Free Astronomy Magazine July-August 2023

37 JULY-AUGUST 2023 V era C. Rubin Observatory has passed a major construc- tion milestone: the telescope structure is ready to be out- fitted with a full-size replica of its 8.4-meter mirror and stand ins for its 3200-megapixel LSST Camera and other critical op- tical components. This major milestone means that Rubin Observatory is on track to help probe the mysteries of dark matter, study the fundamental nature of dark energy, docu- ment the dynamic Universe, and explore other grand chal- lenges of cosmology. [Rubin Observatory/AURA/DOE/NSF] Though Rubin is structurally similar to other 8-meter-class telescopes, it is considerably shorter [f/1.2], giving it a much lower center of gravity, which allows it to quickly and pre- cisely move from one area of the sky to another. Such ease of movement is essential to capture fleeting, tran- sient events, such as gamma-ray bursts and bright flashes of super- novae. One of Rubin’s primary sci- ence goals is to conduct a decade- long survey of the optical sky called the Legacy Survey of Space and Time. This unprecedented campaign, starting in 2025, will collect and process more than 20 terabytes of data each night — and up to 10 petabytes each year for 10 years — to compile detailed composite im- ages of the southern sky. The speed and nimble design of the telescope will allow it to survey the entire visi- ble southern sky every few nights and will essentially create a time- lapse movie of changes over dif- ferent timescales to learn about the risks fromasteroids and many other phenomena in the changing Universe. Over the course of a decade, the LSST Camera will detect and capture im- ages of an esti- mated 30 billion stars, galaxies, star clusters, and aster- oids. “The Rubin Observatory will not just peer across the Universe and look back in time. It will also have the un- precedented capability of studying the Universe as it changes in real time, from night to night,” said Bob Blum, Director for Operations Vera C. Rubin Observatory with NSF’s NOIRLab, which along with SLAC National Accelerator Laboratory, will support Rubin Observatory in its Op- erations phase. The telescope structure was fabri- cated, assembled, and tested at the UTE/Asturfeito factory in Spain. It was shipped to Chile and installation on Cerro Pachón began in late 2019. This process included the installation of drive motors and utility systems, including kilometers of cables, pip- ing, and hoses that provide electric- ity, communications, compressed air and coolants to the different parts of the telescope and camera. With the major hardware in place, the tele- scope and site software team inte- grated the software control system that drives the telescope. Over the past several months, Ru- bin’s team of observing specialists has been testing the integrated hardware and software to study how accurately the telescope points and tracks. The Rubin Systems Engi- neering team has been heavily in- volved in these and other testing campaigns to ensure the telescope meets its technical requirements and is working as designed. Data from these testing campaigns and the Engineering and Facility Database verified that the entire sys- tem to date met the required speci- fications. The telescope structure was then declared ‘substantially complete’, which will soon allow the UTE construction company to offi- cially hand over the telescope to Rubin and over the next weeks move towards final acceptance and contract conclusion. The Rubin sum- mit team is now preparing for the next major systems integration phase: installing the Primary-Tertiary mirror cell and surrogate mirror on the telescope structure. “It's gratifying that after years of hard work by so many people, we have such a huge accomplishment to celebrate,” said Jeff Barr, Rubin Ob- servatory Telescope and Site Man- ager. After more than a decade of planning, development, and con- struction, Rubin is on track to give astronomers and the public a previ- ously unimaginable view of the dy- namic and changing Universe. !