System Level Preliminary Design Review and Cost and Organizational Review Passed with Flying Colors
In January, the GMT team completed two significant reviews, bringing the group closer to the start of the Construction and Commissioning Phase of the project.
The System Level Preliminary Design Review investigated the overall technical readiness of the project, while the Cost and Organizational Review analyzed the financial plan, including a close look at estimated costs and contingencies, and GMTO’s organizational structure. Feedback from both review panels has been highly positive. In their report, the System Level Preliminary Design Review panel recommended that the GMT proceed with the construction phase “as rapidly as possible.”
The Design Phase of the GMT project included a schedule for a set of Preliminary Design Reviews, or PDRs, in which groups leading the design of individual subsystems of the instrument have presented their work for review by external panels to ensure that designs are sound and that potential challenges and risks were addressed.
The final PDR focused on the observatory at the higher system level, in which the components are viewed as a whole to provide a comprehensive look at the overall technical readiness of the project and to ensure that each of the components are fully integrated into the observatory.
Leading up to the review, the GMTO team built on the work and momentum of the individual reviews to prepare. Documents provided to the review panel included four large volumes of material totaling more than 1675 pages. In addition, nearly 500 pages of requirements and system engineering documents were provided to the panel.
Among the areas discussed during the four days of presentations were the project vision, the GMT partnership, science goals, system architecture, software and controls, the telescope enclosure and other facilities, the management plan, and risk assessment.
“Although the material prepared for the review is impressive and will be a valuable reference for the final design work, the process of preparing for these reviews has placed the project in an excellent position, ready for the start of construction,” says Keith Raybould, GMTO Project Manager.
The Review Panel consisted of external senior level engineers, scientists, project managers, and experts in instrumentation. Among their initial comments, the review panel also stated that they were impressed by “the quantity, quality, and timeliness of the information provided” and “the high level of competence of the GMT team.”
“The successful result of the System Level PDR is the direct outcome of years of outstanding work by the entire project team,” says Raybould. “I have been incredibly impressed by how the project has really gelled into an effective collaborative team that also includes engineers from within the GMT partnership and from industry. The technical leadership demonstrated by the project technical team leads has been key to this successful outcome.”
Shortly after the System Level PDR, GMTO held a Cost and Organizational Review to comprehensively examine project cost information, including contingency estimates and schedules, as well as the GMTO organizational structure.
Among the early feedback, the panel stated that the project had a “very competent and experienced project management team with relevant experience for a project of the complexity of GMT.”
The outcome of the reviews will help the Board of Directors in their decision to proceed to the Construction and Commissioning Phase of the project, which is anticipated to take place from 2014 to 2022.
Bruce Bigelow joins GMTO as Opto-Mechanical Systems Lead
In November, Dr. Bruce C. Bigelow joined GMTO as the Opto-Mechanical Systems Lead.
Bigelow has worked on large astronomical telescopes and their instrumentation for more than 25 years. Most recently, he held the position of Research Astronomer at the University of California Observatories, where he was the project manager and lead engineer for the Multi-Object Broadband Imaging Echellette (MOBIE) spectrograph, a wide-field optical spectrograph for the Thirty Meter Telescope project.
Bigelow earned his B.S. in Mechanical Engineering from UC Santa Barbara and his Ph.D. in Physics and Astronomy from University College London. Among his past positions, he was Project Leader for the Keck Observatory ESI Spectrograph, Project Manager and Chief Engineer for the Magellan imaging spectrograph (IMACS) for the Carnegie Observatories, and a Senior Research Engineer at the University of Michigan, where he worked on U.S. Department of Energy “dark energy” missions including the SNAP space telescope and the Dark Energy Camera for the CTIO 4m Blanco telescope.
His field of opto-mechanics deals with the fabrication and mechanical support of optics, to make sure that the qualities of the original optical design are preserved when translated into the real world of obtainable materials and constantly-changing thermal and gravity environments.
His move to GMTO marks a transition in his work from the design and construction of science instruments for telescopes, to work on the telescope itself. He will focus on the opto-mechanics for the optical systems following the GMT primary mirrors, including the fast steering secondary mirrors, the adaptive secondary mirrors, the wide field corrector (WFC) and atmospheric dispersion corrector (ADC), and the tertiary mirror.
“Unlike the perfect world within a computer-based optical design, optics in real telescopes have to deal with a constantly changing orientation with respect to gravity,” he explains. “Similarly, the optical design is typically conceived at one temperature, and that design can be re-examined at different temperatures, but typically not for the range of temperature gradients we see within the telescope enclosure.” Along with considering temperature differences, he says, the effect of gravity and the challenges of joining optical elements to mechanical supports composed of metal or ceramics must also be carefully designed and analyzed.
For some of the GMT optical elements, just procuring materials in the necessary sizes becomes a challenge. “The transmitting optical materials we need for the GMT ADC are reaching the limits of what is physically possible to produce,” he says. As an example, the thermal conductivity and specific heat of a glass control how quickly heat can be moved in and out of it during melting or solidifying. “So, if you’re trying to melt and then solidify a very homogeneous pieces of glass, as we need for the WFC,” he says, “the optical material fabricators must learn how to get the heat out of the optical material in a very controlled and balanced way, to maintain homogeneity and to avoid devitrification (formation of crystal structures rather than glass). With the GMT ADC, we are already pushing the state of the art in terms of size and homogeneity.”
“The GMT is a very exciting telescope and project. We have a very ambitious telescope design. We have, perhaps, the best site in the world – a site that we know and control.”
Also, he says, “the GMT is an exciting extension of many things that the GMT partners already know how to do. We’re doing something new and extremely challenging, but we’re starting with a very solid foundation.”
To be sure, beyond the technical considerations, the GMT partnership itself was a big draw for Bigelow. “One of the great things about the GMT project is its partnership. I’m familiar with most of the partners from earlier projects, such as the IMACS spectrograph for Magellan, so I know many people at most of the partner institutions, and I have a tremendous amount of respect for them. I am also very excited about working with the GMT partners in Korea and Australia. I’m delighted to join the GMT project team.”
Third Segment of the GMT Primary Mirror Unveiled
On December 6, 2013, GMT’s newest primary mirror segment was unveiled at the University of Arizona’s Steward Observatory Mirror Lab. This is the third of seven segments that will function together as one primary mirror once the telescope is operating at full capacity.
The event was attended by the GMT community and distinguished guests. Presenters included University of Arizona President, Ann Weaver Hart; Chair of the GMTO Board of Directors, Wendy Freedman; Dean of the University of Arizona College of Optics, Tom Koch; and Steward Observatory Director, Buell Jannuzi, among others.
Though the workload in the Steward Observatory Mirror Lab is as heavy as ever, with multiple mirrors in line for completion for the LSST, the GMT, and other big telescopes, the staff briefly slowed operations to showcase one of their modern marvels of technology.
The third primary mirror segment produced for the GMT recently came out of the custom-built spinning furnace in which it had been steadily cooling since late August of last year, when it was cast at a temperature of over 2000 ˚F. It is 8.4 meters (27 feet) in diameter and weighs approximately 20 tons. It now awaits the three-year polishing process that will make the mirror exquisitely smooth, with no height variations larger than one millionth of an inch across its entire surface.
“We’re building this for the next generation of researchers,” said Jannuzi, alluding to the decades of research capabilities that the GMT will enable once it comes online in 2020.
The mirror lab utilizes the cumulative knowledge of leading optics scientists, said President Hart. “We’re excited to be a part of understanding the origins of the universe.”
Speaking about the overall effort to construct the GMT, including the optics technology developed, the advancements in software and engineering, and the combined fundraising efforts of the partners, Freedman said, “We are creating a new model to do big science. Every one of these milestones is a time to heave a sigh of relief and celebrate.”
The center mirror segment is scheduled to be cast in January of 2015. These four mirror segments will be in use when the GMT begins its early science phase of operations.
More on the GMT and its primary mirrors can be found below:
Mirrors for giant space telescope take shape from The Christian Science Monitor