EOSDIS ComponentsThe Earth Observing System Data and Information System (EOSDIS) uses a distributed architecture which permits allocation of EOSDIS elements to various locations to take best advantage of each location's different institutional capabilities and science expertise. EOSDIS includes several major components:
The first four components are managed by the Earth Science Data and Information System (ESDIS) Project. The requirements for networks are also managed by the ESDIS Project while the networks themselves are a combination of NASA's, national, and international infrastructure. The last two components in the list, developed as part of EOSDIS, are now managed by the Earth Science Mission Operations (ESMO) Project. EOSDIS Data CentersEOSDIS is designed as a distributed system, with major facilities at data centers located throughout the United States. In general, these data centers exist within other NASA and agencies' institutions and were chosen because they each specialize in a specific science discipline such as atmospheric chemistry, polar processes, or ocean topography. The Data Centers are located at:
These institutions are custodians of EOS mission data and ensure that data will be easily accessible to users. Acting in concert, the data centers provide reliable, robust services to users whose needs may cross the traditional boundaries of a specific discipline, while continuing to support the particular needs of users within the discipline communities. The data centers are currently serving a broad and growing user community with both EOS data and non-EOS data. The data centers work with active user committees that provide advice on priorities for scientific data, levels of service, and the needed capabilities. (Back to top) Science Data Processing Segment (SDPS)The Science Data Processing Segment (SDPS) performs information management and data archiving and distribution at each data center location. Each data center performs these functions using a combination of standard capabilities provided by the ESDIS Project and hardware and software specific to the data center. Special SDPS hardware and software, known as the EOSDIS Core System (ECS), was developed to support the high ingest rates of the EOS instruments. ECS currently resides and operates at three data centers: the Langley Atmospheric Science Data Center (ASDC), the Land Processes Distributed Active Archive Center (LP DAAC) and the National Snow and Ice Data Center (NSIDC). Data products are processed by the Science Investigator-led Processing Systems (SIPSs) or, in a few cases, by systems interfacing with the SDPS at the data centers. The SDPS at the data centers ingests the data from the processing systems and archives them. The SDPS has interfaces with ECHO to provide search and access through ECHO clients, for example, the next generation Earth science metadata and service discovery tool, Reverb. The SDPS also provides software toolkits to assist instrument teams in their development of product generation software at their Science Computing Facilities (SCFs) to facilitate ingest of the resulting products into SDPS or into data center-specific archiving and distribution systems. (Back to top) Science Investigator-led Processing Systems (SIPS)Most of the EOS standard products are produced at facilities under the direct control of the instrument Principal Investigators/Team Leaders (PIs/TLs) or their designees. These facilities are referred to as Science Investigator-led Processing Systems (SIPS). The SIPS are geographically distributed across the United States and are generally, but not necessarily, collocated with the PIs/TLs’ Scientific Computing Facilities. Products produced at the SIPS using investigator-provided systems and software are sent to appropriate data centers for archival and distribution. Level 0 Data Products and Ancillary Data that begin the processing sequence are stored at the data centers and retrieved by the SIPS. (Back to top) EOS Clearing House (ECHO)EOSDIS has developed a clearinghouse of spatial and temporal metadata called the EOS ClearingHOuse (ECHO) that represents all of the EOSDIS data centers through its series of published Application Program Interfaces (APIs), ECHO acts as a middleware between data centers that provide information about their data holdings and Client Partners who develop software to access the metadata and the browse catalog. ECHO technology can act as an order broker for Client and Data Partners while supporting efficient discovery and access to Earth science data. Example clients are REVERB, which provide web-based "one-stop shopping" for search and order capabilities within all of ECHO's data holdings. (Back to top) EOS NetworksEffective access to EOSDIS depends on the end-to-end network connectivity between users and geographically distributed EOSDIS data centers. This connectivity is provided by an EOSDIS internal logical network known as the EOS Mission Support network (EMSn) and an external logical network known as the EOS Science Support network (ESSn). These two logical networks consist of a variety of physical networks including wide area and local area networks. The EMSn (also known as open and closed EBNet) is made up of local-area and wide-area communication circuits and facilities between and among various EOS ground system elements to support EOS mission operations and mission-critical data transfers. The open side of EBnet allows appropriate science data to be transmitted via the Internet to various end users. The closed side of EBnet is protected by firewalls and transports mission-critical data to various EOSDIS subsystems and ground stations via a secure network. The ESSn is a globally connected logical or virtual science data communication network consisting of several segments of shared IP-based internal and external physical networks (such as the NASA Integrated Services Network (NISN) and the Internet2 IP backbone) to serve the diverse needs of NASA's worldwide science and research community. (Back to top) EOS Data and Operations System (EDOS)EOS Data and Operations System (EDOS) captures high-rate science and engineering data from the EOS spacecraft and instruments, processes telemetry to generate and maintain a backup archive of Level 0 Science Data Products (raw satellite data) for the Terra, Aqua, and Aura missions. It removes telemetry artifacts, creates sets of non-overlapping raw data as sensed by the individual instruments over specific time intervals, and sends them to the appropriate data center(s). In the case of a data loss at any of the data centers, the data can be recovered from the backup archive within EDOS. In the case of loss of a part of the backup Level 0 data within EDOS, the corresponding data can be recovered from the appropriate data center. Level 0 data are provided by EDOS to a given data center as Production Data Sets or Expedited Data Sets for processing by the data center or an associated SIPS. The interface between control centers and ground stations for Terra, Aqua, and Aura is provided by the EOS Real time Processing System (ERPS). ERPS provides ground services for data processing, distribution, and storage for low-rate return link data, and processing, delivery, and logging for forward link data conforming to the Consultative Committee for Space Data Systems (CCSDS) Recommendations for Space/Ground Data Communications. The ERPS provides the capability to use Transmission Control Protocol/Internet Protocol (TCP/IP) for the transfer of real-time data between the GSFC-based EOS Operations Center (EOC) and the remote ground terminals. EDOS is operated and maintained by ESDIS’s sister organization, the Earth Science Mission Operations (ESMO) Project. (Back to top) Flight Operations Segment (FOS)The Flight Operations Segment (FOS) consists of the EOS Operations Center (EOC) located at Goddard Space Flight Center (GSFC) and a number of Instrument Support Terminals (ISTs) at the instrument teams' facilities. The EOC controls Terra, Aqua, and Aura, provides mission planning and scheduling, and monitors health and safety of the spacecraft and instruments. It provides tools to coordinate observations from multiple instruments and develop conflict-free schedules, validate commands to assure safety, accommodate unplanned schedule changes, develop and provide mission timelines, and develop and implement contingency plans. The EOC interacts with the various elements of the ground systems and space network as necessary to send commands to the EOS spacecraft and to receive health and safety data from the spacecraft, and also interacts with the International Partners' instrument control centers for exchange of planning and command and control information. The EOC is implemented using a combination of commercial mission control systems and custom software developed as the EOS Mission Operations System (EMOS). As with EDOS, FOS is operated and maintained by the Earth Science Mission Operations (ESMO) Project. (Back to top) |
