Project
Manager's Corner: Whole Lotta Shakin' Goin' On 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 Science Nugget—TMT's Planet Formation Instrument
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. Technology Nugget—Mirror Segment Manufacturing: Part 2
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). Q & A with Larry Stepp
Larry spoke recently with Doug Isbell about the status and challenges of the TMT design. Download Larry Stepp Interview 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. Industry News—A Whirlwind Visit to Potential Glass Suppliers
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. TMT "In The News" Recent articles mentioning TMT in the popular media:
Previous Issues View the TMT Newscast Archive. |
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. 
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.
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.
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.
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.