The SPASE (Space Physics Archive Search and Extract) Data Model is a set of terms and values along with the relationships between them that allow describing all the resources in a heliophysics data environment. It is the result of many years of effort by an international collaboration (see http://spase-group.org) to unify and improve on existing Space and Solar Physics data models. The intent of this Data Model is to provide the means to describe resources, most importantly scientifically useful data products, in a uniform way so they may be easily registered, found, accessed, and used.
The SPASE data model divides the heliophysics data environment into a limited set of resources types. A key resource type is Numerical Data. This type of resource typically consists of a set of files containing values of one or more physical variables and that differ from each other only by the time span. To full describe a Numerical Data resource requires other types of Resources, namely Observatory, Instrument, Person, and Repository, whose names are self-explanatory, and each of which has its own set of attributes. Often, numerical data are presented in prepared images (gif or jpeg), and such presentations are referred to as Display Data resources. The other data related resource types are Catalog which are lists of events; Annotation which enable expert comments on data products; and Granule which describe individual files within another resource (i.e., Numerical Data, Display Data or Catalog). Other types of resources include Document which can contain narratives or supporting information; Service that provide software to use data resources; Repository for storage locations; and Registry for metadata collections. Resource descriptions and the links in them are intended to make the Resource useful to scientific users.
The SPASE Data Model will only be described briefly here. The document defining the SPASE Data Model as well as supporting information about it may be found at the SPASE web site. The model is broken down into a number of main elements known as Resource Types, each defining a main topic of data description. The Resource Types are presently:
- A device that is used to sense and parameterize a physical phenomenon.Instrument
- A device that is used to sense and parameterize a physical phenomenon.
- The host (spacecraft, network, facility) for instruments making observations.Observatory
- The host (spacecraft, network, facility) for instruments making observations.
- An individual human being.Person
- An individual human being.
- A location or facility where resources are catalogued.Registry
- A location or facility where resources are catalogued.
- A location or facility where resources are stored.Repository
- A location or facility where resources are stored.
- Listing of events or observational notes.Catalog
- Listing of events or observational notes.
- Plain or formatted text that may include graphics, sound, other multimedia data, or hypermedia references.Document
- Plain or formatted text that may include graphics, sound, other multimedia data, or hypermedia references.
- A graphical representation of data.Display Data
- A graphical representation of data.
- Data product stored as numerical values in a specified format.Numerical Data
- Data product stored as numerical values in a specified format.
- An accessible portion of another resource.Granule
- An accessible portion of another resource.
- Explanatory or descriptive information that is associated with another resource.Annotation
- Explanatory or descriptive information that is associated with another resource.
- A location or facility that can perform a well-defined task.Service
- A location or facility that can perform a well-defined task.
Each of these elements is broken down into sub-elements that provide sufficient detail for adequate description of data sets. The Resource Types Numerical Data, Display Data and Catalogue are the resources used to describe Heliophysics data products. These data product descriptions reference the other resources which contain descriptions of the observatories, instruments, people, etc. that created the data products. The resources are described using the terms from the SPASE Data Dictionary presented in the Data Model document.
Services and Protocols
SPASE provides a number of services and protocols which work with SPASE descriptions (XML documents that conform to the SPASE metadata schema). Here are those available from the SPASE Group web site.
- SMWG RegistryOpen the SMWG Registry
- A metadata registry containing descriptions common entities. This includes descriptions of observatories, instruments, persons, registries and services.
- EditorOpen the SPASE Editor
- The web SPASE XML editor can be used to create or alter SPASE XML descriptions.
- ValidatorOpen the SPASE Validate tool
- A web based validator for SPASE XML documents. Use it to determine compliance with any version of the SPASE metadata model.
- SPASE Registry ServerOpen the SPASE Tools Registry
- The SPASE Registry Server is a web application written in Java which providers resolver, search, render and download services for SPASE XML resource descriptions. You can use it to set-up your own SPASE based virtual observatory.
Many people from a wide range of organizations have participated in the SPASE consortium. The origanizations include:
- Augsburg College
- California Institute of Technology (CalTech)
- Centre de Donnees de la Physique des Plasmas (CDPP)
- Istituto Nazionale di Astrofisica (INAF)
- Japan Aerospace eXploration Agency (JAXA) - STP/Ehime
- Japan's Inter-university Upper atmosphere Global Observation NETwork (IUGONET)
- Jet Propulsion Laboratory (JPL)
- John Hopkins University/Applied Physics Laboratory (JHU/APL)
- George Mason University
- Goddard Space Flight Center (GSFC)
- National Aeronautics and Space Administration (NASA) HQ
- National Oceanic and Atmospheric Administration (NOAA)
- NOAA's National Geophysics Data Center (NGDC)
- Rutherford Appleton Laboratory (RAL)
- Stanford University
- Southwest Research Institute (SwRI)
- University of California, Los Angeles (UCLA)