- Excavation begins on GMT site
- Developing a science vision for the Astronomy and Astrophysics 2020 Decadal Survey
- 2018 GMT Science Book released
- Phasing the GMT mirrors: prototype testing at Magellan
- Profile: Barbara Fischer, Primary Mirror Subsystem Manager
- GMTO attends SPIE: Astronomical Telescopes + Instrumentation 2018
- GMTO exhibits at the City of Astronomy’s AstroFest 2018
Welcome to the August newsletter
In mid-July the GMT project reached a major milestone: the start of excavation on the site for the foundations for the telescope’s pier and enclosure, and for the primary mirror coating chamber. The rock comprising Las Campanas peak is extremely hard and so a hydraulic hammer is needed to break up the rock before it is collected by a backhoe and hauled away. The entire excavation process is expected to take around 5 months as we remove roughly 5,000 cubic meters of material.
We have recently achieved another significant milestone with the release of the 2018 GMT Science Book that describes GMT’s strengths and its promise for scientific discovery. Spearheaded by the GMT Project Scientist, this spectacular publication was written by GMT’s Science Advisory Committee and by scientists from around the world.
Finally, GMT has begun working with the Thirty Meter Telescope and the National Science Foundation’s National Optical Astronomy Observatory to articulate a community-based science program for presentation to the next Decadal Survey of Astronomy and Astrophysics, which got underway this past month.
Also in this newsletter we profile Barbara Fischer, a new mechanical engineering manager focused on the primary mirror support system, and we describe how the wavefront sensing and control team tested a prototype of the mirror phasing camera on the Magellan Clay telescope. Lastly, you can read about our time at SPIE: Astronomical Telescopes + Instrumentation, and the fun we had exhibiting at “AstroFest 2018”.
Remember you can always keep up to date with what’s happening at GMTO from this website or from our presence on social media.
– Dr. Patrick McCarthy
Excavation begins on GMT site
On August 14, GMTO announced the start of hard rock excavation for the Giant Magellan Telescope’s massive concrete pier and the foundations for the telescope’s enclosure on its site at Las Campanas Observatory in Chile. The work is being performed by Minería y Montajes Conpax, a construction services company that has previously performed site work for other observatories in Chile. Using a combination of hydraulic drilling and hammering, the excavation work is expected to take about five months to complete. We do not anticipate the use of explosives in the excavation work on the summit.
The most challenging part of the work on the summit will be excavation of the rock to a depth of 7 meters (23 feet) to support the concrete base of the telescope pier. Much of this work will be done with hydraulic rock hammers to ensure that the bedrock below the pier remains intact. The team expects to remove approximately 5,000 cubic meters or 13,300 tons of rock from the mountain and will need 330 dump truck loads to remove it from the summit.
Work is progressing apace, with excavation in the area of primary mirror coating chamber nearly complete, and work on the telescope pier well underway. Keep up to date with the progress of excavation via social media, where we will be posting weekly photos from the site.
Developing a science vision for the Astronomy and Astrophysics 2020 Decadal Survey
In May, GMTO, the Thirty Meter Telescope International Observatory (TIO) and the National Science Foundation’s National Optical Astronomy Observatory (NOAO) announced a collaboration to articulate a community-based science program for presentation to the next Decadal Survey of Astronomy and Astrophysics.
Access to both the northern and southern hemisphere’s sky with extremely large telescopes (ELTs) having the capabilities of the GMT and TMT will provide unique scientific opportunities in the coming decade and beyond. We look forward to working with our colleagues in the GMT, the Thirty Meter Telescope (TMT), and NOAO communities to develop the science case for the two telescopes for the upcoming Decadal Survey.
For more information visit the US ELT Program website.
2018 GMT Science Book released
We are pleased to announce that the 2018 Science Book describing the GMT’s strengths and its potential for scientific discovery is now released and available for download as a pdf.
The book is divided into nine chapters that describe the transformative impact that GMT will have on areas spanning observational astrophysics — from exoplanets around neighboring stars to the formation of the first stars, galaxies, and black holes in the universe. The first chapter provides a technical overview of the GMT itself, explaining its unique design and capabilities, including the first-generation instrument suite that has been chosen to maximize the GMT’s scientific impact during early operations.
Each chapter starts with an introduction to the general astrophysical topic and its importance to understanding the universe around us, followed by a more detailed introduction for non-specialist scientists. The main body of each chapter goes into more detail about specific scientific programs that will be enabled by the sensitivity and capabilities of the GMT and its instruments, and how it will complement other observatories operating in the coming decades. While we cannot predict all that the GMT will do, these programs represent a sample of the interesting and transformative science that our community is planning to do with GMT.
This publication is the result of a year of work by the GMT Science Advisory Committee, scientists from around our partnership and the international community led by the GMT Project Scientist Dr. Rebecca Bernstein, with assistance from the communications team at GMTO.
The chapters are:
- Chapter 1: Introduction to the Giant Magellan Telescope
- Chapter 2: Exoplanets and Planet Formation: Are we alone in the universe?
- Chapter 3: The Birth of Stars: Where and how are stars born?
- Chapter 4: The Death of Stars: How do stars die?
- Chapter 5: Building the Milky Way and its Neighbors: How did galaxies grow and evolve?
- Chapter 6: The Growth of Galaxies Over Cosmic Time: How do stars form in galaxies over cosmic time?
- Chapter 7: Building Galaxies from Cosmic Gas: How does the gas that feeds star formation get into galaxies?
- Chapter 8: Cosmology and The Dark Universe: How did the universe form and grow?
- Chapter 9: First Light & Reionization: What were the first sources of light and how did they transform the universe?
Phasing the GMT mirrors: prototype testing at Magellan
In May of this year, a team of scientists from GMTO, Smithsonian Astrophysical Observatory, and the University of Arizona took a prototype of the GMT phasing camera to the 6.5 meter Magellan Clay telescope for testing. The heart of the phasing sensor is the Dispersed Fringe Sensor (DFS) – a set of prisms that spread the light that falls on adjacent primary mirror segments into its constituent colors. When installed on the GMT, the DFS will be able to detect whether the GMT’s seven mirrors are in phase – i.e. whether the edge of one mirror is a fraction of a light wave higher or lower than its neighbor.
The GMT’s unique design of seven close-packed circular mirrors means that the mirrors need to be aligned (“phased”) to a fraction of wavelength so they can act as one coherent surface. The Dispersed Fringe Sensor measures the difference in the phase of the light reflected off the mirror edges on either side of the gaps. The dispersed light allows us to be certain that the GMT will be phased at all wavelengths.
As the name suggests, the DFS will create a set of interference fringes using starlight reflected from either side of each mirror gap and create a spectrum of these fringes using small prisms. The measurements must be made in the infrared to overcome the blurring due to atmospheric turbulence, which is more benign in the infrared. The resulting sensor can measure up to 40 microns of phase difference between the mirrors. When the mirrors are phased, the fringes formed by each pair of mirror edges appear as simple vertical lines, but if the mirrors are not phased, the fringes appear twisted like a barber’s pole.
To test this complex set of infrared cameras and optics on the sky, the team used the Magellan Clay telescope configured with an adaptive secondary mirror and a pyramid wavefront sensor similar to those that will be used on the GMT. The Magellan Clay telescope has a single 6.5 meter primary mirror so using it to test phasing between different mirror segments sounds problematic. However, the DFS prototype uses an optical mask to make the Magellan mirror appear as if it were segmented, mimicking three of the GMT primary mirror boundaries. With the Magellan active optics system we can introduce phase errors that are then sensed with the DFS.
The goals of the experiment were to evaluate the sensitivity of the DFS when using faint stars to measure the phase difference across segment gaps, and the impact of instrumental biases such as alignment errors in the optics that might masquerade as phase differences between the GMT mirrors.
The team reports that the prototype DFS’s hardware and software worked as intended and they were able demonstrate that the DFS is sufficiently sensitive to phase the GMT using stars as faint as 14th magnitude. This will enable the GMT to achieve its ultimate, diffraction-limited resolution over at least 80% of the sky visible from Las Campanas. The instrumental biases were significant, however, and it is clear that careful calibration of the DFS will be necessary. The team is planning to continue the DFS testing campaign in November of this year.
The team on this testing run were: Antonin Bouchez from GMTO, Laird Close, Joseph Long, Jared Males and Katie Morzinski from the University of Arizona, Jan Kansky, Derek Kopon, Brian McLeod and Stuart McMuldroch from the Smithsonian Astrophysical Observatory, and Danielle Frostig from Harvard University.
Profile: Barbara Fischer, Primary Mirror Subsystem Manager
We are pleased to welcome Barbara Fischer to the GMT team. Barbara is the lead engineer for GMT’s primary mirror subsystem. For this newsletter, she answered some questions about her life and career.
What is your role with GMTO?
I have assumed the responsibility of leading the primary mirror positioning, support, and thermal environment systems development team. They are currently undergoing prototype development of the actuators, positioners and control system, and manufacturing of the test cell weldment. Next year, the team will start integration of the test cell to a challenging schedule and budget. The success of the test cell is crucial for ensuring that GMT has a sound support system for the primary mirror, the design is qualified for production and validation of the mount interfaces.
How did you first get into your engineering career?
As a young girl, I asked for a ten-speed bicycle and my Dad said, “you can have your Mom’s old bike, if you rebuild it.” I proceeded to disassemble the bike, replace the damaged parts, and refinish the frame. After I completed it, I proudly rode it throughout high school and relished the independence it gave me. Besides inheriting my family’s nature of building whatever we imagined, my favorite classes were calculus and art. I especially loved to draw and felt engineering would be a great way to express my creativity while achieving that sense of accomplishment when a project is completed.
What inspired you to choose this career?
After reading the book “Outliers” by Malcom Gladwell, I realized I am one. I am the first of my family to earn a college degree. I grew up attending every airshow within driving distance of Gilroy, California. My Dad took me to work while he was a foreman constructing an addition to the Blue Cube at Moffett Field. While I was there, he told me about the U2 flights he would see at lunch time and I was in awe that they were piloted by a woman training to become an astronaut. Years later during my senior year of high school, I worked at NASA Ames Research Center and attended Space Camp in Huntsville Alabama. I knew I wanted to become an aerospace engineer because of this fascination.
What has been your career path to date?
I began my career in mechanical design, analysis, and integration of space-based science instruments that study the Sun. After I completed my last solar observing instrument, I was promoted to subcontract management and systems engineering leadership positions on billion-dollar programs. My career spanned 20 years at Lockheed Martin with growing responsibility in product value, leadership, and customer interaction. I led quick turnaround proposal efforts, short-life cycle studies, and new development programs. My teams were comprised of cross-functional engineers, scientists, and business professionals accomplishing challenging schedules, costs, and technical goals in solar science, military communications, and remote sensing.
What has been your most rewarding career accomplishment to date?
3 – 2 – 1 lift-off! The only thing better than hearing those words is seeing the flawless first image of the Sun from the Helioseismic and Magnetic Imager which launched on the Solar Dynamics Observatory (SDO). It was the result of my team’s dedication and years of hard work. We stood together in anticipation by the countdown clock at Kennedy Space Center as we watched the Atlas lift SDO off the ground. It was my third launch I have been fortunate to observe and be a part of its success.
Within your field and outside of it, who do you respect/look up to and why?
Be willing to learn new things. Be able to assimilate new information quickly. Be able to get along with and work with other people: these are the secrets of success from Sally Ride who did not succumb to the stereotype that science was for boys. I remember when she became the first woman in space: her accomplishment made me believe I can do anything I wanted as long I applied myself. I also admire Elizabeth Citrin, who was the NASA Goddard Project Manager for the Solar Dynamics Observatory. She always had a positive attitude, encouraged collaboration by keeping the team focused on common goals, and listened to your ideas.
What advice would you give to students exploring STEM fields as careers?
When I visit my friends’ classrooms, I look for ways to relate STEM to the children’s experiences and interests. I feel it is important to engage their imagination and show how STEM has direct value to them. My advice for students in STEM is be excited about what you do, find what motivates you, and follow through. You can do anything, once you put your mind to it.
Why did you want to get involved with the GMT?
The Solar Dynamics Observatory (SDO) images of the Sun have been the centerfold of several scientific magazines and the GMT will be the same for decades. Even though I am not an astrophysicist, I love contributing to scientific breakthroughs and being on the cutting edge of technology. SDO was my favorite project and GMTO has similar energy: this zeal for making new discoveries is what drew me to GMTO. It is a great opportunity to apply my background and gain experience in an agile environment.
What are you most looking forward to once the GMT is completed?
Seeing the universe through a new lens and learning what GMT will mark in history.
GMTO attends SPIE: Astronomical Telescopes + Instrumentation 2018
In June, a number of GMTO engineers attended SPIE: Astronomical Telescopes + Instrumentation 2018 in Austin, TX to present their work to their peers. Project Manager James Fanson gave a well-received project status talk; the Site, Enclosure and Facilities lead, Bruce Bigelow, jointly hosted a meeting on enclosure design; and Instrument Manager Adam Contos and Instrument Scientist Rafael Millan-Gabet organized a splinter meeting for all the instrument teams across the GMTO partnership.
GMTO also hosted a booth in the exhibit hall and took part in the job fair. GMTO’s employment opportunities page is here.
GMTO exhibits at the City of Astronomy’s Astrofest 2018
GMTO exhibited at the City of Astronomy’s AstroFest 2018 in Pasadena in July. This family-friendly and free event welcomed over 2,700 people, including the Mayor of Pasadena, Terry Tornek. GMTO’s volunteers enjoyed showing visitors our virtual reality system, the 3D model of the central mirror and our ever-popular hologram. Read more in our blog post here.