The largest digital camera in the world is in Menlo Park, on its way to a north Chilean mountaintop to map the stars, hopefully discovering billions of galaxies and new objects.
The Legacy Survey of Space and Time (LSST) camera at SLAC National Accelerator Laboratory is the largest digital camera ever created. In the works for nearly 20 years, the camera will sit inside a telescope on a mountaintop in northern Chile to map the night sky. While most telescopes have transposable structures, the camera and telescope are inseparable for the LSST.
“No other instrument is going to work, it's not interchangeable,” SLAC Lead Engineer Travis Lange said. “A telescope and a camera, neither one of them really does much without the other. It's a very symbiotic relationship.”
The average camera is somewhere between 16 and 25 megapixels, with some going as high as 100. The LSST reaches 3600 megapixels, with 200 4k sensors. Lange likens that to having 400 widescreen TVs making up a single image from this camera.
The goal of the project is to map the sky, and this camera is particularly well-attuned to do so. The camera’s ability to see into deep space can detect fainter stars, and look to the outskirts of other galaxies. Due to this, the project is expected to discover 6 million new objects in the solar system, according to Risa Wechsler, Stanford Professor and Director of Kavli Institute for Particle Astrophysics and Cosmology. Most of the new objects are expected to be asteroids.
Within the galaxy, Wechsler said the LSST camera is expected to create a map of 17 billion stars, as well as small galaxies of only 500 stars out in the universe. These little galaxies have dark matter changing the way the stars move and can reveal more about the way that dark matter works out in space. They expect to map the universe with LSST all the way to 12 billion light years away and detect 20 billion galaxies.
Scientists at SLAC hope to measure the shapes of these galaxies and detect gravitational lensing through the distortion of these galaxies.
“It's interesting because it actually allows us to make a map of all of the dark matter in the universe,” Wechsler said.
Dark matter takes up over half the sky, and scientists hope to create a map of it from what the LSST camera sees.
“By looking at how (the sky) evolves over time, we can make a map of the dark matter nearby,” Wechsler said. “We can make a map of the dark matter 5 billion light years away, 8 billion light years away, 10 million light years away. And that allows us to probe (into): how is structure forming over that entire time? How fast is gravity doing its job?”
Another goal of the project is to look into "dark energy" through the lens of dark matter. According to Wechsler, scientists don’t know exactly what dark energy is, but they believe that it’s not matter and may be a property of spacetime itself. What they do know is that dark energy is causing the universe to expand and accelerate, and they hope to understand why.
“We're trying to map this thing out at much higher precision than we've been able to do so far,” Wechsler said. “And that's what this dark matter map will basically enable us to do.”
According to Wechsler, each exposure of an image is approximately 15 seconds long. Each sensor has 16 million pixels, adding up to 3.2 billion pixels total in the camera’s lens.
The camera has a variety of lenses to swap out to compile images with the various filters of the same spot in the sky and achieve a more detailed image, according to SLAC Staff Scientist Hannah Pollek. The camera also has a shutter that moves across instead of opening from the center to prevent too much exposure in any one part of the image.
All of the data from this project is going to be publicly available. The data will be hosted at SLAC for the US community, and they are expecting around 10,000 scientific users. Each night, scientists expect one to 10 million alerts that something has changed, which will be sent out within two seconds for others to view through telescopes.