On Friday, March 23, 2012 the GMT project passed another major milestone when it began leveling its mountain top site at Las Campanas Observatory in Chile. Approximately 72 carefully controlled blasts, coordinated with the work of heavy earth moving equipment, will clear an area equivalent to four football fields, leaving a solid bedrock foundation for the giant telescope and its support facilities.
Nearly 4 million cubic feet of rock will be moved to level the site, in some areas the elevation will be lowered by as much as 30 feet. The site leveling work should be completed in July or early August.
Work on the site is being carried out by a Chilean engineering firm with expertise in earth moving and direct experience in preparing mountain top observatory sites. Geophones (sensitive monitors of motion and vibration) are being used to monitor the blasting.
Las Campanas is one of the premier astronomical sites on the planet. With its clear skies, non-existent light pollution and exceptionally sharp images, Las Campanas is one of the few remaining outposts on the Earth where astronomers can expect pristine observing conditions.
The occasion was broadcast live via the web, courtesy of the U.S. Embassy in Santiago. The event also garnered extensive coverage in news and social media, including the Washington Post, MSNBC, The Atlantic Monthly, YouTube, and Wired.com, among other sources. More than 4,000 people viewed the blast remotely, as did scientists at the GMT partner institutions and project staff back in the GMTO offices in Pasadena, California. Dr. Miguel Roth, Las Campanas Observatory Director, arranged for the colored plumes of the explosion and explained that “the red, white, and blue plumes represent the colors of the countries involved in the project: Australia, Chile, Korea and the US.”At a ceremony marking the first blast, Dr. Wendy Freedman, director of the Carnegie Observatories and chair of the Giant Magellan Telescope Organization (GMTO) noted, “Today marks a historic step toward constructing an astronomical telescope larger than any in existence. Years of testing have shown that Las Campanas is one of the premier observatory sites in the world and the Carnegie Institution is proud to host the GMT.”
Dr. Matthew Colless, Director of the Australian Astronomical Observatory stated, “Astronomers from Australia, and countries around the world, travel to Las Campanas to make use of its dark, clear skies and smooth airflow—conditions that produce the sharpest images from anywhere on the surface of the Earth. It is fitting that the world’s largest telescope be located at the world’s best observatory site.”
Dr. Patrick McCarthy, the GMT project director, said “2012 is a banner year for the GMT project as we complete the design process, develop the primary mirrors, and begin work on the site in Chile.”
Out of the Oven
Early this year the second of the GMT’s 8.4m primary mirror segments was cast at the University of Arizona’s Steward Observatory Mirror Laboratory. Since mid-January the mirror blank has been slowly cooling and undergoing a process of “annealing.” During this phase the mirror blank is cooled in a carefully controlled manner to ensure that there are no strains or stresses locked into the glass as it slowly contracts while cooling.
In late April the lid of the furnace was raised and the mirror lab crew got their first direct look at the solid glass surface within. All looked well, but the real inspection would have to await removal of the furnace walls, allowing access to the side of the mirror. All of the furnace structure has now been removed and the mirror blank looks perfect.The next step in the mirror-making process will be to lift the giant mirror off of its furnace hearth and suspend it in a steel frame. The mirror will hang vertically in the frame for a number of months while it is cleaned. The mirror still has over 1,700 hexagonal cores embedded in it from the casting process.
These hexagonal cores were used to mold special honeycomb-like voids into the back of the mirror, yielding a lighter mirror with better thermal stability. While the mirror is hanging vertically, silicon carbide bolts that hold the cores in place are removed and any remaining mold material is cleaned out with high-pressure water jets. The unpolished mirror, called a mirror blank, will then be put on a special grinding machine called a Large Optics Generator, where the mirror’s rear surface will be processed. Then, the first parts of the mirror’s future support system (triangular metal frames called “load-spreaders”) will be attached. After this, work on the front surface of the mirror – the part that will see the sky – can begin in earnest.
