Zen and the Art of Virtual Observatory Maintenance

Abstract:

The NASA Science Mission Directive Science Plan stresses that the primary goals of Heliophysics research focus on the understanding of the Sun’s influence on the Earth and other bodies in the solar system. The NASA Heliophysics Division has adopted the Virtual Observatory, or VxO, concept in order to enable scientists to easily discover and access all data products relevant to these goals via web portals that act as clearinghouses. Furthermore, Heliophysics discipline scientists have defined the Space Physics Archive Search and Extract (SPASE) metadata schema in order to describe the contents of such applicable data products with detail extending all the way down to the parameter level. One SPASE metadata description file must be written to describe each data product at the global level. And the collection of such data product metadata description files, stored in repositories, provides the searchable content that the VxO web sites require in order to match the list of products to the unique needs of each researcher. The VxO metadata repository content also allows one to provide links to each unique data file contained in the full complement of files on a per data product basis. These links are contained within SPASE “Granule” description files and permit uniform access, worldwide, regardless of data server location thus permitting the VxO clearinghouse capability. The VxO concept is sound in theory but difficult in practice given that the Heliophysics data environment is diverse, ever expanding, and volatile. Thus, it is imperative to update the VxO metadata repositories in order to provide a complete, accurate, and current portrayal of the data environment. Such attention to detail is not a VxO desire but a necessity in order to support Heliophysics researchers and foster VxO user loyalty. An application of these basic tenets to the construction of a VxO repository dedicated to providing access to the CDF-formatted data collection hosted on the NASA Goddard CDAWeb data server. Note that the CDF format is self-describing and thus it provides a source of information for initiating SPASE metadata description at the data product level. Also, the CDAWeb data server provides high-quality data product tracking down to the individual data file level permitting easy updating of SPASE Granule metadata.