Thirty Meter Telescope
May 6, 2015
What Is It Again?
The Thirty Meter Telescope Observatory Corp. has decided to build their telescope atop a dormant volcano in Mauna Kea, Hawaii. The organization conveniently named themselves so casual science buffs are not forced to remember obtuse acronyms and what they refer to. Taking cues from other laconic scientists across the globe at CERN (notable for their Large Hadron Collider), the name reflects what it is, a large telescope with a mirror about 30 meters in diameter.
The Humongous Mirror Gap
Scientists are a notoriously competitive bunch, and there is no exception in the construction of giant telescopes. Across the pond, European countries are plotting the European Extremely Large Telescope (EELT) and have slated their first observation for the same year as that for the TMT, 2018. The EELT, at 138 feet in diameter, seems to be something of a compromise after the European Southern Observatory shelved its plans for the, wait for it, Overwhelmingly Large Telescope (OLT). Initially, the OLT was to be 100 meters in diameter. Then it was shortened to 60 meters before finally being scrapped. Confusingly, headlines are touting the TMT as the new "World's Largest Telescope," despite its diminutive size compared to the EELT.
The considerable magnifying power of the TMT will enable it to see deep enough into the cosmos to capture light that's been traveling for 13 billion years. Astronomers will be able to see images of the first stars and galaxies shortly after their inception, just 400 million years after the big bang. Some quick calculations suggest that for just another 0.92 meters they could get all the way to the beginning (30 Meters/13 billion years = 2.3 meters/billion years). Regardless, the TMT represents a landmark in optics technology that promises a never before seen look at the universe.
Not surprisingly, adaptive optics is pretty complicated. A commercial telescope pointed at the night sky is subject to sources of light that are of no interest, blurring the view and causing distortions. The TMT, on the other hand, has a flexible mirror connected to 3,000 actuators that calibrate the shape 800 times each second to account for light passing through Earth's atmosphere. Then, because it can't be that easy, the Tip-Tilt stage adjusts the actual orientation of the mirror about 20 times each second. The testing is complete with this technology, signifying that the TMT has progressed farthest in this ground-based space race.