The Large Synoptic Survey Telescope (LSST) is poised to be the most ambitious survey of the universe to be conducted in the visible band. It will have a primary mirror spanning a diameter of 8.4 meters, a 9.6 square degrees field of view and a 3.2 Gigapixel camera. This enables the LSST to cover about 10,000 square degrees of sky area in pairs of 15-second exposures twice per night every three nights on average. The rapid cadence of the observing program will generate an unprecedented volume of data. Each night, LSST is expected to generate an average of about 15 Terabytes of raw imaging data. As the survey progresses, the amount of computing power required to process the raw data grows from approximately 100 Teraflops at the start of the survey to 400 Teraflops by the end of the survey.
Credit: LSST Corporation
The LSST Observatory will be situated atop Cerro Pachón in northern Chile (Latitude: S 30° 10′ 20.1′′; Longitude: W 70° 48′ 0.1′′; Elevation: 2123 m). Incident light falling on the telescope’s 8.4 m primary mirror is reflected onto a 3.4 m convex secondary mirror and then reflected again onto a 5 m concave tertiary mirror. The light then enters the camera through three refractive lenses before arriving at the focal plane. The focal plane of LSST’s 3.2 Gigapixel camera is tiled by 189 CCD sensors of 4096 by 4096 pixels each. The CCDs are maintained at an operating temperature of 180 degrees Kelvin and are grouped into 27 rafts of 9 CCDs each.
Credit: Todd Mason, Mason Productions Inc. / LSST Corporation
The 4 main science themes of LSST are:
1. Probing Dark Energy and Dark Matter
2. Taking an Inventory of the Solar System
3. Exploring the Transient Optical Sky
4. Mapping the Milky Way
For objects located within the Solar System, the primary data catalogue that LSST will generate is estimated to contain several million main-belt asteroids, 100,000 Near Earth Objects (NEOs), 100,000 Jovian Trojan asteroids, 40,000 Trans-Neptunian Objects (TNOs) and numerous objects with perihelia at several hundred AU. One AU is the Earth-Sun distance and it has a value of 149.6 million kilometres. Since most of these objects in the Solar System will be observed several hundred times, the orbit of each object can be precisely measured. LSST will be capable of detecting massive objects lurking in the dark outer reaches of the Solar System as it can detect a Pluto-sized object out to a few hundred AU and an Earth-sized object out to over a thousand AU, depending on the albedo of the object.
A nominal operational period of 10 years is anticipated for LSST and it is expected to receive first light in 2015. In terms of 2010 U.S. dollars, the estimate cost for LSST is $455 million for construction and $38 million per year for operations. A key challenge in this project is effective data mining of the unprecedented volume of data that will be generated. The enormous catalogue of data that LSST produces will be made available to the world via the Internet, thereby creating a shared resource for anyone in the world who wants to explore it.