Planetary data in the Virtual Observatory: VESPA (Virtual European Solar and Planetary Access)

Kurzfassung

VESPA (Virtual European Solar and Planetary Access) has been focusing for nearly 10 years on adapting Virtual Observatory (VO) techniques to handle Planetary Science data [1] [2]. The objective of this activity is to build a contributive data distribution system where data services are located and maintained in research institutes, as well as in space agencies and observatories. VESPA is part of Europlanet, a series of programs funded by the European Union and dedicated to enforcing collaborative activities in Planetary Science both within and outside Europe. A new program called Europlanet-2024 has started in 2020 for a 4-year period. During the previous Europlanet-2020 program, VESPA has defined an architecture adapted from the astronomy VO, and incorporating concepts and standards from other areas (Earth observation, Heliophysics, etc). The basic system uses the VO infrastructure: data services are installed in any location but are declared in a system of harvested registries with identifiers, end-point (URL), mention of supported access protocols, and rough description of content. Such services are interoperable via clients and tools, which also provide visualization and analysis functions. Data description: VESPA has adopted the Table Access Protocol (TAP) from the International Virtual Observatory Alliance (IVOA) to query data services. In addition to this general mechanism, the EPNCore vocabulary has been designed to provide a uniform metadata system describing observational, instrumental, and physical parameters with fixed names, scales, and units. EPNCore encompasses all fields of Solar System studies and supports simulations and experimental data as well as observational ones. It can be extended to new parameters whenever required. Beyond TAP, EPNCore provides a handy parameter description system that can be used in various contexts, including with personal databases in the course of a research program. A PDS4 dictionary has been provided for future conversion schemes with modern space agency archives. ENPCore is both a project study of the International Planetary Data Alliance (IPDA), and an emerging standard of the IVOA (currently under review to become a proposed recommendation [3]). Data access and tools: Since VESPA data services are responsive to TAP, they can be queried by all TAP clients – either web interfaces, java tools, python libraries, Jupyter notebooks, etc. Some VO tools include specific support for EPN-TAP (i.e., using EPNCore with TAP). The VESPA portal (http://vespa.obspm.fr) is a dedicated web interface oriented towards data discovery, that can query all public EPN-TAP services simultaneously; it also converts EPN-TAP queries to NASA keyword-search queries and the older PDAP protocol. The portal also uses VO-compliant web services as support applications, e.g. Miriade (ephemeris system), quaero (name resolver for solar system objects) and WebGeoCalc (SPICE computation). All tools and search interfaces in the VO can exchange data via a specific protocol called SAMP.