous U.S. project (with international partners): the Thirty Meter Telescope that will be built on Mauna Kea in Hawaii at an estimated cost of $970 million.

    October 11, 2012 at 6:01 am