Thirty Meter Telescope Project Update

by Ray Carlberg

The TMT project is now entering the second half of the detailed design phase (DDP). In Canada our full DDP funding (US$17.5M, modulo exchange rate variations) has now been secured through a new NSERC grant ($6M), with matching funds from NRC ($3M in-kind) and Toronto, UBC and Victoria ($0.5M cash). This marks the fourth successful peer review major funding application for the LOT/TMT project in Canada.

 Our primary goal is to obtain a “second to none” ownership (a 1912 phrase from the Chief Astronomer of Canada arguing to establish what became DAO) of the TMT observatory, which is planned to be 25% of the partnership. To reach this goal we expect to deliver to the project four major sub-systems: the telescope enclosure, the telescope structure, the Wide-Field Optical Spectrograph (WFOS) and the first light adaptive-optics system, NFIRAOS. It is fair to say that Canadians have never been so deeply engaged in the creation of a major astronomical facility. In addition we share in overall procurements for the project. For instance, we are currently purchasing primary mirror blanks (unpolished) from several international glassmakers. These blanks will be provided to polishing firms that we have been working with to help them develop methods that meet our requirements, schedule and cost targets.  

 A very nice development is that TMT has now established that the cost of a high segmented mirror observatory scales as approximately the mirror diameter to the 1.1 power, rather than the classical “Meinel Law” of costs going as diameter to approximately the 2.5 power. TMT has studied 25 and 30m designs, however, the same 1.1 power is close to the inflation corrected cost of the Keck 10m.

 Overall the project is working towards making the transition to the construction phase after the successful cost review and re-scoping work of the fall of 2007. The SAC meeting of December 2007 defined an observatory that is expected to cost about US$750M (2006 year dollars) with a basic operating cost of US$25M per year. Ongoing scientific renewal can be estimated as approximately $15M a year. Therefore an initial twenty year operating agreement has a total cost of about $1550M.

 A draft construction plan is being prepared for external review in June 2007 as one of the major current activities. This core proposal will be used by all the TMT partners as a part of the fund-raising discussion with our individual sponsors. After the proposal is done the project will re-engage in basic design work to better refine the overall design of the telescope in preparation for a construction start in 2009. Particularly important is to revisit the instrument design work now that the SAC has refined specifications and more resources are available to do the work.

 The partners now need to make it clear what their financial commitments are. Caltech and UC are having separate discussions with their donors and internal mechanisms for supporting research. AURA has been required to leave the TMT project (and the competing GMT project) to help NSF resolve which of the two projects (or both, or some merged version) it should support to benefit the US national community. The NSF continues to pay the grant that was awarded to TMT to support the design work. The TMT Board has entered into a series of discussions with the National Astronomical Observatory of Japan to consider their potential role as a TMT partner. Because both NSF and NAOJ need to fulfil their ALMA constructions first, the plan for TMT is that the three initial partners (Caltech, UC and Canada) will begin construction of a very basic (but still very exciting observatory) which future partners will help upgrade. Aside from the basic desire to do TMT science, TMT would like to be in a position to exploit discoveries from ALMA and JWST. Moreover, the European ELT project (now a 42m aperture) just getting underway is a highly credible venture, but one which TMT enjoys a considerable lead which it does not want to lose.

 In Canada we are properly financed for the design phase, but need to press our case for construction funds in 2009. Because the enclosure is one of the first items that must be built, followed immediately by telescope structure work, it is critical to the schedule and our position within the project that we be able to move forward. The Canadian Coalition for Astronomy is doing a truly remarkable job discussing the funding needs of the entire Long Range Plan with the Canadian government. Of course we do not know what the government will decide or what further review will be required before any money can be allocated, but simply knowing that several agencies in Ottawa are listening is important for the project.

The enclosed figure shows many aspects of the current TMT structural design. Most of the structure displayed is the result of work undertaken in Canada by AMEC Dynamic Systems Limited under contract to ACURA. Novel design features include the support structure for the secondary mirror, the “flaps/wind-fence/eyelashes” around the opening, and of course the overall shape of the enclosure. It is interesting to note that the overall footprint is about equal to that of the existing Keck observatory

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