Case Studies
The best way to find out about GSEOS is to review some of the case studies below. They exemplify a few typical use cases of GSEOS in the mission life-cycle.
The MESSENGER Mission
GSEOS is used on all instruments on the MESSENGER mission and GSE Software is responsible for overall GSE and instrument integration. The setup chosen for MESSENGER was to enable all instrument visibility from one common configuration. This allows switching between various instruments within one instance of GSEOS. Although this increases the overall data load on the system it turned out to be a convenient configuration for payload integration. Please take a look at the conference paper that was published at the 2003 RCSGSO conference in Pasadena, CA.
The CASSINI / MIMI Instrument
On CASSINI we only used GSEOS for the MIMI instrument. In this scenario GSEOS is used throughout all mission phases. The initial setup was I&T in the bench test configuration. A driver was customized for the Ballard Technologies MIL-1553 board for use with GSEOS — a universal BIOS that configures bus timing via a simple configuration file.
For end-to-end testing on CASSINI, GSEOS generates SASF files and IEBs. SASF files allow time-tagged instrument command execution and are a spacecraft-wide scripting tool. GSEOS can read, execute, and generate these files.
Besides 1553 hardware interface in bench test, MIMI GSEOS can also communicate with MOC servers to retrieve archived and real-time playback data — enabling rapid system functionality evaluation. Alarm monitors can notify users via email and pager.
Pluto New Horizons
The New Horizons mission to Pluto has a similar setup to MESSENGER: GSE Software supports the entire mission and integrates all instrument customizations within one configuration, enabling side-by-side payload integration.
A key feature on New Horizons is the integration of telecommand (TC) and telemetry (TM) databases via a master Excel spreadsheet. These spreadsheets convert into EPOCH (ground operation system) format as well as GSEOS configuration files — a “zero impact” solution ensuring the GSE always stays current with the latest definitions.
A STOL (Spacecraft Testing and Operations Language) interpreter was implemented allowing instrument teams to execute STOL scripts within the GSE early in the mission phase, enabling smooth system integration. A similar interpreter was used on MESSENGER. MOC server integration was also implemented with an appropriate user interface for querying archived data.