The Triana mission will be supported by a Ground Data System (GDS) to command and control the spacecraft and capture and disseminate the science and image data. An overview of the GDS is shown in Figure 33.
A globally distributed network of five to seven Remote Ground Stations (RGS), five prime and two backup, provides continuous contact with the Triana spacecraft and a continuous feed of telemetry and science/image data to the other ground elements. Each RGS views the Triana spacecraft for up to 8 hours. While in contact with the satellite, each RGS receives the 100-140 kbps downlink, and will then parse the data stream into at least three separate categories‹
Both the Mission Operations Center (MOC) at GSFC and the Triana Science and Operations Center (TSOC) at Scripps receive satellite health and status.
The MOC will separate the time-critical Plasma-Mag instrument science data and forward it to the processing center at GSFC. This processed Plasma-Mag data will be sent to NOAA within minutes of receipt at GSFC. The remainder of the time-critical science/image data is immediately transmitted to the Scripps TSOC for processing and posting.
To minimize bandwidth requirements and therefore costs, the active RGS stores the non-time-critical science data and transmits this data set to the MOC once the Triana spacecraft is no longer in view of the RGS. The MOC transmits this stored science data to the TSOC for processing. While the post-contact transmission time is variable, depending on the time that the RGS was in contact with the satellite and the bandwidth available between the RGS and the MOC, in general the TSOC can expect to receive the stored science data less than sixteen hours after its collection.
The MOC operations crew is responsible for tracking and maintaining the health and status of the instruments and the spacecraft subsystems. The near-real-time telemetry data received from the RGS is processed at the MOC as it is received and displayed to the MOC operations crew. Should any parameters be observed to be out of prescribed limits, or any other anomalies seen on the data, the operations crew is responsible for implementing the appropriate approved corrective action plan. The MOC is also responsible for monitoring the telemetry to verify successful receipt of all uplinked commands. Commands destined for the three science instruments are based on "command scripts" sent to the MOC from the TSOC, nominally once per week. To support the TSOC's generation of these scripts, the MOC provides spacecraft status and orbit data to the TSOC on a periodic basis.
At the TSOC, the time-critical science/image data and the delayed science data is received from the MOC and processed, posted, and stored. Figure 34 shows the functions that are taking place in the TSOC. Within the TSOC, there are two basic processing strings‹science and image processing. The science processor will host the various algorithms that have been supplied by the Triana co-investigators. The NISTAR data will be processed and stored and a "ready for check" message will be sent to NIST. The NIST co-investigator will confirm that the data was collected properly and did not arrive during filter movement, spacecraft slew, or during an instrument calibration period. The TSOC controller will then mark the data as valid for science investigation.
The EPIC science data will be decompressed and have the current instrument calibration parameters applied. The data will be processed using the appropriate co-investigator supplied algorithm and then stored. The various co-investigators can then either use the TSOC facility for additional science analysis or request a download the pertinent portions of the science data for evaluation at their own facility.
The visible science channels (443, 551, and 645 nm) that are collected every fifteen minutes will be routed to the TSOC image product generator. Here the images will be geo-located, geo-registered, and then processed for posting on the Triana web site. With projected downlink and processing delays, the images will be posted approximately 30-45 minutes after being collected by the satellite.
The TSOC will store all the raw and processed science and image data for the life of the Triana mission plus three years. Processed science and image data will be sent to a NASA data archive for long term storage.
To enhance the ability of Triana data products to inspire and to educate, the TSOC is located in the same UCSD facility as the EarthKAM Operations Center. EarthKAM is a NASA program hosted at UCSD and designed to engage the educational community in inquiry-based learning to conduct Earth Science research based on remotely-sensed data, including images taken by students with a camera in Earth orbit. The TSOC hardware and software designs have been selected for compatibility with EarthKAM operations and specific Triana educational web based products can be created and made available to the existing EarthKAM student and educator infrastructure.
