  We present a science-driven discovery portal for all the ESA Astronomy
Missions called ESA Sky that allow users to explore the multi-wavelength sky
and to seamlessly retrieve science-ready data in all ESA Astronomy mission
archives from a web application without prior-knowledge of any of the missions.
The first public beta of the service has been released, currently featuring an
interface for exploration of the multi-wavelength sky and for single and/or
multiple target searches of science-ready imaging data and catalogues. Future
releases will enable retrieval of spectra and will have special time-domain
exploration features. From a technical point of view, the system offers
progressive multi-resolution all-sky projections of full mission datasets using
a new generation of HEALPix projections called HiPS, developed at the CDS;
detailed geometrical footprints to connect the all-sky mosaics to individual
observations; and direct access to science-ready data at the underlying
mission-specific science archives.
