Artist’s conception for the LSST facilities building on Cerro Pachón (Credit: Todd Mason, Mason Productions Inc./LSST Corporation)
On July 18, scientists from New England and around the globe will descend on the University of Oxford in England to discuss the Large Synoptic Survey Telescope’s Dark Energy Science Collaboration. Participants will explore the latest findings on fascinating topics ranging from the mysterious dark energy that is driving the expansion of the Universe, to the potentially hazardous asteroids that may one day impact the Earth.
The Large Synoptic Survey Telescope, or LSST, is a brand new astronomical research facility comprising a massive telescope, camera, and data management system. The goal of the LSST project is to conduct a 10-year survey of the sky to address some of the most pressing questions about the structure and evolution of the universe, and the objects within it.
Construction on the LSST began in 2014. The observatory sits atop Cerro Pachon in northern Chile, a site famed for its clear skies. Full science operations are expected to begin in 2021. The telescope is indeed “Large”: the 8.4-meter LSST uses a special three-mirror design to create an exceptionally wide field of view, and has the ability to survey the entire sky in only three nights. Additionally, the LSST boasts the world’s largest digital camera (3.2 gigapixels), which takes images that cover 49 times the area of the Moon in a single exposure. Its ability to survey the entire sky in three days is a marvel of modern technology.
With such a mammoth data set, the scientific questions that the LSST can address are both ambitious and profound.
Perhaps unsurprising to anyone who has recently filled their iPhone with breathtaking astronomical pictures, this facility will create the largest public data set in the world: up to 200 petabytes of images and data products will be produced during the 10 years of its planned survey. Yes, public: the photographs taken every night by the LSST are non-proprietary and, after processing and use by LSST scientists, will be made available to anyone who wants to use them via a web interface.
As for the “synoptic” in Large Synoptic Survey Telescope, it refers to the way in which the project is looking at all aspects of our Universe. The LSST will image billions of objects in an unprecedentedly large collection, featured in six colors, which can identify changes in near-real time. It will also produce the first motion picture of our universe.
With such a mammoth data set, the scientific questions that the LSST can address are both ambitious and profound. They include: What is the mysterious dark energy that is driving the acceleration of the expansion of the Universe? What is dark matter, how is it distributed, and how do its properties affect the formation of galaxies and clusters of galaxies? How did the Milky Way form, and how might its present configuration have been modified by mergers with smaller bodies over time?
Image produced by DESC members using a hybrid of Hubble Space Telescope observations (Credit: Heitmann et al., arXiv:1411.3396: image from http://lsst-desc.org/CS-SyntheticSky)
The LSST will also turn its sights on our cosmic backyard, and study the nature of the outer regions of the solar system. It will attempt a complete inventory of smaller bodies in the solar system, especially the potentially hazardous asteroids that could someday impact the Earth. And, of course, LSST remains open for any new, exotic, and explosive phenomena in the universe that have not yet been discovered.
As its name suggests, the members of the Dark Energy Science Collaboration convening in Oxford next week are particularly interested in the first of those goals: understanding more about dark energy and the expanding Universe. The Collaboration membership divides itself into several analysis “working groups,” each coming at the formidable problem of understanding the accelerating expansion of the universe through both theoretical and observational work. The conference will give collaborators, normally spread all over the world, a chance to convene in the same room and in the same time zone, to discuss their recent progress and discoveries.
Artist’s rendition of the LSST primary mirror seen through the slit of the dome at sunset. (Credit: Todd Mason, Mason Productions Inc./LSST Corporation)
The forum will open with a popular “Dark Energy School,” where senior scientists deliver lectures to early-career scientists, such as graduate students and post-docs. They’ll discuss topics as diverse as fitting models of dark energy to data, and the way in which the atmosphere distorts the shapes of observed galaxies. The meeting will close with a “Hack Day,” where young, innovate members propose small astrophysics projects to code and solve in a day.
At this early stage, most of the work being done by the collaboration is preparatory: data management strategies, testing of LSST analysis codes on existing and simulated datasets, and the like. A motto for the Dark Energy Science Collaboration could well be “forewarned is forearmed!” But once the project gets fully underway in 2021, their forethought will no doubt be rewarded with unprecedented insights into the inner workings of the Universe in which we all live.
Jacqueline McCleary is a doctoral student in physics at Brown University, specializing in astrophysics.
Artist’s conception for the LSST facilities building on Cerro Pachón (Credit: Todd Mason, Mason Productions Inc./LSST Corporation) 