Once the GMT2 mirror has been lifted off the furnace hearth, work will begin preparing for the casting of GMT3 – the third primary mirror segment. By the time the GMT2 mirror blank is on the large optics generator, the mirror lab team should be ready to fire GMT3. Stay tuned!
GMT Software and Controls Team
The GMT Software and Controls team, headed by José Filgueira, is responsible for developing software that will both operate the observatory and assist astronomers with acquiring and processing their data. This international team of expert software engineers comes to GMT with substantial experience in developing control systems and software for large telescopes and sophisticated scientific instruments. The team will develop software that controls the telescope, aligns its massive mirrors, operates scientific instruments, opens, closes and rotates the enclosure, and many other tasks.
State of the art software and controls are essential to the operations of a complex and highly integrated system like the GMT. Jose’s group is getting an early start on the process by developing the top-level system architecture and by prototyping critical elements of the control system.
In assembling his team, José states, “We were looking for a broad and balanced set of skills and experience.” José brings to GMT nearly twenty years of experience in astronomical software projects, including heading the Control System Group at Gran Telescopio Canarias (GTC) 10 meter telescope project at the Institute of Astrophysics of the Canary Islands (IAC) in La Laguna, Spain. When asked why he was attracted to the GMT project, José replied, “The GMT is a unique project that pushes back technical as well as scientific frontiers.”
Ning Liu, Software Engineer, came to GMT from JPL, where she worked as a Software Engineer in mission planning. She developed multi-mission sequencing tools for deep space probes. She worked on the DAWN and CASSINI missions, spacecraft that are exploring the asteroid belt and Saturn. Ning holds a masters degree in computer science from the University of Illinois at Urbana-Champaign. In her spare time, Ning enjoys experimenting with recipes in her kitchen and cooking food from other countries, such as France, Italy, Spain, and Argentina –sometimes combining recipes to make something new. She learned to speak French because she loves “the musicality” of the language and is now beginning to learn Spanish – “After all, it’s an official language at GMTO,” Ning says.
Team member Matthieu Bec, Real Time Software Engineer, previously worked for the Gemini Observatory, where he created new tools for automated queue observations for twin 8.1-meter telescopes in Hawai’i and Chile. He led the software development team in upgrading and commissioning a new adaptive optics laser guide star facility on Mauna Kea in Hawai’i and on Cerro Pachon in Chile, where he also managed the integration of Canopus, the adaptive optics bench of GeMS. Matthieu graduated from the Department of Mathematics & Signal Theory at the École Centrale de Lyon, France, earning his Master of Science degree.
José Soto, Telescope Electronic Controls Engineer, worked on the Gemini telescopes as an electrical engineer. He has served at both Gemini North in Hawai’i and the southern Gemini telescope at Cerro Pachon in Chile, where he was in charge of several key observatory systems, including the secondary mirror system and the coating chamber. Jose was a member of the Magellan 6.5m telescope project and so is familiar with many common features of the GMT and Magellan Telescopes.
Chien Peng, Scientific Programmer, is the newest member of the Software Controls Team. Chien is a well-known and accomplished astronomer with many highly-cited publications. He created and developed the astronomical image analysis software known as GALFIT, as well as the gravitational lens modeling software LENSFIT. He is a recognized expert in data analysis and numerical modeling. Chien received his doctorate from the University of Arizona and has held distinguished fellowships in the US and Canada. Just before coming on board at GMT, Chien was a visiting scientist at The Carnegie Institution for Science. When he is not busy developing programs or writing scholarly articles for publication, Chien spends his spare time jogging, ballroom dancing, hiking, or playing sports such as basketball, baseball, and volleyball.
GMT will be exhibiting and presenting several papers at SPIE Astronomical Telescopes + Instrumentation 2012. Look for the GMT team at Stand 207, RAI Convention Center, Amsterdam, Netherlands, July 2 through July 4.
The GMT Project is looking for highly-motivated and qualified individuals to work on this world-class facility. Find out about current open positions.