The Rubin Observatorys LSST Camera will take tremendously in-depth images of the night sky from atop a mountain in Chile. Down below the mountain, high-speed computer systems will send the information out into the world. What takes place in between?
When the Vera C. Rubin Observatory begins photographing the night sky in a couple of years, its centerpiece 3,200 megapixel Legacy Survey of Space and Time camera will offer an enormous amount of information helpful to everybody from cosmologists to people who track asteroids that may strike Earth.
You might already have read about how the Rubin Observatorys Simonyi Survey Telescope will collect light from deep space and shine it on the Department of Energys LSST Camera, how researchers will manage the data that comes from the cam, and the myriad things theyll attempt to discover about deep space around us.
What you havent check out about is how scientists will get that mountain of extremely comprehensive photos off the back of the worlds greatest digital camera, down fiber optic cables, and into computer systems that will transmit them off Cerro Pachón in Chile and out into the globe.
Gregg Thayer, a researcher at the U.S. Department of Energys SLAC National Accelerator Laboratory, is the individual in charge of Rubins data acquisition system, which manages this necessary procedure. Here, he strolls us through some of the key actions.
Initial actions of the Rubin Observatory information system Credit: Greg Stewart/SLAC National Accelerator Laboratory
The data acquisition system begins right at the back of the focal plane, a composite of 189 digital sensing units used to take night-sky images, plus a number of more used to line up the electronic camera when taking images. 71 circuit boards take the raw pixels off the sensing units and ready them for the next action.
At this point, two things need to take place. The data requires to get out of the cryostat, a high-vacuum, low-temperature and, Thayer says, “packed” cavity that houses the focal airplane and the surrounding electronics. Second, the information needs to be transformed into optical signals for the fibers that go to the base of the cam.
Since theres so little space inside the cryostat, Thayer and his team decided to combine the steps: Electrical signals first enter circuit boards that permeate the back of the cryostat. Those circuit boards transform the data to optical signals that are fed into fiber optic cables just outside the cryostat.
Data undoubtedly fades into sound if you go far enough along a signal cable television, and the cable television here has to be long– around 150 meters, or 500 feet, to make it from the top of the telescope to the base. The issue is intensified by a three gigabit per second information rate, around a hundred times faster than basic internet; low power at the source to reduce heat near the digital cam sensors; and mechanical constraints, such as tight bends, that require cable interconnects where more signal is lost.
The last actions of the Rubin Observatory data system Credit: Greg Stewart/SLAC National Accelerator Laboratory
As soon as the signal makes it below the electronic camera, it feeds into 14 computer boards established at SLAC as part of a general-purpose information acquisition system. Each board is equipped with eight onboard processing modules and 10 gigabit-per-second Ethernet switches that link the boards together. (Each board likewise transforms the optical signals back to electrical ones.) Three of those boards read out the information from the camera and prepare it to be sent out down the mountain and out to the U.S. data center at SLAC and another in Europe. 3 more imitate the video camera itself– essentially, they permit researchers working on the task to practice taking information, perform diagnostics, and so on when the camera itself is unavailable, Thayer states.
The final eight boards serve a vital but easily ignored function. “Theres a cable that decreases the mountain from the summit to La Serena, where it can get on the long-haul network to the U.S. and European data facilities,” Thayer says. “If that cable television is cut for whatever reason, we can buffer approximately three days worth of data to enable the telescope to keep operating during the repair work.”
From the base of the telescope, theres that a person last leg down the mountain, and then information acquisition is total. Its time for the information to head out into the world– but you can read about that here, here, and here.
Vera C. Rubin Observatory is a federal project collectively moneyed by the National Science Foundation and the Department of Energy Office of Science, with early building and construction funding received from personal donations through the LSST Corporation. The NSF-funded LSST (now Rubin Observatory) Project Office for building was developed as an operating center under the management of the Association of Universities for Research in Astronomy (AURA). The DOE-funded effort to develop the Rubin Observatory LSST Camera (LSSTCam) is handled by SLAC.
Second, the information requires to be transformed into optical signals for the fibers that go to the base of the video camera.
The issue is compounded by a three gigabit per 2nd data rate, around a hundred times faster than standard web; low power at the source to lower heat near the digital camera sensing units; and mechanical restrictions, such as tight bends, that require cable television interconnects where more signal is lost. As soon as the signal makes it down from the video camera, it feeds into 14 computer system boards established at SLAC as part of a general-purpose data acquisition system. 3 of those boards read out the data from the electronic camera and prepare it to be sent down the mountain and out to the U.S. information center at SLAC and another in Europe. 3 more emulate the camera itself– basically, they enable scientists working on the task to practice taking information, carry out diagnostics, and so on when the cam itself is unavailable, Thayer says.
