During these uncertain times of COVID-19, GMTO closed our offices in Pasadena and Santiago in mid-March, but that action has not slowed our work. Our team continues to make progress while working from home via videoconferences. At the telescope site, we completed an important upgrade to the water facilities, then shut down all activities, keeping a skeleton crew for security, safety, and maintenance. In the US, like many businesses we are rolling out our protocols for reopening the offices. At GMTO, we are also stressing flexibility for our employees to continue to make progress in building the telescope.
This newsletter covers a wide range of exciting activities from the first half of this year. Work on the mirror simulator, fabricated at CAID Industries and installed on the test cell at the Richard F. Caris Mirror Lab, has been moving forward with our partners. Early this year, GMTO welcomed our newest member of the Board of Directors, Dr. Sung Hyun Park of Korea who is Professor Emeritus in the Department of Statistics at Seoul National University. At the beginning of the year, GMTO attended the 235th American Astronomical Society meeting in Hawaii, and we also presented to the Astro2020 Panel on Optical and Infrared Observatories from the Ground in Washington, DC. I am excited to share these updates and more with you.
Dr. Robert Shelton – President, GMTO
Mirror Simulator Installed
A significant milestone for GMTO’s primary mirror controls team recently took place at the Richard F. Caris Mirror Lab at the University of Arizona – the bringing together of the mirror simulator, the prototype mirror cell, and the test cell. The mirror simulator is currently resting on top of the static supports attaching it to the test cell top plate. For this procedure, the mirror simulator was gently lowered into the prototype mirror cell until the static supports flex imperceptibly and are fully supporting the simulator representing a crucial dress rehearsal for the process of integrating a glass mirror.
The mirror simulator is a round piece of steel, weighing approximately 14,000kg – somewhat lighter than a glass GMT mirror. The underneath of the simulator looks like a bed of nails – it has a vast array of “interface features” that attach to the mechanisms that support and control the mirrors – the single and triple actuators, the hardpoints, and the static supports. The simulator’s purpose is not to mimic a primary mirror exactly, but to validate the mirror support system, both in hardware and software.
The prototype mirror cell weldment (the steel part of the mirror cell) measures 8.6 m long, 10 m wide by 1.8 m tall, and weighs about 22,700 kg. Its role is to hold all the different support mechanisms that the mirror requires to keep its shape. The weldment was designed by engineers at GMTO and was manufactured at CAID Industries in Arizona. The weldment plus support system comprises the Mirror Cell.
The support system for each off-axis mirror consists of 170 pneumatic actuators and 326 static supports and a few less for the center segment. The actuators are designed to lift and shape the mirrors, and their most important component is a “load cell” which measures how much force the actuator is applying to the mirror – too little and the mirror won’t move, too much and excess stress could be placed on the mirror. To make sure the load cells are making accurate measurements, they need to be calibrated, which GMTO’s software team has been working on. The team has created an Actuator Calibration Stand (ACS) that can calibrate a single actuator in less than an hour. A second ACS that can mimic the sideways force on actuators when the telescope is tilted has also been developed. These ACS’s will be delivered to the Mirror Lab.
The mechanical parts of the actuators are being assembled at Texas A&M University and are being delivered to the Mirror Lab, where the electronics are being integrated. The actuators are then calibrated by the ACS. Even with one calibration taking less than an hour, with 170 to do for each of the seven mirrors, this part of the process will take months!
In parallel, the Software team has been working on the software control system for the actuators. This software needs to be able to send commands and read back the results to all 170 actuators of a mirror in 10 milliseconds. The software they are creating will be the “production” software used on the actual telescope. The team can achieve this because they can test it on a very close analog to the final system and thus save years of software simulations.
At the Mirror Lab, GMTO and UA engineers spent time earlier this year installing static supports onto its top plate in preparation for receiving the mirror simulator. Static supports are designed to hold the mirror when it’s at rest and to catch it during an earthquake.
The GMTO team and UA team have become highly integrated over the past few months as work on this project continues. By the time the testing of the control system with the simulator is complete, and the team is ready to integrate a real glass mirror, the project will have gained a great deal of knowledge about how we can phase and control the primary mirrors.
Welcome New Board Director
GMTO welcomes our newest member of the Board of Directors, Dr. Sung Hyun Park of Korea. Dr. Park is Professor Emeritus in the Department of Statistics at Seoul National University and the President of the Social Responsibility and Management Quality Institute. He is a member of the National Academy of Sciences, Republic of Korea, and he holds a certification as an Academician by the International Academy for Quality (IAQ). Dr. Park currently serves on the Korean Foundation for Quality Board of Directors.
Dr. Park has had a distinguished career. Last year, he received the 2019 Albert Nelson Marquis Lifetime Achievement Award. He previously served as the President and Board member of the Korean Academy of Science and Technology, as well as the Dean of the College of Natural Sciences and the Office of Student Affairs at Seoul National University. He was the President of the Korean Society for Quality Management as well as the President of the Korean Statistical Society. He was the Director of the Directorate of Basic Research in Science and Engineering, National Research Foundation of Korea. Additionally, he was a member of the Presidential Advisory Council on Science and Technology for the Korean Government. He received the Order of Service Merit Red Stripes Medal as well as the Order of Science & Technology Merit Innovation Medal from the President of the Korean Government.
When asked what sparked his interest in joining the GMTO Board of Directors, Dr. Park shared, “I am proud of the fact that the KASI (Korean Astronomy and Space Science Institute) is participating in the GMT Project. As a past president of the Korean Academy of Science and Technology, I would like to strongly support the GMT Project.”
Dr. Park shared the scientific discoveries he’s most looking forward to with the GMT stating, “when the GMT is in operations in the future, I will be most excited to have some knowledge ‘toward understanding how planets formed and how human beings came to earth in the beginning’.”
To learn more about GMTO’s Board of Directors, please visit GMTO’s website.
Unusual Winter Snowfall at the GMT Site
The Giant Magellan Telescope is being constructed in one of the highest and driest regions on earth, Chile’s Atacama Desert. While the GMT will have spectacular conditions for more than 300 nights a year, the rare winter storm does happen like it did a few weeks ago. Las Campanas Peak (“Cerro Las Campanas”), where the GMT will be located, has an altitude of over 2,550 meters or approximately 8,500 feet. The combination of seeing, number of clear nights, altitude, weather, and vegetation make Las Campanas Peak an ideal location for the GMT.
Site construction is paused as a safety precaution during the COVID-19 pandemic, and we look forward to when our staff is able to safely return to work at the site. Amidst this pause, the GMT site welcomed the first day of winter with an unusual amount of snowfall for this generally dry and arid location.
Once in a Decade Presentation
In late February, several GMTO staff traveled to Washington, DC, for a meeting with the Astro2020 Panel on Optical and Infrared Observatories from the Ground. Every ten years, the astronomy community evaluates and prioritizes the cutting-edge science topics and the missions in space and on the ground to make recommendations to the US federal funding agencies. This decadal process is led by the National Academies of Science, Engineering, and Medicine. The process starts with a call for white papers from the community on scientific topics of the highest priority for the coming decade and the technical programs needed to support them (computing, space programs, ground-based programs) and the state of the profession overall. Individual panels evaluate the science and projects on the horizon for the coming decade, and the steering committee compiles and issues a final report, expected early 2021.
The US ELT Program was selected to present an overview of the scientific and technical case for the joint project at the National Academies’ Keck Center near the Penn Quarter of the city for an entire afternoon session. The team presented information about the GMT and the US ELT Program alongside representatives from NOIRLab and the Thirty Meter Telescope Project. The GMT and TMT Project Managers gave comprehensive updates while the GMTO Chief Scientist and TMT SAC Chair described the technical and scientific capabilities that the two-hemisphere program will enable. The NOIRLab presented on their work to provide both observing and data access to the US Community. The panel asked questions about instrumentation, funding strategies, operational models, as well as other topics.
The presentations to the Astro2020 panel were the culmination of months of intensive effort, as well as 18 months of targeted interaction with the community to develop program support. The GMTO team responded in writing to multiple Requests for Information from the panel prior to this meeting and answered detailed questions related to the science, technology, and programmatic issues surrounding the individual telescopes (GMT and TMT) and the entirety of the US ELT Program. It is a testament to the profile and importance of the US ELT Program that observers joined the presentations in person from the National Science Foundation, the Kavli Foundation, and the New York Times, and a broad audience connected online.
US-ELT Program at the American Astronomical Society Meeting
At the beginning of the year, GMTO attended the 235th American Astronomical Society meeting in Honolulu, HI, as part of the US ELT Program, a partnership with NOIRLab and the Thirty Meter Telescope Project. The US ELT Program hosted a social open house, a scientific meeting, and a shared booth in the exhibit hall.
The open house encouraged the community to ask questions of the US ELT Program leadership and find out more about the program. There were briefings on the technical and scientific synergies that will be achieved by the combined power of the GMT and TMT. Dr. Patrick McCarthy, Director of NOIRLab, Dr. Rebecca Bernstein, GMTO Chief Scientist, and Dr. Jessica Lu, faculty at the University of California, Berkeley, presented at this session.
The scientific meeting started with project status updates from Dr. James Fanson, GMTO Project Manager, and Dr. Mike Bolte, TMT Board Member. Following this, members of the astronomical community gave brief scientific presentations. Dr. Nikole Lewis of Cornell University talked about extrasolar planetary systems, Dr. Jonelle Walsh of Texas A&M University discussed the dynamical searches for black holes with ELTs, and Dr. Francis-Yan Cyr-Racine of the University of New Mexico outlined the cosmological applications of gravitational lensing.
The events were well attended by the community, and we enjoyed the great questions about the US ELT Program and the two telescopes. For more information about the US ELT Program, please visit the NOIRLab website.