New generation wide-fast-deep optical surveys: petabytes from the sky

Many fundamental problems in optical astronomy - from planetary science, galactic structure, optical transients, to large-scale structure and cosmology - could be addressed though the same data set with millions of exposures in superb seeing, in multiple passbands, to very faint magnitudes over a large area of sky. This capability is largely driven by technology. In a logical progression towards this scientific capability, several increasingly ambitious wide-field optical surveys are planned in the next few years. A uniform high quality database covering all these science areas would be an ideal match to the VO. The above utopian goal of simultaneous pursuit of parallel surveys is achievable, but it relies on the ability to image a wide field quickly and deeply, and it is a non-linear function of the camera+telescope étendue.