Gallery: 570-Megapixel Camera Prepares to Hunt for Dark Energy
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The world’s largest dark energy–hunting device, also one of the biggest, heaviest and highest-resolution cameras in the world, is close to completion. Construction of the 4-ton Dark Energy Camera is wrapping up next month at Fermilab in Illinois, where it’s being tested on a mock-up telescope mount (above). The [Dark Energy Survey](http://www.darkenergysurvey.org/) hopes to open its $35 million camera for business at its final destination, in the Blanco telescope atop a Chilean mountain, by October 2011. There, it will scan deep space for signs of dark energy, an invisible force that's pulling groups of galaxies — and perhaps space itself — apart at faster and faster speeds. “We’re going to survey 300 million galaxies in the southern sky to measure the speed of those galaxies,” said Tom Diehl, a physicist at Fermilab and a camera-construction leader. “We want to make the best description of the universe’s expansion to date.” The faster an object moves away from the Earth, the more its light shifts toward a red color. Measurements of [distant galaxies](http://stag-komodo.wired.com/wiredscience/2010/10/most-distant-galaxy/) show all of them are red-shifted and moving away from us and each other. “What's more, they’re moving away faster and faster, like pennies on the surface of an inflating balloon,” said Josh Frieman, an astrophysicist who is directing the Dark Energy Survey effort. Since the 1990s, astronomers suspected this expansion of space is accelerating because of a strange form of energy, dubbed [dark energy](http://stag-komodo.wired.com/wiredscience/2010/08/nrc-space-report/) because of its baffling nature. The new survey should improve our understanding of dark energy by about four to five times through improved red-shift measurements, Diehl said, helping get to the bottom of the mystery. “We don’t know why the universe is speeding up, and that’s precisely why we’re doing the Dark Energy Survey,” Frieman said. “We’re trying to pin down the nature of dark energy.” Since 2008, roughly 120 astronomers, engineers, and physicists have worked on the camera. As its construction comes to a close, we take a look at the Dark Energy Camera’s progress. __Above:__ Video: Building the Test Mount ------------------------------ Time-lapse footage of the Dark Energy Camera’s test mount being built from January to October 2010. *Fermilab*
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Imager ------ The Dark Energy Camera’s imager looks more like a souped-up racing engine than a telescope camera. Its 74 camera sensors make for a total resolution of 570 megapixels. The only camera with more resolution, on the Pan-STARRS telescope, has 1,400 megapixels that are being used to detect threatening near-Earth objects. “But our camera will still take on any camera in terms of weight,” Diehl said, noting the imager alone weighs more than 2,000 pounds. Although it doesn’t have enough funding to be built yet, the [Large Synoptic Survey Telescope](http://stag-komodo.wired.com/wiredscience/2009/10/real-time-dark-energy-search/) could easily outdo both telescopes with its proposed 3,200-megapixel camera, also designed to search for dark matter’s effects. *Image: Fermilab/Reider Hahn*
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Imager CCD Plate ---------------- Gregory Derylo, an engineer at Fermilab, inspects the plate he designed to mount the Dark Energy Camera’s 74 CCDs. Twelve of the chips (totaling about 53 million pixels) will be used to guide and focus the telescope while 62 larger chips (about 519 million pixels) are slated solely for imaging galaxies. All of the CCDs were custom-made to be more sensitive to near-infrared light, Diehl said, and thus to millions of distant, red-shifted galaxies. *Image: Fermilab/Reider Hahn*
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Raw Photo --------- A simulated photo from the imager's bed of sensors. Every night the camera will beam roughly 400 full-sized images, each 1 gigabyte, to a substation in Chile. From there, they'll be forwarded by fiber-optic cable to the National Center for Supercomputer Applications in Illinois for processing. *Image: Dark Energy Survey collaboration*
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Camera Barrel ------------- The camera’s heavy components don’t stick onto a telescope by themselves, so engineers designed this sturdy 11-foot barrel. Visible in this underside shot is the imager (left), prime focus cage (right) and two of six shiny pneumatic tubes used to focus the camera (center). *Image: Fermilab/Tom Diehl*
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Inside the Blanco Telescope --------------------------- The [Victor M. Blanco telescope](http://www.ctio.noao.edu/telescopes/4m/base4m.html), situated on a remote mountaintop at the Cerro Tololo Inter-American Observatory in Chile, “was an old telescope looking for a new job,” Diehl said. In this cutaway drawing, two people (red circle) show the scale of the soon-to-be-delivered Dark Energy Camera (green circle). *Image: CTIO/AURA/NSF*
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Filter ------ Packed in a crate destined for Chile is what Diehl describes as "the world’s largest camera filter." As light passes through the central hole, astronomers use four 2-foot-wide filters to narrow the wavelength of light hitting the imager. The camera’s CCDs see only black and white, but Dark Energy Survey team members will tone and layer the separate photos to produce a realistic color composite image. *Image: Fermilab/Reider Hahn*
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Shutter ------- The [Dark Energy Camera](http://www.darkenergysurvey.org/DECam/camera.shtml) also boasts the world’s largest shutter, held here by its creators at Hoher List Observatory in Bonn, Germany. The device has two well-hidden blades which, when astronomers take a photo, will create a narrow slit that sweeps across the imager’s sensors. “It takes a couple of seconds for each blade of shutter to move, and the images are a minute to two minutes long,” Diehl said, adding that such long exposures allow incredibly faint galaxies to show up. *Image: Argelander-Institut für Astronomie der Universität Bonn*
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Big Lens -------- Steve Kent, an astronomer and optics expert at Fermilab, kneels in front of a dome-shaped glass lens. The piece is the largest and heaviest of five components used to correct light reflecting off the Blanco’s 13-foot-wide mirror. When they’re installed, the optics will allow the Dark Energy Survey to scan an area of the sky about 20 times larger than the moon. *Image: Fermilab/Tom Diehl*
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All Together ------------ An illustration showing what the dark energy camera will look like in its barrel and scaffolding when finished later this year. Diehl’s team expects to wrap up testing and disassemble the camera by February 2011. Aside from the imager, which will be sent on a plane in June 2011, everything will be trucked to New York City in cargo containers. From there, a ship will carry the components through the Panama Canal and transfer them to trucks bound for the observatory. *Image: Fermilab/Dark Energy Survey collaboration*
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Chilean Mountaintop ------------------- The Cerro Tololo Inter-American Observatory at night, situated about 225 miles north of Santiago, Chile. The central building with a shiny dome is the Blanco telescope, where the 11-foot-long Dark Energy Camera will be mounted. The device’s creators hope to scan the skies for signs of dark energy for 525 nights over 5 years. In an ideal world, Diehl said, the survey will get to the truth about dark energy. “It might turn out that there’s a new force, that [Einstein’s theory of general relativity](http://stag-komodo.wired.com/wiredscience/2008/12/dark-energy-ein/) isn’t a good description of gravity on the super, giant scale of the universe. I’m an experimenter, so I don’t have a favorite theory,” he said. "I just like to get to the right one.” *Image: T. Abbott and NOAO/AURA/NSF*
