Science Archives in the 21st Century
The European Space Astronomy Centre located near Madrid in Spain hosts most of ESA astronomy and planetary missionsí archives. That currently includes ISO, XMM-Newton, Integral and ESA Planetary Science Archive (regrouping data from Rosetta, Mars Express, Huygens and Giotto for the time being). In the future, Herschel, Planck, Smart-1, Venus Express, Soho and Gaia will also have their archives located at ESAC.
All these archives have been developed and are operated by a single Science Archives Team at ESAC and are using a common, modular and flexible 3-tier architecture, with a Java Object Oriented approach and XML. Data are saved on magnetic disks and metadata is extracted into a relational database. An "application server" ensures transparent access to the archive data and metadata for the front-end clients, like the powerful and easy-to-use graphical user interface, but also the scriptable interface for more expert users and the access to these data holdings through the Virtual Observatory (VO).
From the graphical user interface, users can also access data from other archives outside ESA, related to the data items found in the ESA archives. Additionally, external applications (eg Aladin, VOSpec) can be launched from the ESA archives to offer additional display and manipulate facilities. Link between the data and their related publications has been present for several years in the ESA archives, offering the possibility to view the articles abstracts from the archive and to get directly to the ESA data from the outside publications archive.
Apart from access to "static" data, on-the-fly reprocessing capabilities have been developed for some of the ESA astronomy archives, allowing the scientific user to get the best data processed with the latest version of the calibration software.
The Virtual Observatory (VO) is a world-wide initiative in astronomy which aim is to allow astronomers to perform new science by providing them with a "federation of astronomical archives and databases around the world, together with analysis tools and computational services, all linked into an integrated facility". Since the beginning, ESAC Science Archives Team has been heavily involved in the VO initiatives, both at European and international levels.
The open architecture of the ESA Scientific Archives has allowed easy integration of ESA astronomy archives into the VO without requiring changes in the way data and metadata were stored for each project. By using translation layers, existing services have been adapted to meet the VO interoperability standards. By defining registry of resources, data access protocols and data models, new VO tools could be developed which give seamless access to astronomy resources worldwide enabling astronomers to perform new type of science in a more efficient and productive manner. Re-using this experience on the astronomy side, similar systems have also been developed for the ESA Planetary Science Archive to ensure interoperability with the NASA Planetary Data Systems in the USA, in particular for image data.
The authors and the co-authors want to thank the complete Science Archives Team as well as the projects Archive Scientists who have all played (and are still playing) a very important role in the context of the ESA Scientific Archives and VO activities.