Some said it couldn’t be done, but the Pan-STARRS prototype sky survey telescope PS1 has begun scanning the skies nightly with the world’s largest digital camera. It is searching for asteroids that threaten Earth while mapping the universe and investigating its biggest mysteries, dark matter and dark energy.
Conceived and designed at the University of Hawaii Institute for Astronomy, the observatory sits atop the dormant volcano Haleakala but is operated remotely from the IfA’s Advanced Technology Research Center in Pukalani, Maui. “PS1 has been taking science-quality data for six months, but now we are doing it dusk-to-dawn every night,” says Dr. Nick Kaiser, the visionary principal investigator of the Pan-STARRS project.
With a 1.8-meter primary mirror, the PS1 telescope is modest in size, but it has an extraordinary field of view—six times the width of the full moon, or about the size of your fist held at arms length. “The wide field of view of PS1 requires both a much larger secondary mirror and much tighter tolerances than traditional telescopes,” says Pan-STARRS Engineer Dr. Jeff Morgan. “It has been an interesting challenge,” he adds.
Mounted on the back of the telescope is the refrigerator-size 1.4 gigapixel camera that makes PS1 the world’s most powerful survey telescope. This sensitive digital camera was regarded as an unreachable dream just a few years ago, and was rated as one of the “20 marvels of modern engineering” by Gizmo Watch in 2008. Inventor Dr. John Tonry says, “We played as close to the bleeding edge of technology as you can without getting cut!”
But the PS1 observatory itself is just the front end of a complex computing endeavor that processes the images, identifies and catalogs astronomical objects, and classifies their attributes. Each image, if printed out as a photograph, would cover half a basketball court, and PS1 takes an image every 30 seconds. The wealth of astronomical information in these images can only be cataloged and studied by computer.
“The PS1 system uses the most sophisticated image-processing algorithms and parallel-processing techniques available to manage the huge amount of data, which would fill 1,000 DVDs every night,” says Dr. Eugene Magnier, the leader of the image-processing pipeline team. “Try finding one name in collection of 30 billion objects,” adds database designer Dr. Jim Heasley. “You need a relational database, and the PS1database is pushing the limits of database technology.”
PS1 maps one-sixth of the sky at five wavelengths every month. Smaller programs complement the all-sky survey, including special fields that are visited nightly, a detailed survey of the solar system, a dedicated survey for planets around other stars, and a deep survey of the Andromeda Galaxy, the nearby twin to our own Milky Way.
“From inside the orbit of the moon to the most distant quasars, PS1 is taking a census of the contents of our universe,” says PS1 Director Dr. Kenneth Chambers, head of the PS1 Science Consortium that is funding the initial three-year PS1 Science Mission.
Pan-STARRS (short for Panoramic Survey Telescope & Rapid Response System) exploits the unique combination of superb observing sites and technical and scientific expertise available in Hawaii. Funding for the development of the observing system has been provided by the U.S. Air Force. The project plans to build the full four-telescope Pan-STARRS array that will quadruple the light-gathering capability of PS1. “One down, three to go,” said Pan-STARRS Project Manager William Burgett.
The PS1 Surveys have been made possible through contributions of the PS1 Science Consortium (PS1SC, ps1sc.org): the Institute for Astronomy, the University of Hawaii; the Pan-STARRS Project Office; the Max-Planck Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg, Germany and the Max Planck Institute for Extraterrestrial Physics, Garching, Germany; the Johns Hopkins University; the University of Durham; the University of Edinburgh; the Queen’s University Belfast; the Harvard-Smithsonian Center for Astrophysics; the Las Cumbres Observatory Global Telescope Network, Inc.; and the National Central University of Taiwan.
The PS1 surveys will take a census of our solar system, discovering threatening asteroids, primordial Kuiper Belt objects in the outer solar system, possibly even a new planet. But the most fundamental, if initially mundane, task is producing an catalog of the debris left over from planet formation to discover some of the details of the formation of our solar system.
The PS1 Sky Survey will also catalog and classify billions and billions of stars in the Milky Way, unearthing a fossil record of our galaxy’s formation and the role of dark matter, the unseen material (because it gives off no light) that is believed to be the majority of matter in the universe.
By scanning the heavens nightly and processing the data as quickly as it comes in, PS1 will discover hundreds of supernovae that can be used as “standard candles” for measuring distances in our galaxy and beyond. The wealth of supernovae will enable unprecedented statistical studies of our universe and the Big Bang. PS1’s catalog of galaxies will test theories of how dark energy (the little-understood force that is causing the expansion of the universe to accelerate) determines the distribution of galaxies throughout the universe. Images of distant galaxies will be analyzed to reconstruct a three-dimensional map of the dark matter.
Like all telescopes, PS1 is a time machine that looks back in time as it looks farther into space. At the limit of its vision, PS1 is expected to find the most distant quasars ever discovered.