A 3,200-megapixel digital camera is ready for its cosmic photoshoot


The world’s largest digital camera is officially ready to begin filming “the greatest movie of all time,” according to its makers. This morning, engineers and scientists at the Department of Energy’s SLAC National Accelerator Laboratory announced the completion of the Legacy Survey of Space and Time (LSST) Camera, a roughly 6,610-pound, car-sized tool designed to capture new information about the nature of dark matter and dark energy.

Following a two-decade construction process, the 3,200-megapixel LSST Camera will now travel to the Vera C. Rubin Observatory located 8,900-feet atop Chile’s Cerro Pachón. Once attached to the facility’s Simonyi Survey Telescope later this year, its dual five-foot and three-foot-wide lenses will aim skyward for a 10-year-long survey of the solar system, the Milky Way galaxy, and beyond.

Just how much detail can you get from a focal plane leveled to within a tenth the width of a human hair alongside 10-micron-wide pixels? Aaron Roodman, SLAC professor and Rubin Observatory Deputy Director and Camera Program Lead, likens its ability to capturing the details of a golf ball from 15-miles away “while covering a swath of the sky seven times wider than the full moon.” The resultant images will include billions of stars and galaxies, and with them, new insights into the universe’s structure.

[Related: JWST takes a jab at the mystery of the universe’s expansion rate.]

Among its many duties, the LSST Camera will search for evidence of weak gravitational lensing, which occurs when a gigantic galaxy’s gravitational mass bends light pathways from the galaxies behind it. Analyzing this data can offer researchers a better look at how mass is distributed throughout the universe, as well as how that distribution changed over time. In turn, this could help provide astronomers new ways to explore how dark energy influences the universe’s expansion.

An artist’s rendering of the LSST Camera showing its major components including lenses, sensor array, and utility trunk. Credit: Chris Smith/SLAC National Accelerator Laboratory

To achieve these impressive goals, the LSST Camera needed to be much more than simply a scaled-up version of a point-and-shoot digital camera. While lenses like those within your smartphone often don’t include physical shutters, they are still usually found within SLR cameras. That said, their shutter speeds aren’t nearly as slow as the LSST Camera. 

“The [LSST] sensors are read out much more slowly and deliberately… ” Andy Rasmussen, SLAC staff physicist and LSST Camera Integration and Testing Scientist, tells PopSci. “… the shutter is open for 15 seconds (for the exposure) followed by 2 seconds to read (with shutter closed).” This snail’s pace allows LSST Camera operators to only deal with lower noise—only around 6 or 7 electrons—resulting in capturing much darker skies.

“We need quiet sensors so that we can tell that the dark sky is actually dark and also so that we can measure very dim objects in the sky,” Rasmussen continues. “During this 2 second readout period, we need to block any more light from entering the Camera, so that’s why we have a shutter (one of several mechanisms inside the Camera).”

To further ensure operators can capture the measurements of dim objects, they also ostensibly slow atomic activity near the LSST Camera’s focal point by lowering surrounding temperatures as low as -100C (173 Kelvin).

Beyond dark matter and dark energy research, cosmologists intend to use the LSST Camera to conduct a new, detailed census of the solar solar system. Researchers estimate new imagery could increase the number of known objects by a factor of 10, and thus provide additional insight into how the solar system formed, as well as keep track of any errant asteroids that may speed by Earth a little too close for comfort.

“More than ever before, expanding our understanding of fundamental physics requires looking farther out into the universe,” Kathy Turner, the Department of Energy’s Cosmic Frontier Program manager, said in today’s announcement. With LSST Camera’s installation, Turner believes researchers will be on the path to “answer some of the hardest, most important questions in physics today.”





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