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The Vera C. Rubin Observatory will soon begin its 10-year Space-Time Legacy Survey (LSST), which will make thousands of observations across the skies of the Southern Hemisphere. A mission this big requires an equally large camera.
Fortunately, SLAC National Accelerator Laboratory offers just that. SLAC scientists and engineers have officially completed Rubin’s pioneering 10-year research into his LSST camera, the largest digital camera ever built.
The 3,200-megapixel LSST camera is about the size of a compact car and weighs 3 tons, about half the weight of a male African elephant. LSST’s wide-ranging field of view will attempt to solve remaining mysteries surrounding dark energy, which accounts for about 70% of the matter-energy content of the universe and accelerates its expansion.
LSST will also investigate dark matter, a mysterious substance that we can’t see but makes up about 85% of all matter in the universe, explained Zeljko Ivezic, Rubin Observatory’s construction director. We also plan to answer other astronomical questions that will yield results. as “the greatest movie ever made and the most informative map of the night sky ever assembled”.
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“The data collected by the LSST camera and Rubin will be truly groundbreaking. It will enable really penetrating research into the expansion of the universe and dark energy,” said SLAC Professor and Rubin Observatory Director. Aaron Ludeman, deputy director and camera program leader, told Space. Com. “The LSST survey will allow us to see billions of galaxies, the estimated 17 billion stars in our galaxy, the Milky Way, and millions of Solar System objects.
“We’re not going to look at individual objects. We’re going to look at everything in the night sky from a mountaintop in Chile.”
Look at the big picture again and again
Images from powerful telescopes can often take on a distinctive “look” that makes them distinguishable. For example, bright objects in James Webb Space Telescope images take on characteristic “diffraction spikes” that reveal the origin of these images. So what are the characteristics of the images produced by the LSST camera and Rubin?
“That’s actually a great question because it changes our image a lot,” Rudeman said. “While you won’t be able to see individual galaxies as clearly as you can with a space telescope like JWST, you’ll be able to see large swaths of the sky.
“So what’s surprising about our images is how large they are, how much area across the sky they can cover, and how many stars and galaxies they include.”
However, this huge size doesn’t mean the LSST camera is a slouch when it comes to detail.
“The images are so detailed that they can resolve a golf ball about 25 miles away while covering a swath of the sky seven times the size of the full moon,” Ludeman added.
One of the main advantages of LSST surveys is the fact that they can observe the same part of the sky over and over again. This will allow scientists to accurately monitor any changes occurring in the area over a 10-year period.
This occurs when someone observes a temporary event, such as a supernova, brighten and fade, observing the curvature of light coming from a distant source caused by the gravity of passing matter (including dark matter), and This means tracking the expansion of the cosmic structure as it pushes itself out. A galaxy far, far away. In fact, these galaxies are sliding faster and faster due to the influence of dark energy.
“My main interest in Rubin and the LSST survey is to study the expansion of the universe and dark energy,” Ludeman said. “Dark energy is just a name for a phenomenon that we don’t fully understand. But the data we currently have aren’t as accurate as what we can learn from Rubin.”
But before the LSST camera allowed scientists to play detective and investigate dark energy and other cosmic mysteries, the LSST camera moved from SLAC in Menlo Park, Calif. It must be transported to the top of Mt. Pachong. Once it arrives, it will be hoisted atop the Simonyi Survey Telescope later this year.
It’s not just the size of the LSST camera that makes this transportation task difficult. The camera is also extremely sensitive, with a focal plane comprised of 201 custom-designed CCD sensors. These are 5 micron planes, and the variation in flatness is less than a tenth of the width of a human hair. For comparison, Rudeman says paper is 50 to 100 microns thick.
The gaps between these sensors are approximately 0.5 millimeters wide, so preventing sensor collisions is a major challenge during manufacturing and remains a challenge during transportation.
The team has already tested the route the LSST camera would take using a “mass surrogate” of the same weight and shape as the camera. The proxy is equipped with an accelerometer to test the stresses exerted on the LSST camera, including the stresses it might be subjected to while flying to Chile.
“That testing was very successful. We’ve done a tremendous amount of work to reduce the uncertainty in shipping,” Ludeman said. “However, it can still be nerve-wracking to see it loaded onto a plane and sent to Chile.”
Once attached to the position system on which the LSST relies (such as a unit that cools the image sensor to -148 degrees Fahrenheit (-100 degrees Celsius)), it is set up and operational.
“Then we’ll do some tests to make sure the cameras are working properly and that the whole telescope is working as an integrated system,” Rudeman said. “Then we will begin taking images over an 18-week period.”
As for what the LSST camera will photograph first, Rudeman said a target has not yet been selected, but he expects it to be a part of the sky containing large, bright galaxies. He added that the public release of the first LSST images is currently scheduled for next spring.
“We’re really looking forward to seeing the first LSST images,” the researchers concluded. “I have been working on this project since January 2011, when he first joined the LSST camera team. The history of the project at SLAC goes back even further. The completion of this camera and the first images have been a long time coming. Thing.”. ”
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