Issue 5 • October, 2006
Thirty Meter Telescope

Project Manager's Corner: Whole Lotta Shakin' Goin' On

When Jerry Lee Lewis sang those immortal words, he was probably not thinking of a giant telescope. But many of the world’s giant telescopes got a whole lotta shakin’ on the morning of October 15, when a magnitude 6.7 earthquake disturbed the Big Island of Hawaii. The good news is that all of the observatories, as well as the population of the island, fared pretty well in this exceptional event.

As someone involved in designing the next-generation telescope, an event like the Big Island earthquake is a reminder to be very careful in our design. Of course, earthquake resistance and safety are a standard part of the requirements that all telescope designers use. But an actual event, especially such a big one, is a chance to see if the design solutions taken by past designers worked, what did not work, and what new insights can be gained

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Science Nugget—TMT's Planet Formation Instrument

In the closing years of the 20th century, humankind began its exploration of the planetary systems in the solar neighborhood. Precision radial velocity measurements have now yielded the discovery of over 160 planets. Direct imaging of these planets—as opposed to detection of the effects of orbital motion on their parent star—is now feasible, and the first young planet in a wide orbit may have been detected using adaptive optics systems.

Gemini and the VLT are building the first generation of high contrast “extreme” adaptive optics (ExAO) systems: the Gemini Planet Imager and SPHERE. These systems will combine advanced adaptive optics with a device called a coronagraph (named after experiments to study the corona of the Sun), which blocks diffracted light from a star to make nearby objects visible.

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Technology Nugget—Mirror Segment Manufacturing: Part 2

In the last TMT Newscast, we described the basic challenging of polishing the telescope’s many mirror segments, and the application of Stressed Mirror Polishing (SMP) to polish the desired aspheric surfaces of the segments. For technical reasons, this polishing is done on circular mirror blanks. The warping of the segments is much more readily done if forces can be applied along the smooth circular perimeter. The basic idea is that after the polishing, one cuts away the outer parts of the mirror, leaving the desired hexagonal shape for the segment.

There is another important reason to polish circular mirrors, and then cut them. Since the primary mirror is composed of many hexagonal segments (738 of them), there are lots of segment edges that are in the interior of the primary mirror. Hence, it’s important that the segment edges are polished to the same high accuracy as the interior of a segment. This is important because the polishing process involves a polishing tool moving over the mirror blank, and as the tool moves over the edge of the mirror, the material removal rate tends to change (as it tends to be proportional to the tool pressure).

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Q & A with Larry Stepp

Larry Stepp is the Telescope Department Head for the TMT project, responsible for the overall design and functionality of the 30-meter telescope. Before joining the TMT project office, Larry was a senior engineering manager at the National Optical Astronomy Observatory in Tucson, where he worked on AURA’s design for the Giant Segmented Mirror Telescope, as well as the optics for the Gemini telescopes, the WIYN 3.5-meter telescope, and earlier large telescope concepts.

Larry spoke recently with Doug Isbell about the status and challenges of the TMT design.

Download Larry Stepp Interview
[14:35 min. 11.16 MB MP3]

Project Office News

Dr. David Silva, the TMT Observatory Scientist, discussed the TMT project with several scientific groups in Chile this month. Silva presented project overviews at Universidad de Chile and Pontificia Universidad Católica de Chile, and in La Serena to the staff of the AURA and Gemini offices there.

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Industry News—A Whirlwind Visit to Potential Glass Suppliers

A project like TMT simply cannot take place without a strong industrial component. This space in the Newscast, "Industry News," has featured articles written by several of our current industrial partners (M3 of Tucson, Hytec of Los Alamos, AMEC of Vancouver). We also described a prospective primary mirror glass supplier, Corning, in our first "Focus On" article.

In this installment I want to describe the next steps in acquiring the hundreds and hundreds of finished primary segments that we will need for TMT (which Jerry Nelson began explaining last month, and finishes up in an article on polishing mirrors in this Newscast.)

Actually, this step was quite a bit of fun, though it involved grueling travel and long, but productive, work days. We have to buy glass. We must have the glass blanks polished to shape and tested by optical means. The finished segments must meet our demanding requirements and they must be as cheap as possible. The strategy is to contract with the most capable companies in the world through a competitive process. And so we have to come to know these companies and their capabilities, methods and products.

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TMT "In The News"

Recent articles mentioning TMT in the popular media:

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You have received this issue of the TMT Newscast because of your previous professional contact with the Thirty Meter Telescope Project, the Association of Universities for Research in Astronomy (AURA) Inc., the California Institute of Technology, the University of California, or the Association of Canadian Universities for Research in Astronomy (ACURA).

TMT is supported in the United States by the Gordon and Betty Moore Foundation and the US National Science Foundation. Canadian funding is provided by the Canada Foundation for Innovation, the Ontario Ministry of Research and Innovation, the National Research Council of Canada, the Natural Sciences and Engineering Research Council, and the British Columbia Knowledge Development Fund.

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