Integrated access to distributed data and information services in astrophysics and the space sciences

Scientific advances do not necessarily follow strict research discipline boundaries. In the area of astronomy and space science, data from multiple missions and observatories operating in various parts of electromagnetic spectrum are necessary in order to answer fundamental scientific questions. However, a researcher attempting to locate, understand, and use data from a variety of sources now faces serious difficulties. Many datasets are available on the Internet but finding the ones of relevance, especially outside of one's immediate field of expertise, is difficult. The metadata used to annotate datasets in different fields can be unfamiliar and obscure, even though the same basic data attributes are being described. Once data has been located, it is often in different and incompatible formats. We are now developing a distributed information service for the space sciences – ISAIA – which covers many different subdisciplines with datasets of common interest and which will improve the researcher's abilities to locate and use data from a wide variety of on-line resources. This service builds upon experience in implementing a data location service for astronomy, Astrobrowse. The key to implementing such services is the concept of profiles. Profiles are a generalization of data dictionaries: they define the metadata labels and content for information resources and provide mappings of those labels onto site or service-specific terms and query protocols. In ISAIA profiles may be hierarchical – general at the highest levels, with sub-profiles for certain disciplines or types of instrumentation. In practical terms, a distributed system such as ISAIA will only succeed if existing data providers can make their systems and services available to it with a minimum amount of effort. ISAIA must be “light weight”, imposing no constraints on how an organization manages its data services internally. It must support participation at different levels, from simple registration of a service to full support for query and response interpretation. In addition, ISAIA must preserve the identity and visibility of the participating services. This is important for end-users (who must understand the provenance of the data they are using) and the providers (who need to understand their users' needs and the demands upon their resources).